bluuebunny/crossref_metadata_2025 huggingface dataset:
Biologically Resistant Contaminants, Primary Treatment with Ozone
Authors: Echegaray D. F. , Olivieri R. F.
Published: May 2018

Organic effluent oxidation tests were conducted in petrochemical companies, in the Camaçari Petrochemical Complex, to reduce treatment costs and improve the primary treatment efficiency in each industrial process. Ozone achieved 99.96 percent benzene reduction and 100 percent ethyl benzene and toluene reduction. Process efficiency is strongly dependent on the wastewater chemical composition and concentration. For this reason it is necessary to run pilot plant trials for each specific case. Ozone was obtained feeding commercial oxygen through a corona discharge generator and dissolved in the effluent with a bubble column. Commercial oxygen was used instead of air to increase 250 percent the ozone production, with the same ozone generator.
Industrial Waste Sludge Management for the City of Istanbul: A Case Study
Authors: Kasirga Ersin , Kerestecioglu Merih , Giirdal Necmi , Orhon Derin
Published: May 2018

Istanbul Water and Sewerage Administration (ISKI) has embarked on a programme to build twelve sanitary wastewater treatment plants as well as regulating industrial effluent discharges to sewerage system and imposing a pretreatment program An industrial waste sludge management study was performed as a part of the sludge management efforts for the City of Istanbul In this study, over 1,500 industries with a wide variety of activities in the project planning area have been identified and categorized considering their proximities to the Publicly Owned Treatment Works (POTWs) Since there was little data on industrial sludge, productions were calculated through a three step process which consisted of wastewater characterization, sludge production identification process typically employed to meet pretreatment standards and development of sludge production formulas An important part of the study was the classification of industrial sludges as hazardous or non-hazardous. Identifications were made in accordance with the US Code of Federal Regulations and wastewater characteristics and treatment processes were evaluated Economic and noneconomic analysis were conducted in order to evaluate the possibility of joint treatment of nonhazardous compatible iiudge with the sanitary sludge. Unit costs for joint treatment at each POTW were calculated and it is found that administrative burdens and liability would be the prime concern as opposed to the economic factors
Effects of immobilized cells on the biodegradation of chlorinated phenols
Authors: Lee C. M. , Lu C. J. , Chuang M. S.
Published: May 2018

Effects of immobilized cells on the biodegradation of phenol and chlorinated phenols were studied with a series of batch reactors. Na-alginate was used as the cell carrier. A mixture of identified microorganisms was used as the cell source for immobilized- and suspended-cell study. Immobilized cells could biodegrade phenol within 5 days, even when its initial concentration reached 500 mg-C/L. Immobilized cells also could more effectively biodegrade 2-chlorophenol and 2,4-dichlorophenol in comparison with suspended cells. The utilization of immobilized cells enhanced the removal of chlorinated phenols and decreased the lag phase of biodegradation.
Adsorption of chromium (VI) from aqueous solutions on activated carbon
Authors: Ramos R. Leyva , Martinez A. Juarez , Coronado R. M. Guerrero
Published: May 2018

The adsorption isotherm of chromium (VI) on activated carbon was obtained in a batch adsorber. The experimental adsorption data were fitted reasonably well to the Freundlich isotherm. The effect of pH on the adsorption isotherm was investigated at pH values of 4, 6, 7, 8, 10 and 12. It was found that at pH < 6, Cr(VI) was adsorbed and reduced to Cr(III) by the catalytic action of the carbon and that at pH ≥ 12, Cr(VI) was not adsorbed on activated carbon. Maximum adsorption capacity was observed at pH 6 and the adsorption capacity was diminished about 17 times by increasing the pH from 6 to 10. The pH effect was attributed to the different complexes that Cr(VI) can form in aqueous solution. The adsorption isotherm was also affected by the temperature since the adsorption capacity was increased by raising the temperature from 25 to 40°C. It was concluded that Cr(VI) was adsorbed significantly on activated carbon at pH 6 and that the adsorption capacity was greatly dependent upon pH.
Residual contamination of crops irrigated with effluent of different qualities: a field study
Authors: Armon R. , Dosoretz C. G. , Azov Y. , Shelef G.
Published: May 2018

Unrestricted crop irrigation with wastewater effluents is a major concern for public health. The aim of this investigation was to compare two wastewater effluent reservoirs used for irrigation of a variety of vegetables. The study covers the period from January to the end of July, with sprinkle irrigation starting in mid-April. Lettuce, parsley, cabbage, onion, carrots, fennel, radish and tomato irrigated with highly polluted effluents, displayed elevated numbers of indicator microorganisms. In contrast, vegetables irrigated with slightly polluted effluents, showed significantly lower numbers of indicator microorganisms. Although a low background of microbial indicators was detected in both cases before irrigation started, a significant increase of residual contamination was observed on vegetables irrigated with the polluted effluents, following the irrigation onset in mid-April. Independently of the need to correlate quality standards for unrestricted crop irrigation with epidemiological data, irrigation with poorly managed wastewater, based on microbiological and chemical parameters, results in highly contaminated vegetables. Vegetables often eaten raw or with rich dressings (which may result in regrowth of some pathogenic bacteria) may threaten the public health, without clear outbreaks. It must be borne in mind that drinking water that does not differ much from these vegetables in the way of consumption, has very restrictive quality standards. Similar restrictive standards should be applied for vegetables irrigated with reused water. The results of this study strongly suggest the necessity to treat wastewater effluents to an extent in which no residual contaminants will be detected on irrigated crops.
Neutralization of Acid Mine Water with Calcium Carbonate
Authors: Maree J. P. , du Plessis P.
Published: May 2018

Traditionally, lime is used for the neutralization of acidic effluents. Calcium carbonate should be considered as an alternative because of considerations such as lower cost, low solubility at pH values greater than 7 and simple dosing system required. The paper describes a pilot scale study to determine the technical feasibility of neutralising sulphuric acid-rich water using fluidised bed technology.

Limestone was utilised completely when testing iron(III)-rich water, but with iron(II)-rich water, coated limestone particles accumulated in the fluidised-bed reactor. About 70% of the limestone was utilised in the case of water containing 600 mg/l iron(II).

A contact time of 4 min was sufficient for the neutralization of acid water containing 4 g/l free acid and 580 mg/l iron(III), compared to 40 min when iron(II) replaced iron(III).
Anaerobic Treatment of Industrial Wastewater Containing Organic Solvents
Authors: Terzis Evangelos
Published: May 2018

Industrial water usage results in large volumes of liquid wastes rich in organic pollutants. Waste waters from certain industrial chemical operations (e.g. organic synthesis, perfume industry) will sometimes contain organic solvents at relatively high concentrations. The presence of organic solvents is undesirable in the sewerage system and so must be removed from the industrial effluent. Anaerobic treatment of many of these organic solvents is possible, in which the organic material is converted ~90% to volatile substances -carbon dioxide and methane gas- and ~10% to new bacterial cells (solids). Industry will be using less water in the future. Increased water charges will lead to more precise control and integrated processes will reduce wastage. The smaller volumes of more concentrated waste will be ideal for anaerobic digestion.

In order to evaluate the optimum conditions for the anaerobic digestion of propan-2-ol (iso-propanol) the kinetic parameters of the Monod rate model, namely, maximum growth rate (µm), yield (Y), half velocity constant (Ks) and endogenous decay coefficient (Kd), were determined at the temperature range 25°-40°C, inclusively. The regulatory role of molecular hydrogen was investigated and discussed, and also its possible use as a monitor feature in the anaerobic digestion.
A simplified procedure for setting effluent quality standards
Authors: Espino de la O Ernesto , Limón M. Gualberto , Escalante Ignacio Castillo
Published: May 2018

The discharge of untreated effluents affects the quality of receiving water bodies and impairs their potential beneficial uses; to prevent this from happening, effluent quality standards (EQS) must be set. The conventional procedure for establishing EQS requires extensive knowledge of the receiving body characteristics. When there is an evident need for setting EQS, but all the information needed is not available (a situation probably common to many regions around the world), the need arises for a simplified procedure, such as the one herein proposed. The procedure is based on four tenets:

1) the classification of major water quality parameters into four classes: basic parameters, conservative contaminants, toxic contaminants and pathogens;

2) various sets of maximum permissible contaminant concentration (MPCC), for each class of contaminants;

3) two comprehensive classifications: one of effluent discharges according to their origin, and another of receiving waters based on their intended use and general characteristics; and

4) a two-dimensional matrix for different classes of effluent discharges and receiving bodies; four indices are proposed for each cell of the matrix, specifying MPCC for each class of parameters.
Analyzing and modeling toxicity of mixtures of organic chemicals to microorganisms
Authors: Nirmalakhandan N. , Sun B. , Arulgnanendran V. J. , Mohsin M. , Wang X. H. , Prakash J. , Hall N.
Published: May 2018

Inhibition concentrations of 50 organic chemicals acting singly and jointly in different combinations on activated sludge microorganisms and a surrogate test microbial culture, Polytox, were measured using the respirometric technique. The suitability of the surrogate test culture in toxicity studies was evaluated against activated sludge microorganisms. The toxicity correlation between the two organisms was highly significant with coefficient of determination of 0.922. The joint toxic effects of several 2-, 8-, and 10-component mixtures on the surrogate cultures were found to be simply additive. Using the single chemical toxicity data, Quantitative Structure Activity Relationship (QSAR) models were developed to relate toxicity to molecular structures of the chemicals. The application of these QSAR models in predicting joint effects in six 2-, six 8-, and ten 10-component mixtures was demonstrated. These predictions agreed with the experimentally measured values with coefficient of determination of 0.866 at p < 0.0001.
The toxicity evaluation of wastewater from the chemical industry
Authors: Tišler T. , Zagorc-Koncan J.
Published: May 2018

The purpose of our investigation was the acute and chronic toxicity evaluation of the wastewater from the chemical industry, while the previous study had indicated high toxicity of the receiving streams far away from the point of wastewater inflow. The luminescent bacteria Photobacterium phosphoreum and invertebrate Daphnia magna were used for toxicity tests. The results of the toxicity tests showed that the investigated wastewater contained toxic substances, which caused acute and chronic toxicity to test organisms. Daphnia magna were more sensitive than Photobacterium phosphoreum. The acute toxicity of the wastewater on daphnids disappeared after dilution to 1:420, but the chronic toxicity did not disappear earlier than 1:1350.
Humus transformation at the bank filtration water plant
Authors: Miettinen I. T. , Martikainen P. J. , Vartiainen T.
Published: May 2018

Transformations in the amount and quality of organic matter (humus) during bank filtration of surface water were studied by analyzing the changes in total organic carbon (TOC), non-purgeable organic carbon (NPOC), chemical oxygen demand (COD), color of water, and UV absorbing humus fractions. The amount of organic matter expressed as TOC, NPOC, and COD depended on temperature and filtration distance from lake water. The color of water and the UV absorbing humus peaks presenting different humus molecule fractions decreased more effectively than other parameters measuring the amount of organic matter in water. The ratio of COD to TOC decreased when the filtration distance of water increased. Our observations indicated that bank filtration of humus-rich lake water changed more the quality of organic matter than its total amount.
Vltava cascade as teaching grounds for reservoir limnology
Authors: Straškraba M.
Published: May 2018

The empirical and modelling limnological studies of the reservoirs of the Vltava Cascade spanning over 30 years have demonstrated the major differences between stratified throughflowing reservoirs and lakes. The most significant limnological differences are caused by the generally deep outflows due to the extreme position of the maximum depths, and high flow rates causing flow-driven gradients. Limnological conditions in dam reservoirs are very sensitive to the theoretical retention time of water in the reservoir (RT), in particular in the range RT < 200 days. The primary effect of the high inflow rates is the weakening of stratification, due mainly to increasing bottom temperatures leading to deeper mixing, which results in lower surface temperatures. The hydrophysical changes subsequently affect the fate of chemical constituents and the primary production; the effects are propagated to higher levels and fed back to both chemical and physical water quality. A reservoir being second or successive in a cascade differs limnologically in that it is affected by the dominantly hypolimnetic releases of the upperlying reservoir. The differences in hydrophysics, hydrochemistry and hydrobiology have been specified and the findings are, in general, supported by modelling studies.
Experimental determination of the dissolved oxygen boundary layer and mass transfer resistance near the fluid-biofilm interface
Authors: Zhang Tian C. , Bishop Paul L.
Published: May 2018

The thickness of the dissolved oxygen (DO) concentration boundary layer and the external mass transfer in a biofilm system were investigated using a microelectrode technique. Theoretical analysis was conducted to elucidate the mechanisms of the technique and to interpret the experimental measurements. The measured thicknesses of dissolved oxygen (DO) concentration boundary layers under different conditions demonstrated directly the effect of several factors on external mass transfer resistance. The experimental results indicated that (a) increasing substrate loading rate, (b) increasing fluid streamwise velocity and (c) increasing the roughness of the biofilm surface would decrease the external mass transfer resistance. The measured thickness of the DO concentration boundary layer was not in full agreement with theoretical correlations because the nonuniform biofilm created velocity and concentration fluctuations which resulted in the compression of concentration boundary layers. The microelectrode technique is a useful tool to study the external mass transfer resistance.
The enhancement of nitrification by indirect aeration and kinetic control in a submerged biofilm reactor
Authors: Chen Sheng-Kun , Cheng Sheng-Shung
Published: May 2018

A submerged biological fixed-film reactor packed with plastic corrugated plates was employed to treat a wastewater of 100-400 mg NH4+-N/l and 80-130 mg COD/l. Nitrification and COD removal occurred in the reactor simultaneously. The kinetics of ammonium inhibition was studied, and used to control the bioreactor with the optimum condition. This operation strategy of kinetic control was able to reduce the duration of the acclimation of nitrifying bacteria in the reactor, and to enhance the removal of ammonium up to 95-98 %. The flow mode of indirect aeration in the reactor was able to maintain the suspended solid in the effluent below 4 mg/l without biofilm sloughing-off throughout the 300 operation days. In addition, the kinetic control and indirect aeration strategy of operation were able to obtain stable and low concentrations of COD, ammonium and nitrite in the effluent, and a high biomass of 14 g VSS/l in the reactor, when the influent loading of ammonium was up to 0.74 kg NH4+-N/m3-day associated with the medium surface loading of 10.4 g NH4+-N/m2-day.
Process optimisation for simultaneous biological nitrification and chemical phosphorus removal
Authors: Bliss P. J. , Ostarcevic E. R. , Potter A. A.
Published: May 2018

Environmental regulations require sewage treatment plants originally designed for BOD and suspended solids removal to meet increasingly stringent effluent ammonia and total phosphorus standards. Operating a biological nitrification process in parallel with chemical phosphorus removal to achieve consistent effluent concentrations less than 1mg/L was successfully achieved through process optimisation.

An optimisation program was developed and implemented which effectively allowed the combination of two essentially conflicting processes to produce high quality effluent. The process optimisation program utilised a structured approach to identify process deficiencies which reduced treatment capacity and reliability. Accurate identification of process deficiencies enabled appropriate solutions to be developed and implemented. Additional monitoring quantified improvements arising from process modifications or revised operating procedures.

The average effluent ammonia concentration between June and September 1990 was 23.8mg/L. This was reduced to 0.6mg/L after optimisation in October 1992. The standard deviation of 3.4mg/L during the baseline monitoring program between February and April 1992 was reduced to 0.4mg/L after optimisation, at much lower mixed liquor temperatures. Similarly, the average effluent phosphorus concentration was reduced from 1.1mg/L with a standard deviation of 0.8mg/L to an average value of 0.6mg/L with a standard deviation of 0.3mg/L.

Understanding process operations, combined with the ability to identify process deficiencies resulting from poor operating practices and environmental conditions, reduces the risk of generating poor effluent quality. The performance of any treatment process can derive significant benefits by implementing an effective process optimisation program. This work established that reliable process performance is possible, provided that process deficiencies are identified, and appropriate solutions are implemented and evaluated.
Exploitation of landfill gas: a UK perspective
Authors: Brown Keith A. , Maunder David H.
Published: May 2018

Landfill gas (LFG) is a flammable and potentially harmful mixture of methane, carbon dioxide and a large number of trace constituents produced when waste decays in landfill disposal sites. The need to prevent damage from landfill gas emissions has been recognised since the 1970s, and is now enshrined in landfill site regulations. Sophisticated gas control measures such as actively-pumped gas extraction wells and multi-layered liners are now being implemented on a wide scale. The exploitation of LFG as a fuel or feed stock can complement the objectives of environmental protection and, at the same time, provide an additional revenue stream and reduce the use of fossil fuels. Exploitation of landfill gas in the UK began in the early 1980s, initially as a replacement fuel in kilns and boilers. There are now 13 such direct use projects saving the energy equivalent 50,000 tonnes of coal per year (January 1993). Use of LFG for power generation began in 1985. Government support for electricity from renewable sources has made power generation the dominant use for LFG in the UK. The UK currently has 42 power generation projects with a combined capacity of 72 MWe, saving the energy equivalent to 263,000 tonnes of coal per year (January 1993). This paper reviews current understanding of the processes of landfill gas formation and outlines the considerations required for its use as a fuel. The paper outlines the technology of gas collection and exploitation and assesses the economics of generating electricity from LFG in the UK, and the scope for further development.
Upgrading of activated sludge systems for nitrogen removal by application of the LINPOR®-CN process
Authors: Morper M. R.
Published: May 2018

LINPOR®-systems are modified activated sludge plants, where the aeration tanks contain a certain quantity of highly porous plastic foam particles, which serve as a carrier material for active biomass. Thus a substantial performance improvement is achieved as compared to conventional activated sludge systems without having to renounce the well proven elements of the activated sludge technology.

The LINPOR®-CN process for the simultaneous elimination of organic and nitrogen pollutants is particularly suitable for upgrading existing plants, because it can be made to fit into existing tanks with no or only little change of the once installed facilities.
Application of the UASB technology for sewage treatment in a small community at sumare, sao Paulo state
Authors: Vieira S. M. M. , Carvalho J. L. , Barijan F. P. O. , Rech C. M.
Published: May 2018

Sumare City does not have sewage treatment, leading to the deterioration of water resources and public health conditions. There is a sewage treatment plan for the city's urbanized area. However, difficulties of financing delay the plan's implementation. Meanwhile, new small communities of low income population are built surrounding the city. That was not foreseen in the city's plan. So, the sanitation problem is constantly aggravated. The city's Water and Wastewater Department (Departamento de A'guas e Esgotos - DAE), worried by this situation tried out a new scheme to overcome this problem. One of these communities (235 houses) was chosen and a proposal was made to its inhabitants, which was accepted, to use an anaerobic digester to treat the sewage, DAE being the financer agent and the inhabitants reimbursing DAE. The UASB technology was made available by means of an agreement between DAE-Sumare and CETESB for technology transfer. DAE was responsible for the management and plant construction. The plant was started-up in May 1992. This is a successful experience in view of the non-existence of finance for the construction of sewage systems. A 67.5 m3 UASB reactor was built. The difficulties to establish the real costs for this were extremely high, and lead to cost reduction recommendation. Data collected for performance evaluation, over a period of fourteen months showed a difference compared to the 120 m3 UASB reactor experience, at CETESB, in Sao Paulo City. The influent and effluent Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Suspended Solids (TSS) values, are higher than were experienced at CETESB. The average removal rates of BOD, COD and TSS are also higher, respectively 80%, 74% and 87%.
Upgrading of a two-stage treatment plant for nitrogen elimination
Authors: Burica O. , Vodopivec R. , Stražar M.
Published: May 2018

The paper describes the upgrading of an existing conventional two-stage municipal wastewater treatment plant for 200,000 PE to meet the EEC and Slovenian high effluent quality demands for nitrogen. The incoming wastewater is highly loaded with industrial waste and specifically with effluent from anaerobic pretreatment of piggery sludge. The low-cost concept of extensive wastewater treatment is based on integrating appropriate technologies into an existing treatment facility, preserving as much of the technical infrastructure as possible. The proposed concept uses a predenitrification system for the elimination of nitrogen.
Granule production from raw waste activated sludge
Authors: Noyola Adalberto , Moreno Gloria
Published: May 2018

Granulation is an important characteristic of sludges used in upflow anaerobic sludge blanket (UASB) reactors. As the UASB technology is rapidly spreading, there is a need of granular sludge for inoculation of new reactors, particularly in those countries where anaerobic technologies have been just recently accepted.

Alternative sources of inocula are digested sludge, digested manure, septic tank sludges and pond sediments. Raw waste activated sludges have also been identified as a convenient material for reactor seeding, with previous treatment.

In this work, anaerobic flocculant sludge obtained from raw waste activated sludge has been granulated with hydraulic stress, in a lab-scale column under different upflow velocities (1 to 50 m h−1). A methodology is proposed for enhancing the quality of non granular anaerobic sludges in batch treatments of less than 8 hours. The granular sludge produced was used as inoculum for a UASB lab scale reactor. The seed sludge improved all its characteristics and maintained the granulation, in spite of the low velocity (0.08 m h−1) applied.
Experiences gained in the operation of anaerobic treatment plants in Germany
Authors: Austermann-Haun U. , Seyfried C.F.
Published: May 2018

In the western part of Germany there are 77 full scale anaerobic treatment plants treating industrial wastewater. The ISAH (Institut für Siedlungswasserwirtschaft und Abfalltechnik at the University of Hannover) is or was involved in the investigations, the design and/or operation of 14 of these plants. Some industries (sugar beet, starch, pectin, brewery, vegetable) with their special problems with treating their wastewater anaerobically are described. Experiences of how to handle high nitrate concentrations, to treat a mixture of several industrial wastewaters, to prevent or handle lime, magnesium ammonium phosphate (MAP) or aluminium precipitations are reported.

The first municipal wastewater treatment plant combined with a separate anaerobic stage to treat a wastewater mixture of several small factories is described. Something very special about this plant is the construction of the acidification tank. Using the “teapot effect” to enrich the solid material in the centre of the bottom, the solids can be taken from the bottom of the tank and pumped to the municipal sludge digester.
Influence of the Cross-Section on the Erosion Criteria for Partly Cohesive Sediments
Authors: Torfs Hilde , Huygens Marc , Tito Limbaya
Published: May 2018

Erosion of sediment mixtures, comprising cohesive as well as non-cohesive sediments, has been studied in straight laboratory flumes of circular and rectangular cross-sections. Erosion of mixed sediments depended on the mixture composition (cohesive material content), the type of cohesive sediment, and the shape of the flume cross-section. By increasing the cohesive material content, the erosion resistance of the sediment mixture also increased and the erosion pattern changed from ripples and dunes (noncohesive) to a groove or wavy surface (cohesive). In circular channels, the influence of the “side” walls on sediment transport is important, but the criteria for incipient motion seem to be the same as in the rectangular channels. Hence, sediment transport models developed for rectangular channels cannot be readily applied to circular channels.
Transfer of Combined Sewer Overflows in the Seine River
Authors: Simon L. , Maldiney M. A. , Mouchel J. M.
Published: May 2018

The understanding of transport and dispersion of combined sewer overflows (CSOs), containing both dissolved and paniculate matters, is a major component of a research program dealing with the assessment of impacts of CSOs on the Seine River. This study has combined field measurements and the development of modelling tools. The first experimental results stress the fact that predictions of the behaviour of dissolved matter require the use of a fully two-dimensional hydraulic model, because the dispersion process seems to strongly depend on geometrical features of the river - meanders and the differential advection they induce. Concerning the paniculate matter, it appears that different factors govern its downstream transport, namely, settling properties, critical shear stress, and vertical diffusivity. These factors may produce forces on particles of the same order of magnitude, but in opposite directions. Special experiments are needed to determine precisely how these forces combine.
Pollution from Urban Stormwater Infiltration
Authors: Mikkelsen P. S. , Weyer G. , Berry C. , Waldent Y. , Colandini V. , Poulsen S. , Grotehusmann D. , Rohlfing R.
Published: May 2018

Stormwater infiltration in urban areas gives cause for concern with regard to the risk of soil and groundwater pollution. Compared with conventional storm drainage, infiltration introduces different and widely unknown conditions governing the impacts and the fate of the pollutants, and it is therefore difficult to assess the overall environmental impact. This paper gives a state of the art assessment of the water quality aspects of stormwater infiltration and proposes ways of managing the inherent problems. The major stormwater pollution sources are highlighted and the different processes operating in the soil and groundwater are described. The paper also discusses how the environmental risk of urban stormwater infiltration can be assessed, and outlines the possibilities for designing environmentally safe infiltration systems.
Sewer System for Improving Flood Control in Tokyo: A Step towards a Return Period of 70 Years
Authors: Higuchi Kazuyuki , Maeda Masahiro , Shintani Yasuyuki
Published: May 2018

The Tokyo Metropolitan Government has planned future flood control for a rainfall intensity of 100 mm/hr, which corresponds to a return period of 70 years, and a runoff coefficient of 0.8. Considering that the realization of this plan requires a long construction period and high construction costs, the decision was made to proceed by stages. In the first stage, the improvement of the facilities will be based on a rainfall intensity of 75 mm/hr (presently 50 mm/hr), corresponding to a return period of 17 years, and a runoff coefficient of 0.8. In the next stage the facilities will be improved to accommodate a rainfall intensity of 100 mm/hr. In the Nakano and Suginami regions, which suffer frequently from flooding, the plan of improvement based on a rainfall intensity of 75 mm/hr is being implemented before other areas. This facility will be used as a storage sewer for the time being. The Wada-Yayoi Trunk Sewer, as a project of this plan, will have a diameter of 8 m and a 50 m earth cover. This trunk sewer will be constructed considering several constraints. To resolve these problems, hydraulic experiments as well as an inventory study have been carried out. A large drop shaft for the trunk sewer is under construction.
Influence of Bleaching Conditions and Membrane Filtration on Pilot Scale Biological Treatment of Kraft Mill Bleach Plant Effluent
Authors: Frostell Björn , Boman Bengt , Ek Mats , Palvall Björn , Berglund Marie , Lindström Anders
Published: May 2018

A kraft mill bleach plant effluent was treated in a pilot station with a common pretreatment stage and three parallel biological treatment plants. The possibility to membrane filter the E-stage effluent before biological treatment was provided. In the first pilot plant, three 0.7 m3 anaerobic fixed film reactors were followed by an activated sludge plant with two 0.7 m3 aerobic tanks in series. The second plant comprised a 10 m3 anaerobic hybrid reactor followed by a 2.5 m3 activated sludge plant. The third line was a 4.5 m3 activated sludge plant. All three plants were connected on-line to the bleach plant in a kraft mill. During the study, the bleaching conditions were changed from 75% substitution of chlorine for chlorine dioxide to 100% chlorine dioxide bleaching. In the comparisons, a total hydraulic retention time of 12 hours was used in all the three systems. The influent temperature was kept at 37-38°C. Biomass concentrations were 1.5-4 kg TSS/m3 in the aerobic parts. The concentration of fixed biomass was estimated to be 10-20 kg/m3 in the anaerobic reactors after the experiments.

The change in bleaching conditions decreased the discharge of AOX more than 50% and had a positive effect on the biological treatability of the bleach plant effluent. The transformation of organic and chloroorganic material increased, a more stable operation could be obtained and the quality of the sludge improved. Except for chlorate, there were no major differences in treatment efficiency between the three systems studied. Anaerobic pretreatment resulted in a somewhat higher AOX removal and a somewhat better tolerance to shock loads, especially with chlorine used in bleaching. Membrane filtration of the E-stage effluent gave a significant contribution to the overall treatment result with 75% chlorine dioxide (D) in the first bleaching stage, but contributed only marginally with 100% D.
Clarifier Performance in Activated Sludge Process Treating Pulp and Paper Mill Effluents
Authors: Halttunen Sakari
Published: May 2018

High suspended solids concentrations are typical for pulp and paper industry treated effluents. A new clarifier model was developed to find the reasons for this problem. The model clarifier is divided into four different zones: inlet, settling, thickening and separation. In the inlet zone sludge is transported by water flow and neither thickening nor settling will happen. When water velocity decreases the main part of the sludge will settle until it reaches the thickening zone. Thickening will continue until the sludge is pumped away from the clarifier. Concentration increase depends on sludge concentration, time and specific thickening coefficient. The minor part, which is specific to the sludge, enters the separation zone and will either settle in the thickening zone or stay in the effluent.

In intensive field studies on 12 different activated sludge processes sludge volume in the clarifier, effluent suspended solids concentrations and sludge settling qualities were examined. Modelled sludge blanket volumes were verified with blanket measurements. Modelled effluent suspended solids were also verified by concentration measurements.

Sludge thickening characteristics can be estimated by DSVI. From the data collected two empirical relationships were noticed between sludge settling properties and process operation. Solids concentration in clarified water depends on settling number, which is the mean number of sludge settling during its residence time in the process (sludge age). Sludge settling properties seem to depend on collision load, which is defined as COD-load divided by return sludge biomass flow.
Sequenced Anaerobic-Aerobic Treatment of Hemp Black Liquors
Authors: Kortekaas S. , Doma H. S. , Potapenko S. A. , Field J. A. , Lettinga G.
Published: May 2018

This study evaluates the sequenced anaerobic-aerobic treatment of hemp bark and hemp stem wood black liquors with respect to COD removal efficiency and detoxification. Anaerobic toxicity assays revealed that soda pulping liquors derived from hemp are just as toxic as those derived from wood. Hemp bark and stem wood black liquors caused 50% inhibition at concentrations of 5.9 and 4.5 g COD/l, respectively. Long term experiments were conducted in lab-scale upflow anaerobic sludge blanket (UASB) reactors at 30°C. Black liquor was fed at sub-toxic concentrations (< 4 g COD/l). In the bark column loadings were applied up to 17.5 g COD/l*d with COD and BOD5 efficiencies of 56.0 and 87.9%, respectively. In the stem wood column loadings up to 18.4 g COD/l*d were reached with COD and BOD5 efficiencies of 42.3 and 81.0%, respectively. Aerobic post-treatment displayed only minor extra COD removal and a strong increase of color levels. After sequenced anaerobic-aerobic treatment, the COD removal was 70.9 and 58.4% for bark and stem wood liquor, respectively, whereas the BOD5 removal exceeded 98%. Strong detoxification was accomplished after anaerobic-aerobic treatment, as was demonstrated by anaerobic toxicity assays. After anaerobic-aerobic treatment bemp bark and stem wood black liquors caused 50% inhibition at concentrations of 135 and 21.5 g COD/l, respectively.
Biofilm reactors configuration for advanced nutrient removal
Authors: Ryhiner G. , Sørensen K. , Birou B. , Gros H.
Published: May 2018

Characterization of a new biofilm reactors configuration was carried out on a pilot plant performing nitrification, pre- and post-denitrification. Thereby, degradation rate limitations - whether there are related to mass transfer resistances, kinetic or stoichiometry - were determined for the different stages.

The experimental results showed that under certain conditions moderate aeration of the predenitrification stage enhances both denitrification and organic carbon removal due to an acceleration of diffusion rates. Post-denitrification was limited by the addition of C-source exclusively, whereas nitrification was inhibited by elevated organic loadings as well as low temperatures.

The described system offers a certain flexibility concerning BOD removal in the predenitrification stage because of the potentiality of aeration, as well as the possibility of recirculating nitrate very economically enabled by the small head losses in the systems. Furthermore, combination of pre- and post-denitrification with biofilm systems leads to economic and safe processes for advanced elimination of nutrients such as nitrogen and phosphorus.
A new moving bed biofilm reactor - applications and results
Authors: Ødegaard H. , Rusten B. , Westrum T.
Published: May 2018

A new moving bed biofilm reactor has been developed in Norway. The biomass is attached to carrier elements that move freely along with the water in the reactor. It is demonstrated in the paper that this results in a very compact reactor and a very efficient biomass. Experiences from pilot and full-scale testing of the reactor in municipal and industrial wastewater treatment applications are presented and discussed.
Assessment of aerated biofiltration at industrial scale
Authors: Kleiber B. , Roudon G. , Bigot B. , Sibony J.
Published: May 2018

Experience with biofilters, acquired over many years, has made it possible to control their operating parameters. The goal of this article is to present an assessment of operational biofilters, in particular their air consumptions, their sludge productions, their energy balances as well as the duration of their filtration cycles. Some tests, carried out on medium to large full scale units, are described at the same time as the process results. These experiences in the design and operation of biofilters led to their optimization and make it possible to build very large scale installations. Examples of such plants, now being built or started up, are also presented, treating flows in excess of 50 000 m3/d even for low nitrogen residuals.
Critical process design issues in the selection of the TF/SC process for a large secondary treatment plant
Authors: Parker D. , Krugel S. , McConnell H.
Published: May 2018

The Greater Vancouver Sewerage and Drainage District (GVS&DD) is a major regional wastewater agency serving Vancouver, Canada and surrounding municipalities. It was recently required to upgrade its largest treatment plant from primary treatment to secondary treatment. After initial screening of 17 processes, three were given detailed examination: the oxygen activated sludge process (OAS), the air activated sludge process (AAS), and the trickling filter/solids contact process (TF/SC). A comprehensive alternative analysis was completed consisting of process designs, plant layouts, and contractor-type construction cost estimates. Operations and maintenance costs were prepared from staffing plans, and estimates were made for energy and chemical use. Plants were surveyed and visited to address questions such as ease of operations and reliability. The TF/SC process was selected based upon its lower present value and O&M costs, ease of operation, robustness, and lower energy usage.
A fluidized-bed reactor: the biolift process
Authors: Badot R. , Coulom T. , de Longeaux N. , Badard M. , Sibony J.
Published: May 2018

Biological reactors using a culture fixed on a fluidized bed are suitable for many applications in waste water treatment.

A large number of studies have been carried out at the pilot-plant scale but none exists at the industrial scale for municipal waste water treatment. Examples are:

- Dorr Oliver (Sutton + Mishra) (1)

- The Biolex process developed by EBARA (2)

- The reactor described by Heijnen (Holland) (3)

In the latter two processes, fluidization and aeration are provided by an air-lift system inside the reactor. This article describes the Biolift process whose original feature is that the air-lift system is outside the reactor and is assisted by a system to inject secondary air (process air) into the reactor. This combination allows tight control of fluidization and aeration factors.
Behaviour of an anaerobic/aerobic pilot scale fluidized bed for the simultaneous removal of carbon and nitrogen
Authors: Fdez-Polanco F. , Real F. J. , Garcia P. A.
Published: May 2018

Description of a pilot installation for municipal wastewater treatment. The simultaneous elimination of organic carbon and nitrogen carried out by a fluidized bed reactor with aerobic and anaerobic areas.

The presentation of experimental results corresponding to a model of the flow and behaviour of the above mentioned elimination of organic material and nitrogen. Presentation of information concerning the characteristics of COD, N-NH3, N-NOx, pH, Redox Potential and D.O. throughout the reactor.

Levels of purification reached: CODS>80%; (BOD5)S>90%; N-TKN>80%; N-NTotal>70%.
Dynamics of population and biofilm structure in the biofilm airlift suspension reactor for carbon and nitrogen removal
Authors: Tijhuis L. , Rekswinkel E. , van Loosdrecht M. C. M. , Heijnen J. J.
Published: May 2018

The dynamics of population and biofilm structure of nitrifying and heterotrophic biomass in biofilms on small suspended particles in an airlift reactor were measured during shifts from purely nitrification to a heterotrophic medium and back to nitrification. Biofilms from a full scale reactor with predominantly heterotrophic activity were used as start material. In the first twenty days of the nitrification period ammonia was oxidized to nitrite. Hereafter the oxidation was mainly to nitrate. A conversion of nearly 5 kgN/(m3 d) was reached in fifty days. Following the change to heterotrophic medium the nitrifying biofilm served as carrier for the development of a heterotrophic biofilm layer. The nitrification capacity of the biofilms dropped to 1 kgN/(m3 d) due to oxygen diffusion limitation in the heterotrophic layer. After the switch back to nitrification the heterotrophic biofilm layer was sheared off very rapidly, while the nitrification activity increased very fast to the level at the end of the first nitrification period due to decreased diffusion limitation.
Evaluation of multiple-species biofilm and floc processes using a simplified aggregate model
Authors: Furumai H. , Rittmann B. E.
Published: May 2018

A simplified model of microbial aggregates is developed to evaluate how the key features of aggregation affect the stability of nitrification in multiple-species biofilms and flocs. The foundation of the model is a layered system in which each layer contains a different type of biomass, includes mass-transport resistance for all substrates (i.e., COD, NH4+, and O2), and included formation and consumption of soluble microbial products. The model describes how the outer biofilm layer of heterotrophs protects the inner layers of nitrifiers and inert biomass from detachment, so that an inner layer can have a low specific detachment-loss rate. This protecting function is not important for suspended flocs, because the entire floc is wasted. Comparison of biofilm and suspended flocs shows that the protecting function of the biofilms provides greater nitrification stability. The model also demonstrates that extensive heterotrophic growth induced by high organic loading can cause a deterioration of nitrification when the dissolved oxygen is depleted in the inner layer of the aggregate. Although it is based on a simplified spatial distribution, the aggregate model identifies key differences among biofilm, floc, and dispersed-growth processes.
Domestic plumbing materials and their effect on viruses
Authors: Timms S. , Colquhoun K. O. , Slade J. , Fricker C. R.
Published: May 2018

To examine the virucidal effects of various materials used for tubing in domestic water supply systems, experiments have been carried out that examine the recovery percentages of five viruses allowed to flow through pipes made from “aged” samples of five plumbing materials. Most materials had only modest virucidal effect, but copper produced significant reductions in levels of all five viruses.
Study on storm water control by permeable pavement and infiltration pipes
Authors: Watanabe Satoshi
Published: May 2018

Since 1982, the City of Yokohama has been studying the effects of storm water runoff control measures by setting up a model area in a residential area and installing two types of runoff control facilities – permeable pavement and infiltration pipes. The model area was subdivided into three areas according to the combination of the runoff control facilities. The study results revealed that 15 to 20 percent of the peak runoff control effect was achieved by the use of the installed runoff control facilities. Throughout the study period, no deterioration of the strength and features of the permeable pavement in comparison with ordinary pavement was observed.
Response of a periodically operated halophilic biofilm reactor to changes in salt concentration
Authors: Woolard C. R. , Irvine R. L.
Published: May 2018

A moderate halophilic organism was isolated from the Great Salt Lake, UT, USA which utilized phenol in a simulated waste brine containing 1–15% salt. Growth characteristics of this organism were not affected by preculture salt concentration. When placed in a periodically operated Sequencing Batch Biofilm Reactor (SBBR), the organism formed a biofilm on the gas permeable silicone tubing used to aerate the reactor. Reactor performance was not effected by large (14%) step changes in salt concentration. The results suggest that biofilms of halophilic bacteria can be used to effectively treat waste brines with high and variable salt contents.
Permeable pavements: pollution management tools
Authors: Baladès J-D. , Legret M. , Madiec H.
Published: May 2018

The latest tests on permeable road surfacing demonstrate the rate at which clogging occurs, according to the type of surface, and the best methods for recovering micro-pollutants. In the first year there is little change in underseepage rate but thereafter decline is rapid, reaching 50% of the original rate after 2 or 3 years.

For highly permeable surfacing containing many spaces, absorption capacity remains high even after this period, but methods of preventive maintenance, such as suction, need to be used in order to avoid the use of even more costly methods, such as high pressure water jet with simultaneous suction. However, permeable surfacing does enable the storage and recovery of most micro-pollutants, thus preventing such particles being washed off into the ground.