Mass and energy balances of sludge processing in reference and upgraded wastewater treatment plants

Abstract

This paper describes the preliminary assessment of a platform of innovative upgrading solutions aimed at improving sludge management and resource recovery in wastewater treatment plants. The effectiveness of the upgrading solutions and the impacts of their integration in model reference plants have been evaluated by means of mass and energy balances on the whole treatment plant. Attention has been also paid to the fate of nitrogen and phosphorus in sludge processing and to their recycle back to the water line. Most of the upgrading options resulted in reduced production of dewatered sludge, which decreased from 45 to 56 g SS/(PE × day) in reference plants to 14-49 g SS/(PE × day) in the upgraded ones, with reduction up to 79% when wet oxidation was applied to the whole sludge production. The innovative upgrades generally entail an increased demand of electric energy from the grid, but energy recovery from biogas allowed to minimize the net energy consumption below 10 kWh/(PE × year) in the two most efficient solutions. In all other cases the net energy consumption was in the range of -11% and +28% of the reference scenarios.

Process Optimization of Waste Activated Sludge in Anaerobic Digestion and Biogas Production by Electrochemical Pre-Treatment Using Ruthenium Oxide Coated Titanium Electrodes

“…During treatment of municipal wastewater, waste activated sludge (WAS) is produced in huge amounts as a by-product, with the total solids concentration varying between 0.8 and 1.2% [1]. The transportation, treatment and disposal of WAS is an important issue as it adds to the overall cost of wastewater treatments, as well as for sludge management [2,3]. Therefore, an efficient sludge treatment strategy is highly desired to minimize its volume and reduce the WWTP operating cost.…”

Hydrogen via reforming aqueous ammonia and biomethane co-products of wastewater treatment: environmental and economic sustainability

“…The WWTP can be considered 'large' in a UK context, producing 30% more power than the industry mean. Digestate liquor production of 661 m 3 per day was asserted from an equivalence of 0.63% of total wastewater inow, interpreted from, 31 which stands at a daily average of 105 000 m 3 per day.…”

Dealing with fuel contaminants in biogas-fed solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC) plants: Degradation of catalytic and electro-catalytic active surfaces and related gas purification methods

“…One way to grasp the intrinsic potential of biogas resources is to look at per head (humans or animals) biogas potential. For instance, the average citizen in developed countries uses almost 300 liters/day of water that end up in the sewer [8]. With the total suspended solid in sewage water of 220 mg/l, roughly 60 g/person/day of putrescible organic matter (or sludge) are thus collected in the wastewater plant connected to the sewage system.…”