Plant-wide modelling and analysis of WWTP temperature dynamics for sustainable heat recovery from wastewater

Abstract

Wastewater heat recovery up-stream of wastewater treatment plants (WWTPs) poses a risk to treatment performance, i.e. the biological processes. In order to perform a sustainability analysis, a detailed prediction of the temperature dynamics over the WWTP is needed. A comprehensive set of heat balance equations were included in a plant-wide process model and validated for the WWTP in Linköping, Sweden, to predict temperature variations over the whole year in a temperate climate. A detailed model for the excess heat generation of biological processes was developed. The annual average temperature change from influent to effluent was 0.78 °C with clear seasonal variations. 45% of the temperature change arises from processes other than the activated sludge unit. Hence, plant-wide energy modelling was necessary to predict in-tank temperature in the biological treatment steps. The energy processes with the largest energy gains were solar radiation and biological processes, while the largest losses were from conduction, convection and atmospheric radiation. Tanks with large surface areas have significant impact on the heat balance regardless of biological processes. Simulating a 3 °C lower influent temperature, the temperature in the activated sludge unit dropped by 2.8 °C, which had a negative impact on nitrogen removal.

Plant-Wide Models for Optimizing the Operation and Maintenance of BTEX-Contaminated Wastewater Treatment and Reuse

“…Plant-wide models, on the other hand, provide simulation capabilities of more advancedsuch as granular and biofilm-based-treatment processes, feature more biological processes such as anaerobic digestion, enable pH, precipitation and gas transfer calculations and allow for more complex plant configurations that may include mechanical pretreatment, sidestream treatment or even effluent wastewater recycling. They can further provide oversight of different aspects of facilities such as energy management and operational costs, and additionally, they take into account equipment operational limitations regarding industrial safety [27].…”

Technology Management Leading to a Smart System Solution Assuring a Decrease of Energy Consumption in Recreational Facilities

“…When waste heat is used, it is necessary to identify its sources and available resources [25][26][27]. When designing a wastewater heat recovery plant, the temperature and quantity of wastewater must be taken into account and it must be decided whether the process will be carried out before or after treatment with substances of a biogenic nature [28][29][30].…”