Process modelling and techno-economic analysis of anaerobic digestion of sewage sludge integrated with wet oxidation using a gravity pressure vessel and thermal hydrolysis

Tanmoy Das; Ibrahim Al-Waili; Venkatakrishnan Balasubramanian; Greogry Appleby; Prasad Kaparaju; Rajarathinam Parthasarathy; Nicky Eshtiaghi

doi:10.1016/j.scitotenv.2023.169024

Process modelling and techno-economic analysis of anaerobic digestion of sewage sludge integrated with wet oxidation using a gravity pressure vessel and thermal hydrolysis

Sci Total Environ. 2024 Feb 20:912:169024. doi: 10.1016/j.scitotenv.2023.169024. Epub 2023 Dec 7.

Authors

Tanmoy Das¹, Ibrahim Al-Waili¹, Venkatakrishnan Balasubramanian¹, Greogry Appleby², Prasad Kaparaju³, Rajarathinam Parthasarathy⁴, Nicky Eshtiaghi⁵

Affiliations

¹ Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia.
² Sydney Water Corporation, New South Wales, Australia.
³ School of Engineering & Built Environment, Griffith University, Nathan, Queensland 4111, Australia.
⁴ Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia. Electronic address: rajarathinam.parthasarathy@rmit.edu.au.
⁵ Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia. Electronic address: nicky.eshtiaghi@rmit.edu.au.

PMID: 38065487
DOI: 10.1016/j.scitotenv.2023.169024

Abstract

Anaerobic digestion (AD) of sewage sludge is used to biodegrade sewage sludge into biomethane and digestate. With the addition of thermal processes such as thermal hydrolysis (TH) and wet oxidation (WO), AD biodegradability generally improves. Implementation of additional treatment is challenging due to the limitation in the mass and energy balances. Hence, tools such as process simulation can be utilized to predict the input and output around the process. In addition, an economic analysis needs to be conducted to check the economic feasibility. The techno-economic analysis (TEA), an integrated method to evaluate a process scheme through simulation and subsequent economic analysis, is effective in providing a systematic understanding of economic implications and the feasibility of a process by identifying the bottlenecks and uncertainties that have a significant impact on the technology. TEA of AD, especially incorporating the TH or WO using gravity pressure vessel (GPV) technology, is limited in the literature. A comprehensive TEA of the AD and the pre- and post-treatment schemes can be utilized to determine the most feasible pathway for sludge treatment for implementation in the wastewater industry. In this study, TEA for four different scenarios of AD was conducted using Aspen Plus and economic analysis tools: (1) without any pre- or post-treatment, (2) with TH pre-treatment, (3) with 100 % WO post-treatment, and (4) with 20 % partial wet oxidation (PWO) and acid hydrolysis pre- or post-treatment. A simulation model (GPVM) was developed using Aspen Plus to mimic the GPV reactor. The study outcomes showed that Scenario 3 with 100 % WO post-treatment was the most suitable for processing parameters and sludge treatment cost. The sensitivity analysis concluded that operating cost and plant capacity are the dominant factors that impact the plant feasibility significantly.

Keywords: Anerobic digestion; Gravity pressure vessel; Process simulation; Techno-economic analysis; Wet oxidation.