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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.

Waste-activated sludge (WAS) may be considered a resource generated by wastewater treatment plants and used for biogas-generation but it requires pre-treatment (PT) for enhanced biogas-yields and reduced WAS disposal costs. To date, a number of studies on the optimization of such PT focused on improved biogas yields but neglected inferred energy and resource consumption. Here, we aimed to identify the most promising thermo-chemical PT-strategy in terms of net energy output and cost-efficiency by optimizing PT temperature and the amount and sort of the alkaline reagent used. We compared methanepotentials and disposal costs of untreated and treated WAS and conducted an annual cost-benefit calculation. We defined 70°C and 0.04 M NaOH as ideal PT-conditions being both, low-energy demanding and efficient. Applying these conditions, enhanced biogas-yields and improved dewaterability led to reduced electricity and disposal costs of 22 and 27%, respectively, resulting in savings of approx. 28% of the yearly WAS-related expenditures of a wastewater treatment plant. Despite multiple benefits in running costs, the implementation of WAS-PT was not recommendable in the presented case study due to high investment costs.

No abstract

The thermal hydrolysis process (THP) is applied to enhance biogas production in anaerobic digestion (AD), reduce viscosity for improved mixing and dewatering and to reduce and sterilize cake solids. Large heat demands for steam production rely on dynamic effects like sludge throughput, gas availability and THP process parameters. Here, we propose a combined energy and process model suitable to describe the dynamic behaviour of THP in a full-plant context. The process model addresses interactions of THP with operational conditions covered by the AD model obeying mass continuity. Energy conservation is considered in balancing and converting various energy species dominated by thermal heat and calorific energy. The combined energy and process model was then applied on the THP at Blue Plains advanced WWTP (DC Water) to analyse the process and assess potential energy optimizations. It was found that dynamic effects like mismatched steam production and consumption, temporary gas shortages and underloaded units are responsible for energy inefficiencies with losses in electricity-production up to 29%.