Researchers nears completion of bacteria-based system for treating deadly wastewater

With the increased awareness on the need to clean-up its rivers, Bulacan’s local government units have tapped UP Los Baños-BIOTECH to help in setting up bioremediation solutions which are less costly and more environment-friendly than conventional chemical treatments.

Dr. Lorele C. Trinidad of BIOTECH, who leads the team developing the bioremediation, reports that the developed prototype can remove and at the same time recover precious heavy metals from water discharged during gold processing and leather tanning.

Gold jewelry-making became a popular household-based livelihood in the province of Bulacan, but jewelry makers use crude equipment and inefficient processing techniques.

Silver, a valuable metal, can be recovered from the chemical solutions being used in gold-smelting. In the process, copper-rich wastewater is produced. The wastewater is usually dumped into Bulacan’s river system. When Dr. Trinidad's team sampled industrial wastewater from various sites of the river system, it found out that the wastewater has 5,000-10,000 ppm of copper, when the limit allowed by the Department of Environment and Natural Resources is only 1.3 ppm.

On the other hand, leather tanning operations in Bulacan use chromium III to treat raw animal hide during tanning. According to Dr. Trinidad, processors use so much chromium III that as much as 50% of the applied chemical ultimately goes to the river.

With fund assistance from the Philippine Council for Industry and Energy Research and Development (PCIERD) and the Department of Science and Technology (DOST), Dr. Trinidad’s team identified 12 isolates of bacteria collected from Marinduque and Bulacan with high capability to reduce sulfates and produce hydrogen sulfide gas. These bacteria were used in the fabrication of a small bioremediation system.

The bioremediation system, built by the Industrial Technology Development Institute –DOST for the project, uses the hydrogen sulfide gas produced by the bacteria to precipitate and recover copper and chromium from wastewater.

Results of optimization studies have shown great potential for the prototype to be upscaled to a working unit for installation in actual operation sites.

Dr. Trinidad and her co-researchers are now designing a bench-scale metal recovery system, estimated to cost around P300,000, for completion by the end of 2009.