Modeling and optimization of an algal-based sewage treatment and resource recovery (STaRR) system. Issue 2 (April 2022)

• Record Type: Journal Article
• Authors: Abeysiriwardana-Arachchige, I.S.A.; Delanka-Pedige, H.M.K.; Munasinghe-Arachchige, S.P.; Brewer, C.E.; Nirmalakhandan, N.
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 2(2022)
• Publication Date: 2022-04
• Subjects: AS Activated sludge -- STP Sewage treatment plants -- HRAP High-rate algal ponds -- STaRR Sewage Treatment and Resources Recovery -- AP Aqueous phase -- RSM Response surface design methodology -- GPM Gas-permeable membrane -- GPMR Gas-permeable membrane reactor -- RMSE Root mean square error -- L:S Liquid-to-solid ratio -- MAP Struvite -- CAP Calcium phosphate -- AMM Ammonium sulfate recovery; Integrated algal systems -- Nitrogen recovery -- Phosphorus recovery -- Energy recovery -- Primary effluent treatment; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.107139
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: This paper presents modeling and optimization of an algal-based sewage treatment and resource recovery (STaRR) system composed of the following subprocesses: S, 1) mixotrophic algal sewage treatment; S, 2) hydrothermal liquefaction (HTL) of the resulting algal biomass; S, 3) phosphorus recovery from the solid HTL char via leaching and precipitation; and S, 4) nitrogen recovery from the HTL aqueous phase via a gas-permeable membrane (GPM). Specific models for the above subprocesses have been developed and validated in previous studies. Here, those models are integrated to optimize the STaRR system based on operating cost and profit to reduce wastewater treatment costs. The following operational conditions were identified as optimal for the STaRR system: 1) fed-batch cycle time of 3 d for S, 1; 2) temperature of 350 °C, process time of 1 h, and biomass content of 20 wt% for S, 2; 3) temperature of 60 °C, process time of 72 h, alkali concentration of 0.5 M NaOH, alkali eluent-to-char ( L:S ) ratio of 20 with mixing at 20 rpm to recover calcium phosphate in S, 3; and 4) process time of 70 h and a membrane area:feed volume ratio of 2.32 m 2 /m 3 for S, 4. Under these optimal conditions, the STaRR system incurred 20% lower operating costs than the pre-optimization version with a different P recovery process and without N-recovery via GPM. The optimized STaRR system recovered 69.1 ± 2.4% of P in the primary effluent as calcium phosphate and 42.9 ± 1.9% of N as ammonium sulfate at an operating cost of $0.20/m 3 of primary effluent. Graphical Abstract: ga1 Highlights: Integrated validated subprocess models of the STaRR system for overall optimization. Demonstrated an economical resource recovery pathway for wastewater-derived algae. Demonstrated the recovery of > 69% P and > 42% N from primary effluent. Estimated the cost of primary effluent treatment via the STaRR system at $0.2/m 3 .