Viability of combining microalgae and macroalgae cultures for treating anaerobically digested piggery effluent.

Algal phytoremediation represents a practical green solution for treating anaerobically digested piggery effluent (ADPE). The potential and viability of combining microalgae and macroalgae cultivation for the efficient treatment of ADPE were evaluated in this study. Bioprospecting the ability of different locally isolated macroalgae species illustrated the potential of Cladophora sp. to successfully grow and treat ADPE with up to 150 mg/L NH4+ with a biomass productivity of (0.13 ±â€¯0.02) g/(L·day) and ammonium removal rate of (10.23 ±â€¯0.18) mg/(L·day) NH4+. When grown by itself, the microalgae consortium used in this study consisting of Chlorella sp. and Scenedesmus sp. was found to grow and treat undiluted ADPE (up to 525 mg/L NH4+) with an average ammonium removal rate of 25 mg/(L·day) NH4+ and biomass productivity of (0.012 ±â€¯0.0001) g/(L·day). Nevertheless, when combined together, despite the different cultivation systems (attached and non-attached) evaluated, microalgae and macroalgae were unable to co-exist together and treat ADPE as their respective growth were inversely related to each other due to direct competition for nutrients and available resources as well as the negative physical interaction between both algal groups.

Macroalgae culture to treat anaerobic digestion piggery effluent (ADPE).

Environmental consequences of high productivity piggeries are significant and can result in negative environmental impacts, hence bioremediation techniques (in particular using macroalgae) are therefore of great interest. Here, the growth potential of several freshwater macroalgae in anaerobic digestion piggery effluent (ADPE), their nutrient removal rates and biochemical composition of the biomass were investigated under outdoor climatic conditions. A consortium of two macroalgae, Rhizoclonium sp. and Ulothrix sp. was isolated and could efficiently grow in the ADPE. Maximum ammonium removal rate (30.6±6.50mg NH4+-NL-1d-1) was achieved at ADPE concentration equivalent to 248mgNH4+-NL-1. Mean biomass productivity of 31.1±1.14g ash-free dry weight (AFDW) m-2d-1 was achieved. Total carbohydrate and protein contents ranged between 42.8-54.8 and 43.4-45.0% AFDW, respectively, while total lipid content was very low. The study indicates the potential use of this macroalgal consortium for treating ADPE as well as source of animal feed production.