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Mass balances modelling over wastewater treatment plants III
Expanded Title:To aid finding the most cost effective methods for the design and operation of wastewater treatment plants, for minimization of energy consumption and cost while maximizing nutrient recovery and improving effluent quality, the purpose of this project is to develop three phase (aqueous-gas-solid) steady state and dynamic mathematical models for the anaerobic and aerobic digestion of sludge; including waste activated sludge (WAS) produced by enhanced biological phosphorus removal (EBPR) plants, within a plant-wide setting. To accomplish this goal, the following four objectives were achieved: 1 Carry out an experimental investigation to generate the data required for both steady state and dynamic model development: The experimental set up was large to mimic three real wastewater treatment plant types at laboratory scale, viz nitrification-denitrification activated sludge treating raw wastewater, a nitrification-denitrification (ND) activated sludge (AS) system treating settled wastewater and a nitrification-denitrification enhanced biological phosphorus removal (NDEBPR) activated sludge system treating settled wastewater with separate anaerobic digestion (AD) of the WAS from each system, the primary sludge (PS) added to the settled wastewater to make up the raw wastewater and a PS-WAS blend. 2 Develop a steady state anaerobic digestion model including phosphorus by extending the steady state model of Sötemann et al. (2005a): From the experimental data of five anaerobic digesters, each operated at five different sludge ages, the hydrolysis kinetic rates of primary sludge, ND activated sludge system WAS and NDEBPR activated sludge system WAS were determined and included in the stoichiometric part of the anaerobic digestion model developed by Harding et al. (2009). Since mineral precipitation took place during the anaerobic digestion of NDEBPR WAS containing phosphorus accumulating organisms (PAOs), the steady state mixed weak acid/base chemistry part of the AD model was extended to include three phases (aqueous-gassolid). 3 Develop a dynamic anaerobic digestion model (ADM-3P) that includes phosphorus from NDEBPR WAS by extending the two phase (aqueous-gas) dynamic anaerobic digestion model for PS and ND activated sludge system WAS by Sötemann et al. (2005b), to include multiple organic types and three phase (aqueous-gas-solid) mixed weak acid/base chemistry for multiple mineral precipitation. Due to the significant increase in size and complexity to model the three wastewater treatment plants, as plant-wide configurations, in three phases, the models were coded in WEST®, which is a program capable of simulating many bioprocesses in various unit operations assembled into a wastewater treatment plant. 4 Develop a three phase activated sludge dynamic model (ASM2-3P) by adding full element ©, H, O, N, P) mass balanced stoichiometry to extending the existing NDEBPR activated sludge model ASM2 (Henze et al., 1995) and ensuring its compatibility with the three phase anaerobic digestion dynamic model and its equivalence to the full element mass balanced stoichiometry ASM dynamic model (without P) of Sötemann et al. (2005c).
Date Published:01/01/2015
Document Type:Research Report
Document Subjects:Wastewater Management - Industrial, Wastewater Management - Sludge management
Document Keywords:Municipality, Operation and Maintenance
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:1822/1/14
ISBN No:978-1-4312-0614-8
Authors:Ikumi DS; Harding TH; Vogts M; Lakay MT; Mafungwa H; Brouckaert CJ; Ekama GA
Project No:K5/1822
Organizations:University of Cape Town
Document Size:2 317 KB
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