Establishment of an economic evaluation model for urban recycled water

This study aimed at establishing an economic evaluation model to encourage continuing improvement in performance analysis and applying for any infrastructure system of urban recycled water. A thorough study towards characterization and economic performance assessment of urban water reuse scheme were carried out. An integrated evaluation technique was developed by synthesizing the quantitative and qualitative performance indicators related to the water recycled technology and urban water cycle system. Specific performance indicators and indexes were aggregated into an economic analytical modelling for effective evaluation of the water reuse scheme and technology using uniform economic performance standards. Detailed economic analyses were successfully applied to enable determination of economic lifetime of the technology and the whole water reuse scheme. This research confirmed that productivity, efficiency and reliability measurements and factors could be successfully deployed for determining the scheme performance during various life cycle stages (e.g. design development, operational and functional verification, or comparison with other reuse projects). The economic assessment model was applied to improve uniformity of analytical process and performance measure. This article demonstrates benefits associated with the application of a standardized methodology for performing economic assessment and by maintaining strong correlation between multi-parameter approach and adopted performance criteria in terms of productivity, efficiency and reliability. However, to ensure effectiveness of this assessment, the process would require systematic and perpetual inventory of the scheme performance data, consideration of variable factors such as capital and recurrent costs. © 2012 Elsevier B.V. All rights reserved

Effect of sponge volume fraction on the performance

A novel fluidized bed bioreactor (FBBR) was designed by integration of anaerobic granular activated carbon and aerobic sponge reactors. This FBBR was evaluated at different sponge volume fractions for treating a synthetic wastewater. Polyester urethane sponge with cube size of 1 × 1 × 1 cm and density of 28-30 kg/m3 with 90 cells per 25 mm was used as biomass carrier. The results indicate that the FBBR could remove more than 93% of dissolved organic carbon (DOC). The highest nutrient removal efficiencies (58.2% PO4 -P and 75.4% NH4-N) were achieved at 40% sponge volume fraction. The system could provide a good condition for biomass growth (e.g. 186.2 mg biomass/g sponge). No significant different performance in specific oxygen uptake rate was observed between 30, 40, and 50% sponge volume fractions. © IWA Publishing 2013 Water

Effect of flocculation and/or adsorption as pretreatment on the critical flux of crossflow microfiltration

This study aims at identifying the effect of pretreatment such as flocculation and/or adsorption on the performance of crossflow microfiltration (CFMF). CFMF performance was studied in terms of critical flux. The results indicated that: (1) flocculation alone as a pretreatment could effectively remove the large molecular weight organic matter from 30,000 to 60,000 Daltons; (2) flocculation, together with adsorption as a pretreatment to CFMF, could remove both large and small molecular weight organics; (3) flocculation as a pretreatment was significantly better than adsorption in improving the critical flux; (4) critical flux increased from 100 L/m2.h to 520 L/m2.h when flocculation-adsorption was applied. The critical flux in long-term experiments was the same as that of the short-term experiments. However, the critical flux slightly decreased (5%) in long-term experiments compared to short-term operation with flocculation and adsorption as a pretreatment. © 2005 Elsevier B.V. All rights reserved

Comparison of membrane bioreactor systems in wastewater treatment

This study investigated the performance of four different membrane bioreactor (MBR) systems, namely floating media biofilter-crossflow microfiltration (FMB-CFMF) system, submerged membrane bioreactor (SMBR) alone, submerged membrane adsorption bioreactor (SMABR) and sponge-SMBR system, in terms of critical flux. The results indicated that FMB could be used as a pretreatment unit prior to MBR in order to minimize membrane fouling when the FMB-CFMF system operates under sub-critical flux condition. The addition of powdered activated carbon (PAC) could maintain the sustainable flux at a lower TMP value (7.5 kPa). However, irreversible fouling occurred when the filtration flux exceeded the critical flux. The addition of 10% volume (reactor volume) fraction of sponge could increase sustainable flux of SMBR system to 2 times. © 2008

Experimental investigation on acclimatized wastewater for membrane bioreactors

The inoculation and acclimatization of activated sludge (AS) is one of the vital components to provide preferably suspended aerobic growth and desired treatment mechanism for a treated wastewater using MBR. The performance of a floating media biofilter-submerged membrane bioreactor (FMB-SMBR) and a submerged membrane adsorption bioreactor (SMABR) were investigated during the acclimatization. It was observed that the duration of sludge from wastewater treatment plant in Sydney acclimated to synthetic wastewater was about 25 days for FMB-SMBR system, while SMABR took around 12 days to reach the stabilization. The acclimatized FMB-SMBR (without membrane operation) resulted in significant high dissolved organic removal of 94%. The acclimatized FMBR-SMBR system showed more than 20% TOC removal efficiency than that of the acclimatized SMABR system. Meanwhile, the results of oxygen uptake rate (OUR) measurement suggested that OUR is an accurate and simple indicator to biological process acclimatization. Membrane fouling study of the FMB-CFMF system was also carried out. The results indicate that the acclimatized FMB could be used as a pretreatment unit prior to SMBR in order to minimize membrane fouling when the FMB-SMBR system operates under sub-critical flux condition. © 2007

Evaluation of an integrated sponge - Granular activated carbon fluidized bed bioreactor for treating primary treated sewage effluent

An integrated fluidized bed bioreactor (iFBBR) was designed to incorporate an aerobic sponge FBBR (ASB-FBBR) into an anoxic granular activated carbon FBBR (GAC-FBBR). This iFBBR was operated with and without adding a new starch based flocculant (NSBF) to treat synthetic primary treated sewage effluent (PTSE). The NSBF contains starch based cationic flocculants and trace nutrients. The results indicate that the iFBBR with NSBF addition could remove more than 93% dissolved organic carbon (DOC), 61% total nitrogen (T-N) and 60% total phosphorus (T-P) at just a very short hydraulic retention time of 50min. The optimum frequency of adding NSBF to the iFFBR is four times per day. As a pretreatment to microfiltration, the iFFBR could increase 5L/m2h of critical flux thus reducing the membrane fouling. In addition, better microbial activity was also observed with high DO consumption (>66%) and specific oxygen uptake rate (>35mg O2/gVSSh). © 2010 Elsevier Ltd

Concepts towards a novel integrated assessment methodology of urban water reuse

Traditional supplies of large volumes of water and wastewater disposal technologies have offered a linear solution, thus intensifying environmental stress. In addition, provision of urban infrastructure especially any major augmentations are often the impractical or economically prohibitive. Urban water cycle should be viewed as an interactive and coordinated approach involving: • Available water resources, • Appropriate treatment technology producing fit for purpose water quality, and • Ascertaining long term balance between environmental, social and economic issues. Implementation of integrated water reuse scheme requires major paradigm shift within a number of technical (science, technology and knowledge) and non-technical (socio-cultural, economic, environment) dimensions. There are number of questions that arise from this scenario: • How to make decisions regarding selection, design, implementation and operation of any recycling scheme? • What knowledge is necessary to improve decision-making process? • How to assess and compare performance of the scheme? • What are the parameters for uniform evaluation process? The aim of this paper is to introduce a new concept for integrated assessment methodology that can be applied for urban water reuse schemes. The conceptual assessment methodology relies on decision that treatment technology represents a leading theme and is supported by selection of socio-economic and environmental factors, thus enabling holistic evaluation and quantification of the outcomes. © 2009 Desalination Publications

A review towards finding a simplified approach for modelling the kinetics of the soluble microbial products (SMP) in an integrated mathematical model of membrane bioreactor (MBR)

Soluble microbial products (SMPs) tend to accumulate in the membrane bioreactor (MBR) systems as a consequence of high membrane rejection and apparently low biodegradability within the wastewater treatment system. The extension of the activated sludge models (ASMs) with SMPs, therefore, has received crucial importance in recent days, particularly considering their potential use as indicators of the membrane fouling propensity. This paper presents a critical review of the formation and degradation kinetics of SMP subdivisions that have so far been used for the mathematical modelling of MBR. The paper identified a simplified approach to incorporate the kinetics of the SMP formation and degradation in the general mathematical models of MBR. It suggested that the inclusion of only four additional linear differential equations in the ASM1-SMP integrated mathematical model could simulate well the effluent quality and membrane fouling prediction. The model would also serve as a useful tool in optimizing operation conditions for better treatability and fouling control. © 2013 Elsevier Ltd

Multicriteria assessment of advanced treatment technologies for micropollutants removal at large-scale applications

© 2016 Elsevier B.V. With the introduction and discharge of thousands of new micropollutants (MPs) every year, traditional water and wastewater treatment plants may be incapable of tackling them all. With their low concentrations and diversity in nature, MP removal encounters numerous challenges. Although some MPs are effectively eliminated via conventional treatment methods, most of them can easily escape and are retained in the discharged effluent. Therefore, advanced methods such as (i) adsorption, (ii) oxidation and advanced oxidation processes (O3 and O3-based advanced oxidation processes, UV/H2O2), (iii) membrane processes, and (iv) membrane bioreactors, become an inevitable approach. Despite the unsurprisingly vast number of papers on MP treatment available at present, most of these studies were carried out at a laboratory scale while only a few pilot- and full-scale studies have experimented. Nevertheless, an in-depth assessment of real-world MP treatment methods is extremely crucial for practitioners. To date, no paper has been dedicated to look at this issue. Therefore, this paper aims to review these large-scale treatment methods. First, the paper goes through the regulations and standards which deal with MPs in water courses. It will then assess these methods in various case-studies with reference to different criteria towards serving as a reference for further practical applications

Enhanced biological phosphorus removal and its modeling for the activated sludge and membrane bioreactor processes

A modified activated sludge process (ASP) for enhanced biological phosphorus removal (EBPR) needs to sustain stable performance for wastewater treatment to avoid eutrophication in the aquatic environment. Unfortunately, the overall efficiency of the EBPR in ASPs and membrane bioreactors (MBRs) is frequently hindered by different operational/system constraints. Moreover, although phosphorus removal data from several wastewater treatment systems are available, a comprehensive mathematical model of the process is still lacking. This paper presents a critical review that highlights the core issues of the biological phosphorus removal in ASPs and MBRs while discussing the inhibitory process requirements for other nutrients' removal. This mini review also successfully provided an assessment of the available models for predicting phosphorus removal in both ASP and MBR systems. The advantages and limitations of the existing models were discussed together with the inclusion of few guidelines for their improvement. © 2013 Elsevier Ltd