Characterization of Reject Wastewater of Reverse Osmosis (RO) Used for Municipal Wastewater Reclamation

This paper presents the results of a study conducted to characterize the reject wastewater of the world’s largest reverse osmosis (RO) reclamation plant for municipal wastewater, which is located in Sulaibiya, Kuwait. For three months, samples were collected daily from the brine stream, and routine wastewater quality parameters were determined in the laboratory according to standard water and wastewater examination methods. Distribution functions of the quality parameters were then checked for normality to assess the validity of the calculated descriptive statistics. The results obtained indicated that the RO reject wastewater has high concentrations of nitrogen, phosphorus and sulphates, but it is highly deficient in organics. It was also found that the distribution of the quality parameters, in general, do not follow a normal symmetrical bell-shaped distribution. Most of the distributions are either severely skewed to the right or left, short-tailed, or bimodal. Probable causes of these peculiar characteristics of the RO reject wastewater and their implications for the design of possible further treatment or safe disposal were discussed.