2.2. Description of the added ultrafiltration— reverse osmosis set-up
The UF-RO membrane process was established at the Gorenje company wastewater treatment plant (WWTP) following from the physical-chemical treatment basin, as shown in Fig. 1. The process was implemented as 24 filtration cycles carried out over 61 days. Within each cycle volumes of 5000 L for UF and 3000 L for RO were processed on average. Filtration was monitored and optimised with respect to permeate flux and the chemical cleaning frequency, and the type of membrane chemical cleaning was evaluated and optimised.