Membrane bioreactor vs. oxidation ditch: full-scale long-term performance related with mixed liquor seasonal characteristics

摘要: The relative strengths of membrane bioreactors (MBR) versus conventional activated sludge (CAS) processes have long been debated, but never compared systematically at full scale. To this end, we monitored full-scale wastewater treatment performance and mixed-liquor characteristics (sludge biomass, extracellular polymeric substances (EPS), supernatant with molecular weight hydrophilic/hydrophobic distribution) for parallel MBR CAS (via oxidation ditch—OD), a year. Ammonia suspended solids were better removed by MBR; temperature affected ammonia removal in OD. At low temperatures, settlement declined both processes, solid–liquid separation via filtration continued, although the fouled. EPS similar, organic components varied seasonally, processes. had lower production rate, higher concentration, organics accumulated large molecular-weight polysaccharides. was correlated tightly bound proteinaceous EPS. Polysaccharides, loosely supernatant, responsible effective (OD), fouling (MBR). These results demonstrate how mixed liquor intermediates process performance, that depends on separation. MBRs excel when stringent requirements pollutant-removal extreme environmental conditions exist. much cheaper OD remains competitive under less demanding conditions.