Combined Wastewater Treatment Research Articles

“In Line” Combined Storm and Wastewater Treatment System for Tropical Urban Drainage Catchments

This paper presents a conceptualized combined storm and wastewater treatment system for typical low income, high density drainage catchment similar to the case of Manila City. In many developing and tropical port cities in low-lying floodplains, local and regional floods and non sewered communities compound in a problem that manifests in surface water pollution. This results in particularly difficult situation to introduce major sewerage infrastructure and a centralized wastewater treatment system. Thus, to initiate and invite discussions on different and possible solutions is necessary to address the need to provide appropriate treatment systems in rapidly growing cities and urban populations. This paper aims to contribute to such discussions by suggesting possible treatment processes achievable in limited, under exploited spaces in urban drainage networks. Also the paper mentions systematic estimations relevant to assess and theoretically simulate suggested treatment system. Following Hvitved-Jacobsen etal (2002) recognition of the role of sewers as bioreactors, the proposed system takes reviewed physical and biological techniques to be installed parallel to the track of drainage channels that provides neither on-site nor off-site approaches, but “inline” treatment. Essentially, the system integrates sewers or drains in the entire treatment system. The estimated primary and secondary information on both physical and socio-economic parameters in the study site, and the adapted “alternative” principles of decentralized, small scale systems yielded a multiple site designs including the following treatment processes and units: 1) inline fine and micro screening; 2) vegetated submerged beds (VSB); 3) rotating biological contactors (RBC); and 4) “biotowers”. All were designed to capture and reduce typical wastewater constituents (TSS, BOD, TKN and Coliforms) continuously during “dry” and “average wet” conditions until year 2025. The system embodies an effective and alternative wastewater treatment system for Philippine effluent standards, replicable in other tropical urban drainage catchments.

A serially connected sand filtration and constructed wetland system for small community wastewater treatment

In this study, a newly developed combined natural wastewater treatment system was used for the first time in the Village of Ileydagi, which has a population of 313 situated in the reservoir of Lake Egirdir, the second largest freshwater lake in Turkey. The combined treatment system consists of a combination of buried sand filtration (BSF) and buried subsurface flow constructed wetland (BSSF-CW) systems. The total area of the BSF system is 582 m 2 and that of the BSSF-CW system is 1352 m 2. Performance of the combined treatment system was 5% higher during the summer period than during the winter months. The average removal values of the combined system observed for a 14-month period were as follows: Biological Oxygen Demand (BOD) 97%, total nitrogen (TN) 85%, and total phosphorus (TP) 69%. There is a strong correlation (0.81–0.97) between the loading and removal rates (g/m 2 d). This correlation is also statistically important. The results indicate that the novel sand filtration and constructed wetland treatment system is an optimal solution to the wastewater problems of small settlements.

Sewage treatment using an integrated system consisting of anaerobic hybrid reactor (AHR) and downflow hanging sponge (DHS)

This paper presents an evaluation of a combined wastewater treatment train consisting of an anaerobic hybrid reactor (AHR) followed by a downflow hanging sponge (DHS) system. The combined system was operated at a total constant hydraulic retention time (HRT) of 8 h (AHR: 6.0 h and DHS: 2.0 h) and an average organic loading rate of 1.9 kg COD/m3.d for AHR and 2.1 kg COD/m3.d for the DHS. The combined system was able to remove 95 and 89% of the BOD5total and CODtotal with residual values in the final effluent of only 10 and 49 mg/L, respectively. Ammonia concentration was reduced by 83%. The geometric mean of faecal coliform count was reduced by 4.7 log10. Residual count in the final effluent ranged from 102 to 103 MPN/100 ml. Average concentration of trapped biomass amounted to 20 g VSS/L of sponge volume. The SRT of DHS system was 121 d. Calculated average sludge yield coefficient for the DHS system was 0.08 g TSS/g CODremoved. Analysis of wastewater samples collected at the outlet of each segment along t...

Efficiency of removal of nitrogen, phosphorus, and zinc from domestic wastewater by a constructed wetland system in rural areas: a case study

The effluent from the combined household wastewater treatment facilities used in unsewered areas of Japan is generally high in nitrogen (N) and phosphorus (P). In Japan, environmental quality standards for zinc (Zn) pollution were enacted recently because of the toxicity of Zn to aquatic ecosystems. In 2004 a fallow paddy field at the Koibuchi College of Agriculture and Nutrition was converted into a surface-water-flow constructed wetland (500 m(2)) to clean the effluent from the combined household wastewater treatment facility of a dormitory (100 residents) before discharge to a pond. We evaluated N and P removal efficiencies and the fate of soluble Zn in the wetland from April 2006 to March 2007. Wetland influent contained an average of 18.3 mg L(-1) total N and 1.86 mg L(-1) total P. In the effluent from the wetland, average total N concentration was 10.3 mg L(-1) and average total P was 0.90 mg L(-1). Average removal rates were 0.37 g m(-2) d(-1) for total N and 0.050 g m(-2) d(-1) for total P (percentage removal rates of 40% and 48%, respectively). Soluble Zn concentration decreased from 0.041 in the influent to 0.023 mg L(-1) after passing through the wetland. The average Zn removal rate during the year was 0.0007 g m(-2) d(-1) (percentage removal rate 37%).

From Wastewater to Hydrogen: Biorefineries Based on Microbial Fuel‐Cell Technology

In light of the imminent climate change, the term “hydrogen economy”, as defined by Bockris and Appleby in the early 1970s, has recently become a buzzword and a ray of hope for the development of technologies that lead to a responsible and sustainable handling of our world’s resources. The transition to such an economy requires the development of the respective technologies at the front end, namely for hydrogen production and storage, and at the back end, that is, the technologies that use hydrogen as an energy carrier. The latter has lately seen considerable progress with, for example, the first hydrogenpowered vehicles becoming commercially available. The high-profile marketing of these products provides the public with the impression that society is on a successful way to reach the goal of a sustainable hydrogen economy in the near future. Yet, at the moment, an overwhelming amount of hydrogen is produced from fossil sources such as natural gas, which does not represent a sustainable path but rather simply relocates the CO2 emissions from our streets to the hydrogen producer without providing a solution to the carbon dioxide problem. Owing to its ubiquity (in most regions of this world), water appear to be the future source for hydrogen; however, considerable amounts of energy, derived from sustainable sources yet to be found, have to be consumed for water splitting. As long as technologies such as nuclear fusion power generation remain a vision, this energy will most likely have to be provided by a patchwork of different technologies, some already existent, some still to be developed. One important aspect is that mankind cannot afford to waste energy even if it is contained in streams that appear as worthless as sewage. However, although it has been estimated that municipal wastewater contains about nine times more chemical energy than is necessary for its treatment, in conventional wastewater plants this energy still remains mainly untapped. Moreover, about 10% of municipal electricity consumption usually goes toward the treatment of wastewater. Recent developments suggest that microbial fuel cells (MFCs) may represent a promising technology for combining wastewater treatment and energy recovery. MFCs are electrochemical devices that convert the chemical energy contained in organic or inorganic matter into electricity by means of the catalytic (metabolic) activity of living anaerobic microorganisms. These organisms oxidize the substrate (fuel) and transfer the liberated electrons to the anode, which is connected with the cathode— usually an oxygen electrode (see Figure 1a). It seems reasonable to use such a technology to produce not only electricity but also hydrogen. The first attempts in this direction go back to 1994, when Kreysa and co-workers proposed the combination of microbial fuel cells with water electrolysis. As the voltage delivered by a biofuel cell does not suf-

Cathodic oxygen reduction catalyzed by bacteria in microbial fuel cells

Microbial fuel cells (MFCs) have the potential to combine wastewater treatment efficiency with energetic efficiency. One of the major impediments to MFC implementation is the operation of the cathode compartment, as it employs environmentally unfriendly catalysts such as platinum. As recently shown, bacteria can facilitate sustainable and cost-effective cathode catalysis for nitrate and also oxygen. Here we describe a carbon cathode open to the air, on which attached bacteria catalyzed oxygen reduction. The bacteria present were able to reduce oxygen as the ultimate electron acceptor using electrons provided by the solid-phase cathode. Current densities of up to 2.2 A m(-2) cathode projected surface were obtained (0.303+/-0.017 W m(-2), 15 W m(-3) total reactor volume). The cathodic microbial community was dominated by Sphingobacterium, Acinetobacter and Acidovorax sp., according to 16S rRNA gene clone library analysis. Isolates of Sphingobacterium sp. and Acinetobacter sp. were obtained using H(2)/O(2) mixtures. Some of the pure culture isolates obtained from the cathode showed an increase in the power output of up to three-fold compared to a non-inoculated control, that is, from 0.015+/-0.001 to 0.049+/-0.025 W m(-2) cathode projected surface. The strong decrease in activation losses indicates that bacteria function as true catalysts for oxygen reduction. Owing to the high overpotential for non-catalyzed reduction, oxygen is only to a limited extent competitive toward the electron donor, that is, the cathode. Further research to refine the operational parameters and increase the current density by modifying the electrode surface and elucidating the bacterial metabolism is warranted.

Sustainable industrial development and environment protection: An emerging perspective

AbstractA concept of an integrated industrial complex encompassing three major industries; viz. sugar, distillery and paper along with a cogeneration plant (generating electricity and process steam required by the industries in the complex) is presented in this article. Molasses and bagasse generated in the sugar industry are proposed to be used by the distillery and paper industry respectively. Surplus bagasse would be used as fuel in cogeneration plant. Sugar, distillery, and paper industries generate high strength wastewater in large volume, which when treated anaerobically produces biogas. This scheme would provide twin advantages of pollution load reduction at low cost coupled with energy production, which will also partially meet the energy requirement of the industrial complex. The entailing benefits would be reduction in fuel consumption and lower air emissions. Low strength wastewater from different processes as well as sewage from industries and townships can be treated in a combined wastewater treatment plant. The treated wastewater can be recycled/reused for industrial as well as for irrigation purposes in the complex and/or nearby industries and agricultural land. © 2008 American Institute of Chemical Engineers Environ Prog, 2008

Constructed wetlands for water reclamation

Constructed wetlands have been increasingly used throughout the world for secondary and especially for tertiary treatment of wastewater and stormwater. If well designed and maintained, their effluents can meet the high standards required for reclaiming the water. One can also partially reclaim nutrients by harvesting the aquatic vegetation or by combining wastewater treatment with aquaculture. Constructed wetlands further provide certain ancillary benefits such as wildlife habitat function, recreational facilities etc. This paper gives an overview of treatment performances and consequent reuse possibilities, operation and maintenance requirements, costs and constraints interfering with the application of this technology.

Organics removal of combined wastewater through shallow soil infiltration treatment: A field and laboratory study

Soil infiltration treatment (SIT) was proved to be an effective and low-cost treatment technique for decentralized effluents in the areas without perfect sewage systems. Field-scale experiments were conducted under several conditions to assess organics removals through a shallow soil infiltration treatment (SSIT, with effective depth 0.3 m) of combined wastewater (discharge from toilets, restaurants and a gas station), while bench-scale soil column experiments were performed in laboratory in parallel to investigate biological and abiological effects of this kind of system. From the start-up to the 10th month, the field SSIT trenches experienced the lowest and highest temperatures of the operation period in Shanghai and exhibited effective organics removals after maturation, with the highest removal rate 75.8% of chemical oxygen demand (COD), highest ultraviolet absorption at 254 nm (UV 254) decrease by 67.2% and 35.2–100% removals of phenolic and phthalate pollutants. The laboratory results indicated that more organics could be removed in room-temperatured (25 ± 2 °C) SSIT systems under different influent COD concentrations from 45 mg/l to 406 mg/l, and the highest total COD removal rate could reach 94.0%, in which biological effect accounted for 57.7–71.9%. The results showed that temperature and hydraulic loading rate were the most important factors influencing the removals of COD and organic pollutants in SSIT.

Activated sludge process control—development of operational diagrams

Hindered batch settling experiments were performed on activated sludge generated from dairy wastewater and combined (Dairy-Domestic mixture 1:3) wastewater for different initial Mixed Liquor Suspended Solids (MLSS) concentrations from 2g/L to 20 g/L for varied Mean Cell Residence Time (MCRT) for 5 to 15 days. Bio kinetic coefficients of combined wastewater were determined using a bench scale Continous Flow Stirred Tank Reactor (CFSTR). Vesilind parameters were also determined experimentally. Operational diagrams for long-term fluctuations in plant inflow and substrate concentration have been prepared. The allowable overflow rate to prevent process failure can be predicted from the chart. The adjustments to be made in recycling ratio and MCRT in case of fluctuations could also be predicted from the operational diagrams. From the operating diagrams plotted for both dairy and combined wastewater, it was noticed that, combined wastewater treatment provide greater operational flexibility than treating dairy waste separately.

Control Strategies for a Combined Anaerobic (UASB) – Aerobic (Activated Sludge) Wastewater Treatment System

This paper presents a comparative analysis among four control strategies for the control of a combined anaerobic-aerobic wastewater treatment configuration. The anaerobic stage is an Upflow Anaerobic Sludge Blanket (UASB) reactor, whereas the aerobic stage consists of the Activated Sludge (AS) process. The control variables are solids concentration in the effluent and sludge wastage rate. The proposed control strategy is considered the most reliable among them. It is based on two cascaded PI-controllers for the solids concentration in the effluent and a look-up table for the sludge wastage rate control. Experimental and simulated results are presented.

Dynamics of rain-induced pollutographs of solubles in sewers

When looking at acute receiving water impacts due to combined sewer overflows the characteristics of the background diurnal sewage flux variation may influence the peak loads from combined sewer overflows (CSO) and wastewater treatment plant (WWTP) effluent significantly. In this paper, effects on the dynamic compounds transported in the sewer, on CSO discharges and WWTP loading are evaluated by means of hydrodynamic simulations. The simulations are based on different scenarios for diurnal dry-weather flow variations induced by different infiltration rates.

Immersed Membrane BioReactor (IMBR) for treatment of combined domestic and dairy wastewater in an isolated farm

In many regions dairy farms and milk processing industries discharge large quantities of their wastes to the surroundings posing serious environmental risks. This problem is mostly faced in small dairy farms and isolated communities lacking both central collection and conventional wastewater treatment systems. Dairy wastewater is characterized by high concentrations of organic matter, solids, nutrients, as well as fractions of dissolved inorganic pollutants, exceeding those levels considered typical for high strength domestic wastewaters. With the purpose of treating the combined dairy and domestic wastewater from a small dairy farm in the Negev Desert of Israel, the use of a recent emerging technology of Immersed Membrane BioReactor (IMBR) was evaluated over the course of 500 test hours, under a variety of wastewater feed quality conditions (during the test periods, the feed BOD5 ranged from 315 ppm up to 4,170 ppm). The overall performance of a pilot-scale Ultrafiltration (UF) IMBR process for a combined domestic and dairy wastewater was analyzed based on the Data Envelopment Analysis (DEA) method. The IMBR performance in terms of membrane performance (permeate flux, transmembrane pressure, and organic removal) and DEA model (Technical Efficiency) was acceptable. DEA is an empirically based methodology and the research approach has been found to be effective in the depiction and analysis for complex systems, where a large number of mutual interacting variables are involved.

Application of Cross-Flow Microfiltration for the Treatment of Combined Sewer Overflow Wastewater

Application of cross-flow microfiltration with and without backpulsing is evaluated for the treatment of dilute primary sewage effluent simulating combined sewer overflow wastewater. Four alpha alumina ceramic membranes of various pores sizes (0.2-5.0μm) were tested to understand the impact of cross-flow velocity and transmembrane pressure on the permeate water quality and flux rate. The 0.2 and 0.8μm membranes produced a permeate water quality that is likely to be suitable for surface water discharge. The combination of permeate chemical and biological water quality and long-term flux rates suggest that a 0.2μm membrane would be the most appropriate membrane for the treatment of combined sewer overflow wastewater within sewersheds.

Benchmarking combined biological phosphorus and nitrogen removal wastewater treatment processes

This paper describes the implementation of a simulation benchmark for studying the influence of control strategy implementations on combined nitrogen and phosphorus removal processes in a biological wastewater treatment plant. The presented simulation benchmark plant and its performance criteria are to a large extent based on the already existing nitrogen removal simulation benchmark. The paper illustrates and motivates the selection of the treatment plant lay-out, the selection of the biological process model, the development of realistic influent disturbance scenarios for dry, rain and storm weather conditions respectively, the definition of performance indexes that include the phosphorus removal processes, and the selection of a suitable operating point for the plant. Two control loops were implemented: one for dissolved oxygen control using the oxygen transfer coefficient K La as manipulated variable, the second one for nitrate control in the anoxic zone using the internal recirculation flow rate as manipulated variable. Dynamic simulations for different dissolved oxygen set points illustrate the complex interactions in this plant, and the necessity for a continuous trade off between supplying sufficient oxygen to promote nitrification on the one hand, and the need for low dissolved oxygen concentrations on the other hand to allow sufficient development of phosphorus accumulating organisms. The potential for aeration energy savings in the plant is highlighted based on the dissolved oxygen profiles resulting from open loop simulations with a dynamic dry weather influent scenario. The influence of the dissolved oxygen set point selection on the nitrate control loop performance observed in the simulations further illustrates the need for a plant-wide optimization approach to reach optimal plant performance.

Real time control of a combined UASB-activated sludge wastewater treatment configuration

This paper presents a combined wastewater treatment configuration composed by an Upflow Anaerobic Sludge Blanket (UASB) reactor followed by an Activated Sludge (AS) system. A control strategy has been developed for this innovative (especially for domestic sewage) treatment configuration and tested in a real pilot-scale system called STEPAA-Wastewater Treatment System by Anaerobic and Aerobic Processes. The proposed UASB-AS control strategy, including fault detection and recovery, and its successful implementation in real time is presented. This novel control strategy was developed to keep the final effluent suspended solids concentration in the range specified by the State environmental agency, in spite of incoming load disturbances. The control strategy is based on two cascaded PI (Proportional + Integral) controllers, which manipulates the recycling rate into the AS-reactor to control the effluent suspended solids concentration. A 2-dimensional nonlinear mapping (an empirical look-up table), which gives the sludge waste rate as a function of the influent flowrate and AS-reactor biomass concentration, is used to keep the AS-reactor biomass concentration in a range that guarantees a good substrate removal without inconveniences to the AS-settler operation (and consequently to the solids removal). Experimental results are provided to demonstrate the system performance.

Development of Scale-up Formulations for an Anaerobic Fixed Film Fixed Bed Reactor for Treatment of Tannery Wastewater

An attempt has been made to develop scale-up equations for a fixed film fixed bed reactor system. Kinetic constants for substrate, biomass and biogas have been determined with recourse to laboratory treatability studies. This study involves the treatment of combined vegetable and chrome tan wastewater.

Performance evaluation of a pure oxygen‐based activated sludge system treating a combined paint industry wastewater and domestic sewage

Activated sludge system based on pure oxygen has been developed to increase the biodegradation of wastewater. This system was used for the treatment of combined wastewater from the paint industry effluent and sewage. The results of continuous test showed that it is possible to achieve 87.8–93.6% COD, and 97.7–99.2% of BOD removal resulting in an effluent quality of 55–90mg/L of COD and less than 10.0mg/L of BOD. Dissolved oxygen content through out the tank showed a concentration, ranging between 3.26 and 3.9mg/L, indicating good oxygenation in the system. Excess sludge generated in the ASP was found to be 3.0kg/d and it has a good manurial value with NPK of 112, 68 and 32mg/L, respectively. Moreover the sludge showed very good settling character with a capillary suction time of 8.0 seconds.

Application of the membrane biological reactor system for combined sanitary and industrial wastewater treatment

In the early 1990s, the General Motors Corporation (GM) adopted the use of the membrane biological reactor (MBR) system for treatment of automotive manufacturing plant wastewaters both in the US and internationally. The MBR process consists of a suspended growth biological reactor combined with a membrane unit either located external to the bioreactor or mounted directly within the bioreactor. Recently, the GM Worldwide Facilities Group operated an external membrane MBR system pilot plant at the Delphi Steering manufacturing plant in Saginaw, MI treating combined industrial and sanitary wastewater. The pilot plant study was completed in order to support the design of a full-scale MBR system for the Delphi Steering plant located in Queretaro, Mexico. The major equipment items utilized in the pilot study were a 1.51 m 3 complete mix, aerobic bioreactor coupled to a cross-flow, tubular, ultrafiltration membrane unit containing 0.98 m 2 of membrane area. After a start-up phase, the pilot plant was operated under various wastewater feed ratios (i.e., ratio of sanitary to industrial feed rate) at a constant bioreactor hydraulic retention time (HRT) of approximately 1 day and a solids retention time (SRT) of approximately 70 days. The results from the pilot plant study implied that a full-scale MBR system operating at a sanitary to industrial wastewater feed ratio in the range of 1:1 to 4:1, and at HRT and SRT values of respectively, 1 and 70 days, should result in an effluent chemical oxygen demand and biological oxygen demand of respectively, less than 400 and 10 mg/l.

A multiple‐organic‐pollutant simulation/optimization model of industrial and municipal wastewater loading to a riverine environment

A simulation/optimization model is developed to demonstrate the need for inclusion of interactive pollutant effects in multiple‐pollutant wastewater management, by comparing single‐ and multiple‐pollutant least cost approaches that maintain downstream ambient quality levels. The model chooses biological oxygen demand (BOD), N, and P abatement levels for point sources that minimize the combined wastewater treatment costs of the pollutants in order to achieve chosen ambient quality standards. Nonlinear pollutant interactions result in a nonlinear Jacobian matrix of marginal water quality impacts, creating a nonlinear constraint set. The Jacobian is iteratively updated by the simulation model using iterative solutions from the optimization model. The open modeling framework allows other types of programming problems to be solved as well, such as mixed integer and mixed integer nonlinear problems. Single‐ and multiple‐pollutant management approaches are applied to a case study of the Nitra River Basin in Slovakia. The regrets resulting from implementing BOD‐only or fixed Jacobian solutions are shown, and the robustness of the solution procedure is demonstrated by varying the initial pollution abatement levels.