TOWARDS SUSTAINABLE MUNICIPAL WASTEWATER REUSE IN IRRIGATION OF FOOD CROPS BY UTILIZATION OF HYBRID MEMBRANE PROCESS AND MAGNETIC NANOPARTICLES

Abstract

Wastewater reuse could relieve the global water scarcity issue when applied in the agriculture industry however, the wastewater shall be treated to ensure that the water quality meets the irrigation water quality. In this dissertation, we suggested sustainable solutions for municipal wastewater reuse in irrigation of food crops by utilization of hybrid membrane process and magnetic nanoparticles. In the first part of the dissertation, the public perception for wastewater reuse in Qatar was analyzed and a framework was designed to support decision makers when implementing the technology and achieve high acceptance from the public. Almost 20% of the participants agreed to use treated wastewater for irrigation of food crops. A significant relationship was observed between level of acceptance and age, monthly income and number of children. In the second part of the study, we analyzed and optimize the performance of highly mature membrane technologies such as nanofiltration and reverse osmosis for the reclamation of treated sewage effluent to be used in irrigation of food crops. It was found that nanofiltration is not suitable for the reclamation of wastewater due to its low rejection rate for monovalent ions. In reverse osmosis, the permeate water quality was suitable for irrigation of food crops and the highest recovery rate was 36%. Although reverse osmosis was suitable for the reclamation of treated sewage effluent, the wide implementation is hampered by membrane fouling. In the third part of the study, we designed a full scale forward osmosis plant for the reclamation of treated sewage effluent which was used to dilute reverse osmosis brine. It was found that the specific energy consumption of the forward osmosis process was 0.18 kWh/m3. The diluted brine can be regenerated using reverse osmosis and used as irrigation water for food crops. In the fourth part of the study, a novel Polyamidoamine dendrimer coated magnetic nanoparticle was synthesized to be used as draw solute in the forward osmosis process. The performance of the synthesized magnetic nanoparticles as draw solute was evaluated using a bench scale forward osmosis setup. The average water flux obtained was 12.9 LMH during the first running cycle and decreased with time due to the dilution of draw solution. The magnetic nanoparticles were easily recovered using a permanent magnet and reused as draw solute for multiple cycles.