Two-stage UASB design enables activated-sludge free treatment of easily biodegradable wastewater.
A two-stage lab-scale UASB reactor, incorporating a selector-type UASB prior to the main reactor was operated at 37 degrees C with an easily biodegradable food wastewater having a COD of 3,000 mg/L. Varying the hydraulic retention time from 25 to 5 h, the removal of COD by the two-stage process was higher than 95%. Effluent soluble COD was consistently below 75 mg/L and the methane production rate close to theoretical values. The selector UASB removed the majority of the organic load (70-90%) at high organic loading rate, i.e. between 6 and 30 g/(Ld) and the granular sludge developed was characterized by dense microbial colonies, high volatile suspended solids' content and high substrate degradation efficiency. Design of a two-stage process, incorporating a selector and a second UASB reactor, was able to achieve stable and complete substrate degradation at overall loading rates of the order of approximately 10-15 g/(Ld).
Department of Environmental Engineering, Democritus University of Thrace, 67100, Xanthi, Greece. bdiamant@env.duth.gr
Vasileios
V
Diamantis
Alexandros
A
Aivasidis
D001673:Biodegradation, Environmental; D056804:Biofuels; D018533:Biomass; D019149:Bioreactors; D004867:Equipment Design; D006868:Hydrolysis; D008697:Methane / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D012722:Sewage / Q000737:chemistry; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000379:methods*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods*
D056804:Biofuels; D012722:Sewage; D014874:Water Pollutants, Chemical; D008697:Methane