Potential use of treated domestic sewage for cultivation of biofuel crops in Egypt

Sewage treatment in a biological compact unit and effluent reuse for cultivation of Jojoba, Jatropha and Castor beans was examined. The biological compact unit includes three zones: settling and anaerobic, aerobic biofilm and final sedimentation. Quality of raw sewage and treated effluents was monitored. Impact of water quality on growth rate of biofuel crops and soil properties was investigated. Reuse of raw sewage for irrigation of biofuel crops has major impact on microbial quality and heavy metals concentration of irrigated soil. Sequence of heavy metals accumulation in the soil was Zn > Cu > Cr > Pb. Castor beans irrigated with the final effluent has the highest growth rate and crop yield followed by Jatropha and Jojoba. Growing Castor beans using treated sewage is economically feasible since the plant produces harvestable seeds during the first year and thereafter. Castor beans yield was highest (1.78 ton/ha) with the final effluent. Estimated market price is $1241/ha.