Reclaimed water use in irrigation : do we need stringent reuse standards to enhance water use and reduce climate impacts?

Abstract

Unused reclaimed water in arid and semi-arid regions is a wasted water source considering the increased water demand due to population growth, rapid industrial development and climate change impacts. The legal, administrative, technical, and socio-cultural issues govern enhanced reclaimed water use in agricultural irrigation. The study aims at technical assessment of the Palestinian standards (PSI-742 and TR 34) for reclaimed water use in agricultural irrigation and explores how to enhance the water use in agricultural sector. The methodology entails critical revision of local, regional and international reuse standards reuse projects, and evaluation of reclaimed water quality from three wastewater treatment plants (WWTPs) with effluent reuse schemes (Jericho, Nablus West and Jenin WWTP). In addition, the capacity of laboratories at the three selected WWTPs including four national labs were assessed. The results obtained the following: - The Palestinian reuse standards are based on FAO, WHO and set effluent quality parameters prescribed in the memorandum of Understandings (MoUs) of the joint water committee. The latter entail less stringent quality parameters for the treated effluent destined for agricultural irrigation. However, if discharged into seasonal Wadis, more stringent technical rules apply (10/10/10 as mg/L for BOD/TSS/total N). - Despite seasonal operational disruption, all WWTPs produced reclaimed water (after filtration and disinfection) in compliance with PSI 742 considering salinity parameters (TSS, COD, total-N) and sanitary quality parameters (pathogenic microorganisms). Reclaimed water contained only nine of 14 elements including boron with values below the PSI-742 limits. - Relaxation of the PSI-742 quality parameters entails reduction in the number (half) of heavy metals required, removing BOD, lowering total-N similar to that in TR-34, in the latter raise SAR value as in PSI-742, and add EC and pH. MoA reuse permit shall include priority parameters, as TDS, turbidity, Cl and Na content due to their potential toxicity on soil and produce. - Capacity of local laboratories urges concerned parties recognize specific labs for the analysis of certain lab tests based on equipment availability and staff qualification. This will ensure reliable and credible lab results and monitoring. Training of lab analysts and securing spare parts and sufficient chemicals are essential. To enhance health and environmental protection, enforcement of regulatory monitoring for the WWTPs, regular O&M, preventive and corrective maintenance, control of illicit industrial discharges, pretreatment of heavy industrial polluters, are all urgent measures suggested.