Advanced technologies for municipal wastewater purification: technical and economic assessment

The water resources of Kuwait are limited to desalinated water to meet the requirements for all freshwater needs, unreplenishable brackish water as a supplementary source for blending and agriculture, and municipal wastewater which is treated and mainly discarded to the sea. Limited quantities of the treated effluents are utilized for agriculture and greenery purposes. The large quantities of treated effluents have a great potential to replace the brackish water supplies and to redress the balance of demand for irrigation water. Research work was carried out at the Kuwait Institute for Scientific Research (KISR) to assess the technical viability and economic feasibility of implementing reverse osmosis (RO) technology to renovate Kuwait’s treated wastewater effluent. This paper describes the adopted treatment, alternative pretreatment, characteristics of the permeate and cost of the renovation treatment. The results indicate that municipal wastewater can be treated by advanced technologies to produce an excellent water which is almost devoid of salts, pollutants and microorganisms. The total cost of such treatment is estimated to be almost half of the distillate cost produced by multistage flash (MSF) plants, whereas the cost of treating the tertiary treated wastewater alone by additional advanced treatment constitutes only 25% of the MSF distillate costs. The Government of the State of Kuwait has decided to implement this technology in constructing a wastewater treatment and reclamation plant at Sulaibiya in the context of privitization to produce an effluent of a quality that can be considered an additional water resource for non-potable uses.

This work resulted in the development, construction and verification of an appropriate pretreatment system for wastewater feed for RO plants, which was successfully operated. The results indicate that commercially available RO technology is viable and reliable in the production of an excellent quality of freshwater, free from viruses and bacteria, and almost free from all dissolved and undissolved chemicals. The quality of the produced water can be used safely for all normal purposes except for direct human consumption due to psychological and probably religious reasons. It can be used for greenery (restricted and unrestricted areas), industrial, aquifer recharge and other cleaning purposes. Current average freshwater consumption in Kuwait is more than 200 migd. Over 60% of this quantity ends in the sewers. The State is obliged to collect and treat the effluent to an acceptable standard before discharging it into the sea. The conventional treatment cost is KD 0.120/m³, which represents 28% of the cost of MSF distillate. The purification of the effluents using membrane separation processes proved to be viable, safe and economical. With the additional cost of the advanced treatment (also around 25% of the MSF distillate cost), a huge quantity of excellent and potable quality of water can be secured. And the resource is both reliable and continuously increasing. Based on these facts, the State of Kuwait has decided to construct a new wastewater treatment facility at Sulaibiya, in the context of a privatized “build, operate and transfer” project. Prequalification of the interested consortia has been announced, and the tender document has been distributed to the prequalified consortia. The new project is expected to be implemented during the year 2000, and the construction period is estimated to be less than 36 months. The cost presented in this paper reflects the pilot study and should not be used for quotation purposes. Acknowledgments The author wishes to acknowledge the partial financial support of the Environmental Public Authority (EPA), the in-kind contribution of a 250,000 migd brackish water RO plant from the Ministry of Electricity and Water and the use of the Ardiyah site from the Ministry of Public Works.