Pollution caused by sewage water is one of the major problems in cities the world over. Sewage water is drained off into rivers without treatment. Careless disposal of sewage water leads to creation of a chain of problems like spreading of diseases. The pollution of water occurring from sewage is mainly observed in developing countries. In these countries, sewage water is not disposed in a proper manner. This article is a review of issues related the sewage pollution, treatment of sewage, and environmental and health problems due to untreated waste water. It also states the necessity of Sewage treatment plant.
Sewage pollution is caused by several factors including failing and outdated infrastructure that is compounded by rapid, sprawling development that paves over the farms, forests, and wetlands that naturally soak up storm water. As a result, rain and snow that would have natural drained into the ground or slowly run off the land into streams now gets diverted through culverts, often discharging directly into public sewage systems where it combines with sewage and domestic wastewater. Even cities with separate sanitary sewers find that storm water can flow through cracks and manhole covers into pipes that carry human waste, causing sewer overflows.
Causes of Sewage Pollution
All scientists agree that the law which ignores the consideration of river loading capacity which refers to the greatest amount of pollutants that a river can assimilate without causing the water to get polluted. Also, the regulation only covers premises with more than 150 population equivalent (PE) that contribute to flow to the sewerage treatment system. Another problem in Malaysian rivers is that many public sewage treatment plants (STPs) is still using old technology. According to Indah Water Konsortium , most of the STPs in the country have used primary treatment systems like septic tanks and imhoff tanks. The key informants says that the insufficient public awareness is also another major factor that causes the still persisting problem of sewage pollution. The key informants says that the insufficient public awareness is also another major factor that causes the still persisting problem of sewage pollution. 6.
Impact on environmental and human health
Sewage may contain many types of disease-causing organisms including E-coli that can cause various health problem such diarrhoea, severe abdominal pain, and vomiting. Sewage contains high levels of nutrients like phosphate and nitrates which can affect rivers, lakes and seas through eutrophication caused by nutrient enrichment. It was found that the presence of lead (Pb) in the sewage water can cause abnormal behaviours, especially in children 9.
Fluoride in small amounts is essential for the normal mineralization of bones and formation of dental enamel. The main sources of fluoride are drinking water. But excessive fluoride intake will cause fluorosis cancer, arthritis and other diseases. Around 200 million people from whom the survey was taken all from 25 nations have health risks because of high fluoride in groundwater. In India, there has been an increase in the incidence of dental and skeletal fluorosis with about 62 million people being affected by the high fluoride concentration 1.
The world’s largest canal irrigation system is situated in Pakisthan. The main source of irrigation is canal and ground water but the quality of ground water is so poor for the sustainability of agriculture system. The use of municipal sewage water that consists of domestic liquid waste, as well as industrial effluents, is becoming a common practice for coping up with the current situation. Although the sewage water is a source of many nutrients, it also includes a significant amount of heavy metals like Fe2+, Cu2+, Zn2+, Mn2+, Ni2+, Pb2+ and pathogens. Extensive use of this effluent for irrigation purpose has resulted in an upsurge of such metals in soils and various crops, which ultimately resulted in clinical problems in human beings 4.
Children, elderly, and immunocompromised individuals (e.g. those with HIV/AIDS) are more susceptible to sewage waste pollution in Indore’s water supply. Children who are exposed to harmful pathogens such as G. Lamblia or V. cholera can contract giardiasis or cholera and have potential adverse long-term health effects such as cancer or developmental disabilities 5.
Impact on water and health
Water bodies in their natural form contain small amounts of chemical compounds like bicarbonates, nitrates, chlorides, sulphates, etc. Rising of such chemical compounds can make many problems.
Raw sewage ‘flowing into rivers across England and Wales’
The total amount of raw sewage intentionally being put into rivers is unknown, which is a “huge concern”. Sewage pollution can cause algal blooms that starve rivers of oxygen and kill fish, as well as affecting the wildlife such as kingfishers and otters that depend on them. The pathogens in untreated sewage can also threaten people’s health, causing gastroenteritis and even septicaemia and hepatitis A.
Industrial waste contamination plagues groundwater in Peenya
The wide roads of Peenya industrial estate give way to small congested lanes of Shivapura. A borewell stuck on the side of the road is a critical source of water. Shantha points at a large mug that she uses to wash her clothes on the pavement. The water has a thin layer of whitish froth while sediments float around the mug. It has grease, oil, chemicals and is acidic. When we use it for cooking, vessels turn white.
Raipur is an example of a fast growing city in India as it has been a commercial centre for the steel, cement and forest products of the country. Large quantity (approx. 300 million lit/day) of untreated sewage water gets dumped into the main seven reservoirs of the city. Sewage carries excessive nutrients, heavy metals, organic bacterias etc by dumping into drinking water which cause serious health problems, ranging from common diarrhoea to deadly diseases such as hepatitis, cholera etc.
Water Of Orans
The Water of Orans in the Algerian West coastline is a coastal area which is the prime location of activities demanding water of good physical and chemical purposes i.e for recreational activities, aquafarming and fishing. The studied areas are under the direct influences of wadis and wastewaters, which happens because of watersheds, urban and industrial discharge.
On a one year assessment of water quality of urban sewages from coastal urban centres it is found that Lead has average concentrations high enough at the three studied sewages: 0.23 mg.l-1 at the urban sewage Oran of (standard deviation: 0.22 mg.l-1).The approach concerning quality of the sewages of sloppy waters presented in this work can be described like an ecological approach. This case study helps the public authorities to take effective steps to protect the marine ecosystem during conception ,installation and exploitation of computer systems of sewage waters in different industrial locations which will be in accordance with the national regulation in force.9
Sewage pollution of Malaysian rivers and its challenges
For many developing nations, sewage pollution is a growing problem. The United Nations reported that more than 80 percent of sewage in developing countries is discharged untreated, polluting rivers, lakes and coastal areas. In Malaysia, 72 percent of 473 rivers monitored by the Department of Environment Malaysia (“the DOE”) in 2013 were found polluted with 25 rivers classified as highly polluted. In 2013, A report was published which said that Malaysia had more than 1.2 million sewage treatment systems. These sewage treatment systems formed about 86 percent of some 1.48 million water pollution sources identified throughout the Peninsular Malaysia 6.
A case study of Malamulele sewage plant, South Africa – Pollutants in sewage effluent and sludge and their impact on downstream water quality
In highly populated and developed areas where waterborne sewage system and agricultural practices contribute large amounts of nutrients into the receiving natural water system, promote growth of algae in receiving systems causing a wide array of water quality problems. South Africa has some of the most highly nutrient enriched surface waters in the world.
Removal of nutrients:
The removal process involves bioconversion of nitrates to nitrogen by bacteria, if the sewage plant was designed to provide enough oxygen and a long enough “sludge age” to develop these slow-growing types of organisms. Phosphorous removal is most commonly done by designing an activated sludge system that promotes the development of certain types of bacteria which have the ability to accumulate excess phosphorus within their cells.
Macro invertebrates have been used to assess the levels of toxic chemicals in river systems. Invertebrate communities respond relatively quickly to localise conditions in a river and changes in water quality can easily affect their biodiversity. The Mandzoro River and streams in Malamulele area form a vital part in community livelihood system such as the cultivation of vegetables and fruits and fishing in some places along the river 7.
The sewage workers only have vague awareness about sewage related issues and the safety measures.This awareness is much less in developing countries than developed countries.So they often tend to work without enough preventive measures which results in numerous health hazards.Lead(Pb) and Cadmium (Cd) are widely present in sewage water and workers are exposed unprotected during their work.These heavy metals can cause mutation in DNA and also responsible for lowering of blood total iron(Fe) concentration.It is studied through comet test
The present study has helped to assess the health hazards of sewage workers and many other affected groups in people belonging to their 30’s compared to people belonging to 50’s groups and as per estimation.The young people have lower blood zinc level as well as varies food tastes, etc. that can cause DNA damage.10
Impact on marine bodies
Coastal ecosystems degradation is a serious issue which is of a growing concern. Discharging of the sewage effluents to the sea water contributes heavily to marine pollution. The biogeochemical effects of sewage pollution on the factor and energy reserves of Nerita polita is being examined by this study. 135 molluscs were found to change sewage concentrations of between 5-50 %. Physiochemical parameters were divided accordingly using standard methods. Condition factor of Nerita polita was found daily using the measurement known commonly as Fulton’s index. After the time of exposure, the molluscs were destroyed and energy reserves were found out. Increase in sewage pollution resulted in increase of ammonia amount from 0.01mg/L to 0.08 mg/L, phosphate amount from 0.05mg/L to 156 mg/L, nitrates amount from 0.02mg/L to 1.99 mg/L and temperature from 24.34oC to 25.12oC, while pH amount from 7.75 to 7.29 and dissolved oxygen from 5.62mg/L to 2.38 mg/L were lowered.
Sewage is one of the major forces driving deterioration of coral reefs worldwide. For example, in Malaysia, sewage pollution has led to the spread of algae on coral reefs of several islands 6. Also, The DOE Selangor Annual Report 2013 says that the untreated or partially treated sewage makes high level of ammoniacal nitrogen (AN) in river water and high level of E.coli in water bodies found in the beach in Selangor.
So as a conclusion we can say that energy reserves are bio indicators but that factor is not a realible marker to assess acute sewage toxicity. Also we can say that the increase in sewage pollution leads to a decrease in the water quality and that sewage concentrations above 30% can have very large effects on Nerita polita in the long time.