PERFORMANCE OF A SMALL AQUATIC PLANT WASTE-WATER TREATMENT SYSTEM UNDER CARIBBEAN CONDITIONS

The performance of an aquatic plant wastewater treatment system under Jamaican conditions has been investigated. Eichhornia crassipes was used to determine nutrient removal capacity at a pilot scale. The experiments were conducted in a series of six tanks each of volume 5.4 x 10(3)1 containing E. crassipes, with secondary treated effluent supplied at a rate of 162001/day for seven days. Over seven days, the mean decrease in total N in the effluent as it flowed between tanks one and six was 27.6%. Total P increased by an average of 4.48%. Potassium showed a mean reduction of 20.2% but Na increased slightly (0.88%). Nitrogen content of the plant tissue increased by 2.9% after seven days and P by 6.7%. This removal of nutrients was reflected in the increase in the plant's tissue. Removal of N and P was dependent on the N:P concentration ratio of both the nutrient medium and the plant tissue. The design of the aquatic treatment system in the present study could treat sewage from a community of an average population of 5000 people. The nutrient levels of the water produced were suitable for irrigation purposes. (C) 1995 Academic Press Limited