Är återanvändning av renat avloppsvatten lösningen på Halmstad kommuns årliga vattenbrist?

Sammanfattning: Due to an increased population and future risks of drought in Halmstad municipality, the pres- sure on water reservoirs increases. To address future challenges and decrease the dependency on large amounts of precipitation, Laholmsbuktens Water and Sewer as started to investigate the opportunity to re-infiltrate purified wastewater. Therefore, I studied the possibility to re- infiltrate purified wastewater into a pit and produce drinking water. To investigate the possibil- ity, I selected to conduct a literature study. I started to compile the limit values for drinking water and outflowing concentrations from Western shore wastewater treatment plant for all the substances I studied. Then I investigated the pits purification capacity, through comparing the concentration after purification of the pit with limit values I could establish which substances required further purification. The pits area requirement and suitable further purification treat- ment for the studied substances were also examined. The investigated substances are chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen (tot-N), total phos- phorus (tot-P), ammonium, suspended solids, 7 heavy metals, 10 pharmaceuticals and 11 Poly- and perfluoroalkyl substances (PFAS). The results showed that COD, BOD, diklofenak, kar- bamazepin, zink and all PFAS-substances required further purification before the water entered the pit. The most suitable further purification for the studied substances established to be ultra- filtration as pre-treatment to reverse osmosis and it requires four 1.5 hectare basins to infiltrate the desired amount of water. Therefor the conclusion of this study is, that it is possible to create drinking water by infiltrating wastewater from Western shore wastewater treatment plant into the specific pit. However, the wastewater requires ultrafiltration and reverse osmosis treatment before infiltration in order to remove contamination that will not be removed by the infiltration process.