Operational and structural A‐stage improvements for high‐rate carbon removal

Abstract

Biosorption of organics is investigated at two sites in order to optimize operation and infrastructure for carbon removal and redirection in upstream, high‐rate processes. Sufficient process temperature and stable mixed liquor solids concentration were established as the key impact parameters for the process performance. Improved COD removal was achieved by either substantially enhanced aeration (elevated metabolic state) or by enhanced flocculation capability (dosed chemicals). Separation and thickening of organics are typically operated as continuous‐flow processes. The optimization of performance parameters led to a new A‐stage process named alternating activated adsorption. The AAA process is presented as a novel configuration linking biosorption and thickening capabilities in an alternating scheme without mechanical equipment. The performance data from its first trial indicate benefits from process dynamics including high organics capture rates and thickening capabilities reaching solid concentrations higher than 40 g(TSS)/L. COD removal could be increased further by adding biologically generated polymer, that is waste sludge from B‐stage. © 2020 Water Environment Federation Practitioners Points Enhanced preliminary treatment helps to increase capacity and energy efficiency. Low RAS rates, SRT control, aeration, high temperatures, and metal dosing are key performance parameters for removal rates and energy efficiency. The Triple‐A process offers new possibilities for A‐stage in terms of performance increase and flexibility showing similar or better results compared with conventional A‐stage. Adding B‐sludge improved COD and nutrient removal rates. High preliminary removal rates of COD and N foster sidestream processes.

Efficient Recovery of Organic Matter from Municipal Wastewater by a High-Rate Membrane Bioreactor Equipped with Flat-Sheet Ceramic Membranes

“…The quality of the effluent obtained in this study with the HR-MBR was much higher than that found with other competitive technology for carbon recovery from municipal wastewater. It has been reported that HRAS systems (A-stage systems) can achieve a COD removal rate of 52–64% [ 27 , 28 ]. As another emerging technology for carbon capture, direct membrane filtration (DMF) (in which no biological treatment is promoted) could not produce treated water with a low concentration of COD (<30 mg/L) without using coagulation [ 29 ].…”

Enhancing bioflocculation in high-rate activated sludge improves effluent quality yet increases sensitivity to surface overflow rate

“…This issue can be mitigated by shifting to an AAA™ (Alternated Activated Adsorption) process. AAA is a retrofitted primary clarifier which acts as primary settler and A-stage combined in one tank where the feed is introduced through the settled sludge bed (Wett et al, 2020).…”

Converting rectangular and circular primary tanks into the AAA biologically enhanced clarification settler

“…Most conventional facilities have a "primary process" with clarifiers applying gravitational forces for removal of organics exclusively in form of total suspended solids. Our value proposition is to enhance the primary treatment step to an alternating activated adsorption (AAA) settler instead to (1) make better use of this infrastructure within the existing hydraulic profile, (2) intensify the biological step, (3) use less energy in the biological step, (4) produce more gas in a digester, (5) produce 5% thickened solids, and (6) replace cumbersome primary mechanical equipment such as chains and flights with air lift sludge withdrawal (Wett, Aichinger, Hell, et al, 2020). Hence, the goal of the AAA settler is to convert a portion of influent soluble COD and ammonia through assimilatory means to particulate heterotrophs and to a protein extracellular polymeric substances (EPS) matrix (Homyok et al, 2024), in a very compact design (0.5 days solids residence time and 2 h hydraulic retention time) to achieve both carbon and nitrogen redirection.…”