IJCRR - 4(15), August, 2012
Pages: 67-74
Date of Publication: 15-Aug-2017
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ANALYSIS OF ELECTROPLATING INDUSTRIAL EFFLUENT WITH REFERENCE TO CHROMIUM COMPOSITION
Author: Seema Tharannum, Krishnamurthy V., Riaz Mahmood
Category: Technology
Abstract:Heavy metal pollution of soil and wastewater is an important environmental issue. The industries like tannery and electroplating are the main source of chromium pollution in India. They are required to comply with the regulations of the Central Pollution Control Boards and concerned State Pollution Control Boards. Thus, our present study contributes towards physicochemical studies and analysis of chromium content using Atomic Absorption Spectrophotometry (AAS) in the effluent released by electroplating industries in 4 different seasons specified by met office of a year to help in the understanding of pollution effects. Study reveals that the effluents from these industries contain Cr (VI) at concentrations ranging from tens to hundreds to thousands of mg/l and unfavorable levels of TSS, TDS, BOD and COD. There are standard values set by Pollution control Board for industrial effluent to be discharged on different types of land. Industrial effluent quality exceeding these specifications is thus harmful. It may cause biochemical effects, such as inhibition of enzymes, metabolic disorders, genetic damage, hypertension and cancer. Microbial load was also studied by enrichment technique which can further be applied for study of potential remediation of chromium.
Keywords: Atomic Absorption Spectrophotometry, chromium, Electroplating Industries, Industrial effluent, Pollution.
Full Text:
INTRODUCTION
Heavy metal chromium is one among the top metal pollutant. The sources of chromium pollution include effluents from leather tanning, chromium electroplating industries. These industries in India are required to comply with the regulations of the Central Pollution Control Boards and concerned State Pollution Control Boards. Using government subsidies, the industries have built numerous Common Effluent Treatment Plants (CETPs) to treat the toxic wastewater or effluent. Despite this effort, many of the pollution problems are still exist. Several analyses studies have revealed high concentrations of chromium even in so called treated effluents. The majority of chemicals discharged eventually end up in sediments that may act as major source of pollution. Sediments are ecologically important components of the aquatic habitat. The other major issue being, entering into ground water there after contaminating the drinking water. As the world progress with industries, the pollution of the environment with toxic heavy metals is spreading all way through. Petrochemical industries, mining activities, agricultural run off, industrial and domestic effluents are mainly responsible for the increase of the xenobiotic especially metallic species released into the environment. Improper disposal of hazardous and toxic wastes can cause serious damage to both health and environment. Recalcitrant or Xenobiotics are man made compounds that are of major concern. In contrast to toxic organics, that can be degraded, the metallic species released into the environment tend to persist indefinitely, thereby accumulating in living tissues throughout the food chain. Heavy metal pollution of soil and wastewater is a an important environmental issue (Cheng, 2003).Wastewaters from the industries and sewage sludge applications have permanent toxic effects to human aswell the environment (Rehman et al., 2008).The effluent released from electroplating industries contains higher concentration of total dissolved solids, phenols, chlorides, chromium and other heavy metals, etc. Heavy metal chromium is one among the top 5 metal pollutant. Heavy metal chromium is the second most common contaminant of ground water at hazardous waste sites. Major sources of chromium pollution include effluents from leather tanning, chromium electroplating, wood preservation, alloy preparation and nuclear wastes due to its use as a corrosion inhibitor in nuclear power plants (Thacker, U, et.al, 2006). Chromium can exist in multiple valence states, Hexavalent chromium Cr (VI) and trivalent chromium Cr (III) are the most prevalent species of chromium in the natural environment (Cantle, J. E, 1982). Trivalent Cr is ubiquitous in the environment and occurs naturally, while almost all known sources of Cr (VI) are derived from human activities. Trivalent Cr found in the environment is typically found as insoluble crystalline or para crystalline compounds such as Cr (OH) 3, and Cr2O3 .In contrast, Cr (VI) is highly mobile and is considered acutely toxic, although its occurrence is rare in nature. Chromium has been recognized as an essential microelement for animals and humans, potentiating the action of insulin and therefore being effective in carbohydrate and lipid metabolism (Ducros, 1997). On the other hand, recent works point to the severe toxicity of Cr (VI), with respect to human health. Indeed, hexavalent chromium is known to be a skin irritant and to induce allergic contact dermatitis and is considered a class ?A‘ human carcinogen by inhalation (James et al., 1997). The reduced form, Cr (III), is considered to have low acute and chronic toxicity, mostly because of the demonstrated low capacity to penetrate animal cells. Many metals accumulate to high concentration in the surface layer of soils irrigated with sewage sludge of sewage/industrial effluents. World health organization recommended the maximum allowable concentration of 0.05mg/L in drinking water for chromium VI. It is same with Indian Standard Institution. With reference to Central pollution control board, the allowable chromium concentration in effluents is 2.0-5.0 mg/L. With reference to the updated official list of registered factories of 2008 under Karnataka state factories act obtained from the office of dept of boilers and factories, Karmika Bhavana, Bangalore, Industries such as electroplating and tanneries in India are required to comply with the regulations of the Central Pollution Control Boards and concerned State Pollution Control Boards. Using government subsidies, the industries have built numerous Common Effluent Treatment Plants (CETPs) to treat the toxic wastewater or effluent. Despite this initiative, many of the pollution problems are still unresolved. The major components of the electroplating effluents are the toxic trace metal that is chromium. Several analyses reveal high concentrations of chromium even in so called treated effluents. The majority of chemicals discharged through the effluent into aquatic system eventually end up in sediments that may act as major source of pollution. Thus, study of effluent released by industries and the sediment helps in the understanding of pollution effects.
MATERIALS AND METHODS
Sampling location
Sampling area is in Bangalore which is located at a lat. of 12 º 58´ N and longitude of 77 º 35´ E at an altitude of 921 m above mean sea level (Shivashankara, 1999). Sampling area identified is the Peenya industrial complex established in early 1970‘s is the biggest and one of the oldest industrial estates in the whole of Southeast Asia, located at the northern part of the Bangalore city, Karnataka, India (Fig 1). The area spread over 40 sq kms comprising about 4000 small scale industries and few medium scale industries is one of the biggest industrial areas in the country as well as in Southeast Asia. Peenya industrial area hosts maximum industries, majority of them are electroplating industries. 52 registered factories of electroplating industries are considered for study.
Sample collection
Based on the number of employees, they have been categorized into 3 groups 50 and >100. 10% of each category will all together make up to 5 no‘s. Hence 5 factories are selected. With respect to 4 seasons of a year 2010 obtained from met office, Bangalore [Winter season (Jan-Feb), Pre monsoon (Mar-May), Southwest monsoon ( June-Sep ), Northwest monsoon (Oct-Dec)], Sampling was carried out for one year that is in Jan, April, July and Nov 2010, covering all the four seasons. Hence a total of 4 seasonal samples from 5 industries i.e. 20 samples in triplicates were collected and analyzed for chromium concentration using Atomic absorption Spectrophotometry. The effluent samples of around 1000ml volume from outlets of electroplating industries were collected in autoclaved linear polyethylene containers of 1L capacity with polyethylene cap, labeled properly. 100ml of the samples were preserved immediately by acidifying with conc. Nitric acid (1.5ml Conc. /L sample) and stored at 4? C for further analysis.
Sample analysis
Physico-chemical analysis of effluents:
The physiochemical characteristics of effluents like color, odor, pH, Total Suspended Solids, Total Dissolved Solids, BOD and COD values were immediately measured in the laboratory (Standard methods for the examination of water and waste water, APHA, 2005).
Chromium analysis
The other analysis is heavy metal chromium analysis by AAS for which digestion with nitric acid is the preliminary step. Around 50 ml volumes of the effluent samples in evaporating dishes were taken and acidified with conc. Nitric acid. Further 5 ml of conc. Nitric acid was added and evaporated to 10 ml. Then it was transferred to a 125ml conical flask. 5ml of conc. nitric acid and 10ml HClO4 (70%), per chloric acid (70%) were added and heated gently till white dense fumes of HClO4 appear. The digested samples were cooled at room temp, filtered through whatman no.41 or sintered glass crucible and finally the volume was made upto 100ml with distilled water. Then this solution was further boiled to remove oxides of N and Cl. The solution was then used for the analysis of chromium heavy metal using AAS by flame using air acetylene gas (Cantle, J. E., 1982). The next step is Analysis of chromium by Atomic Absorption Spectrophotometry; Atomic absorption spectrophotometer provides accurate quantitative analyses for metals in water, sediments, soils or rocks. Atomic absorption units have 4 basic parts: Interchangeable lamps that emit light with element, specific wavelengths, sample aspirators, aflame or furnace apparatus for volatizing the sample and a photon detector. In order to analyze any metal, a halo cathode lamp is chosen that produces a wavelength of light that is absorbed by the element. Sample solutions are aspirated into the flame. If any ions of the given element are present in the flame, they will absorb light produced by the lamp and then reaches the detector. The amount of light absorbed depends on the concentration of the element or metal present in the sample. Absorbance values for unknown samples are compared to calibration curves prepared by analyzing known samples. The atomic absorption spectrophotometer ( chemito AA201), with glass flow meters with the operating parameters and working range is given in
Table 1.
Bacteriological analysis
Luria Bertani broth and agar supplemented with chromium concentration of 100 ppm using potassium dichromate was used for enrichment of the microbes, samples were inoculated into broth first and incubated at 30 deg C overnight and then spread plated on to LB agar plates which were further incubated at 30 deg C for 48 hours and the colonies were counted .The pure cultures of isolated strains were preserved by refrigerating LB agar slants as well glycerol stocks at 4 deg C and coded as PES 1- PES 10 for further use.
RESULTS AND DISCUSSION
Physico-chemical analysis of effluents In Effluent analysis, the Physico-chemical characterization of effluents was done and is presented in Table 2. Effluent color is white to grades of yellow and odorless. pH is between 3-9, these values are compared to ISI (Indian Standard Institution) standards recommended for disposal of effluent on land and are found not suitable to irrigation purpose. Total suspended solids ranged between 20-200, Total dissolved solids values being 520-5800, BOD (Biological Oxygen Demand) value is between 16-90; COD (Chemical Oxygen Demand) value lies between 91-831. Chromium analysis Heavy metal chromium analysis by AAS was performed. In the present study, chromium concentration was analyzed in the industrial effluent season wise using Atomic absorption Spectrophotometry (Chemito AA201) and is plotted in graph 1. It was found that there is considerably low or BDL (Below detection level) in industry B, while the chromium concentration was high in Industry A, C, E and D with reference to all the 4 seasons. The concentration of chromium was quite high which varied between 239 to 3156 ppm in industry D and C and moderate in Industry A and E which varied between 50.5 to 585.6 ppm. It is interesting to note that the Cr concentration is all time high during winter season and low during southwest monsoon among the five industries. Bacteriological analysis Ten different forms of the colonies were identified based on colony characterization from 20 effluent samples. 7 of them were Gram positive and 3 of them are Gram negative. Gram positive were mostly of the form bacilli and few were cocci, where as all Gram negative were bacilli. The same is recorded in graph 2.
CONCLUSION
Industrialization means more effluent release into the environment. It becomes mandatory on part of the industry to release the effluent treated by Physical, chemical or biological treatment. However, such treatment systems are not effective for removal of color, dissolved solids; trace elements etc. and thus the effluents are directly discharged into drains, public sewers, rivers, etc. Thus effluents containing heavy metals when released into the agricultural land for irrigation purpose, the heavy metal gets accumulated in soil and it in turn is available to plants and gets into plant material and then the food chain follows then to humans and thus become hazardous to human health. Overall findings indicated that industrial effluents of the major industrial areas of Bangalore city have elevated levels of chromium and the data also reveals that most of these industries are discharging heavy metals above specified limit. The result indicates that effluents contain toxic metals in a relatively high composition, thereby polluting nearby soil and groundwater. Hence it is suggested that the industries should give importance to release of effluent with prior treatment with reference to the standards. The microbial load can further be applied for study of potential remediation of chromium.
ACKNOWLEDGEMENT
We thank the management of PESIT, Bangalore, India for encouragement and research facilities and also UGC, New Delhi for financial assistance.
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