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High nutrient removal rate from swine wastes and protein biomass production by full-scale duckweed ponds

Mohedano, Rodrigo A., Costa, Rejane H.R., Tavares, Flávia A., Belli Filho, Paulo
Bioresource technology 2012 v.112 pp. 98-104
effluents, proteins, nitrogen content, ponds, farms, crude protein, biomass production, dissolved oxygen, swine
Duckweed ponds have been successfully used in swine waste polishing, generating a biomass with high protein content. Therefore, the present study evaluated the efficiency of two full-scale duckweed ponds considering nutrient recovery from a piggery farm effluent (produced by 300 animals), as well as the biomass yield and crude protein (CP) content. A significant improvement in the effluent quality was observed, with the removal of 98.0% of the TKN (Total Kjeldahl Nitrogen) and 98.8% of the TP (Total Phosphorous), on average. The observed nitrogen removal rate is one of the highest reported (4.4g/m²day of TKN). Additionally, the dissolved oxygen level rose from 0.0 to 3.0mg/L, on average. The two ponds together produced over 13tons of biomass (68t/hayear of dry biomass), with 35% crude protein content. Because of the excellent nutrient removal and protein biomass production, the duckweed ponds revealed a great potential for the polishing and valorisation of swine waste, under the presented conditions.