Production of high-quality drinking water from chillers and air conditioning units? condensates using UV/GAC/MF/NF hybrid system

In hot and humid regions, like the Middle East nations, where access to drinking water is minimal, water recycling and purification are essential. In this work, high-quality drinking water was produced by treating the condensates obtained from the air conditioning units. A membrane-based hybrid system consisting of ultraviolet irradiation, granular activated carbon, microfiltration, and nanofiltration membranes (UV/GAC/MF/NF) was applied in series to minimize the NF membrane fouling and enhance the product water quality. The microbial, organic, and ionic species of the feed and the product water were analyzed, and the target was defined to maximize the permeate flux (JV) and minimize the concentration of the organic matter in the product water (CODP). The effects of trans-membrane pressure (TMP, 2-5 bar) and feed flow rate (QF, 340-510 L h-1) on the target parameters were investigated through the Taguchi design of experiments and the ANOVA method. The obtained results showed that at the optimum conditions, almost a complete reduction of TDS (> 98.37%), of COD (> 97.87%), of BOD5 (> 96.04%), of the total and digestive coliforms (100%), and turbidity (91.06%) were achieved. Additionally, it was found that the TMP and the QF were the most influential parameters on JV and CODP, respectively. The product water analysis at different stage cuts showed that the hybrid system is capable of recovering more than 97% of the feed water while the TDS, BOD5, and turbidity of the product water are only 2.58 ppm, 2.62 mg. L-1, and 0.22 NTU, respectively.

Automated summary

In hot and humid regions, water recycling and purification are essential for obtaining high-quality drinking water. A membrane-based hybrid system was used to treat condensates from air conditioning units, and the effects of trans-membrane pressure and feed flow rate on the target parameters were investigated. The results showed that the system can achieve a complete reduction of various contaminants and recover more than 97% of the feed water.