bluuebunny/crossref_metadata_2025 huggingface dataset:
Real time control for minimizing effluent concentrations during storm water events
Authors: Nyberg Ulf , Andersson Bengt , Aspegren Henrik
Published: May 2018

Increased flow rates due to stormwater at the Klagshamn wastewater treatment plant occasionally cause hydraulic overloading of the activated sludge process resulting in sludge loss from the secondary clarifiers. To minimize these problems different operational strategies have been evaluated at the plant. Practical experiences have shown the benefits of using in-line storage for flow equalization even if the available volumes may seem small in comparison to the total daily flow rate during stormwater occasions. Step feed operation at the treatment plant can be used to further ease the problems with sludge loss. By-pass of primary treated wastewater can finally be used to avoid hydraulic overloading of the biological treatment process. By combining these strategies in a real time control system, the need for erecting off-line storage volumes can be minimized.
Overall chemical reaction model of an ozone contactor for a water purification model
Authors: Kageyama K. , Watanabe S. , Baba K. , Komatsu N. , Yamakoshi N.
Published: May 2018

For the removal of odorous compounds such as dimethylisoborneol (2-MIB) and trihalomethanes (THMs) in supplied water, advanced water treatment plants using ozonation and activated carbon absorption processes have been built in Japan. This paper describes an over-all chemical reaction model for the ozone contactor of the ozonation process. In this model, the Potassium Permangante Consumed (PPC) is assumed as an index of typical ozone consuming substances. The experimental data and calculated results for the ozone consuming substances are compared with Total Trihalomethanes Formation Potential (TTHMFP). Furthermore, the promotive or inhibitive reaction of 2-MIB is introduced in the model. This allows the mathematical model to be applied to actual raw water containing many kinds of co-exist substances.

The model appropriateness is discussed using pilot plant data for a year's operation.
Environmental and energy efficiency of different sewage treatment processes
Authors: Karlsson Ingemar
Published: May 2018

This paper summarises the Scandinavian experience that chemical wastewater treatment gives “value for money” in the sense that such treatment gives a low construction volume per removed unit of Oxygen Consumption Potential (OCP) in the receiving water and a low energy consumption per unit of Oxygen Consumption Potential (OCP) removed. The OCP evaluation takes into consideration both the primary oxygen consumption caused by organic matter and ammonium as well as the secondary oxygen consumption from degradation of algae resulting from the discharge of nutrient. The paper demonstrates that in comparison to conventional biological activated sludge treatment (with pre-settling), chemical treatment plants (primary precipitation) are cheaper in terms of cost per unit of OCP removed and that they require less energy per unit of OCP removed. Chemical treatment is considered to be the most suitable method when discharging municipal sewage to sensitive marine receiving waters and should be categorized as secondary treatment, like biological treatment.

It is important when ecological aspects are considered, for instance in terms of energy consumption, that all elements that contribute to the total consumption of energy must be included. For instance, a compact treatment plant, like a chemical one, may require less energy for concrete, while it requires more energy for chemicals. The problem is evaluated in two different ways: (i) an evaluation of energy consumption based on the major energy-associated elements: chemicals, air and biogas; and (ii) an analysis of all ecological aspects based on a model for evaluating the ecological value of the products and processes.
Studies of the dynamic behaviour of a primary sedimentation tank
Authors: Lindeborg Claës , Wiberg Niklas , Seyf Alexander
Published: May 2018

This study concerns the dynamic behaviour of a primary sedimentation tank in a municipal WWTP. It is a part of the effort to estimate the varying biological load on the activated sludge stage under different operating conditions. The primary settlers have been investigated with several methods: (i) cross sectional sampling of suspended solids; (ii) tracer tests with lithium-solution; (iii) finite element method (FEM); (iv) flow measurement with a turbine-type sensor; and (v) cross-sectional flow measurement with a cross-bar metering device. The choice of measurement positions, the number of samples and the methods selected for analyses have all been guided by the ambition to avoid erroneous conclusions due to odd single measurement data. The study demonstrates how modern graphical computer methods like Finite Element Method and MATLAB Toolboxes can be used to increase our understanding of the settler.
The effect of chemical bulking control on biological nutrient removal in a full scale activated sludge plant
Authors: Saayman G. B. , Schutte C. F. , van Leeuwen J.
Published: May 2018

The use of chemicals for sludge bulking control has a direct effect on the biological nutrient removal processes in activated sludge systems designed for this purpose. Chlorine has been used on full scale but information on the use of ozone and hydrogen peroxide is limited to pilot scale tests.

The objective of this study was to investigate the effects of chlorine, ozone and hydrogen peroxide on nutrient removal processes when used on a continuous basis for bulking control in a full scale biological nutrient removal activated sludge plant. The full scale studies were conducted over a period of 39 months at the Daspoort sewage works of the City Council of Pretoria.

The results indicate that at low dosages the oxidants have limited effects on the nutrient removal processes but at higher levels chlorine had a detrimental effect resulting in the phosphate limit of 1 mg P.1−1 being exceeded.

It is concluded that chlorine is the most effective of the three oxidants for bulking control, but that it should be used with caution in order not to upset the biological phosphate removal processes. Ozone at low levels had a small but consistent positive effect on bulking control as well as on nutrient removal. The effects of hydrogen peroxide were very small except at high dosages.
Aeration investigation of biological aerated filters using off-gas analysis
Authors: Harris S. L. , Stephenson T. , Pearce P.
Published: May 2018

The bulk of the operating costs for biological aerated filters are associated with aeration, accordingly, any efficiency improvements which may be made to this aspect of the process could result in significant savings operationally. This study used off-gas analysis to determine the effects on oxygen transfer efficiency of variations to the air flow and substrate loading rates to two pilot scale granular media biological aerated filters (BAFs) treating primary settled sewage. The columns provided a good representation of full scale units, providing up to 99% ammonia reduction. Incremental increases in the mass transfer coefficient (KLa) were observed, as reported elsewhere and attributed to direct interfacial transfer between the bubbles and the biofilm. The OTE varied with flow rate but was far more sensitive at the lower end of the experimental range, rising sharply for air flow rates below 5 to 10 m/h. Increasing the organic loading rate also improved the OTE. The use of fine bubble diffusers did not improve the OTE, however, probably as a result of the packing media used.
Nitrite accumulation in submerged biofilters - combined effects
Authors: Fdz-Polanco F. , Villaverde S. , Garcia P. A.
Published: May 2018

The combined effect of temperature, pH and ammonium concentration over the nitrite accumulation phenomena in situations of free ammonia inhibition, their effect over the ammonia and nitrite oxidizer microorganiisms influence over the nitrification, have been studied in an Up-flow Biological Aerated Filter (UBAF).

The free ammonia inhibition effect highly depends on the values of pH, temperature and ammonium concentration. For the same specific free ammonia concentration different values of temperature, pH and ammonium concentration bring about different nitrite accumulations. In conditions of no free ammonia inhibition and low values of temperature and pH, high ammonium concentrations bring about a higher relative activity of ammonia oxidizer microorganisms of the filter increases the nitratation efficiency in zones close to the outlet and will favour the nitrite accumulation in situations of free ammonia inhibition.
Sustainable sewage treatment plants - application of nanofiltration and ultrafiltration to a pressurized bioreactor
Authors: Krauth Kh.
Published: May 2018

Based on earlier studies and experiences the Institute of Sanitary Engineering, Water Quality and Waste Management at the University of Stuttgart has developed a new technology to purify wastewater to a quality suitable for reuse as industrial water. This technology consists of a pressurized bioreactor under 3 bar with an ultrafiltration unit for sludge retention coupled with a nanofiltration unit. The concentrate retained in the nanofiltration is fed back to the bioreactor resulting in an enhanced biodegradability and a better quality of the effluent. The flux through the ultrafiltration membrane ranged from 100 to 200 l/(m3h); that through the nanofiltration membrane was around 0.05 l/(m3h). While attaining a very high biomass concentration (20 to 40 kg MLVSS/m3) in the bioreactor the excess sludge production is remarkably small with 0.7 to 1.0% of the influent COD.
Application of a simple empirical fixed-film model to the fluidized biofilter process
Authors: Chung Paul-Gene , Kwak Dong-Heui , Kim Youngchul
Published: May 2018

A biofilter process using a spongy media was operated to treat an artificial raw water which has similar characteristics to inflow for the use of public water supply. The growth of biofilm and the increase of specific gravity lowered the expansion rate of spongy media. The fluidized biofilter process was likely to behave as a fixed film type of reactors, but the excessive headloss, clogging, and channeling problems, which are known as a major concern in the operation of fixed film process, were not observed throughout the entire operation period. The operational data were applied to an empirical fixed film model proposed by Eckenfelder. This model was found to be very useful for predicting performance of the biofilter process. The evaluated form of model equation obtained from these studies was Se=S0exp[−0.089(L/v0.46). Also, the analysis of pilot plant operational data in the field shows that the performance of the pilot plant corresponds well with the predicted value.
Performance analysis of the full-scale egg-shaped digester in treating sewage sludge of high concentration
Authors: Li Y. Y. , Noike T. , Katsumata K. , Koubayashi H.
Published: May 2018

A full-scale investigation was conducted to evaluate the performance of an egg-shaped digestion tank in treating sewage sludge of high concentration. The experiment was continued over a half year at 36°C, and the influent concentration of sewage sludge to the digester was controlled at about 50 g/L (5%) with a centrifugal thickener. The total solids (TS) in the raw sludge contained 20% inorganic matters and 80% volatile solids (VS), which were further composed of carbohydrates (45.4%), proteins (34.8%), lipids (13.1%) and volatile fatty acids (about 9.2%). At the mesophilic egg-shaped digestion tank with the retention time of 30 days, the removal efficiencies of carbohydrates, lipids, proteins and VFA reached 75%, 50.6%, 46% and 100%, respectively, and the reduction efficiencies of TS, VS, SS, VSS were 44.2%, 56.6%, 46.6% and 61.9%, respectively. The result of gas production showed that 1 m3 of influent concentrated sludge could produce 21 m3 of digestion gas containing 61% of methane. Of all influent sludge COD, about 57% was converted to methane and as a result, 1 kg of influent VS produced 0.531m3 digestion gas. There was no noticeable scum and foaming problems in the egg-shaped digesters, although they have been continuously operated for over ten years. The metabolic activities and populations of individual trophic groups of bacteria in the digester were also elucidated in this study.
Sludge chemical composition changes under uni-directional freezing
Authors: Huang W. T. , Chang I. L. , Lee D. J. , Hong S. G.
Published: May 2018

The chemical compositions changes for waste activated sludge at different freezing speeds were analyzed via FTIR spectra. With a high speed of freezing, the chemical compositions are little influenced by the action of ice formation, which with a low speed of freezing, the chemical compositions are largely affected. The prerequisite for sufficient dewaterability improvement is found as the global floc migration owing to the ice front formation, which releases some ECPs (basically cellulose) from the sludge and after the resulting cake structure ultimately.
Comparison study on portable wind tunnel system and isolation chamber for determination of VOCs from areal sources
Authors: Jiang Kaiyun , Kaye Ralph
Published: May 2018

Many environmental monitoring programmes require the determination of volatile organic compounds (VOCs) emitted from large areal sources including liquid surfaces. A study was carried out to compare existing sampling techniques. Both the isolation chamber method (static technique) and the wind tunnel method (dynamic technique) were examined. A review of the mechanisms suggested that static techniques would not be appropriate for determining emissions from liquid surfaces which result from gas phase controlled volatilisation processes. A portable wind tunnel developed at the University of New South Wales and an isolation chamber built to USEPA specification were used in an experimental study of emissions from aqueous liquid surfaces. An acetone solution was chosen to represent gas phase controlled volatilisation processes. Toluene and methyl ethyl ketone in aqueous solution were chosen, respectively to investigate (1) liquid phase controlled volatilisation processes, and (2) combined gas and liquid phase controlled volatilisation processes. It was found that the use of the isolation chamber method resulted in different degrees of underestimation of the emission rates for the above three compounds. The wind tunnel method is suitable for sampling all VOC emissions from areal sources.
Integrated water quality management
Authors: Novotny Vladimir
Published: May 2018

Components of the integrated water quality management and planning process are described. The process is initiated by the Use Attainability Analysis (UAA) in which the ambient water quality-use based standards are justified and/or modified for the water body for which water quality management is being considered. The UAA has three components: (1) Water Body Assessment, (2) The Total Maximal Daily Load (TMDL) Process, and (3) Socio-economic Analysis. The first component identifies whether the receiving water body and watershed have a water quality problem and, subsequently, separates such water bodies into those where the water quality problem is caused by natural loads or conditions and those where man-made pollution inputs cause unacceptable water quality deterioration. The TMDL process separates water bodies into those for which water quality goals can be achieved by present and future mandated abatement of point and nonpoint sources (effluent limited water bodies) and those mandated abatement will not achieve the water quality goals (water quality limited water bodies). Extensive water quality management and expenditure of public funds is justified for the latter cases. Watersheds and receiving water bodies which are adversely affected predominantly by nonpoint (unregulated) discharges are declared as impaired and should be managed. Both reduction of waste discharges and enhancement of waste assimilative capacity-habitat restoration of the receiving water body should be considered in management of water quality limited receiving waterbodies.
Nonpoint sources of pollution in the Morava River basin
Authors: Beránková D. , Ungerman J.
Published: May 2018

The diversity of natural conditions as well as the industrial and agricultural character of the landscape are responsible for changes influencing the share of point and nonpoint sources of pollution in the Morava River basin. Nonpoint sources of pollution were specified on the basis of data on agriculture, forestry, erosion, suspended solids, water quality parameters, mass flow of nutrients and atmospheric deposition. The relationship between concentrations of nitrates and application rates of mineral nitrogen fertilizers in the lower part of the Morava River basin was significant. In the longitudinal profile of the Morava River concentrations of mineral nitrogen and total phosphorus were specified and mass flow calculated by characteristic discharge. Changes of political system in 1989 in the Czech Republic initiated dynamic development of the state agricultural policy with consequences for the intensity of nonpoint pollution. Mainly in the field of plant and animal production some influences were evidently reduced. Consumption of industrial fertilizers was minimized to 13 of the former level and livestock population was also significantly decreased. Although privatization in agriculture is practicaly finished, there are not many positive changes in the field of large-area land use and structure of plots. The process of soil erosion still causes damages of land and pollution of surface waters.
Water quality changes in a small plain agricultural catchment area
Authors: Belic S. Sima , Belic Andjelka V.
Published: May 2018

Anthropogenic activities in a catchment area influence in a most direct way the surface water quality. Detailed studies of the factors of all production processes in the catchment enable establishing the degree of their possible individual participation in the pollution of that region, which is the first step in finding out the way of its appropriate protection. Such a study we carried out on the example of the Krivaja catchment area (the river Krivaja and the reservoir Zobnatica), in the north of Yugoslavia during the 1980–1992 period. The analysis encompassed natural characteristics of the soil and production activities in the region, which is characterized by numerous point and nonpoint pollution sources. Surface water quality was assessed on the basis of their physical and chemical properties. Besides, inorganic forms of nutrients, first of all nitrogen, were also analyzed. The results indicate deterioration of surface water quality in the catchment during the investigated period. In view of the fact that the state of point pollution sources did not change during the investigation, it is quite clear that nonpoint pollution, having mainly the origin in agricultural production, were the main cause of deterioration of surface water quality.
Constructed wetlands in the Czech Republic — survey of the research and practical use
Authors: Žáková Zdeñka
Published: May 2018

In the Czech Republic numerous constructed wetlands were designed and built for point and non-point pollution abatement in recent years. The contribution brings a concise survey of the progress made in the research and practical application of these systems. Appx. 39 constructed wetlands were in operation or under construction in 1995. Their treatment effect and function have been monitored and evaluated. The greatest constraint is a lack of practical experience. To prevent unnecessary mistakes it is desirable to use the experience from countries with a longer tradition in construction and operation of such systems. Nevertheless, the research results, which have been obtained in the Czech Republic could be also useful for designers in other countries.
Use of artificial wetland for the treatment of surface and wastewater
Authors: Šálek Jan , Marcián František , Elazizy Iman
Published: May 2018

Vegetative root zone methods are based on self-purifying processes that take place in the soil, wetland and vegetation containing water media. Our studies are concentrated on the course of puryfying in relation with the length of the filtration bed and on the progress of eliminating the ammoniacal pollution. The research proved that the essential part of the puryfying process takes place within the inlet zone (Figs 1 and 2). The decomposition of ammonia proceeds very slowly. The process of nitrification is affected by the lack of oxygen in the filtration media. To improve the effectiveness of vegetative root zone methods we suggest specific steps: an adjustment of the inlet zone, a system of cascades, a water level pulsation system and combinations of different types and arrangements of vegetative root zones.
Microbiological pollution in the Canadian upper great lakes connecting channels
Authors: Marsalek J. , Dutka B. J. , McCorquodale A. J. , Tsanis I. K.
Published: May 2018

The faecal microbiological pollution was investigated in the Upper Great Lakes Connecting Channels by focusing on the near-shore zones of the St. Marys River in Sault Ste. Marie, the St. Clair River in Sarnia and the Detroit River in Windsor (Ontario). Water samples from these rivers and various sources of faecal pollution were analyzed for the indicator organismrecommended by Health and Welfare Canada --Escherichia coli . The observed bacterial counts were characterized by probabilistic distributions and assessed for compliance with the Ontario recreational water quality guideline (100 E. coli/100 mL). The degree and extent of microbiological pollution were related to dry weather sources (malfunctioning sewer systems) and wet weather discharges, particularly combined sewer overflows (CSOs). Excellent water quality was found in Sault Ste. Marie (no CSOs), but poor quality was found in the St. Clair River along a relatively short Sarnia waterfront (5 CSOs) and in a long stretch of the Detroit River in Windsor (25 CSOs). Among the remedial measures, the highest priorities were assigned to both dry and wet weather source controls. Local improvements in microbiological water quality can be achieved by manipulating bacteria transport in rivers - preventing influx of contaminated waters to the areas used for water-based recreation.
Improved modelling of suspended solids discharge from asphalt surface during storm event
Authors: Tomanovic Ana , Maksimovic Cedo
Published: May 2018

Measurements, aiming at the investigation of pollution wash-off from a single asphalt area which is drained into one gullypot, have been carried out at two similar experimental urban catchments: in Lund, Sweden, and in Belgrade, Yugoslavia. At both sites the continuous measurements of rainfall intensity, storm runoff and four water quality characteristics (suspended solids, pH-factor, conductivity and temperature) were carried out, using a similar method and similar equipment. To reach the required level of process dynamics, the data were recorded at short time intervals (10 sec) during a storm event. Statistical analysis of reliably measured data showed the main factor that affect surface solids build-up and wash-off. Based on it, a new physically based mathematical model of suspended solids wash-off has been developed. The model was calibrated and verified for both catchments. The brief description of the measurements, statistical analysis of recorded data, and the model, is presented in the paper.
Improving settling dynamics of activated sludge by adding fine talc powder
Authors: Rasmussen Michael R. , Larsen Torben , Clauss Frédéric
Published: May 2018

The effect of adding varying mixtures of talc and chlorite powder to activated sludge in order to improve the settling characteristic has been studied. The powder is found to improve the settling velocity of the sludge, strictly by increasing the average density of the sludge floc aggregate. The settling velocity was measured with a recirculated settling column under different concentrations and turbulence levels.

Numerical simulation of a secondary settling tank indicates that adding fine powder will improve the overall performance considerably.
Parameter determination and model fitting - two approaches for modelling processes in wastewater treatment plants
Authors: Liebeskind M. , Schäpers D. , Bornemann C. , Brands E. , Freund M. , Rolfs T.
Published: May 2018

This study shows results from four lab-scale wastewater treatment plants, which were installed behind the grit chamber of a municipal wastewater treatment plant. The lab-scale plants were fed with original wastewater, diluted with water from the final clarifier to give a constant concentration of 300 mg /l COD. The activated sludges were adapted to different sludge ages from 1.88 to 24.0 days. The steady-state behaviour was measured along with the decay rate, the yield coefficient, the oxygen demand, the C- and N- balance and the DNA of biomass XBH. The steady-state equations of Marais and Ekama were used to calculate the masses of active biomass, endogenous residue and inert VSS in the reactors. Measured parameter values were different for all sludge ages. They gave similar values for inert particulate VSS (Xi) of 7 to 9%. Parameter values of the IAWQ-Model No. 1 together with Xi-fitting could also be used to solve the equations, but in this case different Xi values for the different reactors had to be used for the same wastewater.
Prediction of flow rates and stability in large scale airlift reactors
Authors: Hinks John W. , Cawte Howard , Sanders David A. , Hudson Adam , Dockree Christopher N.
Published: May 2018

Large-scale High Recirculation Airlift Reactors have been used to treat biodegradable waste waters since the mid nineteen seventies. The system is particularly attractive for situations where the land to locate wastewater works is restricted. Little is known, however, about the fluid dynamics of the gas-liquid mixture flowing around the reactor. This makes the determination of air injection rates difficult if effluent quality and dynamic stability are to be maintained. When the air injected is not sufficient to maintain stable operation the reactor contents may reverse violently resulting in down time, failure to achieve target discharge quality and possible damage to the reactor itself. As a result many reactor installations operate at air injection rates above those necessary for the biological processes. The extra air injected results in higher capital and process costs. This paper considers the effect of air injection rates on the hydrodynamic stability of Airlift Reactors and a two-phase model is proposed to predict stable operation at a reduced air injection rate. Results are presented which show the effect of reactor design on stability.
Seasonal change of microbial population and activities in a building wastewater reuse system using a membrane separation activated sludge process
Authors: Zhang Boran , Yamamoto Kazuo
Published: May 2018

The seasonal change of microbial population and activities in an existing building wastewater reuse system using membrane separation activated sludge process (MSAS) were investigated, and they were also compared with those in a municipal wastewater treatment plant using conventional activated sludge (CAS) process. The operating conditions of MSAS process, such as sludge retention time, biomass concentration, the ratio of food to microorganism (F/M) and so on, are much different from CAS process. Acridine orange direct count (AODC), plate count of heterotrophic bacteria (HPC), MPN of ammonia oxidizing bacteria (MPNa) and microfauna were measured. In the MSAS process, the AODC and MPNa/HPC were high, but the HPC/AODC was low. This means that the MSAS process tended to maintain a high ratio of ammonia oxidizing bacteria and also tended to keep dead cells. The microfauna in the MSAS process was unstable and changed a lot seasonally, but it wouldn't affect the treatment efficiency. Moreover, the specific activities of nitrification, denitrification and organic removal fluctuated largely and seasonally, and were lower than those in the CAS process. However, their volumetric activities were higher than those in the CAS process because the MSAS process could maintain very high biomass concentration. Dehydrogenase activity, ATP content and oxygen utilization rate were measured to estimate the bacterial activities and viability. The OUR and ATP has different relationship in the both processes. Polysaccharides were also determined as metabolic products.
Surface charge and extracellular polymer of sludge in the anaerobic degradation process
Authors: Jia X. S. , Fang Herbert H. P. , Furumai H.
Published: May 2018

Changes of surface charge and extracellular polymer (ECP) content were investigated in batch experiments for three anaerobic sludges, each of which had been enriched at 35°C and pH 639-7.3 for more than 40 batches using propionate, butyrate and glucose, individually, as the sole substrate. Results showed that both ECP and the negative surface charge were dependent on the growth phase of microorganisms. They increased at the beginning of all batches when the microorganisms were in the prolific-growth phase, having high substrate concentration and food-to-microorganisms ratio. Both later gradually returned to their initial levels when the microorganisms were in the declined-growth phase, as the substrate became depleted. The negative surface charge increased linearly with the total-ECP content in all series with slopes of 0.0187, 0.0212 and 0.0157 meq/mg-total-ECP for sludge degrading propionate, butyrate and glucose, respectively. The change of surface charge for the first two sludges was mainly due to the increase of proteinaceous fraction of ECP; but, for glucose-degrading sludge, that could be due to the increases of both proteinaceous and carbohydrate fractions of ECP. The negative-charged nature of anaerobic sludge implies that cations should be able to promote granulation of anaerobic sludge.
Propionic acid accumulation and controlling factors in anaerobic treatment of carbohydrate: effects of H2 and pH
Authors: Inanc B. , Matsui S. , Ide S.
Published: May 2018

Propionic acid is believed to be the most retardative volatile acid appearing in the anaerobic treatment process. However, the mechanisms by which propionic acid accumulates have not been well understood. Several studies and thermodynamical calculations suggest that an increased hydrogen partial pressure in the system is the cause for the accumulation of propionic acid. However, recent findings by the authors and a few other researchers indicated that artificially elevated or reduced hydrogen partial pressure had no discernible effect. Hence, the consensus on the inhibitory effects of hydrogen is lacking. This study was done to test the hypothesis that propionic acid accumulation during start-up or overloading is not caused by high hydrogen partial pressure, rather it is a result of a shift in the dominant species of acidogenic populations. Hydrogen partial pressure and pH were chosen as controlled system parameters. The type of the reactors used was completely stirred tank reactor (CSTR). The results have indicated that hydrogen partial pressure has no discernible effect while low pH around 5 is effective for preventing propionic acid production from decomposition of glucose.
Coupled anaerobic/aerobic treatment of high-sulfate wastewater with sulfate reduction and biological sulfide oxidation
Authors: Fox Peter , Venkatasubbiah Venkatraghavan
Published: May 2018

A pharmaceutical wastewater with a chemical oxygen demand (COD) concentration of 40,000 mg/l and a sulfate concentration of 5,000 mg/l was treated in a anaerobic baffled reactor. Treatment of the wastewater at 10% dilution was effective but at higher influent concentrations sulfide inhibition reduced efficacy of both COD conversion and sulfate conversion. A recycle line with an attached-film biological reactor was inserted into the anaerobic baffled reactor to facilitate biological sulfide oxidation. Recycling anaerobic effluent through a sulfide oxidizing biological system reduced inhibition in the anaerobic reactor by both reducing inhibitory sulfide concentrations within the reactor and by diluting the influent. The major product of the biological oxidation of sulfide by a Thiobacillus species appeared to be elemental sulfur. At an influent wastewater concentration of 40% and a HRT of 1 day, COD removal efficiencies were greater than 50% and the conversion of influent sulfate was greater than 95% with effluent sulfide concentrations of less than 20 mg/l. The major product observed from degradation of isopropyl acetate was acetic acid. Coupled anaerobic/aerobic provided removal of sulfur from the wastewater stream and helped to stabilize the pH in the reactor system.
Mechanism of anaerobic biological activated carbon process examined by using stable isotope
Authors: Saito Toshiaki , Hanaki Keisuke , Matsuo Tomonori
Published: May 2018

This research focused on the mechanism of substrate transfer in anaerobic biological activated carbon (BAC) process. There are two possible pathways of substrate supply to the attached bacteria in BAC process. One is the pathway from the bulk liquid and the other is the pathway directly from activated carbon. Stable carbon isotope was used to determine them. The isotope ratio of produced methane was between isotope ratios in bulk liquid and inside activated carbon. This means that activated carbon can supply adsorbed substances directly to the attached bacteria without releasing them into bulk liquid.
Comparison of start-up of an upflow anaerobic sludge blanket reactor and a polyurethane carrier reactor
Authors: Gijzen Huub J. , Kansiime Frank
Published: May 2018

The start-up and performance of an Upflow Anaerobic Sludge Blanket (UASB) reactor and a Polyurethane Carrier Reactor (PCR) was investigated under similar operational conditions. The presence of polyurethane cubes as a carrier material in the PCR resulted in fast reactor start-up due to quick immobilization of methanogenic associations. Start-up of the UASB was slower compared to the PCR, which was mainly reflected in a lower biogas production and acetate degradation efficiency. However, when enough biomass had accumulated in the UASB reactor after 15 weeks of operation, the performance of the two reactors was almost the same in terms of biogas production and volatile fatty acids degradation. Efficient VFA degradation (about 90%) and biogas production (5.2 l/l.d) were achieved at an organic loading rate of 13.2 g/l.d) and HRT of 6 h. When hydraulic retention time was subsequently reduced from 6 to 2 h, the performance of the UASB reactor was better than that of the PCR. The inferior performance of the PCR may have been attributed to channelling of the influent in the reactor at high liquid flow rate.
Antifouling strategies in technical systems – a short review
Authors: Flemming Hans-Curt , Griebe Thomas , Schaule Gabriela
Published: May 2018

The undesired deposition of microorganisms and the formation of biofilms is called “biofouling”. The consequences of biofouling for water purification, transport and storage are considerable both economically and ecologically. Countermeasures against biofouling include three steps: i) detection, ii) sanitization and iii) prevention of biofouling. The detection has to refer to surfaces. Cell counts in water water samples do not reflect the location or the extent of biofilms. Biocides display only limited value in terms of removal of biofouling layers. First, biofilm organisms are protected against biocides and tolerate 10 to 1000-fold higher concentrations. Second, water systems usually cannot be kept sterile. Thus, dead biofilms provide nutrients and suitable surfaces for further growth of cells imported with the raw water. Cleaning of a system is an integral part of sanitization and even more important than disinfection. It has to be based on a designed strategy. Efficiency control is mandatory and has to occur on representative surfaces. The prevention of biofouling is frequently achieved by continuously dosage of biocides. However, this is only possible with suitable raw waters and many failures are reported. Chlorine is still the biocide most frequently used. Concerns about effectivity and environmental protection give rise to other strategies. “Good housekeeping” is recommended as a general countermeasure. It includes frequent cleaning, efficiency control, biofilm monitoring, limitation of nutrients, maintenance of high shear forces, and a cleaning-friendly design. “Biofouling” is operationally defined and refers to biofilm development which exceeds a given “threshold of interference”. Keeping biofilm development below that threshold offers a new strategy, which considers biofouling as a biofilm reactor in the wrong place. Nutrient limitation is an option to curb biofilm development in sensitive areas. If large colonization areas are offered elsewhere than in the system to be protected, biofilms will develop there, sequestering dissolved nutrients and turning them into immobilized biomass in a place where it can be handled more easily than, e.g., inside a heat exchanger or a membrane module. Combined with effective monitoring techniques, a biocide-free antifouling-strategy can be realized.
Association of PAHs, PCBs, 137Cs, and 210Pb with clay, silt, and organic carbon in sediments
Authors: Razak I. A. Ab , Li A. , Christensen E. R.
Published: May 2018

The association of PAHs, PCBs, 137Cs, and 210Pb with various components of sediments, i.e., clay, silt, and organic carbon is determined. The work is based on the data from 6 deep (2-3 m) vibra cores collected from a stretch of the Kinnickinnic River running through Milwaukee, Wisconsin, USA. Priority organics were determined by extraction, clean-up, and gas chromatography with either a mass selective (PAHs) or an electron capture (PCBs) detector. Loss on ignition, porosity, and radionuclide analyses were carried out by standard techniques, and the association of the variables was investigated by principal component analysis. The results indicate that PAHs are associated with organic carbon, porosity and silt. Both 137Cs and PCBs are associated with clay but not with organic carbon. 210Pb is mainly associated with the organic fraction, but covaries also to some extent with clay.
Remobilization of zinc from Ell-Ren river sediment fractions affected by EDTA, DTPA and EGTA
Authors: Yu Kuang-Chung , Ho Shien-Tsong , Tsai Li-Jyur , Chang Jing-Song , Lee Suen-Zone
Published: May 2018

Ell-Ren river, enriched with heavy metals, is one of the heavily polluted rivers in Taiwan. Batch tests were used to illustrate the remobilization abilities of three chelating agents (ethylene-diaminetetraacetic acid, EDTA; diethylenetriamine pentaacetic acid, DTPA; ethylene glycol-bis (ú]-amino ethyl ether)-N-N′-tetraacetic acid, EGTA) on zinc, as well as to realize the variation and transformation of zinc contents in sediment binding fractions (exchangeable, bound to carbonates, bound to Fe/Mn oxides and bound to organics) as affected by chelating agents and pH. It has been found that DTPA had higher remobilization effect on zinc than EDTA. EGTA could release only little amount (5%) of zinc as its dosage was up to 500 mg/L. At neutral pH, both DTPA and EDTA had higher remobilization effects than at acidic or alkaline conditions. Remobilizations of zinc from sediment affected by both DTPA and EDTA were mainly released from “bound to carbonates” fraction. Meanwhile, the zinc content of “bound to organics” fraction also increased with increasing EDTA dosage, which could be attributed to the transformation from “bound to carbonates” and “bound to Fe/Mn oxides” fractions.
Pesticide contamination of water resources: a case study - the rivers in the Paris region
Authors: Tisseau M. A. , Fauchon N. , Cavard J. , Vandevelde T.
Published: May 2018

For a number of years, the Compagnie Générale des Eaux has been studying pesticide contamination of surface water in order to better understand the origins and the main transfer mechanisms of these pollutants into water resources. Sampling campaigns are being carried out on the three main rivers of the Paris area to monitor a number of products from the triazine and urea families.

This monitoring has confirmed the extension of agricultural non-point source pollution. The products being sought are present in the three rivers and, in most cases, in significant concentrations.

Atrazine is the most important contaminant. Measured concentrations exceed the value of 100 ng/l most of the time, thus proving that the aquifers drained by the three rivers are contaminated. For a period of several months every year, concentrations approaching 1000 ng/l are observed in all the catchment areas being studied. These are the result of rapid transfers of atrazine in run-off water.

This surface run-off transfer mode also seems to be applicable to the ureas found in surface water, especially during the periods when the products are used to treat crops.

These works underline the complexity of agricultural non-point source pollution phenomena. They permit the identification of the predominant mechanisms operating in the transfer of the products. This is the first step towards setting up preventive measures and developing pollution forecasting tools.
Giardia and its implications for sludge disposal
Authors: Hu C. J. , Gibbs R. A. , Mort N. R. , Hofstede H. T. , Ho G. E. , Unkovich I.
Published: May 2018

The beneficial use of wastewater sludge is to some extent restricted by the presence of human pathogens. Following a risk assessment and monitoring programme it was found that the pathogen which posed the highest potential risk of infection in treated sludge was Giardia. Giardia cyst concentrations were found to be approximately 900/g wet weight of sludge following anaerobic digestion, although not all of the cysts may have been infective. In further studies three methods of wastewater sludge disposal or treatment were investigated. Anaerobically digested and mechanically dewatered sludge was stored for up to 60 weeks, incorporated into sandy soil and composted on a laboratory scale. Giardia cysts remained at levels which could be considered a public health concern after storage of sludge for over one year and after composting. However, cysts appeared to be destroyed within 12 weeks following soil amendment. The implications of the presence of Giardia for sludge disposal are discussed.
An assessment of toxic metals content in the marine sediments of the Shuaiba Industrial Area, Kuwait, after the oil spill during the Gulf War
Authors: Al-Muzaini S. , Jacob P. G.
Published: May 2018

A field study was carried out involving seven fixed sampling stations. The sampling locations were selected to cover the distribution of pollutants in the Shuaiba Industrial Area (SIA), which was contaminated with oil released from oil wells and broken pipelines and with a vast amount of burnt and unburnt crude oil from the burning and gushing oil wells. The samples were collected biweekly between July 1993 and July 1994. The concentrations of V, Ni, Cr, Cd and Pb were determined and compared with the previously collected baseline data to assess the degree of environmental damage caused due to the oil spills during the Gulf war. The average concentrations (mg/kg) of various elements in the marine sediment were 17.3 for V, 30.8 for Ni, 55.5 for Cr, 0.02 for Cd and 1.95 for Pb. Our results show that even after the heavy spillage of oil, associated metal concentrations were not very high compared with previously reported base line values.
The role of fulvic acids in phosphorus sorption and release from mineral particles
Authors: Kastelan-Macan Marija , Petrovic Mira
Published: May 2018

The competitive sorption of phosphates and marine fulvic acids on mineral particles (sand, calcite, bentonite and hematite) has been studied under simulated estuarine conditions. Afterwards, the release and desorption of bound phosphates by solutions containing dissolved fulvic acids was determined. It was found out that due to the favorable sorption of fulvic acids onto minerals studied binding of phosphate was significantly decreased. Desorption experiments showed that fulvic acids, present at high concentration level, similar to that in interstitial water of an oxygenated sediment, increase phosphate desorption by 10-20%.
Groundwater protection against pollution by heavy metals at waste disposal sites
Authors: Sergeev V. I. , Shimko T. G. , Kuleshova M. L. , Maximovich N. G.
Published: May 2018

The usefulness of subsoil layer as geochemical barrier against migration of heavy metals from waste disposal sites is assessed. Field and laboratory studies and theoretical calculation are reported that enable the forecasting of pollutant migration through different subsoils and the length of time that such soils will function on geochemical barriers.
Current water recycling initiatives in Australia: scenarios for the 21st century
Authors: Anderson John M.
Published: May 2018

Australia is a relatively dry continent with an average runoff of 50 mm per year. The use of water resources in some river basins is approaching the limits of sustainability. Some adverse environmental impacts have been observed resulting from water diversions and from both reclaimed water and stormwater discharges. The paper describes current water recycling initiatives in Australia. These include: beneficial reuse of reclaimed water for urban, residential, industrial and agricultural purposes; recycling of greywater and stormwater; advanced treatment using membrane technology; and water efficient urban design. Some possible water recycling scenarios for Australia in the 21st century are examined. The implications of these scenarios are discussed.
Assessment of tertiary treatment technology for water reclamation in San Francisco, California
Authors: Jolis Domènec , Hirano Robin A. , Pitt Paul A. , Müller Ashley , Mamais Daniel
Published: May 2018

Tertiary treatment processes were tested to demonstrate their ability to produce effluents that meet the most stringent standards in the California Wastewater Reclamation Criteria. The processes studied were in-line, granular media filtration and microfiltration for particulate removal, and chlorination and UV light for disinfection. In-line filtration met CWRC turbidity requirements, although filter performance was dependent on feed water turbidity, and alum and polymer doses. Microfiltration produced an effluent virtually free of suspended solids and coliforms, and a 1.9-log removal of MS2 phage. This decreased the level of microorganism inactivation required of the UV system. MS2 phage sensitivity to UV light was not constant, which may question its suitability as an indicator organism to assess virus inactivation. Minimum chlorine Ct value of 340 mg.min/l, and UV dose of 800 J/m2 were identified for in-line filtration effluent, while a dose of 450 J/m2 was sufficient for microfiltration effluent. In-line filtration followed by UV disinfection is less costly for water reclamation than any other combination of treatment units tested, and, therefore, these processes were selected for a 53.000 m3/d water reclamation plant in San Francisco.