Prospective plants as biocoagulant-flocculants for removal of total suspended solids in coffee effluent treatment

Abstract

Diverse plant life has been affected by the tropical environment, which includes high humidity and lots of rainfall. This research aimed to discover local plants to be used as biocoagulants in the treatment of coffee effluent. Three species of native plants were chosen: Trichantera gigantea (ketum ayam), Manihot esculenta (cassava plant) and Piper sarmentosum (kaduk). Coffee effluent was chosen because it has high total suspended solids (TSS), contributing to increasing turbidity that exceeds the allowable regulation limits. The coagulation-flocculation method was applied to remove these suspended solids and turbidity in the effluent using a jar test. These potential biocoagulants were extracted using distilled water before being screened and characterized to measure their amount of protein and polysaccharide contents using the Bradford and acid extraction approaches. The protein content for M. esculenta showed the greatest value (87.9 mg/g), while T. gigantea revealed the highest amount of polysaccharide extracted (37.0 mg/g). The optimum operating parameters were set at 300 rpm and 5 min for rapid mixing and then 180 rpm and 30 min for respective slow mixing with 30 min settling time. The findings show that P. sarmentosum was the best biocoagulant with the highest removal of TSS and turbidity at 51.0% and 66.9%, respectively. The mass ratio used in P. sarmentosum was lower when compared to other biocoagulants, which is 45.9 mg biocoagulant/g TSS, with the protein and polysaccharides contained in this biocoagulant were 11.6 mg/g and 34.0 mg/g, respectively.