Pollutants analysis during conventional palm oil mill effluent (POME) ponding system and decolourisation of anaerobically treated POME via calcium lactate-polyacrylamide

The conventional palm oil mill effluent (POME) ponding system is unable to fully decolourise the effluent which is aesthetically important. Several parameters, such as low molecular mass coloured compounds (LMMCC), lignin–tannin, ammonia nitrogen (NH3-N) and chemical oxygen demand (COD) in the cooling pond, are much higher than for the fresh raw POME. The analysis of the POME from each pond revealed that the removal of lignin–tannin is insignificant after anaerobic ponds and hence physicochemical treatment is necessary. The POME colloid repulsion in the aerobic pond is greater than in the anaerobic pond. The coagulation/flocculation process was utilized to destabilize the anaerobically treated POME (AnPOME) colloid and calcium lactate was chosen as a coagulant. The best polymer order was identified based on an overall removal performance. The best polymer can be arranged as QF23912 (58%) > QF25610 (57%) > AN1500 (51%) > QF24807 (50%) > AN1800 (47%). All tested polymers have similarity in removing NH3-N. It can be concluded that calcium lactate-cationic polymer has potential as a pre-treatment for AnPOME.