Systematic Modeling of Municipal Wastewater Activated Sludge Process and Treatment Plant Capacity Analysis Using GPS-X

Nuhu Dalhat Mu’Azu,Ismail Anil,Omar Alagha

doi:10.3390/su12198182

Nuhu Dalhat Mu’Azu, Ismail Anil + Show 1 more

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https://doi.org/10.3390/su12198182

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Journal: Sustainability	Publication Date: Oct 4, 2020
Citations: 31	License type: CC BY 4.0

Affiliation: Imam Abdulrahman Bin Faisal University

Abstract

Mathematical modeling has become an indispensable tool for sustainable wastewater management, especially for the simulation of complex biochemical processes involved in the activated sludge process (ASP), which requires a substantial amount of data related to wastewater and sludge characteristics as well as process kinetics and stoichiometry. In this study, a systematic approach for calibration of the activated sludge model one (ASM1) model for a real municipal wastewater ASP was undertaken in GPS-X. The developed model was successfully validated while meeting the assumption of the model’s constant stoichiometry and kinetic coefficients for any plant influent compositions. The influences of vital ASP parameters on the treatment plant performance and capacity analysis for meeting local discharge limits were also investigated. Lower influent chemical oxygen demand in mgO2/L (COD) could inhibit effective nitrification and denitrification, while beyond 250 mgO2/L, there is a tendency for effluent quality to breach the regulatory limit. The plant performance can be satisfactory for handling even higher influent volumes up to 60,000 m3/d and organic loading when Total Suspended Solids/Volatile Suspended Solids (VSS/TSS) and particulate COD (XCOD)/VSS are maintained above 0.7 and 1, respectively. The wasted activated sludge (WAS) has more impact on the effluent quality compared to recycle activated sludge (RAS) with significant performance improvement when the WAS was increased from 3000 to 9000 m3/d. Hydraulic retention time (HRT) > 6 h and solids retention time (SRT) < 7 days resulted in better plant performance with the SRT having greater impact compared with HRT. The plant performance could be sustained for a quite appreciable range of COD/5-day Biochemical Oxygen Demand (BOD5 in mgO2/L) ratio, Mixed Liquor Suspended Solid (MLSS) of up to 6000 mg/L, and when BOD5/total nitrogen (TN) and COD/TN are comparatively at higher values. This work demonstrated a systematic approach for estimation of the wastewater treatment plant (WWTP) ASP parameters and the high modeling capabilities of ASM1 in GPS-X when respirometry tests data are lacking.

Highlights

Activated sludge system (ASS) is one of the critical treatment processes for various wastewaters, with over 90% of the municipal wastewater treatment plant (WWTP) using it as the core part of their treatment scheme [1,2]
This was achieved by characterizing the influent composition satisfying the mass balance expressions that required changing the GPS-X default values of the influence fractioning for BOD5/BODultimate, Si, Ss, Xi, XBH, XBA, and Snh from 0.66, 0.05, 0.2, 0.13, 0, and 0 to 0.75, 0.0556, 0.32, 0.12, 0.176 and 0.142, respectively (Table 3)
This corroborates earlier observation reported by other authors [10] that achieved lower predictions of simulated chemical oxygen demand in mgO2/L (COD) and BOD5 which they postulated to be as results of overestimation of BioWin model biomass affinity to their studied wSuasstatienwabialitteyr20(r2e0,p1r2e,sxeFnOteRdPEbEyRaRhEValIEf-Wsaturation constant for heterotrophic biomass for their mode1l1).of 28

Summary

Introduction

Activated sludge system (ASS) is one of the critical treatment processes for various wastewaters, with over 90% of the municipal wastewater treatment plant (WWTP) using it as the core part of their treatment scheme [1,2]. Among various dynamic and steady-state mathematical expressions and models describing the ASP, activated sludge models (ASM) such as suggested by the International Water Association (IWA) have most frequently been employed for the design, operation, and optimization of biological wastewater treatment plants [5]. Amongst these models, the ASM number one (ASM1) has become an internationally accepted ASM, describing the biological removal processes of organic matter and nitrogen, including nitrification and denitrification mechanisms [5,6]. The learning and prediction performances of the software mentioned are significantly dependent on the successful calibration and validation of the model [8]

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Results

Conclusion