Application of polyaluminum chloride and anionic polyacrylamide in the solid-liquid separation pretreatment of aquaculture tailwater

Solid-liquid separation is crucial for the treatment of aquaculture tailwater. In this study, a solid-liquid separation process, polyaluminum chloride (PAC) + sedimentation tank + anionic polyacrylamide (APAM) + stacked screw filter press (SSFP), was constructed to improve the solid-liquid separation efficiency of aquaculture tailwater. An investigation was conducted involving the addition of PAC (M_PAC) and APAM (M_APAM), and relevant models were constructed though response surface methodology. The results indicated that SSFP cannot work effectively with only PAC added. The combination of PAC and APAM produced better results. When the daily feeding (M_Feeding) of Litopenaeus vannamei into a recirculating aquaculture system was 230 kg/d, M_PAC = 700 g, and M_APAM = 600 g, the filter residue yield was 61 kg (dry weight), and the recovery rate of solid particles in tailwater reached 90.65 %. The moisture content (MC) of the filter residue was recommended to be within the range of 77 −78 %. When M_Feeding = 70 −230 kg/d and the filter residue MC was 78 %, the PAC and APAM cost for solid-liquid separation was 11.5 −13.4 RMB, and the equipment operating cost was 9.09 RMB. This study developed a treatment method and provides primary data for the solid-liquid separation of aquaculture tailwater, promoting the treatment of aquaculture tailwater and the development of intensive aquaculture.