Advanced Treatment Aquaculture Wastewater By Algae-mollusk Polycuture System

With the rapid development of inshore aquaculture, the pollution resulted from theaquaculture wastewater has been attracted more and more attentions. According to thecharacteristics of shellfish aquaculture wastewater in aqua farm of Qinhuangdao, thisstudy was carried out for advanced treatment aquaculture wastewater by algae-molluskpolycuture system. Bio-ecological treatment technology of shellfish aquaculturewastewater was developed through optimizing the technological parameter, with whichprovides technical reference to improve the aquaculture environment by using thealgae-mollusk polyculture. The main results were as following:1) The absorption of nitrogen, phosphorus and COD by such macroalgae asGracilaria lemaneaformis, Uiva pertusa and Kelp was tested in this study. The mainconclusions were as follows: compared to Uiva pertusa and Kelp, Gracilarialemaneaformis was a better choice for algae-mollusk polyculture since it can remove84.6%of phosphate,48.5%of ammonia nitrogen,78.9%of nitrate nitrogen, and68.4%ofnitrite nitrogen. It was far better than Uiva pertusa and Kelp in removal effect.2) The experiment was made on the removal of nitrogen and phosphorus nutrient bymacroalgae. The main conclusions were as follows: when the stocking density is200g/m3,purification effect is the best. It can remove86.8%of phosphate,51.7%of ammonianitrogen,75.3%of nitrate nitrogen,68.4%of nitrite nitrogen and10.3%of COD. And theaverage concentrations of phosphate, ammonia nitrogen, nitrate nitrogen, nitrite nitrogenand COD were reduced from8.72mg/L,56.02mg/L,5.58mg/L,2.69mg/L and72mg/L to11.5mg/L,27.09mg/L,137mg/L,0.85mg/L and334mg/L, respectively.3) The optimal stocking density of the polyculture system of Gracilarialemaneaformis and Argopectehs irradias was40scallops and200gram per cubic meter.When the proportion of Gracilaria lemaneaformis and Argopectehs irradias was1:1, theeffect of the polyculture system was obvious. The removal rates of phosphate, ammonianitrogen, nitrate nitrogen, nitrite nitrogen and COD were95.1%,91.5%,85.3%,84.4%and77.7%, respectively. And effluent concentration phosphate, ammonia nitrogen, nitratenitrogen, nitrite nitrogen and COD were0.45mg/L,4.79mg/L,0.82mg/L,0.42mg/L and80mg/L, respectively.4) The polyculture of Gracilaria lemaneiformis and Argopectehs irradias caneffectively remove dissolved nutrients and COD from the aquaculture wastewater. Themain effluent parameters had met the discharge requirement of national standards of Integrated waste water discharge standard (GB8978—1996).