A strategy for coupling municipal wastewater treatment using the sequencing batch reactor with effluent nutrient recovery through aquaculture

Abstract

Recovering inorganic nutrients from treated municipal wastewaters prior to discharge, can not only minimize deterioration of receiving water quality, but can also be used to culture fish. Recovery can be achieved by integrating an ecological component, aquaculture, into the treatment scheme. Because of its operating flexibility, a Sequencing Batch Reactor was used to provide biological treatment of a municipal wastewater for oxidation of organic matter, removal of suspended solids, and nitrification. Performance of the reactor's 12-hour cycle for CBOD₅, TSS, and NH₃-N removals was 98%, 90%, and 89%, respectively. To recover inorganic nutrients, effluents were used to fertilize growth of desirable algal groups in an aquaculture component. Desirable algal groups are those which are preferred food sources for those zooplankton considered preferred prey for fish. Desirable algal response is influenced by the ratio of inorganic nutrients put into the system. An SBR's operational strategy was developed to produce effluents with acceptable N:P ratios ranging from 16 to 23. Though wide variation of this ratio resulted from this fertilization in the aquaculture tanks, the resulting algal response throughout the culture period was dominance of edible algal greens.