PRELIMINARY LABORATORY-SCALE INVESTIGATION OF PLANT BIOMASS HARVESTING EFFECT ON WASTE NUTRIENT REMOVAL FROM FISH FARM WASTEWATER

Macrophytes can remediate fish farm wastewater sustainably before discharging them to water bodies. However, macrophytes harvesting could potentially affect the phytoremediation since biomass removal could reduce its performance. In this study, the harvesting effect on the waste nutrient removal performance of Spirodela polyrhiza and Lemna sp. were carried out in fish farm wastewater for 14 days. Water quality assays include ammonia (NH 3 -N), nitrate (NO 3 - -N), phosphate (PO 4 3- ), COD, turbidity and TSS were monitored. The biomass composition of the macrophytes at the end of the experiment was assessed. From the results, biomass harvesting affected the nitrate, phosphate, TTS and macrophyte fresh weight, but not for ammonia, COD and turbidity. Nitrate increased slightly after S. polyrhiza and Lemna sp. were harvested, with their levels still controlled under typical natural level. Harvesting S. polyrhiza and Lemna sp. enhanced phosphate and TSS removal from the macrophytes' wastewater and biomass increment. Overall, harvesting had more improved results compared to the one without harvesting. 83% phosphate, 93% turbidity, 93% TSS, complete ammonia and COD removal from the fish farm wastewater could be attained by the macrophyte groups. The obtained data can help improve the harvesting practice on macrophytes, predicting and elevating the phytoremediation performance in the wastewater.