A research team comprising of members of the sections of biology and chemistry, from the Faculty of Science at King Khalid University (KKU), has proved, in a recent scientific study, entitled "The Impact of fertilization using sewage sludge on the accumulation of heavy metals, and on the growth and productivity of spinach plant" that fertilization using sludge to the rate of 40 g / kg would increase the productivity of the spinach crop three times. In addition, fertilization using the sludge would increase the fertility of the soil and will improve its physical properties.

The study showed that such a use would make it possible to get rid of some sewage pollutants, and would reduce, depending on traditional fertilization, using expensive chemicals, which cause environment pollution as well. The Sledge fertilization would also represent a safe solution to get rid of 90 tons of sludge per day from the city of Abha, in Asir Province.

The study was published in the "International Journal of Phytoremediation"; a specialized scientific journal with 2.08 effect labs. It is noteworthy that the scientific research team of the study included Dr. Ibrahim Mohammed Eid, Dr. Sulaiman Al Rumman, Dr. Ahmed Albebana, Dr. Abdullatif Hisham, Dr. Mustafa Taher, and Dr. Khaled Fahmy.