Poor effluent treatment and its health implication on workers and the environment

Effluent is a waste water generated from a given community or industry. Effluent, which is also known as sewage, contains a large numbers of micro-organism such as viruses, bacteria and protozoan.

According to Gbana (2006) effluent is highly diluted and contains about 99℅ water, while the remainder of the materials consist of partly suspended organic solid such as starch, lipids, granules, proteins, cellulose’s (plants) remains and partly dissolved substances such as sugar, fatty acids, amino acids, uric acid and many organic compounds. He also went further to explain that other contents in effluent includes urine, soap, detergents and small amount of waste food and a lot of micro-organism.

Olorunda et al. (2007), Effluent refers to a liquid, waste semi-solid (paste) or sewage discharge from house hold into community or from industrial establishment. He also classified effluent into groups which are:

  • Domestic sewage
  • Storm water
  • Industrial effluent

Domestic sewage: These are waste generated from homes, laundry operations, bathroom, cooking and kitchen dish washing. They contain a high content of grease, oil foams etc. which greatly influence sewage treatment. Domestic and municipal sewage carries used water from houses, offices and other buildings in a city. It is also called sanitary sewage (effluent). Most of it (nearly 99.9 percent) is water. Though the contaminant adds up to not more than 0.1 percent. They contain a wide variety of dissolved and suspended impurities.

The nature of this impurities and the large volume of effluent in which they are carried makes disposal of domestic waste water a significant technical problem. Sewage or effluent is the primary source of pathogenic organism, oxygen demanding waste matter and plant nutrient, instead of discharging sewage or effluent directly into a nearby body of water. It is first passed through a series of physical, chemical and biological processes that removes most of the pollutants.

Storm water: This is the waste water that arises due to surface run-off from rain. This is mostly experienced in the tropics during the wet season when the quality of surface water is increasingly high.

Storm sewage or storm water is the run- off from precipitation that is collected in a system of pipes or open channels. Such sewage carries organic materials such as suspended and dissolves solids and other substances picked up as the water as the water travels over the ground. Sewage discharge from domestic, municipal food processing and other industrial concerns contains a variety of pollutants detrimental to water quality.

Industrial effluent: This is the waste water from an industry depending on the composition of such an industry. Some industrial waste water is mostly made up of inert solids, organic matter, and inorganic, toxic or non toxic.

Industrial effluents are waste water or sewage produced from manufacturing processes and they consist of an integral component of community waste.

Olorunda et al. (2007) went further to explain that effluent requires by law to undergo a special treatment before being discharged into public services or any surface water.

The major reason of treating effluent before its being discharged into the environment is to render it less toxic so that it will not constitute nuisance and not pose treat to such environment. This reason is why Unuraye and Olojoba (2005) stated that industries should treat incoming water to meet the quality necessary for their use in the process. Sedimentation of organic and in-organic matter passed out into the drainage system.

Sources of industrial effluent

Industrial effluent emanate from different sources which includes the     following:

  • Roof and yard drainage
  • House keeping
  • Sanitary services
  • Boilers operation

Waste water from these sources is transported through the sanitary sewer to the sewage system treatment plants. Solid from industrial boiler operations are removed by purging the boiler periodically or by use of boiler cleansing solutions. Example hydrogen hoses are used to wash down, equipment and floors. Roof and yard drainages in industries are designed to separate sanitary waste from factory root and yard run-off. Unuraye and Olojoba  (2005).

Characteristics of industrial effluent

1         Biochemical oxygen demand (BOD): It is the amount of oxygen consumed by micro-organism during the decomposition of organic matter present in sewage or effluent.

2         Chemical oxygen demand: Is the amount of oxygen required to oxidize waste chemically to carbon dioxide and water.

3         Dissolved solid: These are particles of organic and inorganic matter present in effluent.

4         Synthetic detergents: These are soap present in effluent which emanate from boiler operation and sanitary services.

5         Dissolved oxygen: This is the oxygen present in effluent in order for aleuronic bacteria tom act on it.

  1. PH (concentration of hydrogen ion):This are the acid compound or elements present in sewage(effluent).it is important to determine specific element and compound such as phenol, ammonia, copper, zinc, which may be present in effluent as a result of material used for industrial processes (Eldon and Bradley, 2006).

Due to this problem mentioned poor treatment of effluent has posed a great hazard to man’s health and the environment.

Implication of poor effluent treatment on worker’s health

According to west Africa Health Examination Board (WAHEB) 1991 “Indiscriminate disposal of effluent posses hazards to individual and may cause land and water pollution.” The existence can be favored by either biological factor, physical and Mechanical means, air borne water supply, food supply, direct contact or other means related to social-economic status of a given population.

In the same vein Hanks (1999) found out that land and water serves as a major repository for the effluent waste water of urban and industrial areas .Poor effluent treatment in metropolitan areas has  a number of public health implications on the environment and individuals.

In general it is believed that low concentration of chemical mixture of similar chemicals could have addictive effects similar to the added concentration of one of the chemicals alone. In many cases this is done in part to the increase proximity of interactions between the chemicals and target tissues for example some carcinogens initiate cancer by initiating a DNA (Deoxyribonucleic acid) molecule at a particular site .a mixture of several carcinogens may cause cancer.

Implication of poor effluent treatment on soil/plants

According to Ezinwa (2007), Environmental pollution by industrial waste has become a treat to the continuous existence of plants and animals life. He noted that most plants species are no longer in existence due to the discharging of effluent into the environment without proper treatment.

According to Ichide (2004), effluent can cause damage to plants and micro-organism in the soil if not properly treated before discharged into the environment, these organism serves as nutrients material to the soil which are needed by plants for their growth. All these damages are done due to harmful chemicals present in effluent.

According to Gbana (2006), effluent can destroy phychrophilic organisms which discharge directly into the environment without proper treatment or without cooling. These organisms are cold loving organism which survives within the temperature range of 0⁰c – 25⁰c. These organisms help in enhancing the soil nutrient which serves as food for plants.

Implication of poor effluent treatment on aquatic lives

According to Unuraye (2005), the poorly treated effluent which is discharged into our water bodies’ adverse effect on fishes, water plants which serves as food to fish and other aquatic lives.

Grahan and Trotinan (1985), stated that from 1st of January 1981, a charge is leveled on any direct discharge of effluent to rivers due to changes done to aquatic lives. The book further explained that the change is 12 DM per year for each harmful unit of effluent, but will be increased annually to 4 DM per year in 1986. The minimum will be 50% reduction of the change if;

  • The minimum standard for waste discharge is reached by using recognized standards technology.
  • A higher standard than specific if the permit is reached. It is also reduced by approximately 50% if the harmful unit were unavoidable, having been derived from a polluted water supply.

 Industrial effluent treatment / discharge standards



Temperature Less than 40⁰ within 15 meters of out fall
Color 7
PH 6 – 9
Suspended solids 30
Total solids 2000
BOD 20⁰C 50
Chloride 600
Sulphate 500
Sulphide 0.2
Cyanide 0.1
Detergents 15
Oil and grease 10
Nitrate 20
Phosphate 5
Arsenic 0.1
Barium 5
Manganese 5
Tin 10
Iron 20
Phenolic 0.2
Cl₂ 1
Ca, Cr, Cu, Pb, All less than 1
Mercury 0.05
Ni, Sc, Zn 1
Silver 0.1
Ca 200
Magnesium 200
Iron 5
Source: NESEREA (2007)  




I Copper 1.5mg/1 or ppm  
Ii Zinc 1.5  
iii Magnesium 150  
Iv Chloride 600  
V PH  
I Nitrate 45mg/1 or ppm  
Ii Fluoride 1.5  
I Phesolic 0.002  
Ii Arsenic 0.05  
iii Cadmium 0.01  
Iv Chromium 0.05  
V Cyanide 0.2  
vi Lead 0.05  
vii Solonium 0.01  
viii Radio nuclei (gross beta activity) 100  
I Chemical Oxygen Demand (COD) 10  
Ii Biochemical Oxygen Demand 6  
iii Total nitrogen excluding 1  
Iv Ammonia 0.5  
V Grease 1  
I Treated water total coli form 0 per 100ml  
Ii Treated water total fiscal 0/100ml  
iii 90% of all samples will have total coli form 0/100 less than 1  
Iv Untreated water samples will have total coli form 10/100 less than 1  
V For water requiring disaffection coli form 0-50/100ml  
vi Conventional treatment 50-5000/100ml  
vii Extensive treatment 5000-50,000/100ml  
viii Not good source of potable water 50,000/100ml  

 Importance of effluent treatment to a nation’s economy

According to Davye (200) effluent treatment is of economic importance and a way of preventing pollution’’ He also said that pollution is now so serious that several countries have enforced the treatment of all waste.

Sewage irrigation treatment can de effectively and suitable for developing tropical countries where agriculture is the main source of their economy. They also said that sewage is collected on sewer and sent to the farms to irrigate crops which normally not eaten raw like maize, and rice. According to West Africa Health Examination Board (WAHEB) 1991.

In Nigeria, Federal Environmental Protection Agency (FEPA) 1990, made it mandatory for all industries to treat waste before discharging them into the environment.


Achalu, E.I.( 2000). Occupational health & safety. A summary introduction and outlines of principle. Ibadan Africa link book.

Davey; T.H. & Wilson T( 2005). The control of diseases in the tropics (3rd Ed.) London Chancer Press Ltd.

Eldon,D.E & Bradley, F.S (2006). Waste water treatment in Environmental science (10th Ed.) New York: McGraw-Hill company.

Gbana, U.M.F. (2006). A lecture manual on introduction to Environmental microbiology; S.H.T,Ofuoma-Ughelli (unpublished).

Ichidi, I. (2004). Industrial sanitation and waste disposal.  S.H.T.Ofuoma- Ughelli (unpublished).

Lacus,A.O & Gill H.M.(2003). Industrial waste short textbook on preventive medicine for tropics. ( 4th Ed.) India, charon Tec. LTD.

Olorunda, O. Olowoparija  O, Onojeharho D,  Samuel K.N.  Mercy. O. N & Adams. S. (2007). Monitoring and modeling Techniques of Environmental pollution (1st Ed.)

Park,K.(2007) Modern sewage treatment in preventive  and social medicine(19th Ed.) India: Prem Nagar Publication.

Unuraye, L.O & Olojoba, A.O (2005). Fundamental Health, Management. Ughelli, Ama Ohoror, Printing  Press company.

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