bluuebunny/crossref_metadata_2025 huggingface dataset:
Intensive Treatment by Electrocoagulation - Flotation - Tangential Flow Microfiltration in Areas of High Seasonal Population
Authors: Pouet M.-F. , Persin F. , Rumeau M.
Published: May 2018

In this paper, the authors present an electrochemical treatment associated to flotation. They want to show that microfiltration can be used in waste water treatment. For this, they have studied the coupling electrocoagulation - flotation, and they have studied the influence of this association on the flux of permeate in microfiltration. The conclusion of this work is that the combination of the three processes is a possible alternative to an extensive treatment in coastal areas. Moreover it is a compact process with which they have obtained a water of a quality suitable for irrigation.
The Role and Control of Nutrients in Chesapeake Bay
Authors: D'Elia C. F. , Harding L. W. , Leffler M. , Mackiernan G. B.
Published: May 2018

The results of a workshop conducted by scientists who participated in a 6-year, multidisciplinary study of hypoxia on the Chesapeake Bay suggest that although an exact quantification of the management target for nutrient reduction is difficult to make, at least a 40% reduction in total inputs is needed to reduce hypoxia and restore a trophic structure that maximizes mctazoan food chains and minimizes microbial processes. Nutrient enrichment contributes to the formation of hypoxia in the Bay's main stem and lower tributaries by over-stimulating the growth of phytoplankton that ultimately decompose and consume oxygen in deep water. Enrichment effects can be traced in the sedimentary record to colonial times, but are not as easily discerned in water quality parameters from monitoring in the last 50 years. Initially, agricultural land-use practices that decreased forest coverage and increased erosion accounted for most nutrient inputs, but in this century, point and non-point sources, that result from demographic change and impact in the watershed, predominate.
Advances in Agricultural Nutrient Runoff Controls
Authors: Baker D. E. , Senft J. P.
Published: May 2018

Progress has been relatively slow for reducing nitrate and phosphate losses from the Susquehanna River Watershed to the Chesapeake Bay. It was initially recognized that farmers on the well drained limestone soils of Southeastern Pennsylvania, especially Lancaster County, were land applying excessive N and P in the form of manures and commercial fertilizers. The objective of the authors has been to define “the greatest agricultural production experiment of the century”. The farmers combined manures and commercial fertilizers on these lands over a period of 20 years and experienced a two fold increase in yields of different crops. While it has been relatively easy to convince the farmers to stop applying commercial fertilizers, reductions in nutrient loadings via a reduction in animal numbers per acre or per farm has not occurred. The authors and others have not proposed a reduction in dairy cows per acre because such reductions would not allow these producers to remain in business, and if we can't explain how these farmers were so successful in increasing production, we have little justification for asking that they be denied the technology they have developed. The data summarized below serve to justify the need for a program to increase cellulose and lignin carbon as bedding or direct application to land to increase the water holding capacities of the soils and immobilize an acceptable excess amount of manure N applied.
Hazardous Waste Management Approaches in Canada
Authors: Hrudey S. E.
Published: May 2018

Canada's political, economic and geographic make-up have influenced the approaches to hazardous waste management. Split jurisdiction between the federal and provincial governments on environmental issues has made consensus decisions expedient. These consensus approaches combined with some preference for public sector ownership of hazardous waste treatment and disposal facilities distinguish the Canadian system from the hazardous waste regulatory regime in the United States. Because many of the Canadian hazardous waste management guidelines have been recently developed, they may reflect the benefit of learning from experiences elsewhere, both positive and negative.
Biological or Chemico-Physical Landfill Leachate Purification - An Alternative or a Useful Combination
Authors: Kettern J. T.
Published: May 2018

The passing of the “General Administrative Regulations on Minimum Requirements for the Discharge of Sewage to Waters”, and particularly Annex 51, has far-reaching implications for landfill leachate treatment. The administrative regulations prescribe limits which entail treatment according to good engineering practice and state-of-the-art technology.

The paper describes leachates from different types of landfill, discusses state-of-the-art leachate treatment technology and presents some recent developments.
Bulking and Foaming Organism Control at Phoenix, AZ WWTP
Authors: Albertson O. E. , Hendricks P.
Published: May 2018

A 1630 L/s activated sludge plant at Phoenix was limited to an average rate of 1050 L/s and operated, at 400-600 mg/L MLSS and 0.8-1.3 day solids retention time (SRT) due to bulking sludge and limited clarification capacity. Higher SRTs also produced uncontrolled Nocardia foaming and low dissolved oxygen due to partial nitrification. The City retained the services of a team of consultants to resolve these problems as well as to upgrade the plant to provide nitrification and total nitrogen removal. An anoxic selector design was implemented within the existing basin and the clarifiers were modified to improve inlet design and sludge transport. The modified advanced wastewater treatment (AWT) plant operating at 1450 L/s has averaged an effluent of 7.6 mg/L BOD5, 8.2 mg/L TSS, 1.3 mg/L NH4N, 4.1 mg/L NO3N and 2.9 mg/L TP. Oxygen transfer efficiency has increased about 80% in the nitrification-denitrification (NdeN) mode. The cost of modification/upgrading to AWT was approximately $730,000 and a 400 L/s increase in hydraulic capacity was realized. Upgrading costs were $5.63/m3 ($0.02/gal.)
Advanced Modeling of Mixed Populations of Heterotrophs and Nitrifiers Considering the Formation and Exchange of Soluble Microbial Products
Authors: Furumai H. , Rittmann B. E.
Published: May 2018

Biological process modeling is advanced by explicitly describing heterotroph and nitrifier biomass, incorporating formation of soluble microbial products (SMP) from both the bacterial groups, and allowing degradation of SMP by the heterotrophs. Biomass decay now has two parts, endogenous respiration and formation of biomass-associated products (BAP). The model is applied to investigate interactions between heterotrophs and nitrifiers. Main attention is directed to evaluating the role that SMP produced by nitrifiers plays as a supply of organic substrate to heterotrophs and to predicting the COD concentration in the effluent. The model quantitatively describes the observed accumulation of SMP in the effluent at long SRT and at high influent substrate concentration. The significance of SMP from nitrifiers to support growth of heterotrophs is clearly elucidated through the model experiments under various operational conditions. The results indicated that a high NH4+-N/COD ratio in the influent would decrease original substrate COD due to increased heterotrophs whose growth is supported by SMP from nitrifiers, but total COD increases. The minimum substrate concentration, Smin, is reduced for heterotrophs by the additional growth from SMP.
Simultaneous Nitrification and Denitrification in Micro-Aerobic Biofilms
Authors: Watanabe Y. , Masuda S. , Ishiguro M.
Published: May 2018

Simultaneous nitrification and denitrification (SND) occurs in a micro-aerobic biofilm. Using a partially submerged rotating biological contactor(RBC) whose air phase oxygen partial-pressure is controllable, an experimental investigation was made into the effects of the oxygen flux to the biofilm on the SND. The lower the oxygen flux the lower the nitrification efficiency and the higher the denitrification efficiency until the maximum nitrogen removal efficiency was obtained. The state was reached at an oxygen partial-pressure of about 0.1 atm. (oxygen flux= 0.35 g/m2/hour) in this study. Computer simulation of the SND was carried out based on the biofilm kinetic model proposed by the authors. There was adequate agreement between the experimental and simulation results. The simulation study demonstrated that the nitrification and denitrification occur mainly in the biofilm rotating through the air and water phase, respectively, and that the optimum disk rotating speed is around 3 rpm.
Effect of Shear Stress on Granulation in Oxygen Aerobic Upflow Sludge Bed Reactors
Authors: Shin H.-S. , Lim K.-H. , Park H.-S.
Published: May 2018

Aerobic upflow sludge blanket(AUSB) process is a new biological wastewater treatment method applying the concept of the self-immobilization to activated sludge. Two sets of AUSB system with different mixing velocities of 3 rpm(R1) and 6 rpm(R2) were operated for high-rate treatment of synthetic wastewater. The COD removal efficiency in R2 was higher than R1 at the same loading rate up to 7 kg/m3·day. However, in R1, the sludge bulking was observed at the end of the experiment. The chocolate colored granules were formed about 5 days after the start-up. The morphological study on the granular sludge consortia was made with both scanning electron and optical microscopes. The granules were 0.5-2.5 mm in diameter and mainly consisted of bacteria with pili-like appendages and filamentous bacteria, which were thought to be Sphaerotilus natans and Beggiatoa. In R1, the long multicellular filaments causing bulking were prevalent in the granule, while in R2 overgrowth of filamentous bacteria was prevented with appropriate shear stress resulting in higher MLSS density. Experimental results indicated that granulation could be controlled by physical stress on granular sludge.
Oxygen Consumption and Organics Decomposition in Drainage Systems with Attached Biofilm
Authors: Cao Y. S. , Alaerts G. J. , Hooijmans C. M. , Lubberding H. J.
Published: May 2018

Oxygen consumption and organics decomposition in drainage systems with attached biofilm were investigated using a batch reactor. In order to distinguish the relative contribution to these processes of suspended biomass and attached biofilm parallel experiments were performed. The reactors with low and high glucose concentrations simulated lightly polluted rivers and sewers, resp. The dynamic behaviour was different for the system dominated by biofilm and that with only suspended biomass, due to different controlling mechanisms. The biofilm played a major role in the biodegradation only when the suspended biomass concentration was below a critical value. The ratio of wetted area on which the biofilm grows over the water volume (WA/V) is closely correlated with the biofilm oxygen uptake rate. The relative importance of the suspended biomass and the biofilm did not depend on the initial glucose concentration.
Aromatic Degradation in Yeast Rhodotorula rubra
Authors: Katayama-Hirayama K. , Tobita S. , Hirayama K.
Published: May 2018

Aromatic degradation by two yeast strains of Rhodotorula (R.) rubra was examined. Separation and identification of phenol and protocatechuic acid (PCA) metabolites were carried out using high performance liquid chromatography (HPLC) and gas chromatography/mass spectrometry (GC/MS). For HPLC analysis of β -ketoadipic acid, 2,4-dinitrophenylhydrazone derivative was prepared. For GC/MS analysis, metabolites in the cultured broth were extracted with ethyl acetate and trimethylsilylated by N-o-bis(trimethylsilyl)acetoamide. Based on HPLC and GC/MS analyses, phenol metabolites were identified as catechol, eis, cis-muconic acid, muconolactone, β -ketoadipate enol-lactone and β -ketoadipic acid. β -Ketoadipic acid was also found in the PCA metabolites by crude cell-free extract. From the results obtained in this study, a metabolic sequence for aromatic degradation is proposed. Phenol may be hydroxylated to form catechol prior to ring cleavage, and catechol may be further oxidized to eis, cis-muconic acid, muconolactone, β -ketoadipate enol-lactone and β -ketoadipic acid. Catechol branch as well as protocatechuate branch in β -ketoadipate pathway may exist in R. rubra.
Upgrading of Anaerobic Digestion of Waste Activated Sludge by Thermal Pretreatment
Authors: Li Y-.Y. , Noike T.
Published: May 2018

The effect of thermal pretreatment on the characteristics of degradation of waste activated slduge (WAS) in anaerobic digestion was investigated by laboratory-scale batch and continuous experiments at 35±1°C. The pretreatment temperatures of WAS ranged from 62 to 175°C and the pretreatment times were 15, 30, 60, 90 and 120 minutes. The organic particulates in WAS were solubilized to soluble carbohydrates, lipids and proteins or converted into the lower molecular weight compounds, such as volatile fatty acids, by the thermal pretreatment. Through the thermal pretreatment. the anaerobic degradability of WAS and the gas production from WAS were greatly increased, and the retention time necessary for anaerobic digestion was possible to be reduced by 5 days. The optimum pretreatment temperature and pretreatment time for the upgrading of anaerobic digestion of WAS were 170°C and 60 minutes, respectively. At this pretreatment condition, the COD removal and the gas production were markedly increased. At the digester with retention time from 5 to 10 days, the COD removal efficiency reached over 60% and gas production ranged from 223 to 235ml·gCOD−1 which were about 2 times those of the control. The numbers of methanogenic bacteria existing at retention times from 1.5 to 10.0 days ranged from 107 to 108 MPN·ml−1, and reached the maximum population level at the retention time of 5 days. The increase in solubilization and anaerobic degradation of major organic compounds in WAS by thermal pretreatment decreased in the following order: carbohydrates > proteins > lipids.
The Staging of Large Wastewater Treatment Plants - A “Modular” Approach
Authors: Fleckseder H. , Prendl L. , Meulenbroek H.
Published: May 2018

The primary driving force for re-investments in wastewater treatment plants in Austria - and also other countries in Central Europe - is at present not an increase in load to treatment but a marked increase in effluent requirements to be fulfilled. (The re-investments necessary for sludge handling and treatment remain outside this paper.) Within a period of 20 years, the load specific requirements on aeration tank volume rose five- to tenfold, when Lv = 2.0 kg BOD5/(m3d) was the starting value, and roughly doubled for final clarifiers. In addition, the importance of the application and expansion of primary sedimentation decreased as well. This development over time in Central European countries as well as the need to utilize previous investments as long as possible - 35 to 60 years for civil works are common as periods of depreciation - indicate that investments in new plant at any location in the world have to consider the possible whole life cycle of a plant and that plant hydraulics becomes the “key hook” for expandability.
A Comparison of Different Aeration Systems
Authors: Frey W.
Published: May 2018

Aeration tests have been performed under operation conditions and in clean water in order to obtain information on the economy of different aeration systems. The results of investigations using jet aerators membrane diffusers and surface aerators are reported. The aeration tanks used for the tests were tanks with circulating mixed liquor. Typical α-values are reported for different systems tested and operational experiences are also included.
The Implementation of Biological Phosphorus and Nitrogen Removal with the Bio-Denipho Process on a 265,000 PE Treatment Plant
Authors: Einfeldt J.
Published: May 2018

A process, called Bio-Denipho, for combined biological phosphorus and nitrogen removal in a combination of an anaerobic tank and two oxidation ditches is described. In this process the anaerobic tank consisting of three sections working in series is followed by two oxidation ditches. These too are working in series, but with both inlet to and outlet from the tanks changing in a cycle.

The Bio-Denipho process is described specifically for the process itself and as a case study for the implementation of the process on a 265,000 pe wastewater treatment plant for the city of Aalborg in Denmark. The plant was designed and erected in two stages and the last stage was inaugurated October 31,1989. Lay-out and functions for the plant is described and design loads, plan lay-out and tank volumes are given in this paper together with performance data for the first year in operation.
Activated Sludge Nitrification in Temperate Climate
Authors: la Cour Jansen J. , Kristensen G. H. , Laursen K. D.
Published: May 2018

In Denmark winter temperature of the wastewater is typically 5-10°C, and ammonia concentrations below 1-4 mg/l are normal discharge limits under these conditions. Special attention is needed in design and operation of treatment plants in order to fulfill such limits. Based on a simple energy balance a steady-state temperature model is developed and verified at full scale treatment plants. The model enables a good estimate of expected winter temperatures in the design phase. Deep tanks and good protection against wind exposure are shown to be attractive means to avoid a too low process temperature during winter periods. Successful winter nitrification can be obtained if the plant operator is supplied with tools to identify arising problems. A procedure to predict if the actual plant nitrification capacity is approaching the necessary capacity based on the load is described and tested.
The Influence of Operating Experience on Wastewater Treatment Plant Design in San Francisco, California, USA
Authors: Loiacono J. , Pitt P. , Jenkins D. , Cockburn T.
Published: May 2018

Three main areas will be covered regarding the design and operation of a pure oxygen activated sludge plant.

Air entrainment occurred in RAS and influent lines and gas entrainment occurred at the sixth stage effluent weirs in an enclosed pure oxygen aeration basin. This caused the oxygen feed to be shut off due to overpressurization and resulted in a combination of high apparent O2 usage and high vent gas purities. The use of an anaerobic selector for Nocardia control is discussed. Anaerobic digester operation has been adversely affected by Nocardia-dominated waste activated sludge. The effect of thick anaerobic digester foams on the ability to pump digested sludge is discussed.
Bioflocculation in Activated Sludge, an Analytic Approach
Authors: Urbain V. , Block J. C. , Manem J.
Published: May 2018

A study on the physico-chemical structure of activated sludge flocs was carried out to get a better insight in its relation with sludge settleability. For this purpose, sixteen sludges from different origins were analysed in order to provide information with regard to their settleability, biomass and exocellular composition, surface characteristics and internal hydrophobicity. The presence of filamentous micro-organisms was observed in all samples but was not always associated with poor settleability, supporting to some extent the idea of their role as a backbone in the flocs. The relations between variables were studied through their linear correlations. Exocellular polymers (ECP) were associated with poor settling conditions. The chemical composition of the ECP (the DNA fraction and the C/N ratio) had an influence on the surface characteristics of the flocs. Finally, sludge settleability was described with a mathematical model, opposing the ECP and the internal hydrophobicity of the flocs. The positive role of hydrophobic interactions, in term of settleability, should provide a new approach in the understanding of flocculation mechanisms in activated sludge.
The Effects of MCRT and Temperature on Enhanced Biological Phosphorus Removal
Authors: Mamais D. , Jenkins D.
Published: May 2018

Temperature and low mean cell residence time (MCRT) effects on enhanced biological phosphorus removal (EBPR) were investigated in continuous flow bench-scale activated sludge systems treating settled domestic wastewater supplemented with 50 mg/l acetate over ranges of MCRT and temperature of 2-4 days and 13.5-20° C respectively. Temperature effects (10-37°C) on anaerobic soluble COD (CODsol) uptake and soluble P release (Psol) and aerobic Psol uptake rates were studied in batch. For the temperature range studied, EBPR functioned efficiently at MCRT ≥ 2.9 day; below 2.9 day MCRT EBPR is lost at an MCRT value that depends on temperature. Temperature effects on MCRT for EBPR (13.5-20°C), anaerobic CODsol uptake and Psol release rates and aerobic Psol uptake rates (10-30°C) are described by similar Arrhenius plots indicating a similar temperature dependency for all biological processes involved in EBPR.
Anaerobic-Aerobic Treatment of High-Strength Ammonium Wastewater - Nitrogen Removal via Nitrite
Authors: Abeling U. , Seyfried C. F.
Published: May 2018

The two-stage anaerobic-aerobic treatment is applied by preference for the purification of high-concentrated industrial wastewaters. With regard to the elimination of nitrogen compounds by denitrification the far-reaching reduction of organic carbon during the anaerobic pre-treatment is problematic.

A new process of nitrification/denitrification via nitrite wais found to be available in half-technical experiences with high operation security. The carbon consumption amounts only to 60 % in comparison with denitrification via nitrate. The essential parameter for regulating the process is the concentration of free ammonia in the reactor. Concentrations of 1 to 5 mg NH3/l inhibit the nitratation but not the nitritation. The content of ammonia was controlled by means of continuous NH4− and pH-measuring. The inhibition limit for denitrification was found to be at 0.13 mg HN02/l.
Production of Nitrous Oxide Gas during Denitrification of Wastewater
Authors: Hanaki K. , Hong Z. , Matsuo T.
Published: May 2018

Laboratory-scale experiments were conducted to examine nitrous oxide (N2O) production during denitrification. Substrate containing acetate (909 mgl-1 as COD), yeast extract (91 mgl-1 as COD) and KNO3 with COD/NO3-N of 1.5, 2.5, 3.5 and 4.5 was continuously fed to 3 l mixed flow reactors with varied solid retention time (SRT). N2O in produced nitrogenous gas far exceeded 10% in some conditions, and up to 8% of influent NO3-N was transformed to N2O. Low COD/NO3-N, short SRT and low pH were favored conditions for N2O production. COD/NO3-N of 1.5 and 2.5 at an SRT shorter than 10 days, and COD/NO3-N of 3.5 or 4.5 at an SRT shorter than 1 day resulted in N2O production together with incomplete nitrate and nitrite removal. Lower COD/NO3-N caused higher production of N2O. N2O production at pH of 6.5 was significantly higher than that at pH of 7.5 although pH of 7.5 and 8.5 showed less difference. The mixed liquor from the continuous reactor producing N2O readily produced N2O even when substrate with high COD/NO3-N was dosed in batch experiments, which suggests that N2O producing species may be accumulated during continuous operation in favorable conditions.
Combined Pre-Precipitation, Biological Sludge Hydrolysis and Nitrogen Reduction - A Pilot Demonstration of Integrated Nutrient Removal
Authors: Kristensen G. H. , Jørgensen P. E. , Strube R. , Henze M.
Published: May 2018

A pilot study was performed to investigate advanced wastewater treatment by preprecipitation in combination with biological nitrogen removal supported by biological sludge hydrolysis. The influent wastewater was pretreated by addition of a pre-polymerized aluminium salt, followed by flocculation and sedimentation. Chemical pretreatment resulted in 60% COD-reduction and 75% phosphorus reduction. The chemically precipitated primary sludge was exposed to anaerobic sludge hydrolysis at retention times of 1 and 2 days at temperatures in the range of 15-30°C. At a retention time of two days at 20°C, resulting solubilization was 10-13% of the suspended COD. The liquid phase of the hydrolyzed sludge, the hydrolysate, was separated from the suspended fraction by centrifugation and added to the biological nitrogen removal stage to support denitrification. The hydrolysate COD consisted mainly of volatile fatty acids, resulting in high denitrification rates. Nitrogen reduction was performed based on the Bio-Denitro principle in an activated sludge system. Nitrogen was reduced from 45 mg/l to 9 mg/l and phosphorus was reduced from 11 mg/l to 0.5 mg/l. The sludge yield was low, approx. 0.3-0.4 gCOD/gCOD removed. This in combination with the efficient pretreatment emphasizes the concept as well suited for compact advanced treatment including nutrient removal.
Strategies for Optimized Nitrate Reduction with Primary Denitrification
Authors: Londong J.
Published: May 2018

Full-scale tests carried out for the extension of a 700 000 PE treatment plant are used to show the consequences of advanced denitrification requirements. Three nitrate recirculation strategies were tested: feedback control via the nitrate content at the denitrification zone outflow, control via the redox potential and adaptive control of the recirculated nitrate load in accordance with the input of biodegradable materials, estimated on the basis of a BOD-MS measurement (3 minute BOD).

In a situation in which advanced, process-stable primary denitrification has to be carried out in a restricted space, especially in large treatment plants, controlled nitrate recirculation oriented on the requirement for biodegradables is a feasible method. If denitrification is limited by lack of biodegradable substrate, supplements in line with denitrification requirements will be needed. The necessary control can be implemented via a measurement of BOD-M3 in the influent and measurement of nitrate content in the effluent from the activated sludge tank.
ICA in the UK Water Industry: Highlights of Recent Developments in the Applications of Optical Techniques
Authors: Briggs R. , Grattan K. T. V.
Published: May 2018

The current situation in respect of the impact of recent legislation and funding mechanisms on progress with developments in instrumentation, control and automation (ICA) in the UK Water Industry is discussed, problems with progress identified and potential solutions discussed. Recent developments in applied optical sensing are detailed, particularly those involving the use of Raman Scattering and optical fluorescence utilising non-contact laser probes and detectors and fibre-optic based sensors for use in portable and permanent station monitors.
Simulation of Suspended Sediment Transport in a Tidal River
Authors: Kusuda T. , Futawatari T.
Published: May 2018

Based on the results of field observation in a tidal river, modeling of sediment transport processes is performed and the suspended sediment transport over a long term is simulated with a newly developed procedure, in which the Lagrangian reference frame is used in order to reduce numerical dispersion. The suspended sediment transport in the tidal river is calculated with erosion and deposition of sediments, consolidation of fluid mud to bed mud, and transport by turbidity current. Sediment transport processes concerned with formation and maintenance of turbidity maxima are sufficiently simulated for a fortnightly cycle with the Lagrangian sediment transport model (LSTM).
Environmental Aspects in Mathematical Modeling of Irrigation Systems Planning
Authors: Shnaidman V. M. , Zhemukhov R. Sh.
Published: May 2018

This paper deals with applying computer-oriented technology while selecting water and land resources management strategies lor irrigation systems with special reference to environmental aspects. The technology is based on a system of coordinated mathematical models. The system includes a simulation model of irrigation system functioning, a model for irrigation water demand computation, a set of simplified mathematical models of the anthropogenic impact, viz. soil salinization, non-point pollutions from agricultural plots, rising level of subsurface water and its mineralization. The system also takes into account equations for crop yields as functions of both water consumption and fertilization. This makes it possible to analyze various strategies of irrigation system management with the help of a multicriterial procedure. The models are described in sufficient detail and a computation example is given.
A Novel Approach to Removing Refractory Organic Compounds in Drinking Water
Authors: Yasui H. , Miyaji Y.
Published: May 2018

A basic study has been conducted on the treatment of refractory organics in river water in order to produce safe drinking water. Through ozonation of refractory organics, assimilable carboxylic acids are produced with a slight decrease in total organic carbon(TOC) concentration. The amount of newly formed assimilable organic carbon corresponds to nearly 35% of the initial TOC in sample water.

Re-ozonation after biological treatment of the formed assimilable organics makes it possible to reduce TOC to a much lower level by transforming the residual refractory organic carbon to an assimilable one. The repeated treatment of ozonation-biodegradation processes can minimize TOC and trihalomethane formation potential to below the detectable level with a minimum of ozone consumption.
Effect of Effluent Quality and Application Method on Agricultural Productivity and Environmental Control
Authors: Oron G. , DeMalach Y. , Hoffman Z. , Manor Y.
Published: May 2018

Field studies were undertaken in recent years to confirm the hypothesis that treated secondary wastewater can be disposed by using it in drip systems for irrigation of edible crops. This hypothesis was examined in field experiments conducted with the treated domestic wastewater of the city of Beer-Sheva, Israel. The results indicated that contamination of the soil surface and plants was minimal when subsurface drip irrigation was applied, but maximal when sprinkler irrigation was utilized.
Contamination of Lettuces with Nematode Eggs by Spray Irrigation with Treated and Untreated Wastewater
Authors: Ayres R. M. , Stott R. , Lee D. L. , Mara D. D. , Silva S. A.
Published: May 2018

Field and glasshouse grown lettuces were spray irrigated with raw and treated wastewaters containing known numbers of human intestinal nematode eggs, and with clean water artificially seeded with Ascaridia galli eggs. Plants were examined for egg contamination at weekly intervals until harvest. Eggs recovered were tested for viability and the use of clean water irrigation to remove eggs was investigated. No contamination was detected on crops receiving less than 1 egg per litre. Eggs recovered from plants irrigated with raw sewage, effluent from an anaerobic waste stabilisation pond or seeded clean water were found to be undeveloped and therefore un-infective at harvest, although some were still viable. Clean water irrigation was found to remove eggs from the plants. A relaxation of the helminthological guideline for restricted wastewater reuse is discussed in the light of these findings.
The Effects of Sulphide Generation in Waste Stabilization Ponds on Photosynthetic Populations and Effluent Quality
Authors: Houghton S. R. , Mara D. D.
Published: May 2018

This study concerns the role of sulphide production in the reduction of algal populations and proliferation of purple sulphur bacteria in primary waste stabilization ponds, and the effect of such changes on effluent quality and hydrogen sulphide odour release. Full-scale ponds in Israel were compared to laboratory-scale models fed with domestic wastewater at various organic and sulphate loads. The phenomenon occurred in ponds whose organic loads were between those normally thought appropriate to facultative and anaerobic ponds. Algae of the genus Chlamydomonas were most tolerant of sulphide in ponds, confirming previous in vitro studies. Populations of both photosynthetic groups in the models were related to surface BOD5 loading rates and influent sulphate and sulphide concentrations. Purple sulphur bacteria were unable to prevent all odour release, so situations where they proliferate should be avoided by redesign. Shifts from algal to purple sulphur bacterial dominance caused by increased sulphide concentrations under constant loads were not observed to affect adversely effluent quality in terms of BOD5 and COD.
A System for Control of River Water Quality for the Community of Madrid Using QUAL2E
Authors: Cubillo F. , Rodriguez B. , Barnwell T. O.
Published: May 2018

The Stream Water Quality Model QUAL2E has been applied to the major rivers of the Comunidad de Madrid in Spain by Canal de Isabel II. Canal de Isabel II is the company responsible for management of Madrid's water supply and waste treatment system. Initially, the model was applied in planning a waste treatment expansion program. Now, QUAL2E is being used to assist in the management of waste treatment plants and in the evaluation of river water quality controls. To facilitate interaction with the model, a comprehensive user interface specific to the Madrid network was written. This paper discusses the unique water quality problems of Madrid, shows how the QUAL2E model was calibrated and verified on the rivers of Madrid, and describes the user interface developed to allow interaction with the model by decision makers in the Regional Government.
Simultaneous Removal of Nitrogen and THM Precursor by Developed Submerged Biofilm Process for Drinking Water
Authors: Takasaki M. , Sudo R. , Nishimura O. , Kim H. Y.
Published: May 2018

Reciprocating motion submerged biofilm process(RMSBP) was developed for nitrogen, biodegradable carbon and trihalomethane (THM) precursor simultaneous removal as a pre-treatment of polluted raw water for drinking water supply. The focus of this study is to get a stable treatment water through four seasons under no pre-sedimentation systems. All experiments were done at the lake side, and raw water was introduced from the lake continually. There is no sedimentation tank in the reactors and biofilm carrier clogging dose not occur and biofilm growth is uniform through the whole reactors by reciprocating motion carrier. RMSBP was able to decrease NH4−N, and NO2−N and NO3−N simultaneously under unaerated conditions. Decrease of nonpurgeable DOC and ultraviolet(UV) absorbance (1 cm path length, pH7.0, 260nm) is possible almost two toten times more expensive than the traditional biological filtration process. Nitrification, denitrification, biodegradable carbon and THM precursor removal was stably achieved simultaneously from autumn to spring when water temperature is low
Microbial Activity Evolution during the Acclimation of a Mixed Culture to Phenol: Use of CO2 Evolution Rate as Indicator
Authors: Buitrón G. , Koefoed A. , Capdeville B.
Published: May 2018

The microbial activity during the aerobic acclimation of activated sludge to phenol was studied. Carbon dioxide evolution rate (CER), measured in a sequencing batch reactor coupled to an infra-red system, was utilized as the activity control parameter. It was found that CER is representative of the microbial metabolism. Moreover, it was observed that starvation periods during acclimation had a negative effect on biodegradation rate.
Two-Stage Coalescer for Oil/Water Separation
Authors: Sokolovic S. , Secerov-Sokolovic R. , Sevic S.
Published: May 2018

Many different types of coalescers are used for separation of oil-in-water dispersion.

The investigated results of a newly developed two stage coalescer are given in this work.

The proposed designofthis coalescer includes two independent stages which are set in the same coalescer body.

Expanded polystyrene granules are being used in the first stage.

By using this coalescent material, gravity separation and the large oil droplets, coalescence processes are at the same time being insured.

The second stage of this new type of coalescer uses polyurethane foam.

The surface of this layer has been previously oiled. the proposed two stage coalescer has been tested for different type of oily wastewaters.

A high loaded oilywastewater has been treatedby the new coalescer separator in the field

In a one year working period, a mean oil separation efficiency has been higher than 98 %.

The proposed coalescer can be use for suspended solids separation at the same time. Mean separation efficiency has been 85% duringthe field test.
Competitive Adsorption of Phenoxy Herbicide Chemicals in Soil
Authors: Susarla S. , Bhaskar G. V. , Rao Bhamidimarri S. M.
Published: May 2018

A modified Freundlich-type bicomponent adsorption isotherm proposed by Sheindorf et al. (1981) was used to describe the competitive adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) onto volcanic soil. The adsorption capacities of 2,4-D and MCPA reduced in presence of the other component compared to pure component adsorption capacities.
Use of Biosurfactants Produced by Nocardia Amarae for Removal and Recovery of Non-Ionic Organics from Aqueous Solutions
Authors: Sutton R.
Published: May 2018

Biosurfactant produced by Nocardia amarae grown on hexadecane as a carbon source is being investigated for use in a surfactant/non-ionic organic chemical (NOC) sorption process. Recent experiments at the Illinois Institute of Technology give favorable results using the synthetic surfactant sodium dodecylsulfate (SDS) adsorbed onto ferrihydrite as a removal mechanism for NOC's. Biosurfactant is isolated, characterized, and tested for its adsorbability onto ferrihydrite as well as its potential for NOC removal. Results are being compared to work completed on synthetic surfactant/NOC removal.
On-Line Diagnosis of Do-Probe Condition in the Activated Sludge Process
Authors: Spanjers H. , Olsson G.
Published: May 2018

The dissolved oxygen (DO) probe is repeatedly subjected to a step change of the oxygen concentration with a time interval of 15-30 s. For this purpose an existing measuring technique was used in which the activated sludge was sampled continuously from the aeration tank. At each step the time constant of the probe response is estimated which provides a continuous diagnosis of the probe condition. Therefore the DO concentration measurements along the response are fitted to a first order response model of the probe. It was shown that the probe response time constant is a useful indicator for fouling of the probe membrane.
A Pilot Plant Study of the Anaerobic Digestion of a Mixture of Municipal Sewage and Industrial Sludges
Authors: Sugrue K. , Kiely G. , McKeogh E.
Published: May 2018

With up to 100 tonnes/day of municipal sewage sludge, the municipality of Cork County Council had a problem of disposal. Spreading on agricultural land was the most common method of disposal until the 1986 EC Directive 86/278/EEC imposed severe restrictions on such a method. For industry in the county, the method of disposal was sometimes landfilling, but more often disposal at sea. The Helsinki Agreement terminates sea disposal. An evaluation of treatment and disposal means identified anaerobic digestion as an alternative to land and sea disposal. After anaerobic digestion, the sludge is sufficiently sti ilised to spread on land. A pilot project using a 20m3 reactor was studied for one year, using a fixture of municipal sewage sludge, yeast from a citric acid industry and abattoir waste (including blood, paunch contents and sheep's offal). The results were impressive; input sludge of 10% dry matter was reduced to 2%; the COD reduction approached 90%; in the mesophylic temperature range, the sludge was stabilised after an HRT of 29 days. The sludge after anaerobic digestion satisfies the EC limits for landspreading.
The Aspect of Energetic Uncoupling of Microbial Growth in the Activated Sludge Process - OSA System
Authors: Chudoba P. , Chudoba J. , Capdeville B.
Published: May 2018

A practical application of the concept of uncoupling between catabolism and anabolism during microbial metabolism has been studied in the case of a modified activated sludge system, called OSA (Oxic-Settling-Anaerobic). The OSA system consisted of an oxic completely mixed tank, followed by a settling tank and an anaerobic tank, situated in the returned sludge circuit of the OSA system. The periodic passageway of facultative aerobic activated sludge microorganisms through the anaerobic zone created conditions of uncoupled growth, indicated by ATP stock depletion and resulted in a consecutive reduction of activated sludge production.
Infiltration of Pretreated Wastewater from Stormwater Overflow Tanks
Authors: Rohrer I.
Published: May 2018

Field experiments were conducted to study the fate of noxious substances from stormwater basin overflows during infiltration into soil. The stormwater basins received flow from combined sewer systems. COD of the overflow varied between 80 and 100 mg/l. The COD to BOD5 ratio was about 5.5 . By the time the infiltrated water reached the groundwater table the COD was reduced to values below 30 mg/l.
Wastewater Treatment Technologies Accomplished in a Pseudofluidized Bed Reactor
Authors: Kigel M. Y. , Shultis J. F.
Published: May 2018

A pseudofluidized bed reactor has been developed and successfully used with the purpose of water and wastewater treatment based on both biological and physical-chemical processes. The reactor was tested in a full-scale industrial facility for the treatment of petrochemical wastewater. Major reactor's process and hydraulic components were also investigated for the removal of chromium from ground water. Combined simultaneous biological and chemical treatment was tested to remove organic as well as inorganic contaminants. The reactor provides accomplishment of several process phases proceeding in one apparatus unit including oxygen transfer to water, mixing, gas bubbles removal, creation of pseudofluidized beds, internal recirculation, and liquid/solid phase separation. Hydraulic conditions for the pseudofluidization regime were investigated in a three-column pilot-scale unit then checked in a 1-gpm (0.0631 L/s) reactor prototype. Treatment process parameters were investigated in continuous operation of a 1.5-gpm (0.1 L/s) full-scale facility based on a symbiotic (algae and activated sludge) biological treatment process modification. The obtained results allowed 40 - 50% decrease in total residence time of reaction and phase separation processes.
Solids Concentrations in a Treatment Plant Effluent
Authors: Defrain M. , Schmidt F.
Published: May 2018

In the calculations customarily used to dimension nitrification and denitrification plants in the Federal Republic of Germany, solids in the influent of the biological stage represent a significant output variable. Numerous modified methods based on nationally and internationally standardized analysis procedures are available to determine solids concentrations in waste-water. Tests showed that different values are measured depending on the method of analysis employed. Harmonization of the analysis procedure is advisable to ensure comparable conditions for the calculation of activated sludge tank volumes.

The solids reaching a treatment plant originate from two main sources. Filterable materials are passed to the treatment plant via the preceding sewerage network with its industrial and commercial users, but are also carried by process water from sludge treatment. The influence of process water on wastewater composition is illustrated by reference to the Wuppertal-Buchenhofen treatment plant.
Natural Design and Maintenance of Rivers and Streams: Targets, Features and Conclusions
Authors: Göttle A.
Published: May 2018

Most rivers and streams in Europe have been regulated in the past. By this way the most biologically active parts of the landscape and ecological system, the habitat pattern and the species diversity fell victim to regulatory measures. Natural river design or engineering means giving an optimum consideration to natural conditions in order to conserve, improve or restore the ecological quality of river systems and its flood- plains.

The fundamental features of ecological improvement and restoration are discussed especially the ecological unit, variety of biotopesapproved to natural dynamics of the river system, individuality and continuity. Of great importance are detailed ecological inventory and great variation in channel plan, cross section and slope. The experiences with natural stabilization measures and the importance of vegetation as a regular element in river design are shown.

The planing procedures in Bavaria and the ecological and landscape issues are discussed. It has been shown that all available interests and knowledge must be integrated in the best way in an early stage of planning process. The success of natural river engineering works depends on a well balanced solution of all interests, specially trained personnel and enough space for natural variation of river.
Unifying the Theory of Thickening, Filtration, and Centrifugation
Authors: Tiller Frank M. , Hsyung N. B.
Published: May 2018

Solid/liquid separation operations involve relative movement of solids and liquids in both slurries and porous compactible beds. Thickening, filtration, and centrifugation are governed by the simultaneous flow of liquid through and compaction of porous paniculate beds. In the relative motion, the liquid may have a higher velocity than the solids as in filtration or the reverse as in thickening and sedimentation. Movement of liquid is accompanied by a simultaneous collapse of the structure of the cakes and sediments under mechanical, centrifugal, gravitational, and fluid induced frictional stresses.

A unified approach to solid-liquid separation with cake formation requires the solution of two simultaneous equations. The first rate equation (Darcy-Shirato) involves the gradient of the liquid pressure and the velocity of the liquid relative to the solid. The second stress balance equation contains the gradients of both the liquid pressure and the induced stress on the solid matrix. Neither of these equations can be solved independently. Elimination of the liquid pressure gradient between the equations leads to the particulate structure equation whose solution establishes the cake structure and leads to formula for calculating solid and liquid rates.

If gravitational or centrifugal sedimentation precedes cake formation, a first order hyperbolic partial differential equation governs the suspension concentration and the flux of solids at the cake surface.
Continuous Consolidation of Sludge in Large Scale Gravity Thickeners
Authors: Frost R. C. , Halliday J. , Dee A. S.
Published: May 2018

Improved design and performance of continuous thickeners should be achieved through a better understanding of the sludge transport processes involved and the variability of sludge thickenability. A software package called PHOENICS was used to model the three-dimensional flow of sludge in the transport zone of a 20m diameter thickener. A mass transport efficiency was evaluated to test the efficacy of the ploughing system, and tracer simulations were performed to study the degree of back-mixing induced. Interpretation of the results suggests that:○Optimum orientation of the ploughs to the radial arm is 60° to 70°.○Transport of sludge to a central outlet occurs principally in the wake of the advancing ploughs, and that ploughs are less efficient than conventional theories dictate.○Sludge in the ploughing zone is mixed, thus potentially impairing thickener performance.

The thickenability of mixed raw sludge arising at a large activated sludge works was monitored. Pronounced seasonal variations were observed, with a marked deterioration in thickenability in late summer and autumn. These were confirmed in trials of a 20m diameter continuous thickener. Consequently the proposed thickening strategy for this works has been revised.