Industrial Waste Water Quality Standard Abu Khairul Bashar, Department of Environmental Sciences, Jahangirnagar University, Savar, Dhaka-1342
Introduction Water is a transparent fluid which forms the world's streams, lakes, oceans and rain, and is the major constituent of the fluids of living things. As a chemical compound, a water molecule contains one oxygen and two hydrogen atoms that are connected by covalent bonds. Water is a liquid at standard ambient temperature and pressure, but it often co-exists on Earth with its solid state, ice; and gaseous state, steam (water vapor).Water covers 71% of the Earth's surface. It is vital for all known forms of life. On Earth, 96.5% of the planet's water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Only 2.5% of the Earth's water is freshwater, and 98.8% of that water is in ice and groundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth's freshwater (0.003%) is contained within biological bodies and manufactured products. Wastewater is liquid waste discharged by domestic residences, commercial properties, industry, agriculture, which often contains some contaminants that result from the mixing of wastewater from different sources. Based on its origin wastewater can be classed as sanitary, commercial, industrial, agricultural or surface runoff. Term wastewater need to be separated from the term sewage, sewage is subset of wastewater that is contaminated with feces or urine though many people use term sewage referring to any waste water. Water Standard can provide a reliable supply of process water for constructionsite demands, with flexible contract durations to meet short or long term needs. Almost every industrial process requires water and water demand grows in parallel with increases in the global industrial base. These sectors include power generation, refineries, construction, agriculture, metals and mining. In these sectors, large volumes of treated water are involved in the production process. Companies are increasingly evaluating their water footprint and ways to access, utilize and reuse water more efficiently. For application in industrial sectors, Water Standard’s mobile and power independent vessel-based solutions provide a reliable and cost-competitive alternative, capable of meeting water quality and quantity needs as a site-specific or regional solution. Water Standard can comply with varing water quality and quantity requirements and has the ability to ramp up or down to meet fluctuations in water demand. Water Standard also has the design and operational flexibility to meet a construction site’s wastewater treatment requirements. Water Standard can also design to provide a construction site with additional power, if needed.
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Sources of Industrial Wastewater Iron and Steel industry: The production of iron from its ores involves powerful reduction reactions in blast furnaces. Cooling waters are inevitably contaminated with products especially ammonia and cyanide. Production of coke from coal in coking plants also requires water cooling and the use of water in by-products separation. Contamination of waste streams includes gasification products such as benzene, naphthalene, anthracene, cyanide, ammonia, phenols, cresols together with a range of more complex organic compounds known collectively as polycyclic aromatic hydrocarbons (PAH).The conversion of iron or steel into sheet, wire or rods requires hot and cold mechanical transformation stages frequently employing water as a lubricant and coolant. Contaminants include hydraulic oils, tallow and particulate solids. Final treatment of iron and steel products before onward sale into manufacturing includes pickling in strong mineral acid to remove rust and prepare the surface for tin or chromium plating or for other surface treatments such as galvanization or painting. The two acids commonly used are hydrochloric acid and sulfuric acid. Wastewaters include acidic rinse waters together with waste acid. Although many plants operate acid recovery plants (particularly those using hydrochloric acid), where the mineral acid is boiled away from the iron salts, there remains a large volume of highly acid ferrous sulfate or ferrous chloride to be disposed of. Many steel industry wastewaters are contaminated by hydraulic oil, also known as soluble oil.
Mines and Quarries: Mine wastewater effluent in Peru, with neutralized pH from tailing runoff. The principal waste-waters associated with mines and quarries are slurries of rock particles in water. These arise from rainfall washing exposed surfaces and haul roads and also from rock washing and grading processes. Volumes of water can be very high, especially rainfall related arising’s on large sites. Some specialized separation operations, such as coal washing to separate coal from native rock using density gradients, can produce wastewater contaminated by fine particulate haematite and surfactants. Oils and hydraulic oils are also common contaminants. Wastewater from metal mines and ore recovery plants are inevitably contaminated by the minerals present in the native rock formations. Following crushing and extraction of the desirable materials, undesirable materials may become contaminated in the wastewater. For metal mines, this can include unwanted metals such as zinc and other materials such as arsenic. Extraction of high value metals such as gold and silver may generate slimes containing very fine particles in where physical removal of contaminants becomes particularly difficult.
Food Industry: Wastewater generated from agricultural and food operations has distinctive characteristics that set it apart from common municipal wastewater managed by public or private sewage treatment plants throughout the world: it is biodegradable and nontoxic, but that has high concentrations of biochemical oxygen demand (BOD) and suspended solids (SS).[1] The constituents of food and agriculture wastewater are often complex to predict due to the differences in BOD and pH in effluents from vegetable, fruit, and meat products and due to the seasonal nature of food processing and post harvesting. Processing of food from raw materials requires large volumes of high grade water. Vegetable washing generates waters with high loads of particulate matter and some dissolved organic matter. It may also contain surfactants.
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Animal slaughter and processing produces very strong organic waste from body fluids, such as blood, and gut contents. This wastewater is frequently contaminated by significant levels of antibiotics and growth hormones from the animals and by a variety of pesticides used to control external parasites. Insecticide residues in fleeces is a particular problem in treating waters generated in wool processing. Processing food for sale produces wastes generated from cooking which are often rich in plant organic material and may also contain salt, flavorings, coloring material and acids or alkali. Very significant quantities of oil or fats may also be present.
Pulp and Paper Industry: Effluent from the pulp and paper industry is generally high in suspended solids and BOD. Standalone paper mills using imported pulp may only require simple primary treatment, such as sedimentation or dissolved air flotation. Increased BOD or chemical oxygen demand (COD) loadings, as well as organic pollutants, may require biological treatment such as activated sludge or up flow anaerobic sludge blanket reactors. For mills with high inorganic loadings like salt, tertiary treatments may be required, either general membrane treatments like ultrafiltration or reverse osmosis or treatments to remove specific contaminants, such as nutrients.
Complex Organic Chemicals Industry: A range of industries manufacture or use complex organic chemicals. These include pesticides, pharmaceuticals, paints and dyes, petrochemicals, detergents, plastics, paper pollution, etc. Waste waters can be contaminated by feedstock materials, by-products, product material in soluble or particulate form, washing and cleaning agents, solvents and added value products such as plasticizers. Treatment facilities that do not need control of their effluent typically opt for a type of aerobic treatment, i.e. aerated lagoons.
Nuclear Industry: The waste production from the nuclear and radio-chemicals industry is dealt with as radioactive waste.
Water Treatment: Many industries have a need to treat water to obtain very high quality water for demanding purposes. Water treatment produces organic and mineral sludges from filtration and sedimentation. Ion exchange using natural or synthetic resins removes calcium, magnesium and carbonate ions from water, replacing them with hydrogen and hydroxyl ions. Regeneration of ion exchange columns with strong acids and alkalis produces a wastewater rich in hardness ions which are readily precipitated out, especially when in admixture with other wastewater.
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Water Standards Some of the main parameters listed in the water quality discharge standards are briefly discussed here to give a working knowledge of what they are and why they are important. Colour: Although colour is not included in the Environment Conservation Rules (1997), it is an issue in dye house effluent because unlike other pollutants it is so visible. Reducing colour is therefore important for the public perception of a factory. Consequently, international textile buyers are increasingly setting discharge standards for colour. However, as a health and environmental issue colour is less of a concern than many of the other parameters. BOD and COD: Measurement of the oxidisable organic matter in wastewater is usually achieved through determining the 5-day biological oxygen demand (BOD), the chemical oxygen demand (COD) and total organic carbon (TOC). BOD is a measure of the quantity of dissolved oxygen used by microoganisms in the biochemical oxidation of the organic matter in the wastewater over a 5-day period at 20 C. The test has its limitations but it still used extensively and is useful for determining approximately how much oxygen will be removed from water by an effluent or how much may be required for treatment and is therefore important when estimating the size of the ETP needed. COD is often used as a substitute for BOD as it only takes a few hours not five days to determine. COD is a measure of the oxygen equivalent of the organic material chemically oxidised in the reaction and is determined by adding dichromate in an acid solution of the wastewater. TDS and TSS: Wastewater can be analyzed for total suspended solids (TSS) and total dissolved solids (TDS) after removal of coarse solids such as rags and grit. A sample of wastewater is filtered through a standard filter and the mass of the residue is used to calculate TSS. Total solids (TS) is found by evaporating the water at a specified temperature. TDS is then calculated by subtracting TSS from TS. Metals: A number of metals are listed in the national environmental quality standards for industrial wastewater, including cadmium, chromium, copper, iron, lead, mercury, nickel and zinc. Many metals, which are usually only available naturally in trace quantities in the environment, can be toxic to humans, plants, fish and other aquatic life. Phosphorus, Total Nitrogen, Nitrate and Ammonia. These parameters are all used as a measure of the nutrients present in the wastewater, as a high nutrient content can result in excessive plant growth in receiving water bodies, subsequent oxygen removal and the death of aquatic life. pH: pH is a measure of the concentration of hydrogen ions in the wastewater and gives an indication of how acid or alkaline the wastewater is. This parameter is important because aquatic life such as most fish can only survive in a narrow pH range between roughly pH 6-9. Sulphur and Sulphide: Textile dyeing uses large quantities of sodium sulphate and some other sulphur containing chemicals. Textile wastewaters will therefore contain various sulphur 4
compounds and once in the environment sulphate is easily converted to sulphide when oxygen has been removed by the BOD of the effluents. This is a problem because hydrogen sulphide can be formed which is a very poisonous gas, it also has an unpleasant smell of rotten eggs. The presence of sulphides in effluents can interfere with biological treatment processes. Oil and Grease: This includes all oils, fats and waxes, such as kerosene and lubricating oils. Oil and grease cause unpleasant films on open water bodies and negatively affect aquatic life. They can also interfere with biological treatment processes and cause maintenance problems as they coat the surfaces of components of ETPs. Source: Schedule Âą10, Rule-13, Environment Conservation Rules, 1997 (Page 3132 - 3134 of the Bangladesh Gazette of 28 August 1997)
SI. NO.
Parameter
Unit
Inland Surface Water
Irrigable Land
50
Public Sewer From Secondary Treatment Plant 75
Ammonia cal nitrogen (as elementary N) Ammonia (as free ammonia)
mg/l
mg/l
5
0.05
0.2
Arsenic (as As)
mg/l
0.2
0.05
0.2
BOD at 20 C
mg/l
50
250
100
Boron
mg/l
2
2
2
Cadmium (as Cd)
mg/l
0.05
0.5
0. 5
Chloride
mg/l
600
600
600
Chromium (as total Cr)
mg/l
0.5
0.1
0.1
COD
mg/l
200
400
400
Chromium (as hexavalent Cr)
mg/l
0.5
1
1
5
75
Copper (as Cu)
mg/l
0.5
3
3
Dissolved oxygen (DO)
mg/l
4.5-8
4.5-8
4.5-8
(EC)
mg/l
1200
1200
1200
Total dissolved solids
mg/l
2100
2100
2100
Flouride (as F)
mg/l
2
15
10
Sulfide (as S)
mg/l
1
2
2
Iron (as Fe)
mg/l
2
2
2
Total kjeldahl nitrogen (as N)
mg/l
100
100
100
Lead (as Pb)
mg/l
0.1
1
0.1
Manganese (asMn)
mg/l
5
5
5
Mercury (as Hg)
mg/l
0.01
0.01
0.01
Nickel (as Ni)
mg/l
1
2
1
Nitrate (as elementary N)
mg/l
10
-
10
Oil and grease
mg/l
10
20
10
Phenolic compounds (as C5 H5 OH) Dissolved phosphorus (as P)
mg/l
1
5
1
mg/l
8
8
15
Radioactive substance
mg/l
-
-
-
6-9
6-9
6-9
0.05
0.05
0.05
pH mg/l Selenium (as Se)
mg/l 6
Zinc (as Zn)
mg/l
5
10
10
Total dissolved solids
mg/l
2100
2100
2100
Temperature
mg/l
40
40
40
Suspended solids
mg/l
150
500
200
Cyanide (As Cn)
mg/l
0.1
2
0.2
Table-1: Bangladesh Standards for Industrial Project Effluent according to EQSB of DOE
Industrial Wastewater Quality Standard 6 5 4
3 2 1 0 Category 1
Category 2 Series 1
Category 3 Series 2
Category 4
Series 3
Chart-1: Inland Surface Water, Public Sewer from Secondary Treatment Plant and Irrigable Land
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Source: Arsenic Filters for Groundwater in Bangladesh: Toward a Sustainable Solution Author: Abul Hussam, Sad Ahamed, and Abul K.M. Munir Constituent
EPA (MCL)
WHO Guideline Bangladeshi Standard
Arsenic (total) – g/L Arsenic (III) – g/L Iron (total) – mg/L pH Sodium – mg/L Calcium – mg/L Manganese – mg/L Aluminum – mg/L Barium – mg/L Chloride – mg/L Phosphate – mg/L Sulfate – mg/L Silicate – mg/L
10 0.3 6.5–8.5 0.5 0.05–0.2 2.0 250 -
10 0.3 6.5–8.5 200 0.1–0.5 0.2 0.7 250 -
50 0.3 (1.0) 6.5–8.5 75 (200) 0.1 (0.5) 0.1(0.2) 1.0 200 (600) 6 100 -
Table-2: Water Quality of EPA, World Health Organization (WHO), and Bangladeshi Standards.
Industrial Waste Water Standards Series 1
Series 2
Series 3
6 5 4
5 4.3
4.5
4.4 3.5
3 2
3 2.4 2
2.5
Category 1
Category 2
2
2.8
1.8
1 0 Category 3
Category 4
Chart-2: EPA, World Health Organization (WHO), and Bangladeshi Standards
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Conclusion Wastewater, otherwise known as effluent, as a bi-product of their production. The effluent contains several pollutants, which can be removed with the help of an effluent treatment plant (ETP). The “clean” water can then be safely discharged into the environment. In Bangladesh due to textile dyeing industries, the main negative impact afflicting the local environment severely is the hazards caused by dye effluents, which contain both chemical and organic pollutants. These can be highly toxic. This Research has found that the volume of such effluents often exceeds acceptable standards. Though the volume of effluents from individual small-scale dyers might be small, the concentration of pollutants is generally high. The impact is significant where several producers are located at one place and discharge effluents into the same body of water. Large-scale dyers on the other hand generate greater volumes of effluent but show lower pollutant content per cubic meter of water. The results of the study reveal that, the textile dyeing industries discharge large quantities of effluent composed of various physicochemical pollutants at significant higher level than standard value of DOE except some industries which have authentic waste water treatment plant. From the above findings it can be easily said that, the water of Turag and Shitalakkhya River is getting highly polluted by the effluent discharged by the dyeing industries of the study area. The concentration of these pollutants is increasing in an alarming rate with the increasing number of textile dyeing industries. So the above mitigation measures can be effective to minimize the pollution to a significant extent. Last of all, for the greater benefits of our country, all people involved in textile dyeing should be environmentally conscious to preserve our environment as well as to carry the reputation of our readymade garments in developed countries.
References
www.Wikipedia.com Amio Water Treatment Limited, 2010. Textile Dyeing Industries in Bangladesh for Sustainable Development by M. M. Islam, K. Mahmud, O. Faruk, and M. S. Billah Choosing an Effluent Treatment Plant by M. Akhtaruzzaman, Alexandra Clemett, Jerry Knapp, Mahbubul A. Mahmood, Samiya Ahmed. Government of the People’s Republic of Bangladesh, National Policy for Safe Water Supply & Sanitation 1998 Local Government Division, Ministry of Local Government, Rural Development and Cooperatives Government of the People’s Republic of Bangladesh (2000), The Environment Conservation Rules 1997, (unofficial translation), Ministry of Environment and Forests, Dhaka. Metcalf and Eddy (2003) Wastewater Engineering Treatment and Reuse McGraw - Hill, New York.
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Nicolaou M. and Hadjivassilis I. (1992), Treatment of wastewater from the textile industry, Water Science and Technology , Vol. 25, No. 1, pp s
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