3RD INTERNATIONAL CONGRESS ON TECHNOLOGY - ENGINEERING & SCIENCE - Kuala Lumpur - Malaysia (2017-02-09)

Hydroponics Effluents: A Potential Threat To The Environment
Hydroponics culture is an innovative method of foodcrop production that helps to increase productivity and produce quality. The system of hydroponics commonly used in Mauritius is the open (run to waste) system where the substrate is continually supplied with fresh nutrients while the old is removed from the substrate by the drainage system as waste. However, hydroponics growers are mainly interested with the production side and often ignore the environmental risk associated with the waste discharged from their cultivation. This study was carried out to assess how many hydroponics growers in Mauritius are aware of the environmental impact caused by open hydroponics cultures. 120 hydroponics growers were selected for a survey around the island. 96 % of the hydroponics growers claimed that they were not aware of the pollution caused by waste water discharge from their open hydroponics cultivation while only 4 % of the growers were found to be aware of environmental impact of hydroponics effluents and these growers collected the hydroponics effluents discharge and used them to irrigate garden crops. They even designed a system for collection of their hydroponics effluents. From data collected during the survey, it was also estimated that under normal conditions, out of 100 mL of nutrient solution provided per plant, around 60% of solution was absorbed by the plant and the rest leached out as hydroponic effluent. The amount of hydroponic effluents collected per day from one greenhouse was around 1 litre per square metre with a nitrate concentration of around 108-110 mg/L. The concentration was found to vary with the crop density and size of greenhouses. Assuming that on average 250 litres of hydroponic effluents were leached per day, the amount of nitrate lost for a greenhouse of 250 m2 was 27 g per day. Furthermore, for crops like tomato the amount of nitrate discharged in the environment was estimated to around 6000 g per square metre over one year period.. Thus, for Mauritius with an estimated area of 25 hectares under open hydroponics, it was forecasted that 26 kg of nitrate would be lost to the environment per day.
Prathima Seechurn Poonpoon, Bhanooduth Lalljee