Coagulation and biofiltration by Corbicula fluminea for COD and toxicity reduction of swine wastewater

Abstract The increase on pork meat demand is consequently leading to higher production of swine wastewater. These wastewaters are problematic due to their high organic matter load and nutrients content that can promote soil and aquatic sources contamination. The conventional effluents treatment technologies seem to be inefficient for total organic matter and contaminants removal while demanding high retention times. One of the steps considered for the swine wastewater treatment is solid-liquid separation. In this work, coagulation using polyDADMAC was evaluated and the effect of the coagulant concentration for this purpose was tested. This methodology was compared with an innovative approach involving biofiltration through the invasive bivalve Corbicula fluminea. The effects of the liquid to clam’s ratio was assessed as well as the mechanism of organic matter removal and the clams reuse capacity. The best chemical oxygen demand (COD) removal obtained was 51 % using 1 L of effluent per 150 clams. Moreover, it was possible to reuse the clams during 4 cycles without losing significant efficiency on the COD removal. Moreover, the toxicity of the treated wastewater was evaluated regarding Aliivibrio fischeri and Lepidium sativum. Aeration without clams reduced the toxicity levels. However, for Lepidium sativum germination index the best result was obtained for the wastewater treated by clams. Thus, C. fluminea presents potential for swine wastewater treatment.