Wastewater criteria for irrigation in arid regions

With rapid growth of agriculture coupled with increasing population and urbanization, the demand for water in the Kingdom of Saudi Arabia is continually on the increase, causing alarming drawdown in the deep aquifers, the traditional source of water. Sewage could be a valuable source to augment this dwindling water supply, at least the irrigation supplies, and should not continue to be wasted. However, between the two extremes of use of untreated sewage for irrigation as practiced in some countries and very stringent standards that necessitate an expensive tertiary treatment, there exists a middle- of-the-road approach. This moderate alternative combines flexibility with a permit system on a case-by-case basis to make the best use of this valuable commodity. This viewpoint is strengthened by the experimental results obtained on a 50-m × 25-m (160-ft × 80-ft) University of Petroleum&Minerals (UPM) farm, where secondary treated effluent with chlorination was used through a sprinkler system to grow alfalfa, summer squash, and onions based on the bacteriological analysis of the crops. Possible guidelines for establishing water criteria for the wastewater reuse for irrigation in the kingdom are suggested in light of the experiments and taking into account the practices in various countries.