A polymeric ultrafiltration (UF) membrane was used for stormwater treatment, with the focus on evaluating the increase in the membrane process productivity by adding pulsatile fluid flow to UF membrane treatment. Sedimentation and sieving were used as pre-treatment. The result showed that increasing the pulse frequency from 0 to 4 Hz increased productivity from -6.6 to 82 LMH. UF membrane removed suspended solids, oil and turbidity below detection limit. The UF membrane also separated total coliforms, E. coli and P. aeruginosa below detection limit. Total organic carbon (TOC) was reduced by between 70 and 91%. In addition, the UF membrane was able to reduce BOD7 and COD to below 7 mg/L in the permeate. According to the US EPA, WHO, and national regulations in Canada,  Japan, and South Korea, treated stormwater can be used for flushing toilets and streets irrigation and agricultural use. 

The effect of chemical cleaning and regular backwashing on the efficiency of an ultrafiltration membrane fouled during stormwater treatment was studied. Increasing backwash time from 30 to 60 s resulted in an increase in productivity by 20%. However, the productivity was highest when a backwash time of 45 s was used (3% higher than using 60 s). Chemical cleaning was carried out using an alkaline solution (NaOH with or without NaOCl) followed by acid washing with HCl. The addition of NaOCl to the cleaning chemical did not significantly increase the efficiency of chemical cleaning, and the average pure water permeability increase was 97 ± 13 LMH bar−1 after chemical cleaning with NaOH followed by HCl and 117 ± 15 LMH bar−1 after chemical cleaning with NaOH + NaOCl followed by HCl, on average. In addition, reversibility after chemical cleaning was 96 ± 67%, on average. The result from scanning electron microscopy showed that at the end of the experiments, inorganic foulants existed in both the inner layer (feed side) and the outer layer (permeate side) of the membrane.

After energy recovery from blackwater via anaerobic digestion, technologies such as struvite precipitation and ammonia stripping can be used to enhance nutrient recovery. However, the presence of suspended solids, organics and metals, can negatively impact the nutrient recovery processes. This study examined the treatment of digested blackwater, applying either a ceramic microfiltration membrane or a drum filter, operating in parallel in a source-separated wastewater plant. The digestate as well as the permeates from the membrane and drum filter were sampled regularly and evaluated. In general, the ceramic membrane proved to be more efficient in improving the quality of digested blackwater in comparison to the drum filter. The ceramic membrane reduced total suspended solids to below the detection limit, while the drum filter achieved 74 % removal. The membrane removed 74 %, 85 % and 76 % of TOC, BOD7 and COD-Cr, respectively, higher than the corresponding treatment with the drum filter, which removed 41 %, 42 % and 34 %, respectively. No significant differences in phosphate and ammonium concentrations (P-value = 0.05), before and after both treatment methods were observed. The membrane removed particulate-bound metals (As, Cd, Cr, Cu, Ni, Pb and Zn) up to 25 %, 95 %, 87 %, 95 %, 66 %, 90 % and 98 %, respectively. The drum filter achieved lower removal for particulate-bound As, Cd, Ni, Pb and Zn for 25 %, 79 %, 44 %, 56 % and 86 %, respectively. The removal of metals is critical to maintain struvite purity and prevent the struvite contamination due to co-precipitate of these metals.