BIOREMEDIATION OF MARICULTURE WASTEWATER USING GREEN SEAWEED
Rapid and uncontrolled expansion of the marine aquaculture industry has made negative impact on the marine environment, mainly due to the discharge of organic waste on occasions directly into sensitive marine ecosystems. The rapid growth of aquaculture is accompanied by increased discharge of nutrient-rich wastewaters into rivers and coastal waters, leading to eutrophication, and deterioration of water quality. Bioremediation of aquaculture waste using seaweeds as nutrient scrubbers and oxygenators provides good alternative and cost-effective, conventional treatment systems. Seaweeds may play a vital role in improving water quality and contribute to sustainable aquaculture.
In present study, we evaluated the growth engineering and bio-filtration efficiency of green seaweed sp. Monostroma in mariculture wastewater (MWW) collected from Shrimp farm located in Maharashtra, India. The MWW showed pH of 7.62, Salinity in ppt: 15, total N: 13.83 mg/L and total P: 0.42 mg/L. In artificial light, the DGR (%) of Monostroma sp. at different density (0.25 to 1 g/L of seawater) ranged from 3.78 to 17.84% with optimum at 0.250 g/L. Similarly, the DGR (%) in different light intensity (3000 to 12000 lux) ranged from 4.66 to 15.18% with optimum at 9000 lux.
The optimized growth conditions were further used to grow seaweed sp. in the MWW. The DGR (%) of Monostroma sp. in MWW (in artificial light) was found to be 18.60. The culture of this sp. was further taken to environmental chamber (natural sunlight) for further growth studies. The DGR (%) of this sp. at different density of 0.25 to 9 g/L was found to be in the range of 7.12 to 18.48% in 4 days at sunlight intensity of app. 1900-50000 lux (morning to evening) (Fig.1). After 4th day the reduction in total N (~80%) and total P (~65%) was observed. Further the growth of Monostroma sp. for 12 days showed DGR of app. 17%. All the growth experiments were carried out in AWW without addition of external nutrients.
The proximate analysis of harvested biomass from the AWW has moisture content; 78-80% (FW), ash content; ~25.7%, protein; ~15.7%, carbohydrate; ~40% and lipid content of ~4.8% on dry weight basis.
