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Mengapa klorinasi masih berfungsi?

Mengapa klorinasi masih berfungsi?



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Klorinasi telah digunakan selama lebih dari satu abad untuk mendisinfeksi persediaan air. Mengapa mikroorganisme belum mengembangkan kekebalan terhadap klorin ini sekarang?


Alasan klorinasi masih berfungsi adalah karena spesifik, seperti yang disebutkan @AliceD.

Cara kerja klorinasi terutama dengan mengoksidasi molekul biologis. Klorin, bersama dengan halogen lainnya, adalah agen pengoksidasi kuat. Ini memecah membran bilayer fosfolipid, protein dan enzim. Tidak ada cara organisme dapat mengatasi ini, kecuali jika tidak menggunakan molekul kimia yang bereaksi dengan klorin, yang sebenarnya tidak ada.

Di sisi lain, antibiotik menghambat enzim dan protein tertentu dengan cara tertentu dan dengan membuat satu atau dua asam amino berbeda dalam protein, mikroorganisme dapat dengan mudah mengatasinya.

Referensi - http://www.sswm.info/sites/default/files/reference_attachments/TUE%202011%20The%20Chlorine%20Dilemma.pdf


Mengapa Desalinasi Tidak Bekerja (Belum)

Dengan air cepat menjadi komoditas panas, terutama di daerah rawan kekeringan dengan populasi berkembang, solusi yang jelas adalah untuk mengambil garam dari air laut. Bagaimanapun, teknologi desalinasi telah ada selama ribuan tahun. Bahkan Aristoteles mengerjakan masalah itu.

Menggiurkan sebagai air desalinated mungkin terdengar, biaya energi telah membuatnya agak tidak enak.

"Sampai saat ini, desalinasi air laut adalah solusi sumber air yang sangat mahal," kata Gary Crisp, seorang insinyur untuk Perusahaan Air Australia Barat.

Minum air laut secara langsung adalah ide yang buruk karena tubuh Anda harus mengeluarkan garam dengan buang air kecil lebih banyak daripada yang sebenarnya didapat. Air laut mengandung sekitar 130 gram garam per galon. Desalinasi dapat menurunkan kadar garam hingga di bawah 2 gram per galon, yang merupakan batas aman konsumsi manusia.

Saat ini, antara 10 dan 13 miliar galon air di desalinasi di seluruh dunia per hari. Itu hanya sekitar 0,2 persen dari konsumsi air global, tetapi jumlahnya terus meningkat.

"Ada pertumbuhan signifikan dalam kapasitas desalinasi di seluruh dunia, dan diperkirakan akan terus berlanjut untuk beberapa waktu," kata Stephen Gray dari Victoria University.

Gray telah dipilih untuk memimpin program penelitian baru di Australia&mdash di mana banyak daerah kekurangan pasokan air bersih&mdash untuk meningkatkan efisiensi pabrik desalinasi.

Usaha Aristoteles

Kembali pada abad ke-4 SM, Aristoteles membayangkan menggunakan filter berturut-turut untuk menghilangkan garam dari air laut.

Tetapi praktik desalinasi pertama yang sebenarnya melibatkan pengumpulan uap air tawar dari air asin mendidih. Sekitar tahun 200 M, para pelaut mulai melakukan desalinasi air laut dengan ketel sederhana di kapal mereka.

Energi yang dibutuhkan untuk proses distilasi saat ini membuatnya sangat mahal dalam skala besar. Oleh karena itu, banyak pasar saat ini untuk apa yang disebut "desalinasi termal" berada di negara-negara kaya minyak dan miskin air di Timur Tengah.

Sejak 1950-an, para peneliti telah mengembangkan membran yang dapat menyaring garam, mirip dengan apa yang awalnya dibayangkan oleh Aristoteles. Saat ini, teknik membran ini, kadang-kadang disebut "osmosis balik", membutuhkan seperempat energi dan biaya setengah dari harga penyulingan air asin.

"Dalam sepuluh tahun terakhir, reverse-osmosis air laut telah matang menjadi alternatif yang layak untuk desalinasi termal," kata Crisp.

Energi adalah kuncinya

Tetapi bahkan dengan membran, sejumlah besar energi diperlukan untuk menghasilkan tekanan tinggi yang memaksa air melewati filter. Metode saat ini membutuhkan sekitar 14 kilowatt-jam energi untuk menghasilkan 1.000 galon air laut desalinasi.

Seorang Amerika yang khas menggunakan 80 sampai 100 galon air sehari, menurut US Geological Survey. Seluruh negara mengkonsumsi sekitar 323 miliar galon per hari air permukaan dan 84,5 miliar galon air tanah lainnya.

Jika setengah dari air ini berasal dari desalinasi, Amerika Serikat akan membutuhkan lebih dari 100 pembangkit listrik tambahan, masing-masing dengan kapasitas gigawatt.

Tergantung pada harga energi lokal, 1.000 galon air laut desalinasi dapat berharga sekitar $3 atau $4. Meskipun itu mungkin tidak tampak banyak, masih lebih murah di banyak tempat untuk memompa air keluar dari tanah atau mengimpornya dari tempat lain.

Namun perbedaan harga pasti akan menyempit, terutama di daerah yang bisa mengalami kekeringan lebih hebat akibat perubahan iklim.

Penggunaan air telah tumbuh dua kali lebih cepat dari pertumbuhan penduduk, menyebabkan semakin banyak masyarakat yang mengalami kekurangan air. Permintaan pasokan air tawar akan mendorong harga lebih tinggi, membuat desalinasi semakin menarik.

Brainstorming tentang membran

Jumlah pabrik desalinasi di seluruh dunia telah berkembang menjadi lebih dari 15.000, dan upaya terus dilakukan untuk membuatnya lebih terjangkau.

Bulan lalu, lembaga penelitian ilmiah terbesar di Australia bergabung dengan sembilan universitas besar dalam program penelitian membran untuk mengurangi biaya energi desalinasi, serta biaya pemeliharaan yang terkait dengan kotoran yang menempel pada membran dan mengotorinya.

"Menurunkan energi yang dibutuhkan untuk desalinasi dan kecenderungan pengotoran membran adalah dua tantangan terbesar yang dihadapi desalinasi," kata Gray.

Sebuah tim peneliti yang beragam akan mencoba mengatasi masalah ini dengan mengembangkan jenis bahan membran baru. Tujuannya adalah untuk memotong setengah energi yang dibutuhkan untuk desalinasi.

"Kami berharap untuk memiliki sesuatu yang tersedia dalam 10 tahun ke depan," kata Gray.


Tingkat pertumbuhan vs. Tingkat pembunuhan

Ketika tingkat pertumbuhan mikroorganisme melebihi tingkat pembunuhan klorin, Anda mungkin mengalami wabah. Seperti masalah alga. Makhluk hidup membutuhkan nitrogen dan fosfor sebagai unsur hara mikro. Di kolam renang dan spa, nitrat menyediakan nitrogen, dan ortofosfat menyediakan fosfor . Ketika banyak mikronutrien hadir di dalam air, bakteri dan ganggang dapat tumbuh lebih cepat, dan berpotensi tumbuh lebih cepat daripada klorin dapat membunuh mereka. Kami beruntung telah berbicara langsung dengan ahli kimia kolam terkenal, Richard Falk. Dia memberi tahu kami bagaimana fosfat memengaruhi kimia air:

"Tingkat pembunuhan klorin sama [dengan fosfat tinggi], tetapi laju pertumbuhannya bisa lebih lambat dengan fosfat rendah. Ini adalah perlombaan pertumbuhan reproduksi yang lebih cepat dengan lebih banyak fosfat (hingga batas yang ditentukan oleh sinar matahari dan suhu) vs. membunuh dengan klorin.

Ini menjelaskan mengapa permintaan klorin cenderung lebih tinggi dengan kadar fosfat yang tinggi di kolam renang. Bukannya fosfat secara langsung memengaruhi kekuatan klorin—seperti yang diajarkan dan diterbitkan pada awalnya—tetapi fosfat membantu mendorong pertumbuhan kontaminan. Kontaminan tersebut terus-menerus diserang oleh klorin, yang menggunakannya.

Itu perlu diulang: fosfat tidak memiliki hubungan langsung dengan kekuatan klorin. Lebih tepatnya, perbedaan penyebab fosfat adalah pada tingkat pertumbuhan kontaminan seperti ganggang. Laju pertumbuhan itulah yang meningkatkan permintaan klorin, bukan fosfat itu sendiri.


116 pemikiran tentang &ldquo Mengapa Kolam Saya Tidak Memiliki Klorin? &rdquo

Saya menambahkan 5 3 inci klorin ke skimmer kemarin dan level klorin saya adalah 0 hari ini….apakah ini normal

Saya berasumsi Anda baru saja membuka kolam Anda. Saran saya adalah zap dengan klorin cair dosis tinggi. Sangat berat. Saya memiliki kolam 24000 gal dan ketika saya membuka di musim semi saya menambahkan 5 galon. Bagi saya mencoba untuk lolos dengan 2.5 tidak akan berhasil – Saya mendapatkan bacaan yang kuat dan itu akan dimakan dalam satu atau 2. Pergi berat atau akan berakhir dengan biaya lebih banyak. Setelah saya melakukannya, saya dapat menggunakan dosis reguler saya 2 (kadang-kadang 3 jika benar-benar panas) 3 "tablet.

Saya juga menyukai gagasan untuk benar-benar membuatnya diklorinasi ketika Anda membukanya untuk memastikannya disanitasi.

Kami saat ini memiliki masalah dengan pertumbuhan Alga di kolam kami dan melihat perusahaan kolam kami telah memperlakukan kolam dengan jenis zat granular yang berada di dasar kolam. Zat ini sekarang telah memutihkan warna liner baru kami yang ditempatkan pada bulan April. Ketika saya menanyakan perusahaan mereka mengatakan butiran tidak akan melakukan itu. Setiap akhir pekan kolam kami hijau dengan pertumbuhan alga. Sejak itu saya telah menguji air kolam dua kali dan kedua kali pembacaan menunjukkan. Tingkat nol untuk -total, klorin bebas dan gabungan. ph adalah 7,8 stabilizer 80 ppm. Total alkalinitas adalah 240ppm dan 200 ppm. Ketika saya menanyai perusahaan tentang pembacaan ini, mereka mengirim teknisi baru. Dia bilang aku punya kunci klorin! Saya menunjukkan perubahan warna di liner dan dia berkata dia akan mempertanyakan teknologi lainnya. Kemudian pada hari itu saya mendapat email yang menyatakan bahwa mereka membatalkan layanan saya. Dua pertanyaan Apakah saya memiliki kunci klorin? Dan apakah butiran yang mereka tambahkan menyebabkan kerusakan pada liner saya?

Ya itu akan merusak liner Anda tidak hanya memutihkannya tetapi juga membuatnya tipis di area itu

Jadi ada beberapa hal yang perlu saya klarifikasi sebelum rekomendasi yang solid dapat dibuat untuk memperbaiki masalah saldo Anda. Saya berasumsi dengan liner baru bahwa itu dilapisi vinil, apakah di atas tanah, atau di dalam tanah dengan plester atau beton di sekitar kolam? (Ini akan menentukan persyaratan kekerasan kalsium) Jenis filter apa yang Anda gunakan, pasir atau kartrid? Dan saya berasumsi Anda tidak menggunakan generator klorin air asin dengan menggunakan tab.

Apakah bacaan Anda terdaftar dengan benar? Total alkalinitas dan stabilizer (asam sianurat) terlalu tinggi. Untuk menurunkan stabilizer, hal terbaik yang harus dilakukan adalah menguras sebagian dan mengisi sampai stabilizer turun ke 30-35. Jika alkalinitas Anda lebih dari 200, Anda akan membutuhkan banyak asam muriatik. Lakukan penyeimbangan stabilizer terlebih dahulu, ini dapat mengurangi kerja alkalinitas. Saya akan membayangkan bahwa Anda mengejar pH Anda dengan itu naik ke 8 sangat cepat. Menurunkan alkalinitas hingga 80 akan membantu meningkatkan pH. Tambahkan asam sampai pH turun menjadi 6,8, biasanya tidak lebih dari satu galon sekaligus. Kemudian arahkan jet kembali Anda ke atas untuk mengaduk air permukaan untuk menaikkan pH tanpa bahan kimia (SANGAT PENTING – jangan gunakan bahan kimia untuk menaikkan pH, itu akan meniadakan asam yang bekerja mengurangi alkalinitas) Saat pH naik hingga 7,2 atau lebih, uji alkalinitas dan ulangi jika masih di atas 90. Ketika alkalinitas seimbang dan pH kembali ke 7,2, Anda siap untuk memulai. Jika ganggang masih terlihat, cuci kembali saringan pasir Anda, bersihkan kartrid Anda sesering mungkin. TETAPKAN FILTER BERJALAN 24/7

Berikutnya adalah kesadahan kalsium, mungkin akan rendah. Untuk di atas tanah, tidak terlalu kritis tetapi harus di atas 200, idealnya 250. Tetap menyaring

Sekarang Anda siap untuk membuat kejutan keluar dari kolam untuk membunuh semua ganggang. Gosok dinding dan lantai sebelum menambahkan pemutih cair untuk menghilangkan klorin dari grafik pada 30ppm. Tetap menyaring dan menunggu hingga kadarnya turun di bawah 5. Periksa kembali alkalinitas dan pH selama proses ini dan sesuaikan seperti di atas.

Sekarang bagian selanjutnya ini adalah rekomendasi saya dan yang lain akan berdebat, tetapi itu selalu berhasil untuk saya. Dengan klorin Anda kembali ke 3 dan pembacaan lainnya seimbang, tambahkan Weekly Pool Perfect, tersedia dari Leslie's. Ini akan mengurangi fosfat, memperjelas dan menggumpal partikel keruh ke dasar kolam untuk menyedot debu. Kolam saya berubah dari berawan menjadi jernih dalam waktu kurang dari 48 jam setelah dosis pertama.

Kemudian pertahankan klorin pada 3ppm dan kejut setiap minggu. Jika Anda menggunakan klorin yang distabilkan (diklor atau triwarna), level penstabil Anda akan naik seiring waktu. Stabilizer tinggi akan mengunci klorin Anda, membuatnya mahal dan tidak efektif untuk mempertahankan kadar klorin. Jika Anda menggunakan klorin yang distabilkan, itu hanya akan membuat level stabilizer lebih tinggi. Gunakan kalsium atau natrium hipoklorit untuk menyetrum untuk membantu mencegah kenaikan ini.

Terakhir, dapatkan pengacara. Perusahaan kolam itu merusak liner baru Anda dan tidak kompeten untuk membiarkan alkalinitas Anda tetap setinggi itu, menambahkan bahan kimia secara tidak efektif dan membiarkan masalah tetap ada. Kata lalai didefinisikan oleh praktik itu. Saya harap ini membantu. Rencanakan proses ini memakan waktu beberapa minggu. Pembuangan dan pengisian penuh mungkin lebih cepat, tetapi masih perlu diseimbangkan seperti di atas, hanya saja mungkin tidak perlu superklorinasi untuk membunuh alga jika permukaan kolam dibersihkan dengan sangat baik setelah pengurasan.

Hai, berharap untuk beberapa saran…

Kami memiliki kolam 10 x 6 kaki, lvl cya sangat tinggi yang berdampak pada klorin lvl (0). Ph halus di 7,6 dan alkaline juga OK. Kolam renang yang digunakan setiap hari. Saya menggunakan tablet multifungsi 200g di dispenser apung pada pengaturan 2.

Saya baru saja membeli pompa submersible untuk membantu mengalirkan setengah air dan menghilangkan masalah cyan.(semoga saja)

Kartrid pompa juga susah banget, saya harus ganti tiap hari padahal kolam sudah divakum mingguan/skim setiap hari dll.

Pertanyaan saya adalah berapa banyak butiran klorin yang harus saya gunakan untuk menyetrum kolam setelah saya menguras / mengganti setengah air. Saya menggunakan 18g untuk mencapai 2ppm tetapi tidak ada pengaruh sebelumnya.

Setiap saran tentang kartrid juga akan bagus. (530g/h) telah menggunakan kaus kaki filter beberapa hari terakhir yang sangat bagus untuk mengurangi tekanan pada pompa.

Pastikan untuk membilas filter itu setiap hari dan kejut seminggu sekali coba tes air jika kadar klorin rendah gunakan kejutan klorin jika tidak gunakan kejut non klorin dan gunakan penutup kolam di malam hari Saya sarankan penutup tahan air dan gosok dinding kolam setiap hari sekali pagi atau malam dan gunakan skimmer genggam atau listrik untuk membersihkan daun dan kotoran dari air dan memeriksa Ph air . Jangan terlalu banyak menggunakan klorin atau terlalu sedikit menggunakan alat tes kolam itu! Semoga ini membantu.

Jika Anda sering menyumbat filter, saya akan menggunakan agen flok untuk mengendapkan partikel ke bawah. Kemudian vakum untuk limbah. Karena filter kartrid tidak memiliki opsi ini, konfigurasikan pompa submersible Anda untuk menarik dari vakum Anda sehingga Anda bisa mengeluarkan partikel yang mengendap dengan pekerjaan pembuangan Anda.

Kami baru saja memperbaiki semua kebocoran, masalah ganggang yang mengerikan sebelum itu. Dan pool lady kami kesal mengatakan bahwa kami masih memiliki kebocoran karena pembacaan kami sebagai berikut selama 2 minggu terakhir..
250 ppm kekerasan
0 klorin gratis
0 total klorin
120 ppm total alkalinitas
Dia menambahkan…kedua minggu
3 tab klorin untuk skimmer
kejutan 8 lbs

Apakah kolam kami masih bocor atau kami membutuhkan wanita kolam baru. Kami berada di Florida utara dengan suhu 95. Airnya sangat jernih dan hanya turun paling banyak 1/4 inci per hari.

Berapa level stabilizer (CYA) Anda? Berapa lama tiga tablet selama seminggu? Apakah mereka benar-benar hilang dalam beberapa hari atau ada sisa-sisa pada saat perusahaan kembali?

Kedengarannya tidak seperti kebocoran air bagi saya, tingkat penguapan 1/4″ adalah standar.

Saya memiliki kolam tanah 16 kali 36 I. Pada hari Selasa, kolam kami sangat berawan dengan pembacaan 0 klorin gratis. Saya curiga itu fosfat dan sudah diuji dan dikonfirmasi. Saya memasukkan phosfree untuk menyingkirkan mereka. Lemparkan robot saya ke kolam. Pada hari Kamis sudah jelas tetapi masih belum ada pembacaan klorin bebas. Orang yang menguji air saya mengatakan semuanya terlihat bagus tetapi untuk menambahkan 20 kantong kejutan, yang saya lakukan. Hari ini masih belum ada pembacaan klorin bebas. Dia mengatakan ketika dia menguji air saya, fosfatnya ada di tahun 900-an. Dia melakukan tes fosfat yang sebenarnya tetapi butuh
Sekitar dua hingga tiga menit untuk membiru. Mereka memberi tahu saya bahwa fosfat bukan masalah saya. Bagaimana menurutmu? Saya akan mengambil filter saya dan membersihkannya hari ini. Saya tidak perlu Alga mekar untuk memulai.

Saya harap maksud Anda 2 kantong kejut 20 kantong kejut akan menjadi gila kecuali kolamnya 200K galon. Berapa tingkat CYA Anda? Klorin apa lagi yang Anda gunakan selain kejutan? Kejutan sangat bagus untuk meningkatkan tetapi tidak dapat mempertahankan kadar klorin Anda. Anda perlu menggunakan klorin stabil yang dapat bertahan di air Anda, maka kadar klorin Anda akan meningkat.


Isi

Dalam sebuah makalah yang diterbitkan pada tahun 1894, secara resmi diusulkan untuk menambahkan klorin ke air untuk menjadikannya "bebas kuman". Dua otoritas lain mendukung proposal ini dan menerbitkannya di banyak makalah lain pada tahun 1895. [2] Upaya awal untuk menerapkan klorinasi air di pabrik pengolahan air dilakukan pada tahun 1893 di Hamburg, Jerman. Pada tahun 1897 kota Maidstone, Inggris adalah yang pertama memiliki seluruh pasokan air diperlakukan dengan klorin. [3]

Klorinasi air permanen dimulai pada tahun 1905, ketika filter pasir lambat yang rusak dan pasokan air yang terkontaminasi menyebabkan epidemi demam tifoid yang serius di Lincoln, Inggris. [4] Alexander Cruickshank Houston menggunakan klorinasi air untuk menghentikan epidemi. Instalasinya memberi solusi terkonsentrasi dari apa yang disebut klorida kapur terhadap air yang sedang diolah. Ini bukan hanya kalsium klorida modern, tetapi mengandung gas klorin yang dilarutkan dalam air kapur (kalsium hidroksida encer) untuk membentuk kalsium hipoklorit (kapur terklorinasi). Klorinasi pasokan air membantu menghentikan epidemi dan sebagai tindakan pencegahan, klorinasi dilanjutkan sampai 1911 ketika pasokan air baru ditugaskan. [5]

Penggunaan klorin pertama secara terus menerus di Amerika Serikat untuk desinfeksi terjadi pada tahun 1908 di Boonton Reservoir (di Sungai Rockaway), yang berfungsi sebagai pasokan untuk Jersey City, New Jersey. [6] Klorinasi dicapai dengan penambahan terkontrol larutan encer klorida kapur (kalsium hipoklorit) pada dosis 0,2 hingga 0,35 ppm. Proses perawatan digagas oleh John L. Leal, dan pabrik klorinasi dirancang oleh George Warren Fuller. [7] Selama beberapa tahun berikutnya, desinfeksi klorin menggunakan klorida kapur (kalsium hipoklorit) dengan cepat dipasang di sistem air minum di seluruh dunia. [8]

Teknik pemurnian air minum dengan menggunakan gas klorin cair yang dikompresi dikembangkan oleh seorang perwira Inggris di Layanan Medis India, Vincent B. Nesfield, pada tahun 1903. Menurut catatannya sendiri, "Saya berpikir bahwa gas klorin mungkin memuaskan .jika cara yang cocok dapat ditemukan untuk menggunakannya.Pertanyaan penting berikutnya adalah bagaimana membuat gas portabel.Hal ini dapat dicapai dengan dua cara: Dengan mencairkannya, dan menyimpannya dalam bejana besi berlapis timah, memiliki jet dengan saluran kapiler yang sangat halus, dan dilengkapi dengan keran atau tutup ulir. Keran dihidupkan, dan silinder ditempatkan dalam jumlah air yang dibutuhkan. Klorin menggelembung, dan dalam sepuluh hingga lima belas menit air benar-benar aman .Metode ini akan berguna dalam skala besar, seperti untuk gerobak air servis." [9]

Mayor Carl Rogers Darnall, Profesor Kimia di Sekolah Kedokteran Angkatan Darat, memberikan demonstrasi praktis pertama ini pada tahun 1910. [10] Karya ini menjadi dasar untuk sistem air kota saat ini. pemurnian. Tak lama setelah demonstrasi Darnall, Mayor William J. L. Lister dari Departemen Medis Angkatan Darat menggunakan larutan kalsium hipoklorit dalam kantong linen untuk mengolah air.

Selama beberapa dekade, metode Lyster tetap menjadi standar untuk pasukan darat AS di lapangan dan di kamp, ​​​​diimplementasikan dalam bentuk Tas Lyster yang sudah dikenal (juga dieja Lister Bag). Kanvas "tas, air, sterilisasi" adalah komponen umum dapur lapangan, dikeluarkan satu per 100 orang, dengan kapasitas 36 galon standar yang digantung dari tripod yang sering diimprovisasi di lapangan. Digunakan sejak Perang Dunia I hingga Perang Vietnam, telah digantikan oleh sistem osmosis balik yang menghasilkan air minum dengan menyaring air setempat melalui filter tingkat mikroskopis: Unit Pemurnian Air Reverse Osmosis (1980) dan Sistem Pemurnian Air Taktis ( 2007) untuk produksi skala besar, dan unit Light Water Purifier untuk kebutuhan skala kecil yang mencakup teknologi ultrafiltrasi untuk menghasilkan air minum dari sumber mana pun dan menggunakan siklus backwash otomatis setiap 15 menit untuk menyederhanakan operasi pembersihan.

Gas klorin pertama kali digunakan secara berkelanjutan untuk mendisinfeksi pasokan air di pabrik filter Belmont, Philadelphia, Pennsylvania dengan menggunakan mesin yang ditemukan oleh Charles Frederick Wallace [ kutipan diperlukan ] yang menjulukinya Klorinator. Itu diproduksi oleh perusahaan Wallace & amp Tiernan mulai tahun 1913. [11] Pada tahun 1941, desinfeksi air minum AS dengan gas klorin sebagian besar telah menggantikan penggunaan klorida kapur. [12] [13]

Sebagai halogen, klorin adalah disinfektan yang sangat efisien, dan ditambahkan ke pasokan air umum untuk membunuh patogen penyebab penyakit, seperti bakteri, virus, dan protozoa, yang biasanya tumbuh di reservoir pasokan air, di dinding saluran air dan di tangki penyimpanan. [14] Agen mikroskopis dari banyak penyakit seperti kolera, demam tifoid, dan disentri membunuh banyak orang setiap tahun sebelum metode desinfeksi digunakan secara rutin. [14]

Sejauh ini sebagian besar Klorin dibuat dari garam meja (NaCl) dengan elektrolisis dalam proses klor-alkali. Gas yang dihasilkan pada tekanan atmosfer dicairkan pada tekanan tinggi. Gas cair diangkut dan digunakan seperti itu.

Sebagai agen pengoksidasi kuat, klorin membunuh melalui oksidasi molekul organik. [14] Klorin dan produk hidrolisis asam hipoklorit tidak bermuatan dan karenanya mudah menembus permukaan patogen yang bermuatan negatif. Ia mampu menghancurkan lipid yang menyusun dinding sel dan bereaksi dengan enzim dan protein intraseluler, membuatnya tidak berfungsi. Mikroorganisme kemudian mati atau tidak lagi dapat berkembang biak. [15]

Prinsip Sunting

Ketika dilarutkan dalam air, klorin berubah menjadi campuran kesetimbangan klorin, asam hipoklorit (HOCl), dan asam klorida (HCl):

Dalam larutan asam, spesies utama adalah Cl
2 dan HOCl, sedangkan dalam larutan basa, secara efektif hanya ada ClO (ion hipoklorit). Konsentrasi ClO . yang sangat kecil2 , ClO3 , ClO4 juga ditemukan. [16]

Klorinasi kejut Sunting

Klorinasi kejut adalah proses yang digunakan di banyak kolam renang, sumur air, mata air, dan sumber air lainnya untuk mengurangi residu bakteri dan alga di dalam air. Klorinasi kejut dilakukan dengan mencampurkan sejumlah besar hipoklorit ke dalam air. Hipoklorit dapat berbentuk bubuk atau cairan seperti pemutih klorin (larutan natrium hipoklorit atau kalsium hipoklorit dalam air). Air yang diklorinasi dengan kejut tidak boleh dicelupkan atau diminum sampai jumlah natrium hipoklorit di dalam air turun menjadi tiga bagian per juta (PPM) atau sampai jumlah kalsium hipoklorit turun menjadi 0,2 hingga 0,35 PPM. [ kutipan diperlukan ]

Disinfeksi dengan klorinasi dapat menjadi masalah dalam beberapa keadaan. Klorin dapat bereaksi dengan senyawa organik alami yang ditemukan dalam pasokan air untuk menghasilkan senyawa yang dikenal sebagai produk sampingan desinfeksi (DBPs). DBP yang paling umum adalah trihalomethanes (THMs) dan asam haloasetat (HAA). Trihalomethanes adalah produk sampingan disinfektan utama yang dibuat dari klorinasi dengan dua jenis yang berbeda, bromoform dan dibromochloromethane, yang terutama bertanggung jawab atas bahaya kesehatan. Efeknya sangat bergantung pada durasi paparan bahan kimia dan jumlah yang tertelan ke dalam tubuh. Dalam dosis tinggi, bromoform terutama memperlambat aktivitas otak secara teratur, yang dimanifestasikan oleh gejala seperti kantuk atau sedasi. Paparan kronis bromoform dan dibromochloromethane dapat menyebabkan kanker hati dan ginjal, serta penyakit jantung, ketidaksadaran, atau kematian dalam dosis tinggi. [17] Karena potensi karsinogenisitas senyawa ini, peraturan air minum di seluruh negara maju memerlukan pemantauan rutin konsentrasi senyawa ini dalam sistem distribusi sistem air kota. Organisasi Kesehatan Dunia telah menyatakan bahwa "risiko terhadap kesehatan dari produk sampingan ini sangat kecil dibandingkan dengan risiko yang terkait dengan desinfeksi yang tidak memadai". [18]

Ada juga kekhawatiran lain mengenai klorin, termasuk sifatnya yang mudah menguap yang menyebabkannya menghilang terlalu cepat dari sistem air, dan masalah organoleptik seperti rasa dan bau.

A deklorinator adalah aditif kimia yang menghilangkan klorin atau kloramin dari air. Di mana air keran diklorinasi, itu harus dideklorinasi sebelum digunakan di akuarium, karena klorin dapat membahayakan kehidupan air dengan cara yang sama membunuh mikro-organisme. Klorin akan membunuh ikan [19] dan menyebabkan kerusakan pada filter biologis akuarium. [20] Bahan kimia yang menjalankan fungsi ini adalah zat pereduksi yang mereduksi spesies klorin menjadi klorida, yang kurang berbahaya bagi ikan.

Beberapa senyawa yang digunakan dalam deklorinator komersial adalah natrium tiosulfat, natrium hidroksimetanasulfonat, dan asam natrium hidroksimetana sulfinat.


Bagaimana desinfektan membunuh virus?

Kami menggunakan pemutih, pasteurisasi, dan radiasi UV untuk memurnikan air dan makanan, tanpa benar-benar memahami cara kerjanya. Laboratorium EPFL telah menemukan efek disinfektan umum ini terhadap virus.

Mendidih air, mengklorinasi kolam renang, memutihkan kamar mandi Anda – semua orang akrab dengan metode desinfeksi umum. Meskipun efektif dan digunakan secara luas, kami masih belum sepenuhnya memahami bagaimana metode yang telah terbukti ini membunuh virus.

Profesor Tamar Kohn, kepala Laboratorium Kimia Lingkungan EPFL, dan timnya telah menunjukkan bahwa disinfektan tidak semuanya bekerja dengan cara yang sama. Dia menerbitkan sebuah artikel di Ilmu dan Teknologi Lingkungan. “Virus adalah genom dan beberapa protein. Kami menemukan bahwa setiap disinfektan memiliki efek yang sangat berbeda, menyerang satu atau beberapa fungsi virus. Meskipun hasilnya sama, metode pemberantasannya berbeda. ”

Kohn menemukan tiga fungsi penting yang harus tetap utuh agar virus dapat menular: ia harus dapat menempel pada sel inang, menyuntikkan materinya ke dalam sel inang dan kemudian dapat bereplikasi. Jadi bagaimana virus kita bereaksi terhadap pasteurisasi, desinfeksi klorin, dan radiasi UV?

Pasteurisasi, klorinasi…

Pasteurisasi digunakan untuk melestarikan makanan, seperti susu, untuk jangka waktu yang lama dengan secara drastis mengurangi jumlah mikro-organisme di dalamnya. Panas menghambat ikatan dengan sel inang. Virus tidak lagi mengenali inangnya, sehingga tidak dapat menempel padanya.

Sifat disinfektan radiasi UV telah dieksplorasi selama lebih dari 100 tahun. Jaringan makanan atau sistem ventilasi dan pendingin udara digabungkan ke lampu UV untuk menghilangkan penyebaran agen patogen.

Radiasi bekerja dalam dua cara pada virus. Pertama, memicu reaksi kimia yang menghancurkan genom, sehingga tidak bisa lagi menggandakan diri di inang. Selain itu, ia merusak cangkang protein virus, atau kapsid. Karena materi genetik virus ditahan di bawah tekanan di kapsid, ketika cangkang ini rusak, tidak ada cara bagi virus untuk menyuntikkan materi ke dalam sel inang.

Klorinasi air minum dan kolam renang sudah menjadi hal yang lumrah. Klorin menyerang genom, mencegahnya dari replikasi dan menghancurkan fungsi injeksinya.

Penelitian Kohn memungkinkan kita untuk lebih memahami bagaimana setiap disinfektan bekerja dan dalam jumlah berapa itu akan efektif. Berkat metode ini, akan mungkin untuk lebih efektif memerangi virus yang menginfeksi air dan makanan, seperti virus yang menyebabkan Polio, penyakit gastrointestinal dan Hepatitis A.


Apa itu Klorinasi?

Mikroorganisme dapat ditemukan di air baku dari sungai, danau dan air tanah. Meskipun tidak semua mikroorganisme berbahaya bagi kesehatan manusia, ada beberapa yang dapat menyebabkan penyakit pada manusia. Ini disebut patogen. Patogen yang ada dalam air dapat ditularkan melalui sistem distribusi air minum, menyebabkan penyakit yang ditularkan melalui air pada mereka yang mengkonsumsinya.

Untuk memerangi penyakit yang ditularkan melalui air, metode desinfeksi yang berbeda digunakan untuk menonaktifkan patogen. Seiring dengan proses pengolahan air lainnya seperti koagulasi, sedimentasi, dan filtrasi, klorinasi menciptakan air yang aman untuk dikonsumsi publik.

Klorinasi adalah salah satu dari banyak metode yang dapat digunakan untuk mendisinfeksi air. Metode ini pertama kali digunakan lebih dari satu abad yang lalu, dan masih digunakan sampai sekarang. Ini adalah metode desinfeksi kimia yang menggunakan berbagai jenis klorin atau zat yang mengandung klorin untuk oksidasi dan desinfeksi sumber air minum.

Sejarah Klorinasi

Klorin pertama kali ditemukan di Swedia pada tahun 1744. Saat itu, orang percaya bahwa bau dari air bertanggung jawab untuk menularkan penyakit. Pada tahun 1835, klorin digunakan untuk menghilangkan bau dari air, tetapi baru pada tahun 1890 klorin ditemukan sebagai alat yang efektif untuk mendisinfeksi dengan cara mengurangi jumlah penyakit yang ditularkan melalui air. Dengan penemuan baru ini, klorinasi dimulai di Inggris Raya dan kemudian diperluas ke Amerika Serikat pada tahun 1908 dan Kanada pada tahun 1917. Saat ini, klorinasi adalah metode desinfeksi yang paling populer dan digunakan untuk pengolahan air di seluruh dunia.

Mengapa kita mengklorinasi air kita?

Sejumlah besar penelitian dan banyak penelitian telah dilakukan untuk memastikan keberhasilan di pabrik pengolahan baru menggunakan klorin sebagai desinfektan. Keuntungan utama klorinasi adalah terbukti efektif melawan bakteri dan virus, namun tidak dapat menonaktifkan semua mikroba. Beberapa kista protozoa resisten terhadap efek klorin.

Dalam kasus di mana kista protozoa tidak menjadi perhatian utama, klorinasi adalah metode desinfeksi yang baik untuk digunakan karena murah namun efektif dalam mendisinfeksi banyak kontaminan lain yang mungkin ada. Proses klorinasi juga cukup mudah diterapkan, jika dibandingkan dengan metode pengolahan air lainnya. Ini adalah metode yang efektif dalam situasi darurat air karena dapat menghilangkan kelebihan patogen dengan relatif cepat. Situasi air darurat dapat berupa apa saja, mulai dari kerusakan filter hingga pencampuran air yang diolah dan air mentah.

Bagaimana Klorin Menonaktifkan Mikroorganisme?

Klorin menonaktifkan mikroorganisme dengan merusak membran selnya. Setelah membran sel melemah, klorin dapat masuk ke dalam sel dan mengganggu respirasi sel dan aktivitas DNA (dua proses yang diperlukan untuk kelangsungan hidup sel).

Kapan/Bagaimana Kita Mengklorinasi Air Kita?

Klorinasi dapat dilakukan setiap saat/titik selama proses pengolahan air - tidak ada satu waktu tertentu kapan klorin harus ditambahkan. Setiap titik aplikasi klorin selanjutnya akan mengontrol masalah kontaminan air yang berbeda, sehingga menawarkan spektrum perawatan yang lengkap dari saat air masuk ke fasilitas pengolahan hingga saat keluar.

Pra-klorinasi adalah ketika klorin diterapkan ke air segera setelah memasuki fasilitas pengolahan. Pada langkah pra-klorinasi, klorin biasanya ditambahkan langsung ke air baku (air yang tidak diolah memasuki fasilitas pengolahan), atau ditambahkan ke dalam flash mixer (mesin pencampur yang memastikan dispersi klorin yang cepat dan seragam). Klorin ditambahkan ke air baku untuk menghilangkan ganggang dan bentuk kehidupan air lainnya dari air sehingga tidak akan menimbulkan masalah pada tahap pengolahan air selanjutnya. Pra-klorinasi dalam mixer flash ditemukan untuk menghilangkan rasa dan bau, dan mengontrol pertumbuhan biologis di seluruh sistem pengolahan air, sehingga mencegah pertumbuhan dalam tangki sedimentasi (di mana padatan dihilangkan dari air dengan pengendapan gravitasi) dan media filtrasi ( filter yang dilalui air setelah duduk di tangki sedimentasi). The addition of chlorine will also oxidize any iron, manganese and/or hydrogen sulphide that are present, so that they too can be removed in the sedimentation and filtration steps.

Disinfection can also be done just prior to filtration and after sedimentation. This would control the biological growth, remove iron and manganese, remove taste and odours, control algae growth, and remove the colour from the water. This will not decrease the amount of biological growth in the sedimentation cells.

Chlorination may also be done as the final step in the treatment process, which is when it is usually done in most treatment plants. The main objective of this chlorine addition is to disinfect the water and maintain chlorine residuals that will remain in the water as it travels through the distribution system. Chlorinating filtered water is more economical because a lower CT value is required. This is a combination of the concentration (C) and contact time (T). The CT concept is discussed later on in this fact sheet. By the time the water has been through sedimentation and filtration, a lot of the unwanted organisms have been removed, and as a result, less chlorine and a shorter contact time is required to achieve the same effectiveness. To support and maintain the chlorine residual, a process called re-chlorination is sometimes done within the distribution system. This is done to ensure proper chlorine residual levels are maintained throughout the distribution system.

Residual Chlorine, Breakpoint

Any type of chlorine that is added to water during the treatment process will result in the formation of hypochlorous acid (HOCl) and hypochlorite ions (OCl-), which are the main disinfecting compounds in chlorinated water. More detail is provided later on in this fact sheet.

A Form of Chlorine + H2O -> HOCl + OCl -

Of the two, hypochlorous acid is the most effective. The amount of each compound present in the water is dependent on the pH level of the water prior to addition of chlorine. At lower pH levels, the hypochlorous acid will dominate. The combination of hypochlorous acid and hypochlorite ions makes up what is called ‘free chorine.’ Free chlorine has a high oxidation potential and is a more effective disinfectant than other forms of chlorine, such as chloramines. Oxidation potential is a measure of how readily a compound will react with another. A high oxidation potential means many different compounds are able to react with the compound. It also means that the compound will be readily available to react with others.

Combined chlorine is the combination of organic nitrogen compounds and chloramines, which are produced as a result of the reaction between chlorine and ammonia. Chloramines are not as effective at disinfecting water as free chlorine due to a lower oxidation potential. Due to the creation of chloramines instead of free chlorine, ammonia is not desired product in the water treatment process in the beginning, but may be added at the end of treatment to create chloramines as a secondary disinfectant, which remains in the system longer than chlorine, ensuring clean drinking water throughout the distribution system.

The amount of chlorine that is required to disinfect water is dependent on the impurities in the water that needs to be treated. Many impurities in the water require a large amount of chlorine to react with all the impurities present. The chlorine added must first react with all the impurities in the water before a chlorine residual is present. The amount of chlorine that is required to satisfy all the impurities is termed the ‘chlorine demand.’ This can also be thought of as the amount of chlorine needed before free chlorine can be produced. Once the chlorine demand has been met, breakpoint chlorination (the addition of chlorine to water until the chlorine demand has been satisfied) has occurred. After the breakpoint, any additional chlorine added will result in a free chlorine residual proportional to the amount of chlorine added. Residual chlorine is the difference between the amount of chlorine added and the chlorine demand. Most water treatment plants will add chlorine beyond the breakpoint.
If ammonium is present in the water at the time of chlorine addition breakpoint chlorination will not occur until all the ammonium has reacted with the chlorine. Between 10 and 15 times more chlorine than ammonia is required before free chlorine and breakpoint chlorination can be achieved. Small water treatment plants frequently only add a fraction of the required chlorine (in relation to ammonium ions) and end up not properly disinfecting their water supplies.

The type of chloramines that are formed is dependent on the pH of the water prior to the addition of chlorine. Between the pH levels 4.5 and 8.5, both monochloramine and dichloramine are created in the water. At a pH of 4.5, dichloramine is the dominant form, and below that trichloramine dominates. At a pH above 8.5 monochloramine is the dominant form. Hypochlorous acid reacts with ammonia at its most rapid rate at a pH level around 8.3.

The chlorine to ammonia nitrogen ratio characterizes what kind of residual is produced.

Are there Other Uses for Chlorine?

The main purpose of chlorination is to disinfect water, but it also has many other benefits. Unlike some of the other disinfection methods like ozonation and ultraviolet radiation, chlorination is able to provide a residual to reduce the chance of pathogen regrowth in water storage tanks or within the water distribution system. At times, distribution systems can be a fair distance from the storage tanks and in dead end sections or where water is not used pathogens may re-grow if a proper (chlorine) residual is cannot be maintained in the treated water sent out for consumption. This results in poor water quality as well as slime and biofilms in the distribution systems that will end up contaminating the clean, treated water being distributed. Many government environmental bodies have set guidelines or standards for the amount of chlorine residual that must be present at all points in the system. The guidelines for each province are shown in the table below.

In addition to providing a residual, adding chlorine to water will also: oxidize iron, manganese, taste and odour compounds, remove colour in the water, destroy hydrogen sulphide, and aid other water treatment processes, such as sedimentation and filtration. Oxidizing soluble reduced iron and manganese will result in particle formation as oxidized iron and manganese are not soluble in water.

Is Chlorine All the Same?

The chlorination process involves adding chlorine to water, but the chlorinating product does not necessarily have to be pure chlorine. Chlorination can also be carried out using chlorine-containing substances. Depending on the pH conditions required and the available storage options, different chlorine-containing substances can be used. The three most common types of chlorine used in water treatment are: chlorine gas, sodium hypochlorite, and calcium hypochlorite.

Chlorine Gas

Chlorine gas is greenish yellow in colour and very toxic. It is heavier than air and will therefore sink to the ground if released from its container. It is the toxic effect of chlorine gas that makes it a good disinfectant, but it is toxic to more than just waterborne pathogens it is also toxic to humans. It is a respiratory irritant and it can also irritate skin and mucus membranes. Exposure to high volumes of chlorine gas fumes can cause serious health problems, including death. However, it is important to realize that chlorine gas, once entering the water, changes into hypochlorous acid and hypochlorite ions, and therefore its human toxic properties are not found in the drinking water we consume.

Chlorine gas is sold as a compressed liquid, which is amber in color. Chlorine, as a liquid, is heavier (more dense) than water. If the chlorine liquid is released from its container it will quickly return back to its gas state. Chlorine gas is the least expensive form of chlorine to use. The typical amount of chlorine gas required for water treatment is 1-16 mg/L of water. Different amounts of chlorine gas are used depending on the quality of water that needs to be treated. If the water quality is poor, a higher concentration of chlorine gas will be required to disinfect the water if the contact time cannot be increased.

When chlorine gas (Cl2) is added to the water (H2O), it hydrolyzes rapidly to produce hypochlorous acid (HOCl) and the hypochlorous acid will then dissociate into hypochlorite ions (OCl-) and hydrogen ions (H+).

Because hydrogen ions are produced, the water will become more acidic (the pH of the water will decrease). The amount of dissociation depends on the original pH of the water. If the pH of the water is below a 6.5, nearly no dissociation will occur and the hypochlorous acid will dominate. A pH above 8.5 will see a complete dissociation of chlorine, and hypochlorite ions will dominate. A pH between 6.5 and 8.5 will see both hypochlorous acid and hypochlorite ions present in the water. Together, the hypochlorous acid and the hypochlorite ions are referred to as free chlorine. Hypchlorous acid is the more effective disinfectant, and therefore, a lower pH is preferred for disinfection.

Calcium Hypochlorite

Calcium hypochlorite (CaOCl) is made up of the calcium salts of hypochlorous acid. It is produced by dissolving chlorine gas (Cl2) into a solution of calcium oxide (CaO) and sodium hydroxide (NaOH). Calcium hypochlorite is a white, corrosive solid that comes either in tablet form or as a granular powder. Calcium hypochlorite is very stable, and when packaged properly, large amounts can be purchased and stored until needed. The chemical is very corrosive however, and thus requires proper handling when being used to treat water. Calcium hypochlorite needs to be stored in a dry area and kept away from organic materials. It cannot be stored near wood, cloth or petrol because the combination of calcium hypochlorite and organic material can create enough heat for an explosion. It must also be kept away from moisture because the tablets/granular powder readily adsorb moisture and will form (toxic) chlorine gas as a result. Calcium hypochlorite has a very strong chlorine odour – something that should be kept in mind when placing them in storage.

When treating water, a lesser amount of calcium hypochlorite is needed than if using chlorine gas. Compared to the 1-16 mg/L required with chlorine gas, only 0.5-5 mg/L of calcium hypochlorite is required. When calcium hypochlorite is added to water, hypochlorite and calcium ions are produced.

Instead of decreasing the pH like chlorine gas does, calcium hypochlorite increases the pH of the water (making the water less acidic). However, hypochlorous acid and hypochlorite concentrations are still dependent on the pH of the water therefore by decreasing the pH of the water, hypochlorous acid will still be present in the water. As a result, calcium hypochlorite and chlorine gas both produce the same type of residuals.

Sodium Hypochlorite

Sodium hypochlorite (NaOCl) is made up of the sodium salts of hypochlorous acid and is a chlorine-containing compound that can be used as a disinfectant. It is produced when chlorine gas is dissolved into a sodium hydroxide solution. It is in liquid form, clear with a light yellow color, and has a strong chlorine smell. Sodium hypochlorite is extremely corrosive and must be stored in a cool, dark, and dry place. Sodium hypochlorite will naturally decompose therefore it cannot be stored for more than one month at a time. Of all the different types of chlorine available for use, this is the easiest to handle.

The amount of sodium hypochlorite required for water treatment is much less than the other two forms of chlorine, with 0.2-2 mg of NaOCl/L of water being recommended. Like calcium hypochlorite, sodium hypochlorite will also produce a hypochlorite ion, but instead of calcium ions, sodium ions are produced. NaOCl will also increase the pH of the water through the formation of hypochlorite ions. To obtain hypochlorous acid, which is a more effective disinfectant, the pH of the water should be decreased.

Is Chlorine a Sure Way of Eliminating Pathogens?

Chlorination has been proven to be very effective against bacteria and viruses. However, it cannot disinfect all waterborne pathogens. Certain pathogens, namely protozoan cysts, are resistant to the effects of chlorine. Cryptosporidium and Giardia, two examples of protozoan cysts, have caused great concern due to the serious illnesses they can cause. Cryptosporidium was the cause of the outbreak in North Battleford in 2001, and Milwaukee in April 1993. In raw water with high Giardia and Cryptosporidium levels, another method of disinfection should be considered. For more information on these protozoa, please read their self-titled fact sheets in the public information section.

Is Chlorinating Water ‘Fool-proof’?

There are a number of factors that affect the disinfection process. Of these, the concentration or dosage of chlorine and the chlorine contact time (the time that chlorine is allowed to react with any impurities in the water) are the most important factors.

Chlorine needs time to inactivate any microorganisms that may be present in the water being treated for human consumption. The more time chlorine is in contact with the microorganisms, the more effective the process will be. The contact time is the time from when the chlorine is first added until the time that the water is used or consumed.

The same positive relationship is seen when considering the chlorine concentration. The higher the concentration of chlorine, the more effective the water disinfection process will be. This relationship holds true because as the concentration increases, the amount of chlorine for disinfection is increased. Unlike the relationship between chlorine concentration and disinfection effectiveness, the chlorine concentration and the contact time of chlorine with water show an inverse relationship. As the chlorine concentration increases, the required water-chlorine contact time ultimately decreases. To determine the level of disinfection (D), a CT value can be calculated. This value is the product of the chlorine concentration (C) and contact time (T). The formula is as follows: C*T=D. This concept shows that an increase in chlorine concentration (C) would require less contact time to achieve the same desired level of disinfection. Another possibility would be an increase in contact time that would in turn require a lower chlorine concentration in order for the level of disinfection to stay the same.

The required CT value depends on several factors, including: the type of pathogens in the water, the turbidity of the water, the pH of the water and the temperature of the water. Turbidity is the suspended matter in the water and the types of pathogens can range from bacteria like E.coli and Campylobacter to viruses including Hepatitis A. At lower temperatures, higher turbidity, or higher pH levels, the CT value (i.e. the disinfection level) will have to be increased, but at lower turbidity, there is less suspended material in the water that will prevent contact of the disinfectant with the microorganisms, thus requiring a lower CT value. A higher water temperature and a lower pH level will also allow for a lower CT value.

Impurity Reactions

Chlorine can react with a number of different substances. In raw water, there may be a number of different impurities to react with the added chlorine, resulting in an increase of the chlorine demand. As a result, more chlorine will need to be added for the same level of inactivation. Some major impurities that may exist in water include: dissolved iron, hydrogen sulphide, bromine, ammonia, nitrogen dioxide, and organic material. In some cases, the result of chlorine reacting with impurities will increase the quality of the water (by eliminating the undesired elements), while in other cases, the chlorine-impurity reactions will create undesired side products that are harmful to human health. Chlorine will first react with inorganic impurities (dissolved iron, bromine, ammonia, etc.) before reacting with the organic compounds (dissolved organic material, bacteria, viruses, etc.).

Iron, which will give water an undesirable metallic taste if present, is one of the inorganic compounds that will react with hypochlorous acid (the stronger form of free chlorine that is produced after pure chlorine is added to water). By reacting with hypochlorous acid, the dissolved iron will go from a soluble state to an insoluble state, as a precipitate is formed as a result of the reaction. The iron precipitate, in its insoluble state, can be removed by filtration process within the water treatment centre.

2 Fe 2+ (liquid) + HOCl + 5H2O -> 2 Fe(OH)3 (solid) + 5H + + Cl -

Hypochlorous acid can also react with hydrogen sulphide (H2S), if it is present in the water being treated. Hydrogen sulfide is an undesirable impurity in water because it gives water an undesired smell. At levels below 1 mg/L hydrogen sulphide generates a musty smell to the water, while at levels above 1 mg/L a rotten egg smell will prevail. Hydrogen sulphide is also toxic. The hypochlorous acid and H2S reaction gives hydrochloric acid and sulphur ions as its products.

Bromine in the water can result in the production of undesired compounds. Bromine ions can react with hypochlorous acid to create hypobromous acid. Hypobromous acid also has disinfectant properties and is more reactive than hypochlorous acid. Hypochlorous acid or hypobromous acid will react with organic material in the water and create halogenated by-products, such as trihalomethanes.

Ammonia is a compound that may exist in the water. It is a nutrient to aquatic life, but one that will become toxic in high concentrations. Ammonia is produced as a result of decaying matter and therefore naturally exists in the water however, human activity also releases a large amount of ammonia into the water, which contributes to an increasing level of ammonia that may cause concern. Some ‘human activity sources’ include: municipal wastewater treatment plants, agricultural releases, and industrial releases, such as pulp and paper mills, mines, food processing, and fertilizer production. Reactions between ammonia and chlorine will produce monochloramines, dichloramines, and trichloramines, which are collectively known as chloramines. These compounds are beneficial to the water treatment process as they have disinfection capacity, but they are not as effective as chlorine although chloramines will last longer in the water.

Chlorine also reacts with phenols to produce monochlorophenols, dichlorophenols, or trichlorophenols, which cause taste and odour problem at low levels. At higher levels, chlorophenols are toxic and affect the respiration and energy storage process. Chlorophenols are mainly man-made compounds, but can be found naturally in animal wastes and decomposing organic material.

Are there Health Concerns with Chlorinating Water?

Chlorine can be toxic not only for microorganisms, but for humans as well. To humans,
chlorine is an irritant to the eyes, nasal passages and respiratory system. Chlorine gas must be carefully handled because it may cause acute health effects and can be fatal at concentrations as low as 1000 ppm. However, chlorine gas is also the least expensive form of chlorine for water treatment, which makes it an attractive choice regardless of the health threat.

In drinking water, the concentration of chlorine is usually very low and is thus not a concern in acute exposure. More of a concern is the long term risk of cancer due to chronic exposure to chlorinated water. This is mainly due to the trihalomethanes and other disinfection by-products, which are by-products of chlorination. Trihalomethanes are carcinogens, and have been the topic of concern in chlorinated drinking water. Chlorinated water has been associated with increased risk of bladder, colon and rectal cancer. In the case of bladder cancer, the risk may be doubled. Although there are concerns about carcinogens in drinking water, Health Canada's Laboratory Centre for Disease Control says that the benefits of chlorinated water in controlling infectious diseases outweigh the risks associated with chlorination and would not be enough to justify its discontinuation. In Europe, however, chorination has been discontinued in many communities.

Chlorination By-products

A number of different by-products can be produced from the reactions in the disinfection process. By-products created from the reactions between inorganic compounds and chlorine are harmless and can be easily removed from the water by filtration. Other by-products, such as chloramines, are beneficial to the disinfection process because they also have disinfecting properties. However, there are undesired compounds that may be produced from chlorine reacting with organic matter. The compounds of most concern right now are trihalomethanes (THMs) and haloacetic acids (HAAs). THMs and HAAs are formed by reactions between chlorine and organic material such as humic acids and fulvic acids (both generated from the decay of organic matter) to create halogenated organics. A greater level of THM formation has been found in surface water or groundwater influenced by surface water.

Trihalomethanes are associated with several types of cancer and are considered carcinogenic. The trihalomethane of most concern is chloroform, also called trichloromethane. It was once used as an anaesthetic during surgery, but is now used in the process of making other chemicals. About 900 ppm of chloroform can cause dizziness, fatigue, and headaches. Chronic exposure may cause damage to the liver and kidneys. Other harmful disinfection by-products are: trichloracetic acid, dichloroacetic acid, some haloacetonitriles, and chlorophenols.

Trichloracetic acid is produced commercially for use as a herbicide and is also produced in drinking water. This chemical is not classified as a carcinogen for humans, and there is limited information for animals. Dichloroacetic acid is an irritant, corrosive, and destructive against mucous membranes. This is also not currently classified as a human carcinogen. Haloacetonitriles were used as pesticides in the past, but are no longer manufactured. They are produced as a result of a reaction between chlorine, natural organic matter, and bromide. Chlorophenols cause taste and odour problems. They are toxic, and when present in higher concentrations, affect the respiration and energy storage process in the body.

Kesimpulan

Chlorination is a very popular method of water disinfection that has been used for many years. It has shown to be effective for killing bacteria and viruses, but not for some protozoan cysts. With the concern about trihalomethanes, a carcinogenic disinfection by-product, many communities have become hesitant in the continuation of this process.

Although chlorination does have some drawbacks, it continues to be the most popular, dependable, and cost-effective method of water disinfection.

Find this useful? Please chip in $5 to help us send Operation Water Drop kits to schools so students can measure the amount of total chlorine in the water they drink every day! Or donate $20 or more and receive an Official Donation Receipt for Income Tax Purposes.


Chlorine-36

Chlorine-36 ( 36 Cl) is an isotope of chlorine. Chlorine has two stable isotopes and one naturally occurring radioactive isotope, the cosmogenic isotope 36 Cl. Its half-life is 301,300 ± 1,500 years. [1] 36 Cl decays primarily (98%) by beta-minus decay to 36 Ar, and the balance to 36 S. [1]

Chlorine-36, 36 Cl
Umum
Simbol 36 Cl
Namachlorine-36, Cl-36
Protons17
Neutrons19
Nuclide data
Natural abundance7 × 10 −13
Half-life301,300 ± 1,500 years
Parent isotopes 36 Ar
35 Cl
39 K
40 Ca
Decay products 36 Ar
Decay modes
Decay modeDecay energy (MeV)
Beta minus 710 keV
Electron capture 120 keV
Electron capture 1142 keV
Isotopes of chlorine
Complete table of nuclides

Trace amounts of radioactive 36 Cl exist in the environment, in a ratio of about (7-10) × 10 −13 to 1 with stable chlorine isotopes. [2] [3] This corresponds to a concentration of approximately 1 Bq/(kg Cl).

36 Cl is produced in the atmosphere by spallation of 36 Ar by interactions with cosmic ray protons. In the top meter of the lithosphere, 36 Cl is generated primarily by thermal neutron activation of 35 Cl and spallation of 39 K and 40 Ca. [2] In the subsurface environment, muon capture by 40 Ca becomes more important. [2] The production rates are about 4200 atoms 36 Cl/yr/mole 39 K and 3000 atoms 36 Cl/yr/mole 40 Ca, due to spallation in rocks at sea level. [2]

The half-life of this isotope makes it suitable for geologic dating in the range of 60,000 to 1 million years. [4]

Additionally, large amounts of 36 Cl were produced by irradiation of seawater during atmospheric and underwater test detonations of nuclear weapons between 1952 and 1958. The residence time of 36 Cl in the atmosphere is about 2 years. Thus, as an event marker of 1950s water in soil and ground water, 36 Cl is also useful for dating waters less than 50 years before the present. 36 Cl has seen use in other areas of the geological sciences, including dating ice and sediments.


Frequently Asked Questions (FAQs) about Sodium Hypochlorite Solution(SH)

Investigations have shown sodium hypochlorite to be an effective disinfectant having broad applications. Although a number of other disinfectants (calcium hypochlorite, ozone, UV, solar disinfection) and treatment processes (filters, slow sand filtration) have been investigated, sodium hypochlorite appears to offer the best mix of low cost, ease of use, safety, and effectiveness in areas where there is enough water to drink and water is not excessively turbid. These characteristics are the reasons why most water treatment systems in the US and Europe have been using chlorine for disinfecting drinking water for nearly 100 years. The other disinfection methods noted above also effectively disinfect water and are useful in a number of settings.

Chlorine tablets and/or HTH (also named calcium hypochlorite) are widely available in some areas. A number of potential users of the SWS know that these tablets are used to disinfect water. Unfortunately, we have also found that many people have different levels of knowledge regarding appropriate dosing instructions, which is a concern because the tablets vary significantly in strength. In Haiti, a small saran wrap bag of approximately 100 HTH pellets is widely available and inexpensive. However, the pellets vary in size, the quality of the pellets is unknown, and, depending on impurities in the manufacturing process, they can degrade quickly. In other countries, very high strength tablets may be sold which, when added to water for disinfection, leave a strong, unpleasant taste. It is important for users to know the quality and strength of HTH and/or chlorine tablets and understand the appropriate dosing strategy before attempting to use them for drinking water treatment in most instances, however, this is impossible for users to do. For these reasons, hypochlorite solution is likely to be a better option.

First, it is important that the concentration of the SH solution produced is correct (usually 0.5 to 1.0%). A concentration that is too low requires too high a volume to adequately treat enough water to be practical. A concentration that is too high is difficult to accurately dose, raising the risk of too high a dose (which is unpalatable), or too low a dose (which might not effectively disinfect the water). Second, it is important that the pH level of the solution be at least 11. This increases the shelf life of the solution.

The hypochlorite dose will depend on the characteristics of the local water. Usually an amount in the range of 5 to 10 milliliters added to 20 liters of water is sufficient to inactivate the disease-causing organisms, but not leave an unpleasant taste. Once the size of the cap for your project has been determined, some simple experiments can be used to determine the appropriate dose. To conduct the experiments, you will need locally available SH, source water in your area, and a kit that measures the amount of free and combined chlorine. Please contact [email protected] for more information on how to complete this testing.

Sodium hypochlorite is highly reactive and volatile. At normal pH (6-8), sodium hypochlorite can degrade substantially within 2-3 weeks. This shelf life is not adequate for use in the SWS, which requires that the hypochlorite remain at a high enough concentration to inactivate disease-causing organisms. By raising the pH of the hypochlorite solution, you stabilize the solution. The pH can be raised by the addition of sodium hydroxide, which is widely available. In order to determine the amount of sodium hydroxide to add to your sodium hypochlorite solution, you will need to complete trial-and-error testing. Add a known volume of sodium hydroxide to a known volume of sodium hypochlorite, and then measure the pH with a meter or kit. Because source water quality is different in each location, there is not one standard volume of sodium hydroxide to add to ensure pH is above 11. You will have to start with a known volume (perhaps 1 tablespoon in 1 gallon, or 5 ml in 1 liter) and complete repeat trial-and-error testing. The exact pH is not important in this context&mdashyou simply need to ensure that the pH level is above 11.

No, because when the sodium hypochlorite solution is added to water, the water decreases the pH and the sodium hypochlorite becomes more active. The chemistry behind this is: the pH scale is from 0 to 14. Acids have a pH below 7, bases are above 7, and 7 is neutral. Most natural water is around pH 6-7. When sodium hypochlorite is in water, it is a mixture of two compounds, with the concentration of each compound dependent on pH. One of these compounds is significantly more reactive, volatile, and more effective at inactivating bacteria than the other. At high pH (above 11) the majority of the sodium hypochlorite is in the form of the less-reactive compound. Thus, when you add sodium hydroxide to the sodium hypochlorite, you are converting it into the less-reactive form. However, water is around pH 6-7. When you add a small amount (5 milliliters) of solution at pH 11 to a large amount (20 liters) of water at pH 6-7, the mixture becomes pH 6-7. Thus, when you add the hypochlorite at pH 11 to your water in the SWS, you convert the hypochlorite back into the reactive form, and then it inactivates the disease-causing organisms.

Ini sangat tidak mungkin. If sodium hypochlorite is added to water that is already treated, the water would most likely still be within an acceptable range of chlorine residual. Typically, chlorinated urban water systems have free chlorine levels of around 0.1 to 0.5 parts per million. We calculate our sodium hypochlorite solution dose to give untreated water a free chlorine level of around 1 part per million. So if you add our solution (to achieve 1 part per million) to treated urban water (0.1-0.5 parts per million), the level of the &ldquoovertreated&rdquo water would still be in the acceptable range of 0.5-2 parts per million (which is the range that balances disinfection efficacy and reasonable taste).

Chlorine is an extremely reactive chemical. Right after the sodium hypochlorite is added to the water, chlorine levels decline because the chlorine is reacting with inorganic and organic matter and microbes. After those reactions are complete, chlorine in water will slowly escape into the air as a gas. This is the reason that free and total chlorine levels slowly degrade over time in a covered (but not sealed) container, and also why it is recommended that the pH level of the hypochlorite solution be raised to over 11 to extend the shelf life of the solution before it is used.

It is important to remember that the concentration of the SH used in the Safe Water System (SWS) is approximately 0.5-1.0%. A review of health effects from accidental and intentional ingestion of full strength bleach (sodium hypochlorite), which is 5-6%, in European poison control centers 1 showed that &ldquoacute accidental exposure to household bleach in use or in foreseeable misuse situations results, in the great majority of the cases, in minor, transient adverse effects on health. The authors also cited two studies specifically on children: 1) A study in Chicago showing that of 26 children admitted for accidental bleach ingestion, only one had a moderate health effect (irritation of the esophagus, which healed on its own without intervention), with the remaining children having only &ldquominor transient irritation effects&rdquo, and 2) A study of 23 cases aged 1 &ndash 3 years, with only one case having &ldquosuperficial burns in the esophagus&rdquo, which disappeared two weeks later. Suicide attempts in adults have shown that a lethal dose of sodium hypochlorite varies widely, with lethal results at 200-500 mL of 3-12% strength. As mentioned above, the hypochlorite ingested in the majority of the cases in the review was full strength household bleach: 5-6%. Several factors make it unlikely that the hypochlorite solutions recommended in the Safe Water System could cause harm remembering that in most countries, the SWS SH is sold in 250 ml bottles in some countries, the 500 ml bottles are used. First, it is unlikely that a child would accidentally drink 250 or 500 milliliters of something that tastes as bad as the sodium hypochlorite does. Second, it is even less likely that, at the low concentration used in this project, anything harmful would occur. Despite these safety data, it is highly recommended that part of the educational materials emphasize the need to keep the sodium hypochlorite solution stored somewhere safe (out of sunlight, sealed, away from children) for health reasons to protect the sodium hypochlorite from degradation and to prevent spills in households that, due to limited incomes, would be unable to purchase more solution.

Giardia dan Cryptosporidium are both protozoa and are highly tolerant to chlorination because they exist in water in a cyst or oocyst form. The hard coat of the cysts or oocysts protects Giardia dan Cryptosporidium from being inactivated by chlorine. Cryptosporidium is much more resistant to chlorine than Giardia (see pathogen inactivation table for more details). Both protozoa, however, are fairly large, which means that they can be removed by filtration. Jika Giardia atau Cryptosporidium are a significant health problem in the project area, a filtration step (through ceramic, sand, or other filters) can be added before adding the sodium hypochlorite.

Water that looks dirty or cloudy is called turbid water. Turbidity is a measure of the amount of light that is scattered as it passes through the water sample. If more particles are in the water, more light will be scattered, and the turbidity is thus higher. Water that looks &ldquodirty&rdquo will have a higher turbidity than water that looks clear. Turbidity is often used to represent the amount of total suspended solids and the amount of organic matter in the water. Bacteria and other pathogens may also stick to particles in the water so high turbidity may increase the chance that there are pathogens in the water. There are two issues associated with adding chlorine to water that has a high turbidity: 1) Chlorine reacts equally with all the organic material in the water as well as with the bacteria and other pathogens. If there is a great deal of organic material then it will take more chlorine to fully react with all the dissolved solids and organic material as well as inactivate the bacteria and other pathogens, 2) There is a potential for creating more disinfection by-products if there is a higher concentration of organic matter in the source water. There are three strategies that can be used to treat turbid water: 1) Filter the water through a cloth filter to remove some of the organic matter and then chlorinate 2) Let the water settle for 12-24 hours so the organic matter and solids fall to the bottom and then pour off the clearer water into a separate vessel where it is then chlorinated or 3) Increase the dose of sodium hypochlorite solution added to the turbid water to be sure there is enough chlorine to inactivate the disease-causing organisms. Because every community is different, experiments to determine which is the most acceptable, appropriate, and effective strategy will need to be conducted in the project community.

Disinfection by-products (DBPs) are chemical compounds formed when chlorine is added to water with organic material in it. All natural waters have some organic material in them, and generally waters that are more turbid (dirty) have more organic material. DBPs are a concern whenever chlorine is added to drinking water, whether in the Safe Water System or in a large-scale water treatment plant in the United States, because some studies suggest that ingestion of DBPs in water over a lifetime may be associated with a very low risk of cancer. However, this risk is very small. In areas where many people, and many children, have diarrheal diseases caused by unsafe drinking water, the risk of cancer from DBPs is very small compared to the risk of death or stunting from diarrheal diseases. In their Guidelines for Drinking-water Quality, the World Health Organization states: &ldquoWhere local circumstances require that a choice must be made between meeting either microbiological guidelines or guidelines for disinfectants or disinfectant by-products, the microbiological quality must always take precedence, and where necessary, a chemical guideline value can be adopted corresponding to a higher level of risk. Efficient disinfection must never be compromised&rdquo 2 . For more information, please see our detailed page on DBPs.

A number of companies manufacture hypochlorite generators. There are several advantages in using a hypochlorite generator. First, local production of the sodium hypochlorite minimizes transportation costs. Second, in the event there is not a reliable bleach producer in the country, the hypochlorite generator can provide the capacity. Third, revenues from the sale of the solution can be used to help support operation and maintenance of the machine and to pay the operator. Considerations that must be taken into account when producing bleach in this way include the need for regular operation and maintenance of the machine, the need to test the concentration and pH of the SH solution produced, payment of a reliable person to operate and maintain the machine, replacement of the cell of the generator every 5 years, and the need for a reliable electricity supply.

There are several advantages to having a company make the solution: 1) Most likely, all a company would need to do to make the desired concentration of hypochlorite is to dilute an existing bleach product. 2) If demand for the solution grows, a company is better able to expand production. 3) Many companies have certification from Bureaus of Standards for bleach products that can often be applied to the new dilute solution. 4) Most reputable companies have quality control procedures. In countries around the world, Populations Services International External (PSI&ndasha social marketing, non-governmental organization that has successfully implemented a number of SWS projects) has opted to have private companies make the bleach for them.

In the first year of the country-scale project in Zambia, it cost US$78,000 to manufacture 400,000 bottles. The labor cost was $23,000 and the materials (salt, vinegar, bottles, and labels) cost was $55,000. The total production cost was therefore US.20 per bottle. Assuming a family usage of one bottle per month, the production cost for a year&rsquos supply for one family is about US$2.40. After the first year, costs usually decrease. Costs vary by country, depending on labor, materials, and value-added taxes. In small-scale projects using a local hypochlorite generator and reusable bottles, the production cost of the hypochlorite is only the cost of the salt, water, labor, and electricity.

CDC recommends the following six characteristics for the sodium hypochlorite bottle that is kept in the home: 1) The size of the bottle should be between 250 and 500 milliliters. This is small enough to be affordable and to ensure that the solution will be used before it degrades, but large enough that it will last a family for approximately one month. 2) The neck of the bottle should be compatible with soda bottle caps, which tend to be mass-produced, inexpensive, typically have the desired volume of 5-10mL for dosing, and are available in most locations. 3) The volume of the cap should be between 5 and 10 ml so that it can be used to dose the solution. 4) The bottle should be composed of an opaque plastic to prevent exposure of the solution to direct UV radiation from sunlight, which will decrease its shelf life. 5) The neck and cap should have at least four threads to improve the seal. The cap should have a raised ring inside to help seal the bottle, as well. 6) A handle is not necessary. This only increases the cost and decreases the space available for instructions.

One way to save money when designing the solution bottle is to design the bottle so that an already locally available cap will fit it. We recommend a plastic soft drink bottle cap with a volume of 5&ndash10 milliliters. Using a locally available cap will save you from having to purchase a mold for the caps, and soft drink caps are typically mass produced at very low cost. The existing caps must fit tightly and securely on the project bottle design.

In many projects, PSI has initiated social marketing campaigns, which include activating networks of wholesale and retail outlets and facilitating distribution to communities where vulnerable populations live. For smaller projects, one idea is to purchase space on private delivery trucks that are already going to target locations to deliver goods such as soft drinks and beer, or to request a donation of space by the private companies as a charitable activity.


Ringkasan

Selecting how to measure free and total chlorine can be complicated and is dependent on a number of factors in a program, including the need for accuracy, cost, and number of samples to be tested. The choice is also highly dependent on how the data will be used. Some recommendations for choosing a method based on the sampling goals are detailed below:

  • Dosage testing for a new project: If your goal is to do dosage testing for a national scale project, the SWS Project highly recommends the use of the digital colorimeters. The accuracy of the meters is necessary to ensure the correct dose is obtained.
  • Program Monitoring: If your goal is to determine whether users are using the chlorine in their homes, spot-checks in the home to sample the household water with pool test kits is sufficient and provides a simple indicator of the presence or absence of total chlorine.

Project Evaluation: If your goal is to determine if users are adding the correct amount of chlorine and using the chlorine solution in the home, spot-checks in the home to sample the household water with a color-wheel kit provide more information than the pool test kits (free chlorine), while remaining relatively inexpensive and easy to use.

CDC as a branch of the federal government does not endorse products from specific companies. The above information is for reference purpose only to describe the SWS project experience and represents, to the authors current knowledge, a range of available products to complete this sampling.


Tonton videonya: Menetapkan Dosis Klor: Tutorial Klorinasi. (Agustus 2022).