Microalgae for Effective Nitrogen and Phosphorus Removal from Aquaculture Effluence

  Objective   Microalgae capable of effectively removing nitrogen and phosphorus from wastewater were screened for potential applications on antipollution or effluence treatment at aquaculture farms.

  Method   Three selected microalgae, Chlorella sp. JY-1, Chlorella sp. SY-4, and Desmodesmus sp. SH-1, were evaluated for their capability in removing nitrogen and phosphorus from the wastewater at a shrimp aquaculture farm.

  Result  After 5d of cultivation, the microalgae grew to a cell density in the (7±1)‰ salinity medium at 1.56×10⁷·ml⁻¹ on JY-1, 1.47×10⁷·ml⁻¹ on SY-4, and 6.62×10⁶·ml⁻¹ on SH-1. The removal rate on total nitrogen was 50.36% by JY-1, 41.51% by SY-4, and 49.74% by SH-1; that on ammonia nitrogen, 96.29% by JY-1, 84.92% by SY-4, and 96.65% by SH-1; that on nitrate nitrogen, 15.84% by JY-1, 3.69% by SY-4, and 12.56% by SH-1; and, that on total phosphorus, 93.51% by JY-1, 82.38% by SY-4, and 94.25% by SH-1; but not significant on nitrite nitrogen by any of them. The microalgae appeared to grow normally in a culture medium of 5%, 10%, 20% or 30% salinity. Among them, Chlorella sp. JY-1 performed the best on growth as well as nitrogen and phosphorus removal in the test wastewater.

  Conclusion   Chlorella sp. JY-1 appeared to offer a promising potential for application of purifying aquaculture effluence.