The water pollution in Malaysia is originated from point sources and non-point sources. Point sources that have been identified include sewage treatment plants, manufacturing and agro-based industries and animal farms. Non-point sources are mainly diffused ones such as agricultural activities and surface runoffs. According to Malaysia Environment Quality Report 2004, the Department of Environment has recorded 17,991 water pollution point sources in 2004 comprising mainly sewage treatment plants (54%), manufacturing industries (38%), animal farms (5%) and agro-based industries (3%). Another main cause of water pollution encountered worldwide is oil spills. About 29 million gallons of petroleum enters the oceans off North America each year, shows a new study by the National Research Council.
Water pollution can be classified according to the nature of pollutants, the sources releasing them and the water bodies into which they are discharged. Water pollution is measured by the concentration of pollutants in the water body and their effects on other water uses. Six categories of pollutants are recognized :-
Pathogens – Pathogens are disease-causing bacteria, viruses and protozoa, usually from human sewage. As pathogen numbers increase, so does the risk to human health.
Biochemical Oxygen Demand – Biochemical Oxygen Demand (BOD) is created by organic wastes decaying in the water body. Major sources of BOD are pulp and paper mills and municipal sewage. If dissolved oxygen is depressed to zero, all fish die and anaerobic decomposition generates noxious gases.
Nutrients – Nutrients, particularly nitrogen and phosphorus, enrich waters and accelerate the aging of lakes and streams (eutrophication). The resultant rich plant growth often prohibits recreational activities, and plankton blooms depress oxygen levels. Major sources of nutrients are municipal sewage and urban and agricultural runoff.
Toxic Materials – Toxic materials can affect the health of aquatic organisms and their consumers, and of those drinking contaminated waters. Toxicants include heavy metals, chlorinated hydrocarbons, polycyclic aromatic hydrocarbons and phthalates. They originate from many sources as a result of the large quantities of chemicals used in industries. Mixtures of toxic materials can be toxic even if their individual concentrations are below lethally toxic levels. Oil pollutants are toxic and may also smother aquatic organisms and cause the death of birds, attracted by the appearance of calm water, by destroying the waterproofing properties of their plumage.
Acidification – Acidification, particularly of lakes, results from precipitation of sulphur and nitrogen oxides emitted by industries and automobiles. Acidification, particularly of lakes, results from precipitation of sulphur and nitrogen oxides emitted by industries and automobiles. Acid rock drainage, the leach water from waste rock produced from mining ores containing sulphide minerals, causes acidification of surface and ground water.
Temperature Changes – Temperature changes from waste heat discharges can cause pollution when their elevation reduces dissolved-oxygen levels, accelerates eutrophication, affects ecological processes and blocks migration paths of fishes.
Effect of water pollution
Effects on Ecosystem
Besides the inorganic nutrient input, with the inflow of the waste water most of them from factory, decomposition of organic wastes in river, plant nutrients such as nitrates and phosphates will takes place. This process will promotes the growth of oxygen consuming algae (algal bloom), especially the blue-green algae which produce cynotoxics can cause poisoning to humans and animals. The growth of oxygen consuming algae, which deoxygenates water mostly kill the nearest fish and other animals is referred to as eutrophication. Addition of oxygen not sufficient to support life.
Effects on Human Health
Nitrate polluted water can cause incidence of tumours and ulcers. Contact with pollutants can cause skin disorders due. Water pollution also causing increased case of constipation, diarrhoea and infections to intestine. It also has dangerous effects on growing foetus in pregnant women. Loss of memory power and reduced mental sharpness. One of the biggest threats for the developing countries is the disease caused by polluted water cholera caused by drinking water to Malaria where mosquitoes breed on polluted stagnant water. Regular intake of polluted water may cause sclerosis, skin legions, and problems in blood circulation, mineral deposits in bones, certain cancers and disease of the nervous system. Reduced activity of immune system. Water borne diseases like jaundice, hepatitis, gasteroenteritis will be more prevalent due to water pollution.Diseases caused by water pollution are the major cause of human death across the world. Such toxic material travels up the food chain and effects human through the fish and meat that we eat .Contaminated water causes the food source and plant life to be destroyed , this inversely effects the climatic and environmental properties required for human survival.
Improvement of Water Quality
a) Primary treatment – mechanical screening and sedimentation of undissolved solids in raw sewage is done. But it fails to remove dissolve substance in this liquid.
b) Secondary treatment – Sewage treated- the primary treatment is brought in contact with agent such as oxygen and aerobic micro-organisms. They will break down the organic matter(can be harmfull) into harmless materials as H2O and CO2. Furthermore, chlorination is carried out to reduce the bacteria.Further treated to tertiary level zero measures are adopted for secondary treatment :-
i) Trickling filter method – like the filter of mineral water,sewage water passes through a thick bed of gravel stones(large stone) so that bacteria will consume most of the organic matter.
ii) Activated sludge process — in this stage,the sewage water is pumped into an aeration tank. This tank contains sludge which consisting of bacteria and algae. The bacteria is able to decompose almost all of the organic matter and algae will undergo photosinthesis and produces oxygen to promote the growth of these decomposers.
c) Reverse osmosis
Ways to Help Overcome Water Pollution
Water remains one of our most important primary resources, vital to our survival on Earth, yet water pollution is happenning. It is serious. How can we avoid and possibly stop it? Ignorance is the main factor. Knowledge on how to preventing water pollution and its effects to our health should be spread to community. Tighter laws should be legislated and existing laws can be improved to curb illegal dumping of trash and poisonous chemical wastes into water sources.Moreover, waste materials should be disposed off properly. Faeces have to be sent to treatment tanks. Industrial wastes should be treated before disposal, to make sure the substances are harmless.Daily household rubbish can be buried or thrown away neatly in plastic bags, to be sent to special rubbish collecting areas. Increase the campaign of recycle. Excess use of insecticides and chemical fertilizers should be avoided as far as possible. If you are using chemicals that may be harmful to the environment, store them correctly. Improperly stored chemicals can slowly sweep into the groundwater system, to avoid groundwater contamination,so keep them in tightly sealed containers, inside of structures with cement floors.