29-08-2013, 04:21 PM
EFFLUENT QUALITY ANALYSIS OF DIFFERENT INDUSTRIES
EFFLUENT QUALITY.docx (Size: 229.24 KB / Downloads: 162)
ABSTRACT
The present work is undertaken with a view to study the nature of effluents from different industries and hence to make a comparison of the quality of effluent water. The samples were collected in the month (February to July) year 2011 from the different industries, like (Pharmaceutical Industries, Diary Industries, Food Industries, Hotel & Restaurant, Electroplating Industries and Slaughter House) and physico-chemical parameters were analyzed to assess the pollution load.
The results were compared with ISI standard. Hourly effluent samples were collected for an 8-h period three times per week for analysis of the principal parameters determined were: Temperature, Turbidity, pH, Electrical conductivity (EC), color, Total dissolved solids (TDS),Total suspended solids (TSS) Chemical oxygen demand (COD),Biochemical Oxygen demand(BOD), Phosphate, Nickel ,Sulphate, Oil & Grease, metals (Chromium (Cr), iron (Fe), zinc (Zn), lead(Pb), Cadmium).Using the Standard Methods for the Examination of Water and Wastewater. Measured all the parameters of the effluents were higher the required permissible limits of specified by the Beauro of Indian Standard. Results also indicate that is high pollution load for the effluents from electroplating industries .
INTRODUCTION
Overview
Environmental pollution with metal perhaps being with the discovery of fire and gradually aggravated to its present alarming level with industrial development and advancement of society. Rapid urbanization and industrialization has led to increased disposal of heavy metal radio nucleotide into the environment (Niyogi et al, 1998).A remarkable increase in use of heavy metals over the past few decades has inevitable redacted in an increased flux of metallic substance concern because of their known accumulation in the food chain and resistance in nature (N.R. Bishnoi, M. Bajaj and N. Sharma). Heavy metal such as nickel, copper, zinc, chromium, Lead, cadmium in waste water are hazardous to the environment. The heavy metals are generated from electroplating, cool burning industries, refining, insecticides, fungicides and iron and steel producing industries. According to IS: 2296-1974 the maximum permissible limit of copper in inland surface water used for public water supply and bathing is 10 mg/l and according to IS: 3306-1976 and IS: 7968-1976, tolerance limit of Cu for industrial effluent discharge is 3.0mg/l. Water contains a variety of physical, chemical and biological substances, which are either dissolved or suspended in it. The untreated effluent water usually contains numerous pathogenic microorganisms and nutrients that can stimulate the growth of aquatic plants Effluent components are much higher than the WHO and ISI prescribed permissible limits. So the industrial effluent are completely treated, and then discharged into sewage or land or drain. The present work is undertaken with a view to study the nature of effluents from different industries and hence to make a comparison of the quality of effluent water.
Industrial description and practices
Electroplating processes involves the deposition of a thin protective layer onto a prepared metal surface using electrochemical processes. The process involves pretreatment and other preparation, planting, rising, passivizing and drying. The cleaning and pretreatments stages involve a variety of solvents and surface stripping agents, including caustics soda and a range of strong acids, depending on the metal surface to be plated (Noor Hisham). The use of halogenated hydrocarbon for degreasing is not necessary, as water based system are available. In the plating process, the object to be plated is usually used as the cathode in an electrolytic bath. Plating solution are acid or alkaline and may contain complexion agent such as cyanide (Patterson james W. 1985)
Waste Characteristics:
Any or all of the substance used in electroplating (such as acidic solution, toxic metal, solvent and cyanides) can be found in the waste water, either via rinsing of the product or from spilling and dumping of process baths. The solvents and vapors from hot plating baths result in elevated level of volatile organic compound (VOCs) and, in some cases, volatile metal compound, which may contain chromate. Approximately 30% of the solvents and degreasing agents used can be released as VOCs (CushnieG.C.Jr. 1985).the mixing of cyanide and acidic waste water can generate lethal hydrogen cyanide gas. The overall waste water stream of electroplating industry contains heavy metal including, cadmium, chrome, lead, copper, zinc, and nickel, and cyanide, fluorides, and oil and grease, all of which are process dependent. Air emissions may contain toxic organics such as trichloroethylene and trichloroethane. Cleaning or changing of process tanks and treatment of waste water can generate substance qualities of wet sludge containing high level of toxic organics or metals.
Health Effects of Pollutants on Different Parameters of Water Quality:
1. Colour:
As the colorless pure water travels through nature, it becomes colored by various impurities. (Manganese oxides colour the water brown or black and iron oxides give it reddish tings). The tannins, humic acid etc. present in the organic debris (leaves, wood, weeds etc.) impart a yellowish brown colour to water as it comes in contact with them.
Water also acquires colour when textile and dyeing operation, food processing units, mining, paper production, animal slaughter houses etc. discharge their waste effluents into water bodies. Objectionably coloured water is aesthetically unacceptable and unsuitable for bathing, laundering, beverage manufacturing, food processing etc.
2. Taste and Odour:
The causative agents that impact perceptible taste and odour to water include minerals, metals, soil salts, iron, manganese, phenols, free chlorine, unsaturated hydrocarbons, hydrogen sulphide and end products from biological reaction.
Water tastes bitter when contaminated with alkaline impurities and salty when the impurities are metallic salts.
Biological decomposition of organic debris imparts a characteristics taste and odour of rotten eggs which is mainly due to hydrogen sulphide. Growth of algae, micro-organisms, hydrogen sulphide and ammonia give an obnoxious odour to water making it unfit for use.
The unpleasant taste and odour is aesthetically unacceptable through it may not pose any serious threat to health.
3. Temperature:
Water is use for dissipation of waste heat in power plant and industries. this heated water is subsequently discharge into water bodies where it has deleterious effect on the aquatic life. Increased temperature of water has the following impact
1. Biological activity increases with increase in temperature (double with an increase of 10C).
2. Some aquatic organisms die due to increased temperature (e.g. cold water fishes like trout’s).
3. The oxygen saturation percentage decreases and, therefore, the dissolved oxygen level (DO level) is reduced. Low DO level coupled with high temperatures result in increasing the metabolic activity of micro-organism thereby resulting in the reduction in the availability of oxygen leading to anaerobic conditions.
4. The toxicity of chemical pollutant increases in temperature.
5. Growth of algae is accelerated and becomes problematic when the algal cells cluster to form mats.
Health Effect of Chromium:
Chromium is present in the effluent primary in the form it’s trivalent [Cr (III)] and hexavalent [Cr (IV)] plays a vital role in insulin metabolism as the glucose tolerance factor (GTF). Supplementation of Cr (III) has improved the glucose tolerance in diabetes, malnourished children and elder people. Te lethal dose -50 values for Cr-(III) 10mg/kg of body weight (Kothamdaraman& Swaminathan, 1997). Cr (IV) is highly soluble and about 300 times more toxic than Cr (III) (Armienta et al, 2001). It causes liver and kidney damage, internal hemorrhage, dermatiesrespiratory damage and lung cancer. The long term exposed to the respiratory tract and skin can produce perforated and ulcerated nasal septa,in Flammarion of the nasal passage, frequent nasal bleeds and skin ulcers (Harie et al.,1993). It also damages DNA through through interference with DNA-polkymerase enzyme and free radical formation (Athar and Vohora, 1995).
Plating waste as a source of heavy metals:
Metals after being fabricated into the appropriate sizes and shapes to meet customer’s specifications are finished to final product requirement. Finishing usually involves stripping, removal of undesirable oxides, cleaning and plating. In plating the metal to be plated acts as the cathode while the plating metal in solution serves as the anode, the total liquid wastes are not voluminous; nevertheless they are important sources of pollution because of the extreme toxic nature of the constituents. The most important toxic contaminants are acids and metals, such as chromium, zinc, copper, nickel, tin and the highly dangerous cyanides. In general, the tolerance limits of such wastes are considerably lower than with the organic type of pollution.
Heavy metals and their toxicity:
Heavy metals (s) are widespread pollution of great environmental concern as they are non-degradable and thus persistent (Stratton, 1987). Natural or background levels of most of the metals in seawater , drinking water , plants and animal sure usually very low detectable only by highly sophisticated instrumental and methodologies . But when metal are also released into the environmental by anthropogenic activities such as burning of fossil fuels, discharge of industrial effluents mining and such other actions it leads to the development of higher then tolerable or toxic level of mental in environmental. Once this happens metals pollution sets in. this is what happened at Minamata Bay and in the episodes of itai-itai or genu velgum. In all the three cases, the offending mental-Hg Cd and Mb respectively were already there but in so low concentration as to be harmless.
Methods for Metal removal:
Major objectives for the removal of metals from aqueous solutions are (a) toxicity removal, which entails an environmental aspect and (b) recovery of valuable metals, which involves a technological aspect. Various methods including the conventional ones are available for heavy metal waste management. The commonly used conventional methods include precipitation, ion exchange, adsorption, reverse osmosis, electro dialysis, evaporation, foam flotation, liquid membrane techniques, solvent extraction and crystallization etc. for heavy metal removal. Various techniques used for metal removal recovery are listed. However major shortcoming of the conventional treatment includes.
Sampling of Industrial effluent (waste water):
Sampling of water for physical or chemical testing can be done by several methods, depending on the accuracy needed and the characteristics of the contaminant. Many contamination events are sharply restricted in time, most commonly in association with rain events. For this reason "grab" samples are often inadequate for fully quantifying contaminant levels. Scientists gathering this type of data often employ auto-sampler devices that pump increments of water at either time or discharge intervals.
Sampling for biological testing involves collection of plants and/or animals from the surface water body. Depending on the type of assessment, the organisms may be identified for biosurveys (population counts) and returned to the water body, or they may be dissected for bioassays to determine toxicity.
Planning for sampling:
For planning the sampling, several basic aspects must be understood and appreciated. The various process steps of sampling starting from the point source i.e. where the sampling is to be done to the delivery point i.e. where the sampling would be examined, should include the planning related to the type of sources as also the type of water and variety of parameters for which sampling is to be done including the self-life, logistics etc. of the sample.
CONCLUSION
Recommendations:
Major objectives for the removal of metals from aqueous solution are as follows:
(a) Toxicity removal, which entail an environmental aspect and
(b) Recovery of valuable metals, which involves a technological aspect. Various methods including the conventional ones are available for heavy metal waste management. The commonly used conventional method include bioremediation by algae, bioremediation by bacteria, bioremediation by fungi, ion exchange, adsorption, reverse osmosis, Electro dialysis, Evaporation, foam floatation, Liquid membrane techniques, Solvent extraction and Crystallization etc. for heavy metal removal.