Assessment of different bioremediation strategies on the environmental quality of the aquaculture ponds of Brgy. [Village] Nagbalon, Marilao and Brgy. Liputan, Meycauayan, Bulacan, Philippines

Several bioremediation strategies such as phytoremediation (vetiver grass), use of probiotics and biomin (with filtration as a pre-treatment) were utilized to address the pollution in the aquatic environment of the MMORS. Two sites were chosen as the pilot remediation sites � ponds in Brgy. Nagbalon, Marilao and Brgy. Liputan, Meycauayan, Bulacan. Pond bottom preparation was also done in order to improve the condition of the pond bottom sediments before stocking. Baseline assessment was done as a reference point before applying the remediation technologies. Physico-chemical, biological and heavy metal content were monitored throughout the four months of culture. The dissolved oxygen levels (early morning) in both sites were below the recommended limits (5.0 ppm) for aquaculture but reaches supersaturated levels (20 ppm) in the afternoon. Ammonia (0.1 ppm), phosphate (0.4 ppm) and chemical oxygen demand (100 ppm) exceeded the recommended limit. Copper was observed to be present on water and fingerlings. Numerous phytoplankton and zooplankton species were observed which serves as indicator of pollution in the water. Copper, chromium, lead and zinc were present in sediments for both sites. Compared with the baseline heavy metal content, decreased for chromium, lead and zinc upon application of biomin in the sediments. The pond with probiotics at Nagbalon site had the highest biomass at harvest while in Liputan site applied pond with vetiver, had the highest. The pond applied with probiotics and biomin had the highest percent survival of 98.30% in Nagbalon site; while the pond applied with vetiver grass had the highest for Liputan site (94.70%). Probiotics helped the milkfish to grow more, improve their feed digestibility and feed utilization. Application of biomin on sediments brought decrease in chromium, lead and zinc. The vetiver grass system emerged to be the most effective strategy based improvement in water quality and fish quality parameters. The ammonia had decreasing trend throughout the cultivation period while BOD and COD were relatively lower in phytoremediation ponds. The filtration technology helped in preventing entry of contaminants, suspended solids and predators. These bioremediation strategies brought changes to the environmental quality of the aquaculture ponds in both sites. It may not be significant, but still changes were observed. These strategies could still be improved through engineering design and proper application.