Abstract
This research addresses biological compact unit(BCU)used for onsite wastewater treatment for application and replication in small communities as a non- conventional water resource for agricultural purposes. A (BCU) was fabricated and installed in the in-house experimental zone where the domestic sewage was delivered to the BCU continuously .Operation of the BCU was continuous, hence at different organic loading rates (OLR) and different temperatures .The treated sewage was fed from the BCU to a sand filter upper side. The treated wastewater quality produced from the BCU in terms of physico-chemical and biological characteristics at HRT 12h agree with the Egyptian permissible limits for restricted irrigation. This is because of the substantial reduction of total COD resulting in an average effluent concentration of 67 mg/l and FC of 560/100 ml. The characteristics of sand filter effluent, treating BCU effluent operated at 12h HRT in terms of COD, BOD,TSS and fecal coliform were 35 ,17 ,5 mg/l and 95/100ml. These values are compatible with national legislation for wastewater reuse in un-restricted crops irrigation. The total cost of BCU construction, operation and maintenance will be US$0.34/m3 for restricted crops irrigation. When adding a sand filter, the cost will be US$0.46 /m3 for un-restricted crops irrigation.