Water treatment and re-use at temporary events using a mobile constructed wetland and drinking water production system

Abstract

Temporary events such as music festivals are often organized in places that are not connected to a sewage network. As such, the waste (water) generated and discharged can place a heavy burden on the environment. A mobile vertical flow constructed wetland (MCW) with an area of 15 m2 was constructed, optimized and operated for three years treating grey water (GW) as well as grey and black water (GW + BW) at different festival locations to tackle this problem. During the initial development phase, the appropriate influent type (GW and/or GW + BW) was determined and challenge tests with pre-settled diluted domestic waste water (mimicking GW) were carried out to determine the maximal allowable loading rate. The MCW was able to treat both types of water. However, for further experiments GW was selected as the discharge limits could not be met when treating GW + BW. The challenge tests demonstrated that the MCW could be operated at a maximal allowable hydraulic loading rate of 1.1 m3·m−2·d−1, corresponding to mass loading rates of 68 gTSS·m−2·d−1, 160 gCOD·m−2·d−1 and 137 gBOD·m−2·d−1. During treatment of GW, the MCW achieved effluent concentrations for respectively chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solids (TSS) and total phosphorus (TP) of 43 mg·L−1, 16 mg·L−1, 2.7 mg·L−1 and 1.7 mgP·L−1. This corresponds to a removal of 90% (COD), 95% (BOD), 97% (TSS) and 76% (TP) respectively. Total nitrogen removal was 25% (from 45 mgN·L−1 to 34 mgN·L−1) as particularly denitrification was not complete. As a further development, the MCW was coupled to a drinking water treatment system using ultrafiltration and reverse osmosis (UF-RO) membranes to produce potable water on site. The drinking water system produced potable water that met the legislative criteria. As such, a sustainable and mobile water treatment system aiming at producing potable water at temporary events was demonstrated.