Aquaculture wastewater quality improvement by water spinach (Ipomoea aquatica Forsskal) floating bed and ecological benefit assessment in ecological agriculture district

The current ecological situation of aquaculture water quality in Wushe (Songjiang district, Shanghai city) district is not up to mark. In the present study, characteristic of ecological agriculture park was first investigated and then water spinach floating bed was used to improve the aquaculture wastewater quality. The results showed significant improvement in the aquaculture water quality at the experimental site with removal rates of TN, NH₄⁺-N, NO₂^--N and TP were 11.2%, 60.0%, 60.2% and 27.3%, respectively. Moreover, we found that the removal mechanism of ammonia nitrogen and nitrate nitrogen by water spinach was mostly by microorganism, whereas the removal mechanism of phosphorus was mainly by plant absorption. In addition, water spinach could be harvested at regular time intervals, which could achieve good economic benefits. This research could provide a good case study for sustainable development in ecological agricultural park for other cities around the world.