Wastewater Treatment Works Research Articles

Constructed reed beds clean up storm overflows on small wastewater treatment works

Severn Trent Water is required to treat stormwater overflows that occur at sewage treatment works before discharge to receiving water courses. Where the regulator sets numeric quality standards on stormwater discharges from works serving populations of <2 000, treatment is provided in constructed reed beds. By June 1994 the company had 55 sites with reed beds for stormwater treatment and expects to provide more as an asset renewal programme continues. The paper describes discharge consent issues that are emerging and details the operation of the reed bed systems. Results from three surveys carried out during storm events show the benefit of the systems in reducing discharges of BOD5, TSS, ammonia N, and TON. A tracer study was carried out on one survey and the results are fitted to a simple mathematical model.

The relationship between settling velocity grading and the characteristics of the contributing catchment

A method for measuring the settling velocity gradings of both storm and dry weather flow (DWF) sewage was investigated. This method was then used experimentally to determine whether a relationship exists between the settling velocity grading of a sewage as it enters a treatment works and the characteristics of the contributing catchment. The problems associated with the collection of data on the characteristics of the contributing catchments are discussed. These include the availability of up to date information within the water companies and the time consuming nature of collecting full sets of information for a particular wastewater treatment works. An S-shaped curve was fitted to all the settling velocity gradings produced during the research. Relationships relating the curve constants to the catchment characteristics were derived using multiple regression techniques. The methodology was proved, but the model was not sensitive enough to be used successfully as a predictive tool without further analysis involving either more sites and/or a more careful selection of the test sites.

A strategy for monitoring and control systems at major treatment works

Severn Trent Water operates a large number of major water and waste water treatment works. The monitoring and control of the process plant is typically provided by systems offering supervisory control and data acquisition and distributed control system functionality. The article describes the strategy developed by Severn Trent Water for the monitoring and control of these works. It comments on the progress of the early schemes that are being implemented and looks at some of the plans for the future development of the systems.

Improving the performance of anaerobic digesters at wastewater treatment works: the coupled cross-flow microfiltration/digester process

Trials at a wastewater treatment works indicate that cross-flow microfiltration, using flexible woven fibre tubes, could significantly enhance the performance of anaerobic digesters. The cross-flow microfiltration unit decouples the solids residence time from the liquid residence time and thus enables the volumetric throughput of the digester to be significantly increased while maintaining a constant solids residence time and volatile solids destruction. In trials on a pilot-plant digester, the volumetric throughput was almost doubled, from 70 to 130 1 d−1, while the solids residence time was maintained at 26 days. The economic feasibility of the coupled system was evaluated, using permeate flux data obtained from a cross-flow microfiltration unit coupled to a full-scale digester. The evaluation indicates that the coupled process is economically favourable when compared to conventional digester systems. The coupled system is currently being developed into a full-scale process. A full-scale CFMF unit is being constructed and will be coupled to a full-scale digester. Over a three year project the long-term reliability and operability of the process will be investigated, together with its effect on digester fluid dynamics and biomass viability.

Functional Approach Leads to Successful ICA across 124 Water and 389 Wastewater Treatment Works

Thames Water Utilities Limited operates a complex network of 124 water and 389 wastewater treatment works. Regulatory requirements are driving a massive capital programme of more than ₤2 Billion over 5 years to improve performance of these facilities. Improvements are planned, engineered, and operated by a variety of internal and external groups and individuals. Shareholders are demanding profitability and the Director General is pushing for improvements to customer service. To achieve its objectives, Thames has developed an instrumentation, control and automation (ICA) systems master plan. The plan is based on the utility s water and wastewater functional requirements. The functional approach is applied to the large number of diverse facilities by grouping facilities and processes into classifications. The approach is used throughout the plan. Each process and its associated process control strategy are clearly defined to ensure consistency and the cost-effective implementation of instrumentation and control across Thames. The functional approach was developed for each process control strategy using a series of structured workshops to achieve consensus and company-wide acceptance. Each department of the utility was involved in the workshops (including engineering, operations, maintenance, management systems, research and development, operational science). Top management sponsored the planning effort and committed to making the plan a reality.

Stockholm builds a “snake” tunnel to avoid flooding and improve water quality

Rainwater that falls on the city of Stockholm is led to the wastewater treatment facility at Henriksdal. The water is transported through a network of pipelines where domestic wastewater is mixed with rainwater. The existing network does not have sufficient capacity during heavy precipitation. To avoid flooding, the mixture of rainwater/wastewater is allowed to overflow into the nearest stretch of water. To reduce this overflow, a wastewater tunnel is being built where the “surplus” water can be temporarily stored until the pressure on the pipelines and the wastewater treatment works is reduced. This new tunnel, called “The Snake” because of its winding course, will have a capacity of approximately 35.000 m 3. This will be sufficient to reduce the risk of flooding considerably, while simultaneously stopping the undesirable discharge into Brunnsviken completely. To achieve the best interaction between the tunnel and the system of water mains, the water level will be regulated and monitored with the help of computers.

Phosphate Precipitation with On-Site Alkali Generation

Commercially available membrane electrolysis equipment can be used to produce substantial quantities of caustic soda from salt (NaCl) with chlorine gas being produced as a by-product. This caustic soda may be employed to raise the pH of the final effluent in order to achieve high levels of phosphate precipitation or removal in the form of crystallization. The pH may then be lowered, prior to final discharge, by re-carbonation utilising combusted biogas, which is produced on-site. At the Kempton Park wastewater treatment works, which achieves biological phosphate removal by means of the Phostrip process, laboratory scale tests proved the commercial viability of this process. It was found that a dosage of 150 mg/l of caustic soda was needed to reach a redox potential of −250 mV, at which point the phosphate content of the stripper overflow was reduced from 30 mg/l to under 1 mg/l. The savings effected in the cost of chlorinating the final effluent, entirely offsets the cost involved. A number of other possible process configurations are proposed, with treatment costs varying from 0,8 to 5,3c/kl, which compares favourably with biological or other methods of chemical treatment, which typically range from 3 to 6 c/kl (costs given in SA cents = 0,35 US cents).

Instrumentation control and automation in the control of biological effluent treatment

The role of instrumentation, control, and automation (ICA) in the management, operation, and control of domestic and industrial wastewater treatment works is examined following an historical account of developments in the UK over the past two decades. Included also are aspects of process optimization and process selection, taking into account size and types of works and populations served. The particular ICA requirements of individual unit processes are examined and the effects of unattended operation and remote supervision are considered. Particular attention is paid to measurement technology, the shortcomings of available instruments and systems, and recent developments of relevance, with particular emphasis being placed on microelectronic and fibre- and electro-optic-based sensors and on the role of advanced commenting methods including expert systems. Progress with biologically based sensors is also discussed.

Aspects of the phosphorus cycle in Hartbeespoort Dam (South Africa) Phosphorus loading and seasonal distribution of phosphorus in the reservoir

Hartbeespoort Dam, a hypertrophic, warm monomictic impoundment in South Africa, receives extremely high phosphorus loads (14.6–25.9 g m−2 a−1) that are dominated by point source discharges from municipal wastewater treatment works. The reduced state of the phosphorus discharged from the works has led to the dominance of the dissolved phosphorus pool by low molecular weight orthophosphates which are analytically detectable as soluble reactive phosphorus (SRP; 60% of total phosphorus pool). Seasonality in the in-lake total phosphorus pool is regulated by a combination of abiotic and hydrological processes; biotic processes appear to play a minor role. Mass balance calculations indicate that between 62 and 77% of the annual total phosphorus inflow load is retained within the impoundment each year.

Investigations on the concentration of radionuclides in sewage sludges of Ruhrverband wastewater treatment plants 1960 through to 1986

The Ruhrverband operates a total of 118 municipal wastewater treatment works. Predominantly, biological treatment is applied. Annually, some 1.9 million m 3 of raw sludge is produced and mainly anaerobically digested. Supplementary to common analyses the digested sludges are investigated concerning radioactivity since 1960. Thus, the additional loading resulting from fall out and wash out after the reactor accident on 26 April 1986 in Chernobyl could be precisely recorded. p ]Prior to the description of the effects of the Chernobyl accident on river water, potable water and on wastewater sludges, a short background information on the occurrence of the accident and its consequences for the F.R.G. is given.

Metapolicy Transition and Policy Implementation: New Federalism and Privatization

Mandated local implementation of national policy poses a complex issue. What happens to the decisionmaking and implementation processes at the local level of government when broad change in policy direction occurs at the national level? The importance of this question depends on the extent to which local government officials are responsible for implementing policy which the national government has helped to form in some substantial way. Local governments in the United States have acquired many such responsibilities as a result of the categorical and block grants of the 1960s, revenue sharing of the 1970s and 1980s, and, more recently, President Reagan's New Federalism. However, the national policies in each of these periods differ substantially in the specific roles expected of local governments. In the first periods, local governments addressed local problems, in part, through the administration and implementation of national programs with national funding. The most recent iteration of federalism-New Federalism-calls for local governments to address local problems with their own resources. This latter expectation has created complex problems of local administration. In this article we consider the specific problems of policy implementation in the substantive area of clean water and wastewater treatment. The problem is on its face not unusual: How do municipal officials make decisions about financing mandated and needed facilities? In the clean water policy context, however, this problem is of particular interest because it flows from radical changes in national policy which have maintained or tightened clean water standards while reducing national resources available to cities to meet those standards. Practical as well as theoretical issues arise in such a setting. In this article these issues are addressed using the results of a survey' of 16 municipalities across the United States which have considered privatization2 of wastewater treatment works (WTWs) as one way of implementing clean water policy in a period of reductions in resources. In a comprehensive sense, privatization means the participation of the private sector in the production and/or delivery of public services. Within the comprehensive definition, however, there are old and new forms of privatization. Old privatization, long in use, involves contractual relationships between a government and a private sector entity as a basis for service * This article considers the issue of mandated local government implementation of national policy in the context of broad policy changes and reduction or elimination of available national resources. Specifically, the article addresses this issue using the results of a survey of 16 municipalities across the United States which have privatized or have considered the privatization of wastewater treatment works as one way of implementing national clean water policy. The policy requires compliance with national standards by 1988 with or without nationalfunding. The conclusion is that privatization evolved in the absence of coherent national policy as a viable option for those municipalities which needed increased water treatment capability due to population or industrial expansion and had the innovative managerial and institutional strengths to overcome resistance to the attendant political and economic risks.

GC‐MS analysis of odorous emissions from the dissolved air flotation units treating surplus activated sludge at a wastewater treatment works

Odorous air from the dissolved air flotation (DAF) unit of a wastewater treatment plant was scrubbed through an activated carbon column and air samples analysed by gas chromatographic‐mass spectrometric techniques. Chromatographic profiles of the gases emitted at the DAF units were obtained. Compounds identified included mainly the aliphatic hydrocarbons from C9 to C14. The odorous compounds detected were toluene, meta‐, para‐ and ortho‐xylenes, phenol, dimethyl disulphide and dimethyl trisulphide, alkyl benzenes and chlorinated hydrocarbons such as chloroethylene and chlorobenzenes. Phenol and toluene were found to be the most dominant compounds detected.

Impact of ‘Organic' Pollutants on Coastal Waters, Gulf of Trieste

The main sources of potential ‘organic' pollutants (essentially pathogens, nutrients, floatables, suspended solids and detergents) discharged to the Gulf of Trieste by sewers and rivers are briefly reviewed; about 470,000 people live in the coastal area, and nearly 400,000 of them discharge sewage effluents to the Gulf. This brief review is followed by an evaluation of the impact of such discharges on the quality of marine waters, with reference to the impairment of uses such as bathing and shellfish cultivation. The sanitary and aesthetic aspects of faecal pollution which typically affect coastal waters are examined together with the water quality standards pertaining to bathing waters and shellfish cultivation areas; the extent of pollution of the coastal waters is determined. Experience gained at some wastewater treatment and disposal works is cited. On the whole, the Gulf of Trieste appears to be in a satisfactory condition: more than 85% of the shoreline (totalling 42 km in Yugoslavia and 93 km in Italy) is unpolluted, according to the pertaining standards. Ameliorations are, however, urgently needed in many respects. Recommendations regarding adequate forms of sewage treatment and disposal are made.

Bench Scale and Pilot Scale Experiments on Biological Phosphorus Removal

In connection with studies aimed at developing low-energy wastewater treatment processes considerable interest has been shown in the possibility of removal of phosphorus biologically rather than chemically. The results over one year from bench and pilot scale tests conducted with synthetic and settled domestic wastewaters respectively are reported. The pilot plant was installed in one of the Rome urban wastewater treatment works and consisted of a two stage (anaerobic-aerobic) system. The wastewater was withdrawn downstream from the primary settling tank and conveyed to the anaerobic reactor of the pilot plant. A similar experiment was conducted in a three reactor (two anaerobic and one aerobic) bench scale plant, where a synthetic solution (peptone, sodium acetate and potassium phosphate) was fed under rigorously controlled conditions of temperature, pH and dissolved oxygen. Both bench and pilot scale tests were designed to verify and quantify the biological removal of phosphorus; the performances of both phosphorus removal test scale systems were compared with those from a reference aerobic plant operating under the same conditions. The impact of several parameters on the biological removal of phosphorus were examined. These parameters were: nature of carbonaceous substrate, carbonaceous/phosphorus ratio, sludge age; etc. Considerable care and attention was given to checking phosphorus balances, once the steady state conditions had been obtained. The results can be summarized as follows:-Phosphorus removal was found to be greater in plants with an anaerobic stage than in the reference plants. At pilot scale level this is clearly shown by the plot of the daily phosphate concentration in the effluents. At bench scale it is shown by comparison between P contents in sludges (9.9% vs. 5.0%) and by the fact that, at the end of the experiment, large deposits of inorganic phosphate (mainly of Ca and Mg) were found on the walls of both anaerobic reactors. The unstable operating conditions of the reference plant due to the poor sedimentation characteristics of the sludges leading to uncontrolled losses of biomass meant it was impossible to obtain a reliable mean phosphorus abatement value, which in any case was always well below that found for the P-removal plant.-As reported above, the deficit in the phosphorus balance was due to inorganic phosphate precipitation. In this connection an excellent quantitative agreement was found between the deficit in the balance and the quantity of phosphorus collecting in the anaerobic reactors.-Phosphorus release from the biomass under anaerobic conditions has already been completed in the first anaerobic reactor (where carbonaceous substrate uptake also occurs) and the use of the second anaerobic reactor seems to allow a more complete phosphate precipitation.-Part of the carbonaceous substrate which disappears during the first anaerobic stage is metabolized. In fact, in this reactor, the complete disappearance of organic nitrogen is accompanied by the release of large quantities of ammoniacal nitrogen. Lastly, despite the fact that the values of the main operative parameters, such as hydraulic retention time, sludge age, temperature, pH and dissolved oxygen, were kept rigorously constant, a certain instability was found in the biomass as regards the maintaining of such high phosphorus removal efficiencies over long periods of time. This may be due to the highly variable biological population dynamics.

ON THE CENTRALIZATION OF WASTEWATER TREATMENT FACILITIES1

ABSTRACT. Two factors affecting the centralization of wastewater treatment facilities were investigated; the cost of collection and treatment systems and the performance of treatment plants. Based on computer‐generated minimum cost designs, wastewater collection networks were found to be characterized by diseconomies of scale of magnitude similar to the reported economies of scale for wastewater treatment works. The combined costs of collection and treatment are U‐shaped functions from which the least cost size of collection and treatment systems were found for particular values of population density. Examination of the day‐to‐day performance of five metropoitan‐area waste‐water treatment plants revealed that, for time series shorter than one month, the day‐to‐day variation in effluent quality was random, although the variation in quantity discharged was distinctly non‐random. The performances of all five plants on any given day showed little correlation. This suggests that the decentralization of treatment facilities can produce benefits both through the reduction in quantities of waste discharged at a given point and through in‐stream averaging of the varying performances of several treatment plants. Since the cost function of collection and treatment combined is generally flat in the region of the minimum‐cost size, little penalty is invoked to gain the potential benefits of treatment plant decentralization.

The Governance of the Metropolis as a Problem in Diplomacy

Previous articleNext article No AccessThe Governance of the Metropolis as a Problem in DiplomacyMatthew Holden, Jr.Matthew Holden, Jr. Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Politics Volume 26, Number 3Aug., 1964 Sponsored by the Southern Political Science Association Article DOIhttps://doi.org/10.2307/2127511 Views: 3Total views on this site Citations: 20Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Jay Rickabaugh Regional Public Sector Organizations: A broader taxonomic classification to cross‐pollinate empirical research, Public Administration 81 (Aug 2021).https://doi.org/10.1111/padm.12779David K. Hamilton Assessing the Future of Regional Governance in North America, (Jul 2012): 167–180.https://doi.org/10.1007/978-1-4614-1626-5_10David K. Hamilton The Government Centralization-Decentralization Debate in Metropolitan Areas, Review of Policy Research 21, no.55 (Sep 2004): 663–680.https://doi.org/10.1111/j.1541-1338.2004.00100.xVolker Schneider Organizational Governance — Governance in Organisationen, (Jan 2004): 173–192.https://doi.org/10.1007/978-3-531-90171-8_9James A. Visser Understanding Local Government Cooperation in Urban Regions, The American Review of Public Administration 32, no.11 (Jul 2016): 40–65.https://doi.org/10.1177/0275074002032001003H. George Frederickson The Repositioning of American Public Administration, PS: Political Science & Politics 32, no.0404 (Sep 2013): 701–712.https://doi.org/10.1017/S1049096500056547Joseph McCormick, Steven M. Teles Matthew Holden Jr.: Between Theory and Practice, PS: Political Science & Politics 31, no.0303 (Sep 2013): 653–657.https://doi.org/10.1017/S1049096500055074Kathryn A. Foster Regional Impulses, Journal of Urban Affairs 19, no.44 (Dec 2016): 375–403.https://doi.org/10.1111/j.1467-9906.1997.tb00503.xMichael N. Danielson, Paul G. Lewis City Bound: Political Science and the American Metropolis, Political Research Quarterly 49, no.11 (Jul 2016): 203–220.https://doi.org/10.1177/106591299604900113BRUNO DENTE Metropolitan Governance Reconsidered, or How to Avoid Errors of the Third Type, Governance 3, no.11 (Jan 1990): 55–74.https://doi.org/10.1111/j.1468-0491.1990.tb00107.xR L Morrill Regional Governance in the United States: For Whom?, Environment and Planning C: Government and Policy 7, no.11 (Mar 1989): 13–26.https://doi.org/10.1068/c070013John G. Heilman, Gerald W. Johnson SYSTEM AND PROCESS IN CAPITAL-INTENSIVE PRIVATIZATION: A COMPARATIVE CASE STUDY OF MUNICIPAL WASTEWATER TREATMENT WORKS, Review of Policy Research 8, no.33 (Mar 1989): 549–572.https://doi.org/10.1111/j.1541-1338.1989.tb00979.x John R. Logan Growth, Politics, and the Stratification of Places, American Journal of Sociology 84, no.22 (Oct 2015): 404–416.https://doi.org/10.1086/226790Max Neiman Analogues and Policy Analysis, American Politics Quarterly 5, no.11 (Nov 2016): 3–26.https://doi.org/10.1177/1532673X7700500101E. Torgovnik Urban Political Integration in Israel: A Comparative Perspective, Urban Affairs Review 11, no.44 (Jun 1976): 469–488.https://doi.org/10.1177/107808747601100403W. Bruceshepard Metropolitan Political Decentralization, Urban Affairs Quarterly 10, no.33 (Aug 2016): 297–313.https://doi.org/10.1177/107808747501000303Richard Child Hill Separate and Unequal: Governmental Inequality in the Metropolis, American Political Science Review 68, no.44 (Sep 2013): 1557–1568.https://doi.org/10.2307/1959941John Rehfuss Comparative Politics and the Study of American Local Government, Journal of Comparative Administration 3, no.44 (Sep 2016): 491–510.https://doi.org/10.1177/009539977200300405Timothy Schiltz, William Moffitt Inner-City/Outer-City Relationships in Metropolitan Areas, Urban Affairs Quarterly 7, no.11 (Aug 2016): 75–108.https://doi.org/10.1177/107808747100700105John J. Hebal APPROACHES TO REGIONAL AND METROPOLITAN GOVERNMENTS IN THE UNITED STATES AND CANADA, Canadian Public Administration/Administration publique du Canada 10, no.22 (Jun 1967): 197–208.https://doi.org/10.1111/j.1754-7121.1967.tb00975.x