Jumat, 20 Mei 2011

Water Analysis

Water Quality Analysis

1. Conductivity
Conductivity is a measureof the ability of an aqueous solution to carry an electric current. This ability depends on the presence of ions; on their total consentration, mobility and valence; and the temperature of measurement.
Most problems in obtaining good data in conductivity monitoring equipment are related to electode fouling and to inadequated sample circulation. Conductivities grater than 10.000 to 50.000µmhos/cm or less than about 10 µmhos/cm may be difficult to measure with usual measurement electronic and cell capacitance.
Laboratory conductivity measurements are used to :
• Establish degree of mineralization to assess the effect of the total concentration of ion on chemical equlibria, physiological effect on plants or animals, corrotion rates, etc.
• Assess degree of mineralization of distilled and deionized water.
• Estimate sample size to be used to common chemical determinations and to check results of a chemical analysis.
• Estimate total dissloved solid(mg/L) in a sample by multiplying conductivity(in µmhos/cm) by an empirical factor. This factor may vary from 0,55 – 0,9, depending on the soluble components of the water and on the temperature measurement.
• Approximate the miliequivalents per liter of cations or anions in some waters by multyplying conductivity in units of µmhos/cm by 0,01.

2. pH
Measurement of pH is one of the most important and frequently used test in water chemistry. Practically every phase of water supply and wastewater treatment e.g., acid-base neutralization, water softening, precipitation, coagulation, disinfection, and corrosion control, is pH dependent pH is used in alkalinity and carbon dioxide measurements and many other acid-base equlibria. At a given temperature the intensity of the acidic or basic character of a solution is indicated by pH or hydrogen ion activity.
3. Acidity
Acidity of a water is its quantitative capacity to react with a strong base to a designated pH. The measured value may vary significantly with the end point pH used in the determination.
Ideally the end point of the acidity titration should corespond to the stoichiometric equivalence point for neuralization of acids present. The pH at the equivalence point will depend on sample, the choice among multiple inflection points, and the intended use of the data.
4. Alkalinity
Alkalinity is significant in many uses and treatments of natural waters and waste waters. Because the alkalinity of many surface waters is primarily a function of carbonate, bicarbonate and hydroxide content, it is taken as an indication of the concentration of these constitutents. Alkalinity measurement are used in the interpretation and control water and waste water treatment processes.
Ideally the end point of the alkalinity titration when the alkalinity is due entirely to carbonate or bicarbonate content, the pH at the equivalence point of the titration is determined the concentration of carbon dioxide(CO2) at the stage. The pH values are suggested as the equivalence point for corresponding alkalinity concentration as miligrams CaCO3 per liter. “Phenolphthalein alkalinity” is the term traditionally used for the equantity measured by titration to pH 8,3 irrespective of the colored indicator, if any, used in the determination.
5. BOD
The Biochemical Oxygen Demand (BOD) determination is an empirical test in which standardized laboratory procedures are used to determine the relative oxygen requirements of waste waters, effluents, and poluted waters. The test measures the molecular oxygen utilized during specified incubation period for the biochemical degradation of organic material (carbonaceous demand) and the oxygen used to oxidize inorganic material such as sulfides and ferrous iron. The seeding and dilution procedures provide an estimate of the BOD at pH 6,5-7,5.
6. COD
The chemical oxygen demand (COD) is used as a measure of the oxygen equivalent of the organic matter content of a sample that is susceptible to oxidation by a strong chemical oxidant. COD can be related empirically to BOD, organic carbon, or organic matter. The test is useful for monitoring and control after correlation has been established. The dichromate reflux methode is preffered offer procedures using other oxidant because of superior oxidizing ability, applicability to a wide variety of samples and ease of manipulation. Oxidation of most organic compounds is 95 to 100% od the theoritical value.
Most types of organic matter are oxidized by a boiling mixture of chromic and sulfuric acids. A sample is refluxed in strongly acid solution with a known excess of potassium dichromate (K2Cr2O7). After digestion, the remaining unreduced K2Cr2O7 is titrated ferrous ammonium sulfate to determonate the amount of K2Cr2O7 consumed and the oxidizable organic matter is calculated in terms of oxygen equivalent.

Water Analysis

Water Quality Analysis

1. Conductivity
Conductivity is a measureof the ability of an aqueous solution to carry an electric current. This ability depends on the presence of ions; on their total consentration, mobility and valence; and the temperature of measurement.
Most problems in obtaining good data in conductivity monitoring equipment are related to electode fouling and to inadequated sample circulation. Conductivities grater than 10.000 to 50.000µmhos/cm or less than about 10 µmhos/cm may be difficult to measure with usual measurement electronic and cell capacitance.
Laboratory conductivity measurements are used to :
• Establish degree of mineralization to assess the effect of the total concentration of ion on chemical equlibria, physiological effect on plants or animals, corrotion rates, etc.
• Assess degree of mineralization of distilled and deionized water.
• Estimate sample size to be used to common chemical determinations and to check results of a chemical analysis.
• Estimate total dissloved solid(mg/L) in a sample by multiplying conductivity(in µmhos/cm) by an empirical factor. This factor may vary from 0,55 – 0,9, depending on the soluble components of the water and on the temperature measurement.
• Approximate the miliequivalents per liter of cations or anions in some waters by multyplying conductivity in units of µmhos/cm by 0,01.

2. pH
Measurement of pH is one of the most important and frequently used test in water chemistry. Practically every phase of water supply and wastewater treatment e.g., acid-base neutralization, water softening, precipitation, coagulation, disinfection, and corrosion control, is pH dependent pH is used in alkalinity and carbon dioxide measurements and many other acid-base equlibria. At a given temperature the intensity of the acidic or basic character of a solution is indicated by pH or hydrogen ion activity.
3. Acidity
Acidity of a water is its quantitative capacity to react with a strong base to a designated pH. The measured value may vary significantly with the end point pH used in the determination.
Ideally the end point of the acidity titration should corespond to the stoichiometric equivalence point for neuralization of acids present. The pH at the equivalence point will depend on sample, the choice among multiple inflection points, and the intended use of the data.
4. Alkalinity
Alkalinity is significant in many uses and treatments of natural waters and waste waters. Because the alkalinity of many surface waters is primarily a function of carbonate, bicarbonate and hydroxide content, it is taken as an indication of the concentration of these constitutents. Alkalinity measurement are used in the interpretation and control water and waste water treatment processes.
Ideally the end point of the alkalinity titration when the alkalinity is due entirely to carbonate or bicarbonate content, the pH at the equivalence point of the titration is determined the concentration of carbon dioxide(CO2) at the stage. The pH values are suggested as the equivalence point for corresponding alkalinity concentration as miligrams CaCO3 per liter. “Phenolphthalein alkalinity” is the term traditionally used for the equantity measured by titration to pH 8,3 irrespective of the colored indicator, if any, used in the determination.
5. BOD
The Biochemical Oxygen Demand (BOD) determination is an empirical test in which standardized laboratory procedures are used to determine the relative oxygen requirements of waste waters, effluents, and poluted waters. The test measures the molecular oxygen utilized during specified incubation period for the biochemical degradation of organic material (carbonaceous demand) and the oxygen used to oxidize inorganic material such as sulfides and ferrous iron. The seeding and dilution procedures provide an estimate of the BOD at pH 6,5-7,5.
6. COD
The chemical oxygen demand (COD) is used as a measure of the oxygen equivalent of the organic matter content of a sample that is susceptible to oxidation by a strong chemical oxidant. COD can be related empirically to BOD, organic carbon, or organic matter. The test is useful for monitoring and control after correlation has been established. The dichromate reflux methode is preffered offer procedures using other oxidant because of superior oxidizing ability, applicability to a wide variety of samples and ease of manipulation. Oxidation of most organic compounds is 95 to 100% od the theoritical value.
Most types of organic matter are oxidized by a boiling mixture of chromic and sulfuric acids. A sample is refluxed in strongly acid solution with a known excess of potassium dichromate (K2Cr2O7). After digestion, the remaining unreduced K2Cr2O7 is titrated ferrous ammonium sulfate to determonate the amount of K2Cr2O7 consumed and the oxidizable organic matter is calculated in terms of oxygen equivalent.
DEPOSISI ASAM

 Deposisi asam telah menjadi wacana politik pembangunan global karena telah mengancam dan mendistorsi kualitas dan keberlanjutan kehidupan di muka bumi.
 Pada waktu planet bumi terbentuk pertama kali, kemampuan atmosfer membersihkan diri berjalan lancar, tetapi sekitar lima puluhan tahun yang silam komposisi atmosfer berubah sangat nyata akibat aktivitas manusia.
 Pertumbuhan penduduk dunia yang diikuti oleh kemajuan teknologi menyebabkan konsumsi bahan bakar fosil meningkat tajam, sehingga terjadi krisis ekologi berupa pencemaran lingkungan global yang sangat memprihatinkan.
 Akibat berbagai aktivitas sosial budaya manusia, seperti pembakaran batubara, minyak bumi, kebakaran hutan, penggundulan hutan tropis, serta pertanian berpindah telah menimbulkan bentuk pencemaran berupa deposisi asam.

Terjadinya Deposisi Asam
Terbentuknya deposisi asam diakibatkan adanya zat kimia berupa oksida asam (SOx, NOx ) yang dihasilkan dari proses pembakaran bahan bakar fosil pembangkit tenaga listrik, juga dari gas buang kendaraan bermotor yang dipancarkan kedalam udara atau yang dibawa angin ke atmosfer.
Turunnya gas-gas ini ke udara terjadi dengan 2 cara :
1. Deposisi cara basah (wet deposition)
2. Deposisi cara kering (dry deposition)

Asam-asam yang dihasilkan :
1. Asam nitrat dan asam nitrit
Sumber gas : pembakaran fosil, pembakaran hutan,
nitrogen dan oksigen yang ada diudara
N2 + O2 --------- 2 NO
NO + O2 --------- NO2

Dari ozon O3 + NO2 ----------  NO3 * O2,
bersama-sama dengan uap air membentuk :
NO + NO2 + H2O ----------  2 HNO2 (asam nitrit)
NO3 + NO2 + H2O --------- 2 HNO3 (asam nitrat)
2. Asam Sulfit dan asam Sulfat
Sumber gas : letusan gunung berapi, aktivitas manusia
(antropogenik),bahan bakar dari fosil (batubara
dan minyak bumi), aktivitas industri dan
transportasi, pembakaran hutan dll.
SO2 + H2O --------- H2SO3
SO3 + H2O --------- H2SO4
 Gas SO2 bila bertemu dengan oksigen di udara membentuk gas
SO3, gas SO3 mudah bereaksi dengan uap air (H2O)
membentuk asam sulfat.
 Asam sulfat bersifat reaktif, karena mudah bereaksi dengan
benda-benda lain yang mengakibatkan korosif (pengkaratan)
dan proses kimia lainnya.




DAMPAK DEPOSISI ASAM
Dampak pada ekosistem perairan :
1. Ion hidrogen (H+) dapat mengganggu pengaturan keseimbangan ion pada organisme akuatik.
2. Meningkatkan kadar logam dalam ekosistem air sehingga menurunkan kualitasnya.
3. Siklus makanan pada ekosistem air terganggu (karena menurunnya kadar P dalam air).
4. Mengganggu produktivitas primer di ekosistem air (hilangnya tumbuhan air dan mikroalga yang sensitif).
5. Ikan dan beberapa jenis zooplankton akan punah dan beberapa jenis avertebrata pemangsa akan tumbuh. Sehingga hujan asam akan mengubah status tropik pada rantai makanan.

Dampak pada ekosistem darat :
1. Kerusakan pada tanaman akibat hujan asam terjadi dengan
ditemukannya bintik-bintik kuning pada daun, yang menjadi efek
“bleaching“ larutan asam terhadap klorofil .
2. SOx dapat mengganggu sistem pernafasan karena menyerang
selaput lendir pada hidung, tenggorokan, saluran pernafasan
sampai ke paru-paru.
3. Gas NOx akan menyebabkan paru-paru bengkak sehingga
mengganggu tranportasi oksigen dalam darah.
4. Bangunan yang berupa gedung, jembatan, patung dan sebagainya
banyak mengalami pengkaratan akibat hujan asam.
5. Cat pada bangunan seringkali terdekomposisi oleh gas SOx dan
warnanya berubah menjadi kehitaman.

PENGENDALIAN DEPOSISI ASAM
Global
Emisi sulfur dioksida dan nitrogen dioksida menjadi masalah internasional, negara-negara industri menaikkan cerobong asapnya 6 kali lipat lebih tinggi, agar polutannya berada di atmosfir.
Pada tahun 1960-an Swedia menjadikan polusi udara sebagai isu politik lingkungan global karena terjadi pengasaman di danau-danau di Swedia. Hal ini menjadi pencetus bagi Swedia untuk mengadakan konferensi lingkungan hidup dunia (PBB) di Stockholm pada tahun 1972.
Regional
1. Tahun 1977, The Economic Communication of Europa (ECE) mensponsori pengawasan polusi udara di Eropa, sehingga negara yang terpolusi seperti Swedia, Filandia dan Norwegia membuat aturan ketat tentang emisi SOx dan Nox.
2. Tahun 1984 diadakan konvensi tentang emisi di Ottawa, untuk mengurangi 30 % emisi dan dilanjutkan pula pada 1985 oleh 21 negara untuk menandatangani Helsinki protokol.
3. Tahun 1988, Sofia Protokol yang khusus mengatur pengawasan tentang emisi nitrogen oksida (NOx) ditandatangi oleh 23 negara.

EANET ( East Asia Network for Acid Deposition):
Lembaga pengawas deposisi asam di Asia Timur
Tahun 1993 beranggota 10 negara : China, Indonesia, Japan, Malaysia, Mongolia, Philippina, Republik Korea, Russia, Thailand, Vietnam.
Tahun 2001 tambah 2 negara yaitu: Cambodia, Lao P.D.R
Tugas EANET adalah:
1. Untuk mengelola informasi tentang deposisi asam yang ada di negara-negara anggota.
2. Untuk membentuk pemahaman dan pengetahuan ilmiah yang umum diantara para anggota
3. Untuk memperjelas sumber emisi dan pentingnya menurunkan jumlah emisi.

Nasional
1. Baku Mutu Emisi (BME) yang dituangkan dalam Keputusan
Menteri Negara Lingkungan Hidup No : KEP.13/MENLH/1995.
2. Kepmen LH No. 141 tahun 2003 tentang ambang batas emisi gas buang kendaraan bermotor tipe baru dan kendaraan yang sedang diproduksi, dengan mengacu pada standar UN-ECE (United Nations-Economic Commission for Europe), menyebutkan :
• Semua kendaraan bermotor tipe baru yang diproduksi di Indonesia mulai Januari 2005 harus memenuhi standar emisi kendaraan Euro 2.
• Sepeda motor 4 langkah, yang akan diberlakukan 1 Juli 2006.
Kendaraan bermotor roda empat yang sedang diproduksi dan sepeda motor dua langkah, diberlakukan 1 Januari 2007
3. Program pengendalian emisi kendaraan dari KLH : Program Mandatory Disclosure of Automotive Emissions.
4. Pihak industri saat promosi juga diwajibkan mengumumkan hasil pengujian emisi gas buang kendaraan yang diproduksi di media cetak dan elektronik.
5. KEP-13/MENLH/3/1995 tentang Baku Mutu Emisi Sumber tidak bergerak. Peraturan ini menentukan batas maksimum emisi dari industri kertas, besi, pembangkit listrik, semen dll yang diperbolehkan dimasukkan ke dalam lingkungan.

Lokal
Metode pencegahan yang mampu mengurangi emisi polutan dalam gas buang yang dikeluarkan cerbong, dari pusat pembangkit listrik dan industri lainnya yang membakar batu bara (clean coal technology), yaitu :
1. Fluidised Bed Combustion (FBC)
* suhu operasinya 7500C - 9500C
* emisi NOx dikurangi hingga 33 %
2. Flue Gas Desulfurization (FGD)
* SO2 bereaksi dengan air membentuk asam sulfat (H2SO4).
* Asam sulfat direaksikan dengan Ca(OH)2 diperoleh gipsum
sintetik
3. Electron Beam Machine (EBM)
Gas buang yang mengandung polutan sulfur dan nitrogen diiradiasi dengan berkas elektron dalam suatu tempat yang mengandung gas amonium sulfur nitrogen sehingga berubah menjadi ammonium sulfat dan amonium nitrat. Kedua senyawa ini dapat dimanfaatkan sebagai bahan baku pupuk sulfat dan pupuk nitrogen (dalam bentuk kristal).







Kategori titik pemantauan
• Titik pemantauan deposisi asam
– Pemantauan deposisi basah dan dep. kering
– 3 klas : urban, rural dan remote
• Titik survei/pemantauan ekologi
– Pemantauan tanah dan tumbuhan, air permukaan
– 2 klas : basic survey dan ecosystem analysis

Tujuan dan kriteria pemilihan titik pemantauan deposisi asam
• Urban Site
– Melihat kondisi deposisi asam di kawasan perkotaan
– Data untuk evaluasi dampak deposisi asam terhadap bangunan, monumen bersejarah atau kesehatan manusia
– Lokasi di kawasan perkotaan dan industri serta perbatasan perkotaan
• Rural Site
– Melihat kondisi deposisi asam di kawasan pedesaan
– Data untuk evaluasi dampak deposisi asam terhadap hasil pertanian, hutan, dll
– Lokasi lebih dari 20km dari sumber polusi besar seperti kota, pembangkit listrik dan jalan tol
• Remote Site
– Melihat kondisi deposisi asam di kawasan terpencil
– Data untuk evaluasi ‘long-range transport’ dan model deposisi.
– Lokasi > 50km dari sumber polusi besar seperti kota, pembangkit listrik dan jalan tol dan min 500 m dari jalan utama (> 500 kendaraan perhari)

Tujuan dan kriteria pemilihan titik pemantauan ekologi
• Basic Survey Site
– Pengumpulan data dasar untuk tanah, hutan dan air permukaan’
– Lokasi disekitar lokasi pemantauan deposisi asam
• Ecosystem Analysis Site
– Melihat dampak deposisi asam terhadap ekosistem bumi
– Lokasi di kawasan yang sensitif terhadap perubahan keasaman atmosfir

Jumlah titik pemantauan
• Deposisi basah dan deposisi kering
– 20 remote
– 11 rural
– 19 urban
• Tanah dan tumbuhan
– 26 titik di 18 area
• Air permukaan
– 17 titik