Changes in physico-chemical composition of wastewater by growing Phragmites australis and Typha latifolia in an arid environment in Saudi Arabia.

The Kingdom of Saudi Arabia is facing an acute shortage of high-quality water, which is further aggravated due to inadequate and nonrenewable groundwater resources. Hence, it is crucial to explore other alternatives, such as natural wastewater treatment (phytoremediation), for water supplies that can both lower the dependence on groundwater resources and overcome the challenges and limitations associated with conventional wastewater treatment technologies. Therefore, the main objective of this research was to study the performance and efficiency of green plants such as Typha latifolia L. (T. latifolia) (broadleaf cattail) and Phragmites australis (Cav.) Train, ex Steud. (P. australis) (common reed) for wastewater treatment in eastern Saudi Arabia. The experiment was conducted in fiberglass tanks (each with a capacity of 4.0 × 7.0 × 0.5 m3) in the field. There were a total of 4 fiberglass tanks with 2 replications. A percent decrease of 72.86% and 49.74%, 39.30% and 18.07%, 39.84% and 52.87%, 38.73% and 40.86%, 74.49% and 57.82%, and 66.82% and 63.14% was observed for turbidity, TSS, nitrate, ammonia, BOD, and COD by growing P. australis and T. latifolia, respectively. Heavy metals such as aluminum, zinc, and arsenic showed a considerable reduction in pollutants in treated water compared to raw wastewater under both plants. Overall, it appears that the improvement in wastewater quality was better by growing P. australis than T. latifolia; however, there were no statistically significant differences (p > 0.05) between the two plant means in their performance of raw wastewater treatment. The study results indicate that green plants could be used in a phytoremediation system to treat wastewater in rural and small communities.

Occurrence of organic compounds in groundwater of Saudi Arabia.

The presence of organic compounds in drinking water is well recognized in many developing countries; however, the occurrence of organic contaminants in the groundwater of Saudi Arabia, which is the main source of drinking water in the country, is not well documented. A national comprehensive study was carried out to assess the occurrence of organic compounds in groundwater wells used for drinking water purpose, in different regions of Saudi Arabia. A total of 993 well water samples were collected from all 13 administrative regions of the kingdom. Samples were analyzed for a total of 131 organic compounds using the standard methods. The results indicated that total organic carbon values were in the range of 0.01 to 84.13 mg/L with an average weighted value of 12.61 mg/L. Organic compounds were detected in only 9 regions, with 19.84% of the samples containing organic compounds. Only 96 wells (9.67%) showed contents of organic compounds above the safe limits. Pesticides were not detected in any of the well water samples. Overall, organic compounds were found in only 197 out of 993 wells (19.84%) in the whole country. Most of the wells containing organic compounds were located in residential, industrial, and agriculture areas. Riyadh region and Eastern Province were found to have the most affected wells as compared to other regions. Several regions did not show any organic compounds in the well waters.It can be said that the problem of groundwater contamination with organic compounds in Saudi Arabia is not acute and is manageable at present. It is, however, recommended that a regular monitoring of drinking water wells of all regions should be carried out by the competent authorities for organic compounds to know any contamination if and when it happens. Preventing such contaminants from reaching drinking water sources and protecting drinking water well heads from such contaminants remains a priority.