Water hyacinth (Eichhornia crassipes) was found to be useful in enhancing the final discharge quality of some agroindustrial wastewaters treated in lagoon systems. With a hydraulic retention time (HRT) of 5 days, the macrophyte was able to further reduce the biochemical oxygen demand (BOD) of anaerobically and aerobically treated palm oil mill effluent by 40% to 50 mgl-1, accompanied by remarkable removal of ammoniacal nitrogen (AN) and total kjeldahl nitrogen (TKN) by 53.7% and 68.8% respectively. It also assisted in the settling of suspended solids (SS) to below 20 mgl-1. In the secondary treatment of small-scale piggery effluent, the aquatic weed was found in a pilot field investigation to be 17-112% more efficient than algae in removing BOD and COD loads from a reconstituted effluent. A study at an institutional farm confirmed that >97% reduction of the major pollutional parameters was achieved. Introduction of hyacinth to a pilot plant treating sugar refinery wastewater resulted in the removal of BOD, COD and SS by 43.5%, 35.8% and 21.9% respectively with a HRT of 7 days. However, a chloride content exceeding 100 mgl-1 would inhibit its healthy growth. In the tertiary treatment of natural rubber processing effluent, removals of 85% BOD, 80% COD, 88% SS, 50% AN and 53% TKN were achieved with a HRT of 10 days. Increasing the HRT to 15 days resulted in higher removal efficiencies. Harvesting data indicated that the average biomass produced was 6-10% per day. The average growth rate of the aquatic plant could be as high as 505kg ha-1day-1 on dry weight basis.

You do not currently have access to this content.