Researchers near completion of bacteria-based system for treating hazardous wastewater

A heightened awareness of the condition of its rivers had led local government units and concerned agencies in the province of Bulacan to tap BIOTECH of UP Los Baños for help in setting up bioremediation solutions, which are less costly and more environment-friendly than conventional chemical treatments.

Dr. Lorele C. Trinidad, researcher at BIOTECH, and leader of the team that is developing the bioremediation system, reported that the prototype they have developed can remove and at the same time recover heavy metals from water discharged during processing of gold and leather tanning.

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

Silver, a valuable metal, can be recovered from the chemical solutions used in gold-smelting. The recovery process, however, results in copper-laden wastewater that is usually dumped into Bulacan’s river system. When Dr. Trinidad's team examined industrial wastewater from various sites of the river system, samples were found to contain 5,000-10,000 ppm of copper. The limit allowed by the DENR is only 1.3 ppm.

Also a common means of livelihood in Bulacan, leather tanning operations use the chemical called Chromium III in the treatment of raw animal hide. According to Dr. Trinidad, the process uses up so much Chromium III that as much as half of the applied chemical ultimately ends up in the river.

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

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

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

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