Assessment of the Effect of Remediation Strategies on the Environmental Quality of Aquaculture Ponds in Marilao and Meycauayan, Bulacan, Philippines

Abstract

Background.Water quality in the Marilao-Meycauayan-Obando river system (MMORS) of Bulacan, the Philippines, is of great concern due to the pollution load from local industries. The river system is currently used as a source of water for the aquaculture industry in Bulacan.Objectives.In order to address organic and heavy metal pollution, several remediation strategies were tested in aquaculture ponds along the river system. Strategies such as phytoremediation (vetiver grass pontoons), application of probiotics and zeolite (with filtration as pre-treatment) were utilized in ponds to decrease or remove toxic pollutants in water and sediments.Methods.Two sites were chosen as the pilot remediation sites – ponds in Barangay Nagbalon, Marilao and Barangay Liputan, Meycauayan, Bulacan. Pond bottom preparation was done to improve the condition of the pond bottom sediments before stocking by adding zeolite. Physicochemical parameters of water such as dissolved oxygen (DO), temperature, pH, salinity, ammonia, phosphate, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were monitored throughout the culture period. Heavy metals in sediments and fish were monitored. Fish parameters such as average body weight and feed conversion ratio were determined.Results.The DO levels were below recommended levels in the morning and reached a supersaturated level in the afternoon. Ammonia and COD levels were above recommended limits. A decreasing trend was observed for ammonia levels in treatment ponds. In terms of the growth of milkfish, the pond with probiotics showed the highest growth and better feed conversion ratio in Nagbalon and in the phytoremediation pond in Liputan. Percentage survival of milkfish was much higher at Liputan. Copper, chromium, lead and manganese were detected in pond sediments. After application of zeolite, there was a decrease in lead levels throughout the culture period.Conclusions.The different remediation studies were compared in terms of cost, effectivity and application and phytoremediation (vetiver grass pontoons) was determined to be the most cost-effective remediation strategy.Competing Interests.The authors declare no competing financial interests.

Evaluating Microbial Biofertilizers for Root Colonization Potential in Narra (Pterocarpus indicus Willd.) and Their Efficacy in Heavy Metal Remediation

“…Phytoremediation is defined as a bioremediation strategy that uses plants and their physical, chemical, biological, and microbiological processes in contaminated sites to minimize the toxicity of pollutants. This method is a low-cost and environmentally friendly technology that involves not only the degradation of pollutants but also the removal of the pollutants from the environment without causing further degradation (Broda, 1992) as cited by [17]. In the study of [18], there were four (4) tree species, namely Ipil-ipil (Leucaena leucocephala Linn.…”

Plankton Community Structure of the Aquaculture Ponds in Marilao and Meycauayan, Bulacan, Philippines

“…The river system is currently used as a source of water for the aquaculture industry in Bulacan. Heavy metal and organic matter pollutants are detrimental to the river system and had caused environmental resource degradation and posed numerous public health risks (Pleto et al 2018). Different organisms are severely affected by the pollutants present in the water.…”

Analysis of the copper removal kinetics of the Philippine giant bamboo (Dendrocalamus asper) in hydroponics

“…In Bulacan, Philippines, industries involved in electronics, metalworking and jewelry are forced to discharge copper-containing wastes to the Meycauayan-Marilao-Obando River System (MMORS). In one of the test points near a dump site, copper concentrations of up to 3.14 ppm were detected [ 5 , 6 , 7 ]. This could have been caused by surface runoff during the rainy season.…”

“…This could have been caused by surface runoff during the rainy season. Sediments tested exceeded the threshold element level and were possibly toxic to the milkfish being reared in the area through aquaculture [ 6 , 7 ]. As such, various techniques and technologies are being further developed in order to restore the copper concentrations back to habitable levels [ 8 ].…”

“…Phytoremediation is one form of bioremediation that uses plants in removing pollutants such as heavy metals from a water/soil matrix. It was the recommended solution to treating the MMORS [ 6 ]. Although the mechanism for copper removal differs among plant species, the treatment is proven to be cheaper, less invasive and requires less energy/labor intensive compared to conventional in-situ and ex-situ methods such as pump and treat, thermal desorption, encapsulation, soil washing, electrokinetic removal, and chemical immobilization [ 8 ].…”