ENFORCING water pollution laws depends wholly on strict and difficult congruity between different readings of pollutants in a given water source. To standardise water pollution measurements, scientists at the Delhi-based Centre for Biochemical Technology (CBT), a research laboratory of the Council for Scientific and Industrial Research (CSIR), have recently developed and filed for patent a product called Bodseed.

Bodseed measures the biological oxygen demand (BOD) of a water sample. BOD is an indicator of the level of polluting organic matter, such as sewage, in a water body. It discloses the amount of oxygen dissolved in water, oxygen that allows naturally-occurring microorganisms to decompose polluting organic matter in the water. The more polluted the water, explains S D Makhijani, scientist with the Central Pollution Control Board in Delhi, the greater its BDO.

Bodseed "is a unique collection of 7 to 8 bacterial strains found in sewage which can be stored in a powdered form, making their use possible anytime," says scientist Reeta Kumar, who worked on this project for the past 3 years.

The conventional method of measuring BOD entails the innoculating of a water sample with a small amount of sewage. The BOD test used earlier in India and elsewhere in the world required the measurement of dissolved oxygen of the water sample. Then the sample was maintained at a temperature of 20 degrees Celsius for 5 days, at the end of which its dissolved oxygen content was measured again. The difference in the dissolved oxygen measurements were an indication of the sample's BOD.

"The temperature of 20 degrees centigrade," says Makhijani, "is not an universal average temperature, and is especially inappropriate for a tropical country like India, where the temperatures of water in rivers and lakes varies from 20 to 35 degrees Celsius." The new method, says CPCB's S D Makhijani, "is not only more in keeping with requirement of a tropical country like India, but cuts down the measurement time from 5 days to 3. Moreover, it does away with the need for incubators which were a must in earlier methods."

He also says that the conventional method has several limitations. For one, sewage has to be collected prior to testing the water sample, which involves exposing people to disease-causing germs. For another, obtaining a uniform microbial population to ensure consistent and repeatable results is a problem.

According to Kumar, Bodseed surmounts these problems and will help environmental laboratories standardise BOD measurements: "Not only are the bacterial strains in our product non-pathogenic, using this product will negate the need to visit sewage farms, because Bodseed has a shelf life of one year and can easily be stored at temperatures between 4 to 37 degrees Celsius." Moreover, Bodseed is a uniform mix of microorganisms, reducing the chances of erroneous BOD reading.

CPCB and the Nagpur-based National Environmental Engineering Research Institute have tested industrial effluents, including from the textile and dairy industries, with Bodseed and have obtained consistent results that were remarkably consistent.