Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.75...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.76...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.77...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.78...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.79...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.80...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.81...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.82...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.83...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.84...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.85...
Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.86...
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  1. 1. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.75Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.Practical Case StudyINDUSTRIAL EFFLUENTS AND THEIR IMPACT ON WATER QUALITY OFRECEIVING RIVERS IN NIGERIAKANU, IJEOMA and ACHI, O.K.*Department of Microbiolog, Michael Okpara University of Agriculture, Umudike, PMB 7267, Abia State,Nigeria.*Corresponding Author: Phone/Fax: +23408068750963; Email: omekachi@yahoo.comReceived: 15th April 2011 Revised: 9th May 2011; Accepted: 9th May 2011Abstract: Industrial wastewaters entering a water body represent a heavy source ofenvironmental pollution in Nigerian rivers. It affects both the water quality as well as themicrobial and aquatic flora. With competing demands on limited water resources,awareness of the issues involved in water pollution, has led to considerable publicdebate about the environmental effects of industrial effluents discharged into aquaticenvironments. Industrial effluents are characterized by their abnormal turbidity,conductivity, chemical oxygen demand (COD), total suspended solids (TSS), biologicaloxygen demand (BOD), and total hardness. Industrial wastes containing highconcentration of microbial nutrients would obviously promote an after-growth ofsignificantly high coliform types and other microbial forms. Organic pollution is alwaysevident and the pollution is made worse by land-based sources such as the occasionaldischarge of raw sewage through storm water outlets, and industrial effluents fromrefineries, oil terminals, and petrochemical plants. Waste effluents rich indecomposable organic matter, is the primary cause of organic pollution. Waste watersfrom textile, brewery, food and beverages, paper, pulp and palm oil industries, thecases chosen, are believed to give a broad outline of industrial wastes as well asdisposal problems.Keywords: Industrial effluents, water quality, BOD, COD, TSSINTRODUCTIONOne of the most critical problems of developing countries is improper management of vastamount of wastes generated by various anthropogenic activities. More challenging is the unsafeISSN 2088-3218V o l u m e 1 , N u m b e r 1 : 7 5 - 8 6 , J u l y , 2 0 1 1© T2011 Department of Environmental EngineeringSepuluh Nopember Institute of Technology, Surabaya& Indonesian Society of Sanitary and Environmental Engineers, JakartaO p e n A c c e s s h t t p : / / w w w . t r i s a n i t a . o r g / j a t e sThis work is licensed under the Creative Commons Attribution 3.0 Unported License, which permitsunrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
  2. 2. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.76Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.disposal of these wastes into the ambient environment. Water bodies especially freshwaterreservoirs are the most affected. This has often rendered these natural resources unsuitable forboth primary and/or secondary usage [1].Industrial effluent contamination of natural water bodies has emerged as a major challengein developing and densely populated countries like Nigeria. Estuaries and inland water bodies,which are the major sources of drinking water in Nigeria, are often contaminated by the activitiesof the adjoining populations and industrial establishments [2].River systems are the primary means for disposal of waste, especially the effluents, fromindustries that are near them. These effluent from industries have a great deal of influence on thepollution of the water body, these effluent can alter the physical, chemical and biological nature ofthe receiving water body [3]. Increased industrial activities have led to pollution stress on surfacewaters both from industrial, agricultural and domestic sources [4].Wastes entering these water bodies are both in solid and liquid forms. These are mostlyderived from Industrial, agricultural and domestic activities. As a result, water bodies which aremajor receptacles of treated and untreated or partially treated industrial wastes have becomehighly polluted. The resultant effects of this on public health and the environment are usuallygreat in magnitude [5].Over the last years, in many African countries a considerable population growth has takenplace, accompanied by a steep increase in urbanization, industrial and agricultural land use. Thishas entailed a tremendous increase in discharge of a wide diversity of pollutants to receivingwater bodies and has caused undesirable effects on the different components of the aquaticenvironment and on fisheries [6]. As a result, there is growing appreciation that nationally,regionally, and globally, the management and utilization of natural resources need to be improvedand that the amount of waste and pollution generated by human activity need to be reduced on alarge scale.Industries are the major sources of pollution in all environments. Based on the type ofindustry, various levels of pollutants can be discharged into the environment directly or indirectlythrough public sewer lines. Wastewater from industries includes employees’ sanitary waste,process wastes from manufacturing, wash waters and relatively uncontaminated water fromheating and cooling operations [7]. High levels of pollutants in river water systems causes anincrease in biological oxygen demand (BOD), chemical oxygen demand (COD), total dissolvedsolids (TDS), total suspended solids (TSS), toxic metals such as Cd, Cr, Ni and Pb and fecalcoliform and hence make such water unsuitable for drinking, irrigation and aquatic life. Industrialwastewaters range from high biochemical oxygen demand (BOD) from biodegradable wastessuch as those from human sewage, pulp and paper industries, slaughter houses, tanneries andchemical industry. Others include those from plating shops and textiles, which may be toxic andrequire on-site physiochemical pre-treatment before discharge into municipal sewage system [8-10].Organic pollution of inland water systems in Africa, in contrast to the situation in developedcountries of the world, is often the result of extreme poverty and economic and social under-development. According to Tolba [11], it is in these countries that the quality of water, and oftenthe quantity, is lowest, sanitation and nutrition the worst and disease most prevalent.Unfortunately, there are very few water quality studies for most African inland waters. In general,the available data come from scattered investigations, which were carried out by individuals andby very few scientific projects concerned with African waters. Few reviews exist on the state ofpollution of African inland waters [12-14].
  3. 3. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.77Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.With competing demands on limited water resources, industrial pollution remains one of themajor problems facing Nigerian cities. As societies throughout the world become more aware ofthe issues involved in water pollution, there has been considerable public debate aboutenvironmental effects of effluents discharged into aquatic environments [15].Effluent discharge practices in Nigeria are yet too crude and society is in danger, especiallyin the industrialized part of the cities. The Federal Environmental Protection Agency (FEPA)established to check these environmental abuses has had little or no impact on pollution controlin our cities [16]. The aim of this review is to assess the impact of industrial wastewater pollutionon aquatic environments in Nigeria.THE USE OF WATER BODIES AS SINK FOR INDUSTRIAL EFFLUENTSPopulation explosion, haphazardous rapid urbanization, industrial and technologicalexpansion, energy utilization and wastes generation from domestic and industrial sources haverendered many water resources unwholesome and hazardous to man and other living resources.Water pollution is now a significant global problem [17].Industrial effluents are a main source of direct and often continuous input of pollutants intoaquatic ecosystems with long-term implications on ecosystem functioning including changes infood availability and an extreme threat to the self-regulating capacity of the biosphere. Theseindustrial discharge or wastes include heavy metals, pesticides, polychlorinated biphenyls(PCBs), dioxins, poly-aromatic hydrocarbons (PAHs), petrochemicals, phenolic compounds andmicroorganisms [1], [18-21]. These wastes are usually discharged into water bodies and thecumulative hazardous effects it has on the environment have received much attention. Industrialwastes containing high concentration of microbial nutrients would obviously promote an after-growth of significantly high coliform types and other microbial forms. Some heavy metalscontained in these effluents have been found to be carcinogenic while other chemicals equallypresent are poisonous depending on the dose and duration of exposure. Undoubtedly,wastewaters from industries and residential areas discharged into another environment withoutsuitable treatment could disturb the ecological balance of such an environment [21].Historically, the availability of water supplies has long been a dominant criterion in citingtowns or cities and the development of great civilizations. The Egyptians civilization flourishedaround the river Nile. In Nigeria, cities like Kaduna, Lagos and Aba depend very much on itsrivers. However, the rush by African countries to industrialize has resulted in discharge ofpartially treated or raw wastes into the surrounding bodies of water since the development oftreatment facilities cannot keep pace with the rate at which the wastes are generated by theindustries [22].The industrial discharge, therefore contribute a larger portion of the flow of the river duringthe dry season, with the result that the water quality of the river is further deteriorated. Uses, forwhich the river is employed involving body contact, expose serious hazards to users due to thebacterial situation. Many bodies of water in Nigeria experience seasonal fluctuations, leading to ahigher concentration of pollutants during the dry season when effluents are least diluted [23].NATURE AND CHARACTERISTICS OF EFFLUENTSWastewaters are generated by many industries as a consequence of their operation andprocessing. Depending on the industry and their water use, the wastewaters contain suspended
  4. 4. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.78Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.solids, both degradable and nonbiodegradable organics; oils and greases; heavy metal ions;dissolved inorganics; acids, bases and colouring compounds (Table 1)[24].Table 1: Examples of Waste Effluents Generated by Selected IndustriesType of waste Type of plantOxygen-consuming Breweries, Dairies, Distillers, Packaging houses, Pulp and Paper,Tanneries, TextilesHigh Suspended Solids Breweries, Coal washeries, Iron and Steel Industries, Distillers, Pulpand Paper mills, Palm oil millsHigh dissolved solids Chemical plants, Tanneries, Water softeningOily and grease Laundries, Metal finishing, Oil fields, Petroleum refineries, Tanneries,Palm oil millsColoured Pulp and Paper mills, Tanneries, Textile dyehouses, Palm oil millsHigh acid Chemical plants, Coal mines, Iron and Steel, Sulfite pulpHigh alkaline Chemical plants, Laundries, Tanneries, Textile finishing millsHigh Temperature Bottle washing plants, Laundries, Power plant, Textile[24]Industrial effluent characteristics provide basic information about the integrity of the aquatichabitat within such rivers and streams into which they are discharged. Most of these effluentspose inestimable harm to which the microbial entity is the most adversely affected. In Nigeria,there are many small to large cottage industrial establishments that discharge such harmfulwastewater effluents. Although, the physicochemical analysis of the effluents indicates that mostof these industries conform to the recommended FEPA [25] guidelines, however, exceptionsoccur in the total dissolved solids (TDS) and Nitrate (NO3-) contents. These are found to be veryhigh in most of the effluents sampled to which humans and the aquatic habitat are adverselyaffected. It is known that the pH analysis of such effluents shows that effluents from food andbeverage industries tend to be abnormally very acidic [26]. An important pollution index ofindustrial wastewaters is the oxygen function measured in terms of chemical oxygen demand(COD), and biological oxygen demand (BOD5), while the nutrient status of wastewater aremeasured in terms of nitrogen and phosphorus. In addition, other important quality parametersinclude pH, temperature and total suspended solids [27].Industrial effluents are characterized by their abnormal turbidity, conductivity, chemicaloxygen demand (COD); total suspended solids (TSS) and total hardness. The effluent totalhardness concentrations of a chemical-biological treatment plant were found greater than theinfluents. The results are presented in terms of the relative flux as a function of time related tohydrodynamic conditions and pollution characteristics of wastewater [28]. The dominant solublenitrogen form in a typical industrial effluent is NO3-N followed by Kjeldahl-N, NO1-N and non-ionicammonia Mean values of NO3-N, NO2-N, Kjeldahl-N and non-ionic ammonia ranged from 0.50to 2.37 mg L-1, 0.022 to 0.084 mg L-1, 0.33 to 0.99 mg L-1 and 0.007 to 0.092 mg L-1 respectively.Mean values of P-PO4 at most sampling sites were higher than 0.1 mg L-1 for subject toeutrophication and the characteristics of rivers and the nearby soils near them affect theequilibrium concentrations of N and P between the soil and the overlying water Industrial effluentsare also known to exhibit toxicity toward different aquatic organisms.The coastal residential environment in any industrial effluent site is always underconsiderable stress due to the prevailing harsh environmental conditions, especially hightemperature and salinity, restricted benthic fauna diversity and overall development of a fragile
  5. 5. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.79Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.intertidal ecosystem. The fauna inhabiting the intertidal zone is most likely dominated by a fewspecies probably living at their limit of tolerance [29]. Organic pollution is always evident and thepollution is made worse by land-based sources such as the occasional discharge of raw sewagethrough storm water outlets, and industrial effluents from refineries, oil terminals, andpetrochemical plants [30].Wastes produced by the textile industries have characteristically high concentration ofchemicals. The net effect is a variation of the acid or basic nature of the water. Textiles industriesproduce chemicals with high concentration of caustic chemicals resulting in high pH valuesvarying between 10.0 -11.0. The discharge from the textiles, also bear intense colouration derivedfrom the dyes fibrous materials.SOURCES OF INDUSTRIAL EFFLUENTSPharmaceutical industryPharmaceutical and personal care products (PPCPs) industries suffer from inadequateeffluent treatment due to the presence of recalcitrant substances and insufficient carbon sourcesand nutrients. A large number of pretreatment systems are employed to remove these pollutantsto prevent a host of problems that may otherwise arise in the biological process, and reduce theefficiency of the treatment plant. Problems caused by excessive PPCPs in the environmentinclude possible inhibition on microorganisms, a reduction in the cell-aqueous phase transferrates, a sedimentation hindrance due to the development of filamentous microorganisms,development and flotation of sludge with poor activity, clogging and the emergence of unpleasantodours. Therefore, it is not surprising that research efforts have been directed towards thedevelopment of efficient treatment technologies including various physicochemical and biologicalprocesses. Some of the most representative pharmaceutical and personal care products found inreceiving waters include antibiotics, lipid regulators, antiinflammatories, antiepileptics,tranquilizers, and cosmetic ingredients containing oil and grease with very different chemicalstructures [31]. Conventional biological processes (activated sludge, trickling filters) caneffectively accomplish carbon and nitrogen removal, as well as microbial pollution control.However, pharmaceutical and personal care products contain many different compounds forwhich conventional technologies have not been specifically designed. Their removal efficienciesare influenced, apart by the chemical properties of specific compounds, by microbial activity andenvironmental conditions. The application of a pretreatment to hydrolyze the effluents andbioaugmentation, may improve the biological degradation.Soap and detergent IndustryAlkyl sulfates (AS) are anionic surfactants widely used in household and personal cleansingapplications. Aquatic toxicity of AS under laboratory conditions indicated effects at relatively lowconcentrations (50-230 µg L-1) for some sensitive species. Belanger et al, [32] conducted acomprehensive study of an AS mixture composed of tetra-C14) and pentadecyl (C15) chainlengths to better understand effects on microbial and macroinvertebrate populations andcommunities. A 56-d exposure of AS was performed at concentrations ranging from 57 to 419 µgL-1 (analytically confirmed exposures) and was accompanied by detailed investigations ofperiphyton community function (autotrophy, heterotrophy, and metabolism of test chemical).Periphyton structure (algal population and community dynamics based on taxonomic identity),invertebrate structure (benthic abundance, drift), and insect emergence patterns based on
  6. 6. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.80Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.taxonomic identity were also studied. A no-observed-effect-concentration (NOEC) of 222 µg L-1was concluded for several individual algal and invertebrate species based on univariate statisticalanalyses. An apparent energetic subsidy from C14-15AS at the highest concentrations of 222 to419 µg L-1 was observed and tied to changes in microbial community processing of AS whenadded at these high concentrations. A multivariate analysis based on principal response curves(PRC) indicated that communities in streams exposed to 222 to 419 µg L-1 were significantlydifferent from the controls leading to an overall conclusion that 106 µg L-1 was the ecosystemNOEC [32].Industrial effluents from soap manufacturing industries are known to contain complexchemicals most of which are very toxic and capable of destroying the microbial habitats in aserious adverse way. For example, characterization of the composite wastewater from both soapand food processing plants indicated that the waste was highly contaminated with organiccompounds as indicated by COD and BOD values [33].In a study to assess the seasonal variation in bacterial heavy metal biosorption in a receivingriver as affected by industrial effluents, Kanu et al. [23] observed an overall seasonal variation ofheavy metals such as lead, Zinc and Mn in the rainy season as compared to other metals for dryseason. The concentrations of heavy metals were also, generally low in some samples and nosimilar trends were observed in the control samples. Except for iron and zinc, the concentrationsof the other heavy metals were relatively low. Moreover, effluent from the soap manufacturingplant contained significant concentrations of oil and grease amounting to 563 mg L-1. Soapmanufacturing effluent and the combined wastes discharged from an industrial complex weresubjected to different treatment processes, namely dissolved air flotation, chemical coagulation-sedimentation, and biological treatment via a completely mixed activated sludge process.Although coagulation using alum followed by sedimentation removed 52% of COD, residualvalues did not comply with the regulatory standards. Biological treatment of the compositecombined wastewater significantly removed the organic contaminants in wastewater. Averageresidual BOD, COD, oil and grease values were 30, 92 and 8.3 mg L-1 respectively [34].Paper mill industryProcess water in paper and board mills contains a lot of sugars and lignocelluloses, whichsupport the growth of bacteria, mold and some yeast. Effluent from fertilizer plants contain a highconcentration of potentially toxic wastes rich in ammonia-nitrogen, urea, nitrate-nitrogenorthophosphate-phosphorus which support the growth of algae, yeast and cyanobacteria.Cellulolytic bacteria such as Klebsiella pneumonia and Enterobacter have been isolated fromspent water from the paper and pulp industries. The occurrence of these microbes in the effluentslead to excessive oxygen demand loading and also disturb the ecological equilibrium of thereceiving waters with much loss of aquatic life and intense consequences [15].Textile mill effluentThe textile industry is distinguished by raw material used and this determines the volume ofwater required for production as well as waste generated. Heavy metals have been associatedwith the textile effluents [35]. The nature of the processing exerts a strong influence on thepotential impacts associated with textile manufacturing operations due to the differentcharacteristics associated with these effluents (Table 2).
  7. 7. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.81Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.Table 2 Effluent Characteristics From Textile IndustryProcess Effluent composition NatureSizing Starch, waxes, carboxymethyl cellulose(CMC),polyvinyl alcohol(PVA), wetting agentsHigh in BOD, CODDesizing Starch, CMC,PVA, fats, waxes, pectinsBleaching Sodium hypochlorite, Cl2, NaOH, H2O2, acids,Surfactants, NaSiO2 sodium phosphateHigh alkalinity, high SSMercerizing Sodium hydroxide, cotton wax High pH, low BOD, high DSDyeing Dyestuffs urea, reducing agents, oxidizingagents, acetic acid, detergents, wetting agentsStrongly coloured, high BOD,DS, low SS, heavy metalsPrinting Pastes, urea, starches, gums, oils, binders,acids, Thickeners, cross-linkers, reducingagents, alkaliHighly coloured, high BOD,oily appearance, SS slightlyalkaline, low BOD.Brewery industryWastewater from Brewery Industry originates from liquors pressed from grains and yeastrecovery and have the characteristic odour of fermented malt and slightly acidic [23].Brewery effluents are high in carbohydrates; nitrogen and the cleaning and washingreagents have been proved water pollutants. The introduction of wastewater, high in organicmatter and essential nutrients bring about changes in the microflora. Ekhaise and Anyansi [33]reported high counts of bacterial population in Ikpoba River in Benin City Nigeria receiving abrewery industrial effluent. Similar results were reported by Kanu et al, [23] of the effect ofbrewery discharge into Eziama River, Aba, Nigeria.Tannery industrial effluentThe wastewater effluents from tannery industries were studied to determine the chromium(II) contamination levels.Three aqueous oxidants, hydrogen peroxide, sodium hypochlorite andcalcium hypochlorite were employed independently in oxidizing chromium (III) containing tannerywastewaters to solubilize chromate (CrO42-) under alkaline conditions. The amount of chromaterecovered was determined via spectrophotometry. Hydrogen peroxide was potentially a suitableoxidant as it could recover chromate (CrO42-) up to 98% (from synthetic Cr3+ solution) and 88%(from effluent I). The percentage recoveries by the hypochlorites were lower than with those byhydrogen peroxide. For example, with NaOCl, the recovery was up to 94% (from synthetic Cr3+solution) and 67% from effluent I). Similarly, with Ca(OCl)2, recovery was 90% from synthetic Cr3+solution and 49% from effluent I. For all three oxidants, complete (100%) recovery could not beachieved despite different experimental conditions (temperatures and oxidation time). The resultsclearly indicate that hydrogen peroxide is the most efficient among the three oxidants.Onwuka et al., [36] studied eighty-eight (88) samples of the groundwater near industrialeffluent discharges in Enugu in order to evaluate its potability. The parameters of interest arecommon waste-derivable chemical constituents such as nitrate (NO3-), chloride (Cl-) and sulphate(SO42-), and indicator microorganisms, like Escherichia coli. The study showed that about twenty-two percent (22%) of the samples had concentrations of NO3- higher than the WHO permissiblelevel (45mg/l) while eight out of the ten samples analyzed to test the bacteriological quality of thegroundwater showed evidence of sewage and industrial effluent contaminations. Theidentification of E. coli in the water indicates faecal contamination. Improvement in themanagement of domestic wastes, such as the use of a central sewer, will preserve the aquifer,and consequently improve the quality of the groundwater [36].
  8. 8. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.82Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.Soft drink effluentIbekwe et al., (37) analyzed the wastewater in the accumulation pond and final dischargepoint of Nigerian Bottling Company PLC in Owerri, Nigeria to determine their bacteriological andphysico-chemical characteristics. Species of organisms isolated included Staphylococcus,Bacillus, Lactobacillus, and Streptococcus. Others include Klebsiella, Escherichia, Proteus andSerratia. However, species of Lactobacillus and Proteus were isolated from the final dischargepoint only. Bacterial count after 72 hours was higher with a maximum count of 6 x 107 cfu/ml inthe final discharge point. The waste water from both points were clear and had the same residualchlorine (1ppm) and iron (1ppm) concentration, while the accumulation pond showed more aciditywith a pH of 6.6±1.2. The final discharge contained more dissolved solids (20±1.8ppm) whichwas double that of the accumulation pond (10±2.2ppm). It was also found that dissolved oxygenwas slightly higher (6.0±0.26mg/ml) in the final discharge point than accumulation pond(5.0±0.33mg/ml). Although, these findings were found to be within the permissible limits ofeffluent discharge specified by the Federal Ministry of environment in Nigeria[25], the consequentlong-term bioaccumulation effects on microbial ecosystem were not reported.Chemical industryThe toxicity of benzene, hydroxylbenzene (phenol), chlorobenzene, methylbenzene (toluene)and dimethylbenzene (xylene) to four chemolithotrophic bacteria (Nitrosomonas, Nitrobacter,Thiobacillus and Leptothrix isolated from the New Calabar River water were investigated byOdokuma and Oliwe, [38]. The static method of acute toxicity assessment was employed.Mortality within a period of 5 hours exposure to toxicant was the index of assessment. Toxicity ofthe chemicals to the bacteria decreased in the following order: phenol > xylene > benzene >chlorobenzene > toluene for Nitrosomonas, chlorobenzene > phenol > benzene > toluene >xylene for Nitrobacter, phenol > chlorobenzene > benzene > xylene > toluene for Thiobacillus,while phenol > chlorobenzene > xylene > toluene > benzene was for Leptothrix, The toxicity ofthe chemicals to the test organisms decreased in the order phenol > chlorobenzene > benzene >xylene > toluene. Sensitivity of the bacteria to the test chemicals decreased in the order;Nitrosomonas > Leptothrix > Thiobacillus > Nitrobacter. Toxicity of the methyl and dimethylsubstituted derivatives of benzene was probably a function of the genetic make up of the bacteria.The toxicity generally decreased with increased methyl substitution in the case of Nitrobacter andThiobacillus, but increased with increased methyl substitution in the case of Nitrosomonas andLeptothrix. Hydroxyl and halogenated substituted derivatives were more toxic than methylsubstituted derivatives. These results indicate that wastes containing hydroxyl andchlorosubstituted derivatives of benzene may pose a greater toxicity problem to microbiota thanwastes containing methyl-substituted derivatives. The nitrification stage of the nitrogen cycle willalso be greatly impaired in the presence of these groups of chemicals in a river [38].Impact of organic wastesContributing to the menace of indiscriminate discharges of industrial effluents in receivingwater bodies is the improper disposal of domestic wastes, particularly in urban centres of mostdeveloping countries. Open and indiscriminate dumping of solid wastes in drainages andriverbanks is one of the most critical problems facing the city of Ibadan [39]. Sewage effluents richin decomposable organic matter, is the primary cause of organic pollution. Domestic wastes inthe country like in many other developing countries may now contain modern environmentalhealth hazardous substances thus posing additional risk to public health [40-42].
  9. 9. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.83Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.Due to population and industrial growth, inland waters (rivers, lakes, etc.) become often therecipient of organic matter in amounts exceeding their natural purification capacity, while in thepast, natural purification and dilution were usually sufficient (5).Secondary organic pollution is defined as the surplus of organic matter, which is the sum ofundecomposed organic material introduced into the water body with primary pollution and of thematerial resulting from an extremely increased bioproductivity within the polluted ecosystem itself[40]. Organic wastes mineralize in the receiving water bodies and the resulting nutritive elementsstimulate plant production, leading to eutrophication. In this situation, the biomass increasesconsiderably and goes beyond the assimilation limit by herbivores. This secondary organicpollution is considerably greater than the primary organic load. The excessive production oforganic matter leads to the build up of “sludge” and the mineralization process consumes alldissolved oxygen from the water column, which causes fish kills[5]. Consequently, organicpollutants are called oxygen-demanding wastes. The relatively high temperatures in tropicalcountries accelerate this process.Except for a few regions, in Nigeria urban areas do not have any central sewerage systemor sanitary excreta disposal system. The wastewater from most parts of more than 186 urbancentres is carried in open drains into streams and rivers, a characteristic feature of manydeveloping countries [42]. Nitrogen and phosphorus are the major causes of eutrophication.Eutrophication affects aesthetics on lakes, rivers and results in odour and appearance problems.Open drains, carrying various pollutants, contribute to the pollution of streams, since they travelshort distances and consequently offer only limited self-purification of the wastewater.POME as a source of wastewaterPalm oil mill effluent is an important source of inland water pollution when released withouttreatment into local rivers or lakes. In Nigeria palm oil is processed locally and industrially throughthe oil palm belt stretching from Cross River to Lagos State. Beside the main product i.e. thecrude palm oil (CPO), the mills also generate many by-products and liquid wastes, which mayhave a significant impact on the environment if they are not dealt with properly. Palm oil milleffluent (POME) is one of the major sources of pollutant produced during oil palm processing.The palm oil mill effluent (POME) is generated from three major sources, namely sterilizercondensate, hydrocyclone waste and separator sludge.. On an average 0.9–1.5m3 of POME isgenerated for each ton of crude palm oil produced [43]. POME is rich in organic carbon with abiochemical oxygen demand (BOD) higher than 20 g/L and nitrogen content around 0.2 g/L asammonia nitrogen and 0.5 g/L total nitrogen [44] It contains various suspended componentsincluding cell walls, organelles, short fibres, a spectrum of carbohydrates ranging fromhemicellulose to simple sugars, a range of nitrogenous compounds from proteins to amino acids,free organic acids and an assembly of minor organic and mineral constituents. Also, palm oil millwastewater treatment systems are one of the major sources of green house gases due to theirbiogas emission (36 % CH4 with a flow rate of 5.4 l/min.m2) from open digester tanks and/oranaerobic ponds [45]. POME has generally been treated by anaerobic digestion, resulting difficultto perceive the magnitude of pollution being caused to the receiving waters by such discharges.The characteristic problems associated with palm oil mill effluents are pH, dark color, highlevels of biochemical oxygen demand (BOD), chemical oxygen demand (COD), color, andsuspended solids. High values of COD also indicate the recalcitrance of chemicals that haveescaped biodegradation. These chemicals may be persistent in nature and may cause severeenvironmental problems like bioaccumulation. The POME characteristics shown in Table 2 areaverage values and actual values at a mill can be influenced by the quality of the fruits harvested.
  10. 10. Kanu, Ijeoma and Achi, O.K., 2011. Industrial Effluents and Their Impact on Water Quality of Receiving Rivers inNigeria.84Journal of Applied Technology in Environmental Sanitation, 1 (1): 75-86.The wastewater is hot and this makes it more difficult to directly treat it aerobically since oxygentransfer would be less efficient [46].Table .3. Palm oil mill effluent (POME) characteristics[45]Parameters Average valuesBOD 23,000mg L−1COD 55,000mg L−1TN 650mg L−1TP 120mg L−1Oil 10,000mg L−1Volatile fatty acids 1,000mg L−1pH 4–5Temperature 45–70oCApproaches to pollution controlThe above review of the effects of industrial effluent pollution on inland waters evidences theneed for control of this type of pollution in developing countries, which can best be achieved byreduction or prevention at the source. Such measures do lead to raw material recovery andreduction in effluent discharges or lower treatment costs.Legal, administrative and technical measures are also necessary to reduce oe eliminate theundesirable effects of industrial effluents in receiving waters. This can be controlled by standardsimposed by the authorities. Levies can be imposed to cover the cost of off-site treatment anddisposal.CONCLUSIONThe discharge of industrial effluents into receiving water bodies in Nigeria invariably result inthe presence of high concentrations of pollutant in the water and sediment. The pollutants havebeen shown to be present in concentrations, which may be toxic to different organisms. Theeffluents also have considerable negative effects on the water quality of the receiving waterbodies and as such, they are rendered not good for human use. It is therefore recommended thatthe careless disposal of industrial wastes without pretreatment should be discouraged. Impositionof direct charges on industrial effluents by the regulating agency, as well as continuousmonitoring and surveillance is imperative in order to ensure the protection of water resourcesfrom further degradation.References1. Fakayode, S. O. 2005 Impact assessment of industrial effluent on water quality of the receiving Alaroriver in Ibadan Nigeria AJEAM-RAGEE 10: 1-13. (good style)2. Sangodoyin, A.Y. 1995 Characteristics of control of industrial effluents-generated pollution Env. Mgt.& Health 6: 15-183. Sangodoyin, A.Y.1991 Groundwater and Surface Water Pollution by Open Refuse Dump in Ibadan,Nigeria. Journal of Discovery and Innovations, 3 (1): 24-31.4. Ajayi S.O. and Osibanji O.1981 Pollution studies on Nigeria Rivers 11; Water quality of someNigerian Rivers. Environ. Pollut. Series 2: 87-955. Osibanjo,O. Daso A P. and Gbadebo A M. 2011 The impact of industries on surface water quality ofRiver Ona and River Alaro in Oluyole Industrial Estate, Ibadan, Nigeria Afr. J. Biotechno. 10(4): 696-702,
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