Combined Wastewater Treatment Research Articles

Concept development for the optimisation of the Hamburg Wastewater Treatment Plants

The Hamburger Stadtentwässerung (HSE) is planning to take on a further approximately 250,000 PE in addition to the 1.85 m PE already served by its combined wastewater treatment plants at Köhlbrandhöft/Dradenau. To cope with the increased load, a concept for the extension of the plants had to be developed. Various concepts were compared and evaluated using a dynamic computer simulation. The very wide-ranging simulation study showed that the required effluent standards can still be achieved after the volume of the sludge liquor storage capacity has been increased. As many concepts had been assessed in detail, the final solution chosen was considerably less expensive than if the wastewater treatment plants had been extended in a traditional manner.

Investigation of nitrogen transformations in a southern California constructed wastewater treatment wetland

A 9.9-ha combined habitat and wastewater treatment demonstration wetland was constructed and planted in the summer of 1994, at Eastern Municipal Water District’s (EMWD) Hemet/San Jacinto Regional Water Reclamation Facility (RWRF) in southern California. From January 1996 through September 1997, the marsh–pond–marsh wetland system was operated to polish an average of 3785 m 3 d −1 (1×10 6 gal day −1) of secondary-treated effluent from the RWRF. Nitrogen removal was a major objective of this wetland treatment. Weekly inflow/outflow water quality monitoring of the wetland was supplemented with biannual, 45-station synoptic surveys within the system to determine internal distribution patterns of the nitrogen species (total ammonia, nitrite, nitrate, and organic nitrogen), total organic carbon (TOC), and ultraviolet absorbance at 254 nm (UV 254). Synoptic surveys were carried out during May 22 and September 17, 1996, and May 6 and September 25, 1997 and the results were mapped using the ARC/INFO processing package and inverse distance weighted mathematical techniques. Distribution patterns of the various nitrogen species, TOC, and UV 254 within the wetland indicate that the nitrogen dynamics of the system are influenced both by variations in treatment plant loading, and, increasingly, by the degree of coverage and maturity of the emergent vegetation.

Combined anaerobic treatment of wastewaters and sludges

One of the most recent and progressive reactor principles used in anaerobic wastewater treatment technology is a vertical compartmentalization, which is used in the USSB (Upflow Staged Sludge Bed) reactor. Thanks to its specific design and features the operation of such a reactor can be very flexible. Examples are given showing tested alternatives of operation with combined wastewater and sludge treatment. A high treatment efficiency and a very low specific sludge production was achieved with the operation of a technological system consisting of a USSB reactor and an aerobic biofilm reactor. In the USSB reactor wastewater and surplus sludge treatment can not only be combined but also anaerobic pretreatment and biological denitrification.

Optimisation of the Hamburg wastewater treatment plants by dynamic simulation

At present the combined wastewater treatment plants Köhlbrandhöft/Dradenau serve approx. 1.85m PE for the treatment of Hamburg wastewater. It is planned to add a further 250,000 PE and therefore it is necessary to carry out optimisation measures. With the help of an extensive project for dynamic simulation, the necessary comparative tests were carried out. Various variants for the optimisation were tested and compared on the basis of 14-day and annual hydrographs. The results show clear differences in the performance of the variants. The dynamic simulation was able to provide very useful results on the basis of which decisions have been made on the most suitable measures to be taken in practice. During work on the project the creation of a project team consisting of representatives from the works (planning and operational staff) and the simulation expert, who cooperated intensively in working on the ideas and concepts, proved invaluable. It meant that wide-ranging possibilities for optimisation were tried out and plausible results achieved.

Combined anaerobic treatment of wastewaters and sludges

One of the most recent and progressive reactor principles used in anaerobic wastewater treatment technology is a vertical compartmentalization, which is used in the USSB (Upflow Staged Sludge Bed) reactor. Thanks to its specific design and features the operation of such a reactor can be very flexible. Examples are given showing tested alternatives of operation with combined wastewater and sludge treatment. A high treatment efficiency and a very low specific sludge production was achieved with the operation of a technological system consisting of a USSB reactor and an aerobic biofilm reactor. In the USSB reactor wastewater and surplus sludge treatment can not only be combined but also anaerobic pretreatment and biological denitrification.

Optimisation of the Hamburg wastewater treatment plants by dynamic simulation

At present the combined wastewater treatment plants KShlbrandhdfUDradenau serve approx. 1.85m PE for the treatment of Hamburg wastewater. It is planned to add a further 250,000 PE and therefore it is necessary to carry out optimisation measures. With the help of an extensive project for dynamic simulation, the necessary comparative tests were carried out.Various variants for the optimisation were tested and compared on the basis of 14-day and annual hydrographs. The results show clear differences in the performance of the variants. The dynamic simulation was able to provide very useful results on the basis of which decisions have been made on the most suitable measures to be taken in practice.During work on the project the creation of a project team consisting of representatives from the works (planning and operational staff) and the simulation expert, who cooperated intensively in working on the ideas and concepts, proved invaluable. It meant that wide-ranging possibilities for optimisation were tried out and plausible results achieved.

A Benders decomposition model for sewer rehabilitation planning for infiltration and inflow planning

Infiltration and inflow (I/1) to a wastewater treatment plant can contribute significantly to the quantity and cost of domestic wastewater treatment. A known pipe or manhole defect can be repaired in a number of ways. Leaking pipes, for example, can be chemically grouted, lined, or burst/lined or excavated and repaired/replaced. Each repair option for eliminating the infiltration or inflow has a unique cost and efficiency. A general Benders decomposition model was developed to optimize the repair and replacement strategy for a sewer network. The model determines the least cost solution by minimizing the combined wastewater treatment and repair costs. The results of a detailed analysis of an existing sewer are presented.

Salix vegetation filters for purification of waters and soils

During recent years it has become obvious that it is both environmentally and economically appropriate to use vegetation filters of short rotation willows ( Salix spp.) to purify waters and soils. Swedish and Polish experiences of vegetation filter efficiencies have been demonstrated in several laboratory, field lysimeter and full-scale experiments. However, there are still many questions to be answered; for example, how the uptake and allocation mechanisms of heavy metals and recalcitrant organic constituents function, or which maximum doses are possible in a particular situation without any risk of leaching losses. During the past two decades of integrated research in Sweden on plant nutrition it has been demonstrated that willows have the capacity for efficient uptake both of macro and micro nutrients, which is reflected in their high productivity. This paper presents results on how vegetation filter stands of willow, irrigated with municipal wastewater, can function as purification plants while at the same time producing fuel wood. This two-fold utilisation benefits both the environment (e.g. with less air pollution from wood compared with fossil fuels) and the economy (by combining wastewater treatment and fuelwood production). Treatment plants for wastewater purification using various types of vegetation filters have been used both in Poland and Sweden. The Polish experience has been in three sites, namely the Wroclaw experiment, the Zoo at Oliwa near Gdansk, and Turwia near Poznan. In Sweden both nutrient and heavy metal uptake have been followed incorporating the whole process chain from establishment, cultivation and harvesting of the wastewater-irrigated willows to the utilisation of the wood in heating plants.

Nitrogen separation from domestic wastewater by reverse osmosis

Norway is committed by the North Sea Convention to reduce nitrogen in liquid effluents in general by 50% by 1995. The base year is 1985. Communities treating more than 10 000 p.e. are ordered to remove a minimum of 70% total nitrogen from domestic effluents in specified sensitive areas. The Norwegian Enviromental Protection Agency has completed a three-year study on alternative nitrogen removal processes suitable for Norwegian conditions. Existing secondary-treatment plants are by and large based on chemical precipitation which therefore could be considered pretreatment for future nitrogen removal plants. Nitrogen separation trials by reverse osmosis (RO) was performed between October 1990 and August 1991 on domestic wastewater as well as on combined domestic-industrial wastewater. Separate RO trials were performed with both tubular and spiral-wound membrane elements. For domestic wastewater the separation efficiency was 95% for total nitrogen. No pretreatment was necessary for tubular RO membranes in addition to the existing chemical precipitation performed in the main treatment plant. Chemical precipitated effluent from the main treatment plant was the feed to the RO units. The spiral RO elements, however, did receive additional 25–200 μm cartridge filters as pretreatment. This was essential as solid separation in the chemical precipitation pretreatment plant was unpredictable, and carry-over solids easily clogged the spiral-wound flow channels. This was especially a problem for treatment of combined domestic-industrial wastewater and not during treatment of domestic wastewater only. Chemical cleaning of the spiral-wound membranes was performed every other day for treatment of domestic wastewater. This ensured a permeate flux of 201/m 2/h at 25°C and an inlet feedwater pressure of 35 kg/cm 2. No optimization of recovery rate was attempted during the trials. A full-scale design, however, for treating 40 and 200 m 3/h is included in the paper. Also, steam stripping of NH 3 from the retentate is suggested, with nitrogen recovered as (NH 4) 2SO 4, NH 4NO 3 or (NH 4) 3PO 4.

JOINT CONSIDERATION OF SEWERAGE SYSTEM AND W ASTEW ATER TREATMENT PLANT

The total efficiency of combined sewerage systems and wastewater treatment plants (WTP) sbould be considered. By an overall planning procedure the benefits of the whole system can be optimized. For the estimation of the system behaviour with different rain events, computer simulations of the sewerage system including storage tanks and the treatment plant have to be carried out. The two systems are not coupled mathematically allowing separate simulation. Hydrographs of different scenarios computed for the sewerage system can be used for simulations of the WTP. For comparing the effects of different throttle flows on the treatment plant an example bas been simulated. In this example the BOD5 and phosphorus loads could be reduced with a higher throttle flow. The large difference in total discharges from combined sewerage without storage tanks and with well-dimensioned tanks could also be demonstrated.

特集 シンポジウム「環境用水の浄化および水処理の高度技術」より （２） 生物膜流動層を用いた複合有機廃水の処理

特集 シンポジウム「環境用水の浄化および水処理の高度技術」より （２） 生物膜流動層を用いた複合有機廃水の処理

Leachate Treatment: Design Recommendations for Small but Extremely Fluctuating, Highly Polluted Quantities of Water

Today's practice in leachate treatment and disposal in the FRG comprises two possibilities:a) the combined leachate domestic wastewater treatment (transportation to the treatment plant either using the sewer system or tank trucks)b) complete, decentralized treatment at the source of the leachate production. As a result of the updating of the general water management law (WHG § 7a) the discharge of waste waters containing dangerous substances (e.g. AOX) into sewer systems is no longer permitted. As there is no possibility of a selective removal of the hazardous substances, the future consequence will be that the whole amount of leachate has to be treated at the landfill site. Existing leachate treatment plants are often designed for average loading rates. Because of the high fluctuations of the leachate quantity such plants are often overloaded. In the past there were two solutions:a) temporary transportation to a municipal treatment plant using trucks,b) recycling of the excessive leachate volume. As transportation is no longer accepted there is only the possibility of recycling left. The feasibility of buffering the runoff peaks has not yet been studied in detail (reservoir management). This cost-favourable option (earth basin with sealing) offers two advantages. First, the plant design can be based on mean conditions while secondly the loading of the plant will be almost constant (no variation concerning the hydraulic loading; concentration equalization effect of the storage tank). Herewith an attractive way of adapting existing plants to the time dependent changing requirements is available.

Management of wastewater from soap and food industries: A case study

This paper presents the wastewater management of an industrial complex which produces different products, i.e. soap, perfume extract, macaroni, jam and juices. A continuous monitoring programme for departmental as well as final effluents was carried out for almost 3 months. Characterization of the composite wastewater from both soap and food processing plants indicated that the waste was highly contaminated with organic compounds as indicated by COD and BOD values. Moreover, effluent from the soap manufacturing plant contains significant concentrations of oil and grease amounting to 563 mg l −1. Soap manufacturing effluent and the combined wastes discharged from the whole industrial complex were subjected to different treatment processes, namely dissolved air flotation, chemical coagulation-sedimentation, and biological treatment via a completely mixed activated sludge process. Although coagulation using alum followed by sedimentation removed 52% of COD, residual values did not comply with the regulatory standards. Biological treatment of the composite combined wastewater significantly removed the organic contaminants in wastewater. Average residual BOD, COD, oil and grease values were 30, 92 and 8.3 mg l −1 respectively. Based on the laboratory results a final process design was developed.

Cost Comparison of Aerobic and Anaerobic Wastewater Treatment Systems

The costs of different types of aerobic, anaerobic and combined wastewater treatment systems are compared in this study. The assumed BOD or COD-loads from typical forest industry processes form the basis of comparison. General cost curves for various waste treatment processes and some case examples are also presented. In the calculations it is assumed that the wastewater is treated to the same effluent quality by using activated sludge, modified activated sludge and combination of anaerobic-aerobic treatment process. In anaerobic-aerobic systems different types of combinations are analyzed. Investment, running and annual costs have been evaluated for each system. The study shows that selection of the method or combination of methods must always be made case by case. It has been found out that in some cases the anaerobic-aerobic process combination is economically competitive. Competitiveness will increase if biogas can be utilized and a moderate price could be calculated for it. In some cases activated sludge, and especially aerated lagoon processes, has a disadvantage of requiring larger treatment spaces. Poor soil conditions and long distances to lead effluent may significantly increase the cost of these aerobic treatment methods.

Modeling and Control of the Activated Sludge Process by Use of Autoregressive Model

The authors have insisted that the control systems must be constructed hierarchically. In the bottom level of this system, the statistical model is suitable to express the dynamics of the activated sludge process. In this paper, it is shown that an AR model which belongs to the statistical model is applicable to the activated sludge process in the combined wastewater treatment plant. Next, it is discussed how to change the manipulated variables on purpose to clearly determine the effects of the manipulated variables, because the manipulated variables are generally maintained almost constant in the actual plants.

The Gulf Coast Waste Disposal Authority: A Regional Approach to Water Quality Management

The Gulf Coast Waste Disposal Authority is a regional public agency created by the State of Texas to design and implement water quality management systems in three counties surrounding Galveston Bay. This article will outline the water quality management strategy employed by the Authority for a highly industrialized and populated region. Regional treatment and public and private sector cooperation will be presented as a management objective for muncipal and industrial waste disposal. A description of the background and operations of the Authority will be included along with examples of joint or combined wastewater treatment. The pressing problem of hazardous waste management in Texas will be discussed. The Authority's experiences with facility siting and public reaction will be summarized and a new approach to help resolve these issues will be presented. The article will conclude with some thoughts on strategic planning for public managers.

Granular Activated Carbon and Preozonated Granular Activated Carbon Treatment for Biologically and Physically-Chemically Treated Wastewater Effluents

The Duck Creek Wastewater Treatment Plant is a combined municipal-industrial wastewater treatment facility serving a municipal population of over 200,000 and an industrial community of over 600 various light industries. This 30 MGD treatment facility operates in a split-stream mode, with 7.5 MGD treated by biological processes and 22.5 MGD treated by physical-chemical processes. Final treatment for both systems is supposed to consist of granular activated carbon treatment and chlorine disinfection. Problems in operation and implementation of the granular activated carbon systems for the combined biological and physical-chemical treatment effluents prompted The University of Texas at Dallas to design and construct a pilot plant facility composed of 5 pilot plant systems. This facility provides for evaluation of granular activated carbon (GAC) treatment and preozonated granular activated carbon (POGAC) treatment for biologically, physically-chemically, and blended (biologically and physically-chemically) treated wastewater effluents simultaneously. The UTD-Duck Creek Pilot Plant Facility has been operating since November, 1979, demonstrating the improved operation and treatment efficiency of preozonated granular activated carbon treatment for biologically, physically-chemically, and blended wastewater effluents. In addition to improved treatment efficiency demonstrated by the preozonated granular activated carbon systems, average operational life prior to bed exhaustion was extended from an average 70 days for GAC to over 300 operational days for POGAC.

Disposal of Sludge by Land Spreading

The Gulf Coast Waste Disposal Authority owns and operates a 23,000,000-gal/day (87,000-m³/day) combined industrial wastewater treatment facility in Texas City, Tex. Area which treats wastes generated by a large refining and petrochemical processing complex. Note that all wastes of sanitary origin are treated separately to preclude contamination and chlorination requirements of the total waste flow. Associated with this treatment facility, a parcel of land has been developed to sludge disposal by land spreading. The term land spreading is used instead of land farming simply because no vegetation is intended to be grown on the area. The bulk of the wastewater and resultant sludges are discharged by two subsidiaries of Standard Oil Company of Indiana (Amoco Texas Refining Company and Amoco Chemical Corporation). Both design and engineering work on the land spreading operation were performed by Standard Oil Company of Indiana.