Saving our water

Disna Mudalige

In the present era, the water pollution caused by releasing wastewater from industries directly to waterways is a major issue of concern in Sri Lanka. Specially the textile waste water containing dye and industrial wastewater containing organic materials have raised many environmental and health problems. Due to the consumption of these contaminated water, the extinction of fish and other kinds of species living in water is reported time to time in many parts of the country.

Not only fish, but also the birds which hunt fish are also affected by this. This shows the degree of disturbance human activities cause to the natural cycle of the nature.

Kelaniya River, Beira Lake, Bolgoda Lake and Lunawa lagoon are visible examples for the water pollution by human activities. The aquatic life of the Lunawa lagoon has been degraded due to continued discharge of wastewater into its tributaries. The lagoon is now devoid of aquatic life and considered to be biologically dead.

Wastewater disposal

As recorded a considerable number of people use rivers and tanks to get drinking water. The safety of these means for drinking water purposes is becoming hazardous day by day. Most of these rivers are also being used by the general public for various purposes such as washing and bathing etc.

Among major illnesses of water pollution, typhoid/paratyphoid fever, shigellosis, food poisoning, amoebiasis, intestinal infections, malaria and dengue fever are reported to be quite common. As Central Environmental Authority (CEA) Environmental Protection Director Ramani Ellepola brings out in her paper ‘Implemention of Industrial Pollution Control Programs in Sri Lanka’, the industries which generate the largest quantities of wastewater in Sri Lanka are the textile, natural rubber processing and food processing industry sectors.

These three industry sectors are widely distributed throughout the country. The effluents generated from these industries are generally disposed into nearby water bodies such as rivers, lakes or into the ocean, due to the lack of a proper system for the disposal of wastewater.

Irrigation purposes

The National Environmental Act No: 47 of 1980 with amendments Act No: 56 of 1988 lays down that, ‘no person shall pollute any waters of Sri Lanka or cause or permit to cause pollution in the inland waters of Sri Lanka’. Understanding the seriousness of the issue general standards have been laid down by CEA for the discharge of effluents into inland surface waters.

As Ellepola discribes industrial effluent standards are as follows:

a. General standards for discharge of effluents into inland surface waters.

b. Tolerance limits for industrial effluents discharged on land for irrigation purposes.

c. Tolerance limits for industrial and domestic effluents discharged into marine coastal areas.

d. Tolerance limits for effluents from rubber factories discharged into inland surface waters.

e. Tolerance limits for effluents from textile industry discharged into inland surface waters.

f. Tolerance limits for effluents from tannery industry.

These are included in the Environment Impact Assessments and Environmental Protection Licence. All new industries as well as the existing industries are encouraged and recommended to establish central treatment plants within them.

As a good solution to the existing problem of wastewater disposal in the country University of Moratuwa Chemical and Process Engineering Department senior lecturer Padma Amerasinghe has designed a waste biomass for the removal of heavy metals from wastewater. This biomass can be operated by using rice husk, saw dust, tea waste or choir pith, which are called solid absorbents. Dyes and industrial wastewater can be cleaned in this way.

The liquid is sent through an absorption column with a perpetrated bottom filled with one of the solid absorbents. In the process, the dye component will be transformed to the solid material.

Natural waterways

As Dr Amerasinghe mentioned, 1,000 liters of wastewater containing roughly 30 milligrams of dye per liter can be cleaned by using five kilograms of rice husk. The water coming out of this system is checked with the COD and BOD standards, and results are within the possible limits of these standards. The outcome is safe to release to natural waterways. She suggested to burn the used solid absorbent to get energy, and further said that the ashes can be used in cement.

She also mentioned that better results can be acquired if this method is coupled with other established methods to clean water such as coagulation. In that way, less quantity of solid can be used as well.

It should be noted that innovative methods like the above must be given serious consideration and attention, as a means to reduce the existing water pollution in the country.