bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of nutrient removal with on-line monitoring and dynamic simulation
Authors: Leeuw E. J. , Kramer J. F. , Bult B. A. , Wijcherson M. H.
Published: May 2018

Many Wastewater Treatment Plants (WWTP) have to reach stricter effluent standards. WWTPs loaded with a low F/M-ratio can often reach these standards by process optimization, without extension of the plant. This paper presents the step by step approach of the process optimization. An important step is a three week period of on-line monitoring of ammonium, nitrate and phosphorus: the analyses provide information about changes of effluent quality within the day. Another important step is process modelling. The model is calibrated by the on-line measurements. Process modelling enables a comparison of the effectiveness of different process modifications. This approach is applied at a WWTP of the Friesland Waterboard.
Control of nitrogen removal in wastewater treatment plants with predenitrification, depending on the actual purification capacity
Authors: Hoen K. , Schuhen M. , Köhne M.
Published: May 2018

In this paper, a control strategy for a wastewater treatment plant with predenitrification is presented, enabling the control of nitrogen removal depending on the current capacity of the purification process. The concept is based on a simple on-line identifiable model of the nitrogen removal process. The model allows the precalculation of process data for several hours in advance. By this, the controller is able to consider future changes in concentration of the effluent variables of interest. For the demonstration of the efficiency of this approach, different controllers are presented in a simulation study. By means of the variation of the volumes of nitrification and denitrification, by an equalizing basin or by the addition of external carbon sources, the ammonium and inorganic nitrogen concentration in the effluent of the biological purification stage will be controlled. Finally, these controllers will be integrated into an overall strategy.
Monitoring runoff conditions in a combined sewer system: experience and results of ten years' application
Authors: Weyand M.
Published: May 2018

To get knowledge about the runoff, storage and combined sewer overflow (CSO) conditions since 1985 a measuring and monitoring system is working in the sewer network of the community Ense-Bremen (near Dortmund). Within this semi-urban catchment seven detention facilities are fitted out with devices for monitoring information about basin outflow, grade of volume and CSO. Since October 1986 the determined data are also used for the real-time control of that sewerage. Since its installation the monitoring system works rather satisfyingly. Especially the operating staff use its possibilities to get information about the actual condition of the sewer system. Thus, differences to the normal runoff conditions can be realised in very short time. That allows an immediate reaction in order to clear malfunctions or errors as well. However, within the ten years there have also occurred some failures at the measuring devices caused by different reasons up to a complete breakdown of the whole system during thunder-storms. All in all the results of that pilot project have been positive and are now the basis for the equipment of further detention facilities in other sewer systems with monitoring devices.
Recovery analysis in risk management of hazardous materials
Authors: Rossi Esko , Ettala Matti
Published: May 2018

Recovery analysis as an adjoint activity in risk assessment is to account for situational and technical aspects of a plant's preparedness for incident response and accident management. Recovery analysis has been well established in nuclear industry in evaluation of the means to prevent accident propagation. The aim of this study was to apply recovery analysis principles in the management of accidental water pollution events due to uncontrolled releases of hazardous materials. A checklist comprising possible means to prevent accident propagation, was worked out. The checklist included correction measures at equipment level, remediation measures along migration routes and release treatment systems. All the correction and remediation measures included two phases: detection of the accident evolution and the actual response actions. Methodology was tested at two paper mills with different environmental settings. First, various potential accidental releases of hazardous materials were identified and estimated using traditional methods like preliminary hazard analysis and Hazop. After that possible recovery measures were analyzed. Recovery analysis appeared a worthwhile tool in evaluating the entire event chain causing accidental water pollution. The recovery procedures along release migration routes were often considered more efficient than system modifications trying to reduce release probability. That was because releases originating from numerous sources may be recovered along the migration route.
Achieving reliable and cost effective water treatment
Authors: Egerton Amanda-Jane
Published: May 2018

There is increasing pressure from financial and quality regulators both to reduce costs and to improve levels of service within the water industry. It is possible to reduce costs to some extent without affecting levels of service unduly. However, there comes a time when further reductions have a major impact on the reliability of the treatment process and the reductions are no longer cost-effective.

On examination, it is typical to find that the overall risk of treatment failure is dominated by a small number of significant problem areas or pinch-points within a system. Removal of these pinch-points through design or operational changes will lead to improvements in levels of service. Alternatively, if the pinch-points dominate the risk and cannot be removed cost-effectively, there is little point in over-protecting other areas through the inclusion of standby equipment or with unjustified levels of maintenance. Thus costs in these areas can be cut back without unduly increasing the overall risk of failure.

This paper shows how risk analysis can be used to identify those areas of a system that dominate its risk of failure. This allows its design and operation to be optimised, thereby enabling levels of service to be met at minimum cost.
Air monitoring at Camaçari Petrochemical Complex
Authors: Neves N. M. S.
Published: May 2018

Camaçari Petrochemical Complex, the largest integrated industrial complex in Latin America, began its operation in 1978, in one of the most populated areas of Greater Salvador, near the cities of Camaçari and Dias D'ávila. With more than sixty industries in operation, the Complex is a potential source of pollution requiring rigorous environmental protection efforts. From its initial planning phase, in the mid 1970s, the Camaçari Petrochemical Complex ranked environmental issues as one of its highest priorities. It was the first industrial complex in Brazil to be conceived and planned with a marked interest in the environmental impacts resulting from its activities. CETREL, which began operations at the same time as the Petrochemical Complex, is a product of this concern for the environment. Built to treat the effluents and industrial residues generated by the complex, it was called the Center for Treatment of Liquid Effluent. CETREL's functions have been gradually diversifying, and today the Company performs a variety of tasks in the area of environmental protection. Besides treating the liquid effluents, CETREL operates an incinerator for hazardous liquid residues; it processes hazardous solid residues in special industrial landfills; it monitors the complex's environment and all of the complex's area of influence (the air, aquifers, sea and rivers of the region) and it provides environmental engineering consulting services to several Brazilian companies. Moreover, CETREL develops projects like the Pronatura Program, the objective of which is the afforestation of a 500-hectare area using the biological sludge produced at its own Central Treatment Station, and the Fauna Preservation Program that monitors and protects wildlife living on Company grounds.
15 years of practical sewage treatment in Venezuela
Authors: Lansdell M.
Published: May 2018

A summary of fifteen years of experience of the design, operation and performance several Venezuelan municipal wastewater treatment systems to serve a population of 5 million is presented.

Technical and institutional problems which occurred during construction and operation are described and some of the solutions are presented. It was found that the most simple systems were the most effective and that it was important to develop solutions appropriate to local needs and avoid the technological dependance on imported spare parts.
Domestic sewage treatment in an upflow anaerobic sludge blanket - sequencing batch reactor system
Authors: de Sousa J. T. , Foresti E.
Published: May 2018

Domestic sewage treatment in up-flow anaerobic sludge blanket (UASB) reactors has presented significant results in tropical regions. This reactor configuration has proven to be efficient in removing organic matter and total suspended solids as well as in producing smaller amounts of excess sludge than conventional aerobic reactor. On the other hand, its effluent often requires to be post-treated in order to achieve the emission standards.

This paper is concerned with the alternative proposed here for treating domestic sewage in a combined anaerobic-aerobic system composed of an UASB reactor followed by sequencing batch aerobic reactors (SBR). In such a system, the UASB reactor removes considerable fraction of the influent organic matter, while the SBRs oxidize part of the remaining organic matter and ammonium nitrogen. A proper system operation would also permit the removal of nutrients (N and P).

In order to investigate on the performance of this system for sewage treatment, a bench scale installation fed with synthetic substrate simulating domestic sewage was operated continuously during 38 weeks. The results permit to confirm the hypothesis proposed, since the system has consistently produced high quality effluents (BOD5 and VSS lower than 10 mg.L-1).

The results also indicate that such combined anaerobic-aerobic system compete favorably with conventional aerobic systems in three essential cost features: energy consumption, excess sludge production and nutrient removal.
Disinfection of municipal wastewater by sensitized photooxidation
Authors: Li X. Z. , Chua H. , Zhang M.
Published: May 2018

To optimize the disinfection of treated municipal wastewater by sensitized photo-oxidation as a new alternative disinfection method, secondary unchlorinated activated-sludge-treated effluents from a sewage treatment plant were treated by semiconductor-sensitized photo-oxidation. Experiments of disinfection were performed in a photo-reactor system, which is a cylindrical borosilicon glass reactor with an effective volume of 1.1 litre. A NEC black light lamp (T10 20W) is placed at the centre of the reactor as an artificial light source to provide near UV irradiation with a maximum intensity at 350 nm. Hydraulic retention time (HRT) was used up to 60 minutes in this study. The effluents, after adding titanium dioxide as sensitizer, were exposed to the illumination of near UV light for various irradiation time and incident light intensities. Number of bacteria and coliforms were significantly declined from 35,000/100 ml to 59/100 ml after 60 minutes treatment, with existing of titanium dioxide, light irradiation and aeration. After the photo-oxidation process, the titanium dioxide in the treated effluent was separated by precipitation. The influence of light energy from 5.2 to 45 W/m2, absorbed by the sensitizer in the visible range, on micro-organisms in secondary effluents was determined by testing forEscherichia. coli (E. coli) and total coliforms. An optimum titanium dioxide concentration found in the test is about 1 g/L. While the destruction rate of E. coli was affected by pH, dissolved oxygen (DO) and temperature (T), it was found that number of bacteria destroyed during disinfection mainly depends on incident light intensity (IO) and irradiation time (t), which follows an exponential relationship. A kinetic model has been developed using the product of IO and t defined as a Dose Number (D) for this disinfection reaction.
Policy options for environmentally sound technology in India
Authors: Khanna P.
Published: May 2018

The emergence of the concept of sustainable development in recent years has brought in the general realisation that societal perceptions must shift towards ecological determinism so as to achieve qualitative growth within the limits of the ecosystem's carrying capacity. The carrying capacity based planning process, innovative technologies for enhanced material and energy effectivity of production and consumption, structural economic change towards less resource-intensive sectors, and preventive environmental management through increasingly interventionist policies are some of the strategies for reconciling developmental goals with ecological capabilities.

The paper analyzes existing and future environmental issues emanating from developmental objectives and policies in population, agriculture and forestry, energy, industry and human settlement sectors in India and suggests an agenda for action, with focus on environmentally sound technology, to ensure discernible positive movement towards the overall aspirational goal of sustainable development.

It argues for a dynamic policy framework for environmental management in which the time lag between problem awareness, technological solution and remedial action is minimized through anticipation and prevention of environmental problems that may arise as a consequence of decisions taken within various sectors of the economy; restoration of environmental quality wherever necessary; structural changes in the economy; and inter-policy coordination.
Aquatic toxicity emission from Tokyo: wastewater measured using marine luminescent bacterium, photobacterium phosphoreum
Authors: Asami Mari , Suzuki Noriyuki , Nakanishi Junko
Published: May 2018

Aquatic toxicity of point-source discharges are examined with the MICROTOX system using luminescent bacteria, Photobacterium phosphoreum. Samples include treated wastewaters from industrial dischargers, municipal sewage treatment plants and community sewage treatment plants, all of which eventually flow into Tokyo Bay. Among 34 samples from industry, 11.7% exhibit high toxicity (EC50 =< 0.2), 17.6% exhibit low toxicity (0.2 < EC50 =< 1), and 70.7% were non- or only slightly toxic (1 < EC50). Aquatic toxicity of treated wastewater is mostly due to the chlorination process. Results suggest that 96% of the total toxicity load of all point-source discharges is caused by chlorination. The toxicity assessment with luminescent bacteria is shown to be effective and of practical use, since it facilitates the evaluation of the total toxicity which cannot be well embodied in the current regulation systems by specific indices.
Biodegradability characterization of mixtures of chemical contaminants in wastewater - the utility of biotests
Authors: Nyholm Niels
Published: May 2018

A practical scheme for assessment of the functional biodegradability of industrial effluents in terms ofdegradable and persistent toxicity is suggested, and the general problems of biodegradability characterization of complex mixtures is discussed. Persistent toxicity is assessed after a long-term stabilization (aging) of the effluent brought about by incubating an effluent sample with at least an equal volume of test medium (nutrient enriched surface water or mineral medium) containing a natural consortium of microorganisms. Degradable toxicity is the toxicity of the fresh effluent less its persistent toxicity. The two categories of toxicity should be managed differently. While for example dilution in the receiving water can be an effective means of mitigating degradable toxicity, dilution is in principle an insufficient control instrument for persistent toxicity. A degradability study with an unbleached sulphite pulp mill effluent, highly toxic to algae, is presented as a case history to illustrate the suggested biodegradability assessment scheme and the results' interpretation.
A method for screening the potential toxicity of organic chemicals to methanogenic gas production
Authors: Madsen Torben , Rasmussen Hanne Beck
Published: May 2018

The objective of this study was to examine a simple anaerobic gas production test for screening the toxicity of organic chemicals to anaerobic metabolism. Inhibition of anaerobic digestion can pose a problem in sludge treatment systems as it may limit the biodegradation of hazardous pollutants. The method used was based on a single measurement of the headspace pressures in closed bottles containing inoculated medium and serial dilutions of the test chemicals. Under the applied methanogenic conditions, the anaerobic gas production was particularly sensitive to surfactants and Cl and NO2 substituted phenols. E.g., the EC50 values for the surfactants alkyl dimethylbenzylammonium chloride and sodium alkyl ethersulfate were 6.7 and 11 mg/l. Two of the surfactants and two of the phenols were also examined in the Microtox bioassay and in the growth inhibition test with Pseudomonas putida as these tests are commonly used for screening the toxicity of chemicals. The anaerobic gas production test was considerably less sensitive to toxic chemicals than the Microtox bioassay. However, for the surfactants, the anaerobic tests gave lower effect concentrations than obtained in the tests with P. putida. Screening the toxicity of chemicals to anaerobic processes may predict the potential effects of pulse loadings to anaerobic digesters. Furthermore, knowledge about inhibitory concentrations may be very useful prior to anaerobic biodegradability testing.
Evaluation and modification of the simpletreat chemical fate model for activated sludge sewage treatment plants
Authors: Mikkelsen Jørgen , Nyholm Niels , Jacobsen Bo Neergaard , Fredenslund Fei Chen
Published: May 2018

The SimpleTreat model of Struijs et al. (1991a,b) for chemical fate in a generic activated sludge type wastewater treatment plant (WWTP) has been examined together with an improved model version (vers. 2.1jm) which gives more flexibility in the specification of the WWTP design and operating conditions and which includes a more accurate description of the process of volatilization. Model predictions for 15 different organic chemicals have tentatively been compared with observed removals in three specific Danish WWTP's, all low loaded plants with nitrogen removal. Biodegradation rate constants were either default values for readily or inherently degradable chemicals proposed in the EU Technical Guidance Document on Environmental Risk Assessment of New and Existing Substances (EUTG), or were judged from literature data. The model predictions were generally in fair agreement with the observed removals although exceptions were noted. For 10 chemicals the data allowed estimations of “full scale” biodegradation rate constants by model calibration. Rate constants (extrapolated to 20°C reference temperature) ranged from 0.07 L/(g SS ·d) for pentachlorophenol to 12 L/(g SS ·d) for the every readily degradable compound, p-cresol. Finally, example calculations with parameter values representing a generic Danish WWTP have been compared with example results stated in the EUTG. The predicted emissions in the generic EU WWTP were up to 3-4 times less to water and air and the emission with excess sludge up to 10 times higher than the corresponding figures for an average Danish WWTP.
Phosphorus removal from wastewater using an algal turf scrubber
Authors: Craggs Rupert J. , Adey Walter H. , Jenson Kyle R. , St. John Matthais S. , Green F. Bailey , Oswald William J.
Published: May 2018

Algal turf scrubbing is a novel technology for the treatment of agricultural runoff and eutrophic lake water and may have application for wastewater treatment. The algal turf scrubber (ATS)TM consists of a natural, mixed assemblage of attached periphyton, microalgae and bacteria which colonise an inclined floway over which wastewater flows in a series of pulses. A large-scale ATS (152.4 m long 6.5 m wide) was constructed in Patterson, California and tested in conjunction with UV disinfection over one year for its ability to treat secondary effluent from an evaporation pond. The hydraulic loading rate of the wastewater was varied between 436 and 1226 m3 per day and various operational parameters were tested. The biomass was mechanically harvested from the floway at one or two week intervals depending upon the season. This paper will present the results for phosphorus removal and productivity of the algal turf. Phosphorus removal from the secondary wastewater was measured twice a week during four, 8 week quarters corresponding to the solar seasons. The phosphorus content of the harvested solids was also measured during these periods. Based on the mean percentage of P (2.1 %) in the harvested solids and the mean productivity (35 g m−2 d−1), the yearly mean removal of phosphorus was 0.73 ± 0.28 g m−2 d−1. An inverse relationship was found between reduction in hydraulic loading rate and increase in pH, phosphorus removal and hardness reduction by the ATS. This indicated that pH mediated precipitation probably accounts for much of the phosphorus removal by the ATS and for the high mean phosphorus content of the harvested solids. Measurement of nutrient concentrations in influent and effluent of the ATS over 24 hours showed that at night phosphorus removal declined. These results indicate the potential of the ATS for phosphorus removal from wastewaters and suggest that removal may be easily controlled by altering the hydraulic loading rate.
Wastewater treatment with bacterial augmentation
Authors: Chin K. K. , Ong S. L. , Poh L. H. , Kway H. L.
Published: May 2018

Commercially available bacterial products were used in enhancing biodegradation of monoaromatic hydrocarbons in an attached-growth bioreactor and the treatment of wastewaters containing high concentration levels of organic wastes. For the augmented attached growth system empty bed hydraulic retention times (EBHRT) of 1.9 hours to 11.6 hours were run. Results showed that at 11.6 hour EBHRT 80% removal of 10.8 mg/L feed benzene, 96.8% removal of 8.1 mg/L feed toluene and 12.7% removal of 6.1 mg/L feed xylene were achieved. In the treatment of high strength sewage, significant removal of COD, BOD and oil and grease was observed over a 4 month trial run period.
Finite element digital model for longitudinal dispersion of pollutant in porous media
Authors: Rao K. Srinivasa
Published: May 2018

Surface and groundwater sources of water are being contaminated in the course of rapid urbanization and industrialization. The groundwater environment is being assaulted with an ever increasing number of soluble chemicals and human and industrial wastes which are let out on to the surface without treatment. Groundwater pollution often results in aquifers being damaged beyond repair. To prevent the pollution of groundwater resources, first we should identify the areas and mechanisms by which the pollutants enter the groundwater systems and the development of reliable predictions of the transport of the contaminant within the flow systems. These predictions will become the basis for minimizing the impact of existing or proposed industrial, agricultural and municipal activities which may affect the groundwater quality.

It is necessary to study the different engineering aspects of groundwater quality control. The different aspects include 1) anticipating the probable future solute concentration distribution in the groundwater aquifer at any time since the beginning of the contamination and 2) deciding whether the contamination of a particular groundwater zone has crossed the limits of tolerance. From the above points, it is strongly felt that there is need to study the phenomenon of dispersion of pollutant in the porous media flow.

The study necessitates the solution of a differential equation describing the solute transport process. In this study, a finite element digital model has been developed for longitudinal dispersion of the pollutant in the porous media. The results obtained from the above model are found to be in close agreement with those of the analytical solution given by earlier researchers.
Stochastic modeling of multicomponent adsorption kinetics with non-linear isotherm
Authors: Lee Seung-Mok , Mathews A. P. , Nassar R.
Published: May 2018

A Markov process coupled with the Langmuir adsorption isotherm is developed to simulate bisolute adsorption kinetics. Estimates of all model parameters were obtained from a single-solute experiment for the adsorption of 1,1,1-trichloroethane (TCEA) and trichloroethylene (TCE) from dilute aqueous solutions onto granular activated carbon (GAC). The model verifications indicate that the representation of the rate mechanisms are adequate. The solution of the resultant model equations, which are ordinary differential equations, is simpler than the solution of the partial differential equations involved in the deterministic formulations. This model approach can be extended for the modeling of multicomponent adsorption in fixed-beds.
Bioremediation of metal-contaminated industrial effluents using waste sludges
Authors: Atkinson B. W. , Bux F. , Kasan H. C.
Published: May 2018

Metal contaminated industrial effluent, from a metal plating company, was exposed to waste activated sludge to optimise the biosorption process at laboratory scale. Metals assessed were Zn2+, Cu2+, Cd2+, Ni2+, Cr3+ and Cr6+, of which, Zn2+ was most prevalent. Biosorption rates of up to 96% were recorded for Zn2+ within the first 15 min., of the reaction, at initial concentrations of 110mg.1−1. Biomass displayed an average adsorptive capacity of 80% at metal concentrations of 50mg.1−1 and above. Both fully mixed and upflow column bioreactors were employed during experimentation, using wet and dried sludge. The findings of this study show that wet sludge, utilised as biosorbent in a fully mixed process, has superior potential for metal ion biosorption from an industrial effluent.
A study of WC derived sewer solids
Authors: Friedler Eran , Brown David M. , Butler David
Published: May 2018

Little is currently known about the nature, quantity or variability of WC derived sewer solids. This work describes results of a one week domestic WC usage survey in the UK. Specific attention is paid to solid production including faecal matter, toilet paper and sanitary refuse. Significant quantities of solids were found to be produced. The results illustrate distinctive diurnal usage patterns including the surprisingly low evening faecal related flush usage. Weekend usage exceeded week day usage on average, but with reduced morning peaks. Differences between males and females usage were also noted, in particular the much larger toilet paper usage and sanitary refuse disposal associated with females.
Optimized removal of arsenate(III) by adaptation of oxidation and precipitation processes to the filtration step
Authors: Borho M. , Wilderer P.
Published: May 2018

Processes for the removal of arsenic from water have been widely studied. Realizable and reliable concepts, however, exist only for the removal of inorganic arsenate(V). The question of how to optimize removal of arsenate(III) has not yet been addressed sufficiently. To improve this specific knowledge, the potential of coupled oxidation and precipitation processes to eliminate arsenate(III) was examined in pilot-scale experiments. Potassium permanganate and manganese dioxide coated quartz sand filter grains have been found to be highly effective agents for the oxidation of arsenate(III). Iron(II) in combination with oxygen proved to be comparable to iron(III) with respect to arsenate(V) binding capacity. The entire process can be optimized by selecting oxidation and precipitation agents with regard to the final filtration step. The best and most reliable of the investigated combinations was the coupling of manganese dioxide coated quartz sand for arsenate(III) oxidation with iron(II) / oxygen to bind the generated arsenate(V) molecules.
Near bed solids transport in sewers
Authors: Arthur Scott , Ashley Richard M. , Nalluri Chandramouli
Published: May 2018

This paper describes the results of three sewer sediment studies, carried out in Dundee, financed by the Engineering and Physical Sciences Research Council (EPSRC) and the Water Research centre (WRc). The work was carried out by the University of Abertay Dundee (Wastewater Technology Centre) as part of a collaborative research project undertaken with the University of Newcastle and the University of Sheffield.

In Dundee, through collaboration with the sewerage system operator (Tayside Regional Council Water Services Department), three field sites have been established in interceptor and trunk sewer sites, since 1992, to monitor, as closely as possible, sediment and other pollutant erosion, their transport and the effects of first flushes.

The physical and biochemical nature of the material being transported near the bed of real sewers has been measured. The importance of this mode of transport, in terms of mass transported and pollutant potential, is demonstrated based on data collected from the Dundee system sites. Comparisons are made between measured transport rates at the bed, at sites with and without deposited beds, with results obtained by applying empirical relationships developed to predict near bed transport in laboratory studies. A modified relationship is proposed which best fits the Dundee system data.
Photocatalytic degradation kinetics of humic acid in aqueous TiO2 dispersions: the influence of hydrogen peroxide and bicarbonate ion
Authors: Bekbölet Miray , Balcioglu Isil
Published: May 2018

The degradation of humic acid in water by means of photocatalytic method has been studied. The influence of hydrogen peroxide and bicarbonate has also been investigated. The kinetics of the photocatalytic degradation of humic acid in various concentrations (50-500 mg/L) has been followed by the determination of TOC, COD and UV-vis spectra of the reaction solution. While the pseudo first order rate constants of 50 mg/L humic acid were found 0.016, 0.03 and 0.036 for TOC, Color400 and UV254, the degradation rate constants for these parameters were found 0.029, 0.069 and 0.057 in the presence of 1×10−2M H2O2. The Langmuir-Hinshelwood kinetic has also been sucessfully applied to the photocatalytic degradation data. It was found that bicarbonate ions slowed down the degradation rate by scavenging the hydroxyl radicals. Low pH value has been found to be favorable for color removal in the absence of hydrogen peroxide whereas natural pH gave the best results for color removal in the presence of hydrogen peroxide.
Empirical equations for solids transport in combined sewers
Authors: Coghlan Brian P. , Ashley Richard M. , Smith George M.
Published: May 2018

An investigation of the transport of solids in combined sewers during both dry weather flow (DWF) periods and storms is described. The study was based on data obtained from a number of sites in the combined sewer system of Dundee, Scotland. The relationship between hydraulic conditions in a combined sewer and the transport of solids in suspension was examined. The aim was to arrive at a methodology by which an appropriate model could be selected or developed which would predict solids transport rates given information on hydraulic conditions. It was found that for individual sites, site-specific regression equations could be developed separately for dry weather and storm conditions. A non-site-specific regression equation was also developed, which was found to be preferable to the site specific equations, in terms of accuracy and ease of use. More important, however, were the fundamental procedures (ie the methodology) developed by which the model type was in each case selected and subsequently developed.
Suspended solids in combined sewer flows
Authors: Gupta Kapil , Saul Adrian J.
Published: May 2018

Many studies have identified the first flush phenomenon as being the relatively high concentration of pollutants in the initial phases of combined sewer flow following a storm. One way of controlling the first flush is by the provision of a storage tank such that the effluent can be discharged in a controlled manner. To optimise the storage volume, both the total pollutant load discharged and the temporal variation in pollutant concentration within an event need to be predicted. Sophisticated models to predict the pollutant concentrations in urban sewer flows, for example QSIM and MOUSETRAP are already available. However, the data requirements for these models are extensive, which usually limit their application to major or environmentally sensitive schemes.

This paper describes attempts to relate the peak concentration of suspended solids in combined sewer flows to observed storm characteristics. In this study, it was hypothesised that the peak concentrations of suspended solids could be related to the hydrological parameters of maximum rainfall intensity, storm duration, and antecedent dry weather period prior to the storm which are commonly used as the basic parameters for urban sewer design. Data from two sites at Great Harwood and Clayton-le-Moors in the North-west of England has been used in the study and an attempt has been made to define an upper limit of the first flush concentration of suspended solids corresponding to storms which have been categorised into bands defined by their peak rainfall intensity.
Design options for self-cleansing storm sewers
Authors: Nalluri Chandramouli , Ghani Aminuddin Ab.
Published: May 2018

A list of available codes of practice for self-cleansing sewers is presented and a review of appraisals of minimum velocity criterion is summarised. Comparisons of newly developed “minimum velocity” criteria and “minimum shear stress” criterion are presented. Some design charts are also given. These charts are applicable to non-cohesive sediments (typically storm sewers). It appears that sediment size and concentration need to be taken into account, and that a limited depth of sediment bed is recommended for large pipes (diameters > 1000 mm) to maximise their transport capacity.
Influence of configuration and substrate on the properties of dynamically formed membranes
Authors: Diaper C. , Stephenson T. , Judd S.J.
Published: May 2018

Dynamically formed membranes (DFMs) are produced by forming a chemical sub-layer on an inert porous support surface (substrate). In this study, various DFM substrates have been examined: a tubular carbon substrate coated with a ZrO2-TiO2 layer, a flat sheet ceramic substrate supported by a stainless steel mesh, a selection of polypropylene woven media and an extruded polymeric microfiltration membrane. The woven media used are made from combinations of monofilament, multifilament and staple fibres - and a surface-coated polyester weave has also been examined. Zirconium (IV) oxide and polyacrylic acid (ZrO/PAA) are used to form the DFM on the substrates. The influence of the configuration and substrate material on the performance of the DFM has been studied in terms of the normalised permeate flux and salt rejection. A stable DFM was formed on the carbon, ceramic and the extruded polymer substrates. An unstable Zr(IV)O membrane was formed on the surface-coated polyester substrate and a fumed silica precoat has been used to form a DFM on one of the woven polypropylene media. However, the DFM formed on the latter did not exhibit a rejection performance comparable to the other DFMs formed.
Characterization of immobilized cells in biodegradation of ABS resin manufacturing waste-water
Authors: Wen-Chin Chen , Sheng-Shung Cheng
Published: May 2018

Because of the presence of refractory and biologically inhibitory organic compounds in ABS resin wastewater, which would retard the bioactivity of the autotrophic nitrifier and make the efficiency of nitrification process unstable, the application of cell immobilization for ABS wastewater treatment has been investigated by immobilizing the enrichment culture of nitrifying bacteria with alginate. The characterization of the immobilized cells in various alignate concentrations was conducted by a series of biodegradability studies with electrolytic respirometry and compared with the differences from the dispersed cells.

Results clearly indicated that immobilized cells achieved higher efficiency of COD and TKN removal than that of the dispersed cells during the period of high initial concentration of wastewater. Meanwhile, high concentration of cells were growing near the gel surface and reduced the effects of diffusional restriction. No remarkable difference was found while the concentration of alginate ranged from 3% to 5%. According to mass balance of total nitrogen, more than 25% of total nitrogen was removed in the batch system of the immobilized cell. Simultaneous nitrification and denitrification could occur due to the oxygen gradient throughout the gel matrix. Compared with the complete mixing system of the dispersed cell, the approach for the immobilized-cell system provided a more effective method for treating the special wastewater with high strength of nitrogenous and inhibitory compounds.
Redox potential as a controlling factor in enhancing carbon tetrachloride biodegradation
Authors: Jin G. , Englande A. J.
Published: May 2018

Biodegradation of hazardous waste is often the most cost-effective technique suitable for purifying large quantities of polluted groundwater and industrial effluents. In an effort of optimizing environmental conditions for microorganisms to degrade carbon tetrachloride, culture redox potential (Eh) was demonstrated as having a critical role. The microorganisms tested were isolated from contaminated field sites and included Pseudomonas cepacia and Providencia stuartii. Ti(III) citrate was used as a reducing agent to poise Eh at designed values. Over 99% degradation of carbon tetrachloride was effected in 3 days at −250 mV ≤ Eh ≤ −200 mV. Lesser rates were observed at Eh ≥ 0 mV. Kinetic analysis indicated that the overall degradation rate constant increased from 2.75×10−3 h−1 to 4.75×10−2 h−1 by controlling Eh at about −200 mV compared with Eh at ≥ 0 mV. Results indicated that the implementation of critical redox potential may be effective in optimizing CT biodegradation activity.
Integrated catchment management of deep bay, Hong Kong
Authors: Kueh C. S. W. , Chui H. K.
Published: May 2018

Deep Bay contains one of the most important wetlands in southern China. It is located at the border of Hong Kong and the Shenzhen Special Economic Zone (SEZ). Over 50,000 birds rely on this wetland as a breeding, feeding, resting and refuelling station in winter. The Deep Bay catchment is also one of Asia's fastest developing areas. Its population has doubled since 1984. The rapid population increase and economic development have exerted considerable pressure on the wetland environment. Efforts have been made to reduce the pollution loads by both the Hong Kong and Shenzhen Governments to protect this ecologically important wetland. Through the implementation of a series of environmental programmes, including: sewerage master plans, the livestock waste control scheme, and enforcement of the Water Pollution Control Ordinance, the pollution loads arising from Hong Kong decreased from 125,000 to 45,000 kgBOD5/day between 1988 and 1994 and are expected to further reduce to around 3,000 kgBOD5/day by the year 2000. To protect the wetland community while promoting sustainable development in the catchment, Hong Kong initiated a study in 1995 to develop a mathematical model for the bay and a water quality management strategy for the future.
Policy analysis for strategic choices in integrated water management
Authors: Verbeek Martin , Post Henk , Pouwels Ivan , Wind Herman
Published: May 2018

The Northwestern part of Overijssel in The Netherlands is an area where water management is characterised by various interrelated and often conflicting functions. To safeguard a sustainable use of water in this area, decisions have to be made. However, these decisions involve large amounts of complex and uncertain information. Using models and decision-methods, this information can be made available and understandable, in order to support decision-making and help water authorities to choose those measures that best meet the policy objectives. In this paper the usefulness of these models and decision methods, combined in an integrated decision support system, and the sensitivity of the decision support system, is discussed.
Mödling WWTP – treatment efficiency and relationship to receiving water quality
Authors: Franz A. , Nowak O. , Kroiss H.
Published: May 2018

The relationship between water protection of small receiving waters and the reliability of treatment efficiency is represented by a 100,000 PE plant. On the basis of stringent emission and immission standards a concept for a one-stage activated sludge plant was developed that meets the current demands on removal efficiency and limit values in Austria with a high degree of reliability. Classic saprobiological analysis of the receiving creek showed saprobic class II. The operation of the treatment plant has been tested in a period of more than two years under normal operational conditions. In this period several modes of operation were investigated and the concept has proved to be successful. A comprehensive data base has been worked up for process comparison and design evaluation. Relevant effluent parameters of a filtration unit in pilot scale are also given. Mass balances for a validation of the data and statistical characterisation of treatment efficiency combined with saprobiological characterisation of the receiving river has proved the applicability to similar cases. These investigations may serve as an example of how to relate treatment efficiency to saprobity of small receiving rivers.
An alternative approach for evaluation of lake water quality: Lake Sapanca – a case study from Turkey
Authors: Baykal B. Beler , Gönenç I. E. , Meriç M. , Tanik A. , Tunay O.
Published: May 2018

Lake Sapanca is the major water resource supplying drinking water as well as water for industrial and agricultural uses for one of the more industrialized areas of Turkey. Currently, the sustainability of its beneficial use is an issue of concern. Initially the water quality in the lake was classified according to the Turkish Regulations. With this conventional approach, a detailed water quality evaluation could not be achieved due to certain drawbacks, and this required the search for a new approach. Therefore, a more detailed classification was accomplished by taking German Technical Standards as a basis that would lead to more usable and understandable classification necessary to promote a rational management strategy. Both classifications dictate that classes 1 and 2 may be used for water supply effectively. The detailed classification indicates that at present water quality in the lake is overall of first class; however, it is tending towards Class 2, with the lake in a state of transition from oligotrophy to mesotrophy and the most critical issues being nutrient concentrations in the lake and land based nutrient sources.
Strategies and management models for metropolitan wastewater, implementation and evaluation in the East Rand, South Africa
Authors: Korf A. W. , Wilken J. W. , Nel N. J.
Published: May 2018

South Africa is a country where first world wastewater treatment technology and management must take into account third world related problems. In the past, the diversity of a large number of local authorities within the PWV area of South Africa aggravated the problem of proper wastewater management.

On the East Rand in the Gauteng province of South Africa, the problem was attended to by means of a strategic analysis and strategic plan. In the evaluation of the options, the various wastewater management models in use in various regions of the world were evaluated. The investigation resulted in the formation of the ERWAT wastewater management model and implementation.

The paper also evaluates the success of the wastewater management model utilizing the tariff model and other qualitative parameters.
Control of pollution in organized industrial districts: A case study from Turkey
Authors: Filibeli Ayse , Sengül Füsun , Müezzinoglu Aysen
Published: May 2018

At Manisa Organized Industrial District (OID) chosen as pilot study area, a detailed wastewater profile and pollution control study has been realized. A pretreatment strategy was determined and a wastewater management plan was prepared. Existing central treatment plant was studied and cost items were determined. These evaluations were compared with the redesign options generated from our own wastewater management plan. Same treatment units and their combinations were successively designed for variable flow rates between 100-50,000 m3/d. Thus data for new OIDs of similar nature as Manisa, an optimized treatment scheme as well as its approximate cost varying with the wastewater inflow was generated. Proposals for preparing environmental criteria to be considered and applied in newly establishing or planned OIDs are summarized.
Development of privatized operator training and certification programs for Malaysia
Authors: Kerri Kenneth D. , Kumarasivam K. , Hor Lily
Published: May 2018

Wastewater operator training and certification programs are needed to protect public health and the environment. These training and certification programs are also needed to protect the capital investment in the facilities and to ensure that the facilities are in compliance with government regulations. The Government of Malaysia has passed an Act requiring the certification of municipal wastewater (sewage) treatment plant operators. ENSEARCH (a Malaysian professional organization) has prepared a program to develop municipal and industrial wastewater operator training and certification programs. The procedures developed begin with separate advisory committees for both the operator training and certification programs. The committees work together throughout the entire development and implementation process. The first step is to develop “Need-to-Know” criteria which identify the knowledge and skills needed to safely operate and maintain a wastewater treatment facility. These criteria are used to develop both the training and certification programs and also the training materials and the certification examinations. After development of the training materials and certification examinations, both are reviewed, tested and the results are evaluated. The nex t step is to determine the effectiveness of the training and certification program by evaluating operator and plant performance. Recommendations for implementation include four levels of operator training and certification: (1) Basic, (2) Middle, (3) Advanced and (4) Administration/Management/Supervision.
Development, delivery and evaluation of interactive technology training – a case study
Authors: Skerratt R. Glynn
Published: May 2018

A case study is described which seeks to explain some of the key factors in the rationale, development, delivery and evaluation of a series of in-company process/technology training courses. The main points to emerge are the benefit to the training experience associated with interactive delivery and the advantages that are associated with developing group exercises which are coordinated with, and embedded within a site visit, and which are reviewed and discussed during a post-visit debriefing session. Guidance is given on ways of including these activities into training courses together with methods for evaluating their effectiveness.