bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological nutrient removal from meat processing wastewater using a sequencing batch reactor
Authors: Thayalakumaran N. , Bhamidimarri R. , Bickers P.O.
Published: May 2018

Meat processing effluents are rich in nutrients (nitrogen: 75-200 mg L−1 and phosphorus: 20-40 mg L−1) and COD (800-2,000 mg L−1) after primary treatment. A laboratory scale sequencing batch reactor (SBR) was operated for the treatment of a beef processing effluent from slaughtering and boning operations. An effective SBR cycle was found for removal of COD, nitrogen and phosphorus at 22°C. The solid retention time was 15 days while the hydraulic retention time (HRT) was 2.5 days. The total nitrogen in the wastewater was reduced to less than 10 mg L−1, while the total phosphorus decreased to less than 1.0 mg L−1. The residual effluent soluble COD was found to be non-biodegradable as reflected by no further soluble COD removal following prolonged aeration. Removal of biodegradable soluble COD, ammonia nitrogen and soluble phosphate phosphorus of greater than 99% was achieved in the SBR. Good prediction of ammonia and nitrate nitrogen removal was obtained using IWA Activated Sludge Model. The operating cycle is shown to be appropriate to achieve simultaneous removal of COD and nutrients from the meat processing wastewater. Alkalinity and pH have an inverse relationship during the initial anaerobic and aerobic stages due to production and stripping of CO2. Use of a low level of DO in the final aerobic stage ensured complete ammonia removal and enhanced denitrification.
Modelling the influence of irrigation abstractions on Scotland’s water resources
Authors: Dunn S.M. , Chalmers N. , Stalham M. , Lilly A. , Crabtree B. , Johnston L.
Published: May 2018

Legislation to control abstraction of water in Scotland is limited and for purposes such as irrigation there are no restrictions in place over most of the country. This situation is set to change with implementation of the European Water Framework Directive. As a first step towards the development of appropriate policy for irrigation control there is a need to assess the current scale of irrigation practices in Scotland. This paper presents a modelling approach that has been used to quantify spatially the volume of water abstractions across the country for irrigation of potato crops under typical climatic conditions. A water balance model was developed to calculate soil moisture deficits and identify the potential need for irrigation. The results were then combined with spatial data on potato cropping and integrated to the sub-catchment scale to identify the river systems most at risk from over-abstraction. The results highlight that the areas that have greatest need for irrigation of potatoes are all concentrated in the central east-coast area of Scotland. The difference between irrigation demand in wet and dry years is very significant, although spatial patterns of the distribution are similar.
Fuzzy-control for improved nitrogen removal and energy saving in WWT-plants with pre-denitrification
Authors: Meyer U. , Pöpel H. J.
Published: May 2018

In the last few years, numerous studies were carried out, dealing with the application of fuzzy-logic to improve the control of the activated sludge process. In this paper, fuzzy-logic based control strategies for wastewater treatment plants with pre-denitrification are presented that should lead to better effluent quality and, in parallel, to a reduction of energy consumption. Extensive experimental investigations on a large scale pilot plant as well as simulation studies (ASM1 with SIMBA®) were carried out in order to design, evaluate and compare different fuzzy-controllers with each other and with comparable conventional control systems. The fuzzy-controllers were designed as high-level controllers that determine the DO-setpoints in the aerated zones and the ratio between aerated and non-aerated zones. Conventional PI-controllers were used to maintain the DO-concentration at the set-point levels. The ammonia and nitrate concentration in the effluent and the ammonia load in the influent were considered as input variables for the different fuzzy-controllers. Compared to the operation with fixed nitrification/denitrification zones and constant DO concentrations, the required air-flow could be reduced up to 24% by using fuzzy-logic based control strategies. In comparison with a more advanced conventional control strategy (relay controller with two thresholds and the NH4-N concentration in the effluent as single control variable) a reduction of air-flow-rate up to 14% could be achieved. At the same time, NH4-N peaks in the effluent that are normally caused by peak flow conditions could be reduced significantly. The large scale experiments show that the fuzzy-controllers can be easily implemented in modern control and supervision systems and that the control characteristics can be followed and modified during operation. It therefore can be expected that the developed fuzzy-control systems will be accepted by the operating personnel in wastewater treatment plants.
Nitrogen removal in industrial wastewater by nitration and denitration - 3 years of experience
Authors: Degn Pedersen P. , Jensen K. , Lyngsie P. , Henrik Johansen N.
Published: May 2018

CPKelco ApS, Denmark is the largest pectin plant in the world and the second largest refined carrageenan plant. The products are used for texturising purposes, primarily within the food industry, but also within the pharmaceutical industry. The products are extracted from imported natural raw materials, like dried citrus peel and special seaweed plants. In the production processes a considerable amount of water and energy are used. The excess water from the production processes is led to CPKelco's own WWTP, which is one of the largest industrial WWTPs in Denmark.

In order to obtain higher process stability and lower energy consumption in the WWTP, CPKelco decided to change the nitrogen removal process from a conventional nitrification/denitrification process to a nitration/denitration process, which comprises an oxidation of ammonium to nitrite and a controlled reduction of nitrite to N2. Theoretically this process will decrease the oxygen consumption for oxidation by 25% and the use of carbon source for the reduction will be decreased by 40% compared to the conventional process.

This paper presents and discusses the experiences and results from three year's continuous operation of the nitration/denitration process in an activated sludge plant, and the overall performance results are discussed in relation to the previous results. Accordingly the implementation of the nitration/denitration process was done successfully, and today the plant operates with much higher process stability than obtained before, and even the most stringent effluent requirements for nitrogen can be obtained.
Modelling the effect of shear history on activated sludge flocculation
Authors: Biggs C. , Lant P. , Hounslow M.
Published: May 2018

The aim of this paper is to investigate the effect of shear history on activated sludge flocculation dynamics and to model the observed relationships using population balances. Activated sludge flocs are exposed to dramatic changes in the shear rate within the treatment process, as they pass through localised high and low mixing intensities within the aeration basin and are cycled through the different unit operations of the treatment process. We will show that shear history is a key factor in determining floc size, and that the floc size varies irreversibly with changes in shear rate. A population balance model of the flocculation process is also introduced and evaluated.
Improving titrimetric techniques by modelling pH change in activated sludge systems
Authors: Pratt S. , Yuan Z. , Keller J.
Published: May 2018

Existing titrimetric techniques rely on a well defined hydrogen ion production rate. In particular, they are only suitable in circumstances in which constant background pH influencing reactions take place. This is rarely the case due to the presence of the carbonate acid/base system. In this paper, a model, which describes the influence of the nitrification process on pH and accounts for the action of the carbonate system, is presented. The validity of the model is tested by comparison of model predictions for the important state variables with that of experimental data from a batch oxidation of ammonium nitrogen. The two cases studied are the responses of an endogenously respiring nitrifying sludge to: an ammonium chloride pulse and a pulse of both bicarbonate and ammonium chloride. The results are most encouraging as the dynamic HPR response is mirrored by the model simulation. Furthermore, using the model for data interpretation, the initial nitrogen substrate levels are recovered. It is shown that this could not have been achieved in either case using existing titrimetric techniques.
Dimensional analysis for establishing the testing criteria of kinetic study with respirometry
Authors: Wu Y.-S. , Chiang C.-F. , Lu C.-J.
Published: May 2018

The kinetic study of a microbial system requires the determination of kinetic parameters under a set of operating variables. Previous researchers indicated that initial conditions, such as So/Xo and So/Ks, may influence the reliability of the parameter estimation. However, little study has been done to identify the sensitivity of system variables to the parameter estimation. This study proposes a novel dimensional analysis and identifies six dimensionless groups: μm/fw, kd/fw, Yg, So/Ks, Ks/So, and 1/(fwθc - 1). By incorporating the SP-moving algorithm proposed by Wu and coworkers in 2001, an algorithm was proposed in this study to perform a sensitivity analysis on the six dimensionless groups. Results of this analysis reveal that So/Xo is more sensitive than So/Ks, as also evidenced by the fact that gross growth yield (Yg) is sensitive and affecting So/Xo. The analysis also suggests that the θc-based wasting frequency (fwθc) is more sensitive than the daily wasting frequency (fw). A critical minimum value of 1.3 for So/Xo and a maximum value of 0.1 for So/Ks were suggested to establish the testing criteria for the kinetic study under the respirometric conditions.
Theoretical and practical results of the optimisation of Hamburg's WWTPs with dynamic simulation
Authors: Ladiges G. , Günner C.
Published: May 2018

To assess the influence of the connection of a further 250,000 PE in addition to the 1.85 m PE already served by the combined WWTPs Köhlbrandhöft/Dradenau, a dynamic simulation study was started in 1996. A previous study developing the extension of the WWTP proposed several solutions with costs between €25 million and €100 million euro. Those concepts were examined by a dynamic simulation study for comparison and further optimisation.

The simulation results indicated that with an increased volume for the storage of sludge liquor it would be likely to fulfil the effluent requirements in spite of the increased load. The construction of the additional storage tank was finished at the end of 1999 together with the connection of the additional load to the WWTP. The cost of this concept was less than 1 million euro, which is significantly less than if the plants had been extended in a traditional manner.

The first two years of operation showed that the chosen solution is able to fulfil the requirements. The effluent values can be kept within the required limits. A very good correspondence between the measured and the simulated values could be observed.
A high rate clarifier for load levelling in sewerage systems
Authors: Jago R.A. , Davey A. , Li H.
Published: May 2018

The combining of chemically assisted clarification with a proprietary physical separation technology has led to a high rate process for clarifying flocculated sewage and other waste streams. This hybrid physico-chemical system, known as the CDS Fine Solids Separation (FSS) System, was developed over a two year period within a sewage treatment plant environment.

This paper summarises the results of a recent field trial of the system with a Victorian water authority which experiences heavy loading of sewers in a coastal town during holiday periods. The trial sought to evaluate the FSS as a tool for smoothing the load on the 11 km long sewer to the sewage treatment plant (STP). The FSS system could possibly enable the costly augmentation of the sewer to be deferred, particularly as the capacity of the existing sewer pipe is satisfactory for most of the year.

Water quality parameters were determined for a range of flowrates and operational conditions over a two month period. Large reductions were achieved in TSS, TP, FC, turbidity and BOD5, with only minimal reductions in NH3 and TON. These results showed that the FSS could meet the authority's objectives for load levelling and would provide a 20-25% increase in effective sewer capacity. The data are also discussed in terms of possible use of the effluent from the FSS for water reuse applications.
The evaluation of a density current experiment as a verification tool of a secondary clarifier model
Authors: Kim J. , Kim S. , Yoon J.
Published: May 2018

The prediction of the spatial and temporal flow regime is important for the efficient design and operation of the settling tank. The impact of the gravity current has been investigated by the temperature difference or artificial glass particles. This experimental study is designed to obtain the steady state of stratified flow with the consideration of the heavy density flow. Two different approaches were performed at lab scale considering the hydraulic similarity. One is the investigation of a heavy density current of saline water intrusion. The characteristics of the internal hydraulics are monitored using Particle Image Velocimetry (PIV). As a result of the saline intrusion, the internal flow established a continual density stratification of 3-layers in steady state. The other is the movement of activated sludge from a sewage treatment plant. The video image is captured to analyze the behavior of activated sludge in the settling tank. The experiments with various inlet baffle conditions suggest that the hydraulic characteristics of the two experiments are significantly different. As the distance between the baffle and inlet point was decreased, significant strength of saline density currents in the bottom layer was observed. However, the strength of the velocity in the bottom density currents appeared to be the opposite in the case of the activated sludge. The reason for the slower density current in the bottom layer is associated with the compressibility of activated sludge characteristics.
Strategies for waste management in small and medium towns of developing countries: a case study of India
Authors: Sundaravadivel M. , Vigneswaran S.
Published: May 2018

This paper evaluates the issues of waste management in small and medium towns (SMTs) (with population in the range of 10,000-100,000) of India, and identifies the need for a multi-disciplinary approach encompassing technological, economic and financial aspects of the issues to effect improvements. A comprehensive set of cross-disciplinary strategies is suggested to improve the prevailing conditions with environmentally appropriate, economically efficient and financially self-sustaining waste management services. Based on a case study of four SMTs in the State of Tamil Nadu in India, this paper evaluates the application of the suggested strategies and offers policy recommendations.
The influence of experimental conditions on the assessment of the toxicity of 2,4-dichlorophenol to the anaerobic bacteria of landfilled refuse
Authors: Nitayapat N. , Watson-Craik I.A.
Published: May 2018

The toxicity of 2,4-dichlorophenol (2,4-DCP) to anaerobic bacteria in refuse cultures was investigated at two temperatures (30° and 37°C) and after two different exposure periods to the toxicants. It was shown that at 0.52mM 2,4-DCP the time of exposure of microorganisms to 2,4-DCP affected the relative activity (Av) of the production of methane. Values of Av at the beginning of the steady-state phase were lower than those recorded two weeks later. The incubation temperature selected also critically affected the assessment of anaerobic toxicity; at 37°C an imbalance of the activities of fermentative bacteria and acetogens with those of methanogens was observed.
Bacterial source tracking and shellfish contamination in a coastal catchment
Authors: Geary P.M. , Davies C.M.
Published: May 2018

Introduced pathogens from faecal material can make their way into the aquatic environment from a number of catchment sources. These sources typically include sewage outfalls, seepage from septic tanks, and urban and agricultural runoff. Shellfish as filter feeders are particularly susceptible to contamination in faecally contaminated waters and a range of microbiological indicators have been developed to assess the levels of contamination and likely risks to public health (Hackney and Pierson, 1994). This paper outlines the application of bacterial source tracking (BST) in a shellfish growing area in part of the Port Stephens estuary along the NSW north coast. The approach is based on the premise that bacterial isolates from different faecal sources will have significantly different resistance patterns to the battery of antibiotics and concentrations tested. Faecal streptococci (FS) were isolated from several possible faecal sources: beef and dairy cattle, chickens and humans. The resistance patterns of these isolates to four different concentrations of four antibiotics were compared to those of FS isolates obtained from samples collected upstream and in the vicinity of the oyster leases. Discriminant analysis was performed using the patterns from the known source isolates and the rate of correct classification was determined for each source. The predictive function of discriminant analysis was then used to determine the most probable source of each of the unknown isolates from Tilligerry Creek, the drainage channels to the estuary, and the shellfish leases. Preliminary results are presented here and suggest that there is no single significant source of faecal contamination, rather there are contributions from a range of sources. The findings may have implications for the ways in which land use activities and catchments are managed in similar estuarine locations with a shellfish industry.
Climate change and reliability of urban water supply
Authors: Maheepala S. , Perera C.
Published: May 2018

This paper describes a probability-based method for assessing the potential impact of climate change on urban water supply systems. Specifically, the assessment method uses probability distributions to place a confidence level on the plausible values of response variables. The Benalla water supply system has been used to demonstrate applicability of the proposed assessment method. For the application, the impact of the 2030 climate change scenarios on streamflows and system yield has been examined. The preliminary results have demonstrated that the proposed assessment method can provide valuable insights into the impact of climate change on water supply systems, allowing it to be incorporated into planning decisions.
Agricultural land use and N losses to water: the case study of a fluvial park in Northern Italy
Authors: Morari F. , Lugato E. , Borin M.
Published: May 2018

An integrated water resource management programme has been under way since 1999 to reduce agricultural water pollution in the River Mincio fluvial park. The experimental part of the programme consisted of: a) a monitoring phase to evaluate the impact of conventional and environmentally sound techniques (Best Management Practices, BMPs) on water quality; this was done on four representative landscape units, where twelve fields were instrumented to monitor the soil, surface and subsurface water quality; b) a modelling phase to extend the results obtained at field scale to the whole territory of the Mincio watershed. For this purpose a GIS developed in the Arc/Info environment was integrated into the CropSyst model. The model had previously been calibrated to test its ability to describe the complexity of the agricultural systems. The first results showed a variable efficiency of the BMPs depending on the interaction between management and pedo-climatic conditions. In general though, the BMPs had positive effects in improving the surface and subsurface water quality. The CropSyst model was able to describe the agricultural systems monitored and its linking with the GIS represented a valuable tool for identifying the vulnerable areas within the watershed.
A comparative analysis: storm water pollution policy in California, USA and Victoria, Australia
Authors: Swamikannu X. , Radulescu D. , Young R. , Allison R.
Published: May 2018

Urban drainage systems historically were developed on principles of hydraulic capacity for the transport of storm water to reduce the risk of flooding. However, with urbanization the percent of impervious surfaces increases dramatically resulting in increased flood volumes, peak discharge rates, velocities and duration, and a significant increase in pollutant loads. Storm water and urban runoff are the leading causes of the impairment of receiving waters and their beneficial uses in Australia and the United States today. Strict environmental and technology controls on wastewater treatment facilities and industry for more than three decades have ensured that these sources are less significant today as the cause of impairment of receiving waters.

This paper compares the approach undertaken by the Environmental Protection Authority Victoria for the Melbourne metropolitan area with the approach implemented by the California Environmental Protection Agency for the Los Angeles area to control storm water pollution. Both these communities are largely similar in population size and the extent of urbanization. The authors present an analysis of the different approaches contrasting Australia with the USA, comment on their comparative success, and discuss the relevance of the two experiences for developed and developing nations in the context of environmental policy making to control storm water and urban runoff pollution.
Indigenous soil bacteria and low moisture may limit but allow faecal bacteria to multiply and become a minor population in tropical soils
Authors: Byappanahalli M. , Fujioka R.
Published: May 2018

The soil environment in Hawaii is generally characterised as sub-optimal but permissive to support the in situ growth of E. coli and enterococci. However, soil desiccation and competition for nutrients by major indigenous soil microflora have been identified as potential factors that could limit a rapid and continual growth of faecal indicator bacteria in this soil environment. Despite these limitations, the genetic capacities of E. coli and enterococci are robust enough to enable these bacteria to become established as minor populations of Hawaii's soil microflora. Although the concentrations of E. coli and enterococci may have represented a fraction of the total soil microbiota, their presence in this habitat was very significant, for two important reasons: (a) soil was a major environmental source of E. coli and enterococci, and (b) the elevated counts of these bacteria in streams that routinely exceeded the EPA standards were due to run-off from soil. As a result, E. coli and enterococci were inadequate indicators to measure the degree of faecal contamination and potential presence of sewage-borne pathogens in Hawaiian streams.
Online estimation of wastewater nitrifiable nitrogen, nitrification and denitrification rates, using ORP and DO dynamics
Authors: Spérandio M. , Queinnec I.
Published: May 2018

Biological nitrogen removal is susceptible to disturbances in activated sludge processes. Significant improvement of performances are obtained by controlling the process taking into account wastewater modifications and sludge activity. In this work a specific sensor is developed, based on oxidation-reduction potential (ORP) and dissolved oxygen (DO) measurements performed in a completely mixed reactor which can be the activated sludge basin itself. This reactor is continuously fed by wastewater and sludge issued from the recirculation stream of the process, and submitted to alternating aeration. DO profiles and ORP bending point are linked to nitrification and denitrification in the sensor. Signal dynamics are treated with a physical model for simultaneously estimating nitrifiable nitrogen concentration in wastewater, nitrification rate, and denitrification rate. Results show very good prediction of experimental oxygen profiles and the software sensor allows us to recalculate nitrate and ammonia profiles in the reactor with a good accuracy. The estimation of nitrifiable nitrogen and removal rates has been validated experimentally. The system allows us to follow highly variable influent nitrogen concentration, toxic events, and changes in the COD concentration or quality in wastewater.
Comparison of different primer sets for the RT-PCR detection of hepatitis A virus and astrovirus in mussel tissues
Authors: Romalde J.L. , Ribao C. , Luz Vilariño M. , Barja J.L.
Published: May 2018

In the present study, the efficiency of several primer sets for the RT-PCR detection of hepatitis A virus (HAV) and astrovirus from both crude viral extracts and experimentally infected shellfish tissues was evaluated. Differences were observed depending on the primer set employed in the sensitivity of amplification of both viral types. For HAV primers, HAV240/HAV68 yielded the higher sensitivity: showing a detection limit of 0.02-0.1 infectious particles/μL or mg of tissue (either crude extracts or seeded mussel tissues). Regarding detection of AsV, a better performance was observed with primer set A1/A2 achieving a sensitivity of 0.1-1 PFU/μL or mg of tissue. The results obtained in this work strongly indicated that selection of primer sets to be employed for the routine detection of enteric viruses was a critical point in the design of the RT-PCR protocols.
Preparation and characterization of activated carbon from sewage sludge: carbonization step
Authors: Rio S. , Faur-Brasquet C. , Le Coq L. , Lecomte D. , Le Cloirec P.
Published: May 2018

Sewage sludges produced from wastewater treatment plants continue to create environmental problems in terms of volume and method of valorization. Thermal treatment of sewage sludge is considered as an attractive method in reducing sludge volume which at the same time produces reusable by-products. This paper deals with the first step of activated carbon production from sewage sludge, the carbonization step. Experiments are carried out on viscous liquid sludge and limed sludge by varying carbonization temperature and heating rate. The results show that carbonized residue properties are interesting for activated carbon production.
Aerobic bacterial spores as process indicators for protozoa cysts in water treatment plants
Authors: Galofré B. , Israel S. , Dellundé J. , Ribas F.
Published: May 2018

The possibility of using aerobic spores as indicators (surrogates) of water treatment efficiency for the removal of Giardia cysts and Cryptosporidium oocysts was evaluated in a water treatment plant that supplies the Barcelona area of Spain. The water treatment consists of pre-chlorination, flocculation-sedimentation, double filtration (sand and granular activated carbon, GAC) with intermediate ozonation and post-chlorination. Aerobic spores significantly increased after GAC filtration, which indicated an active propagation of aerobic spore-formers. However, anaerobic (Clostridium) spores could be a good surrogate for Cryptosporidium oocysts, especially if their detection in samples at low concentrations was improved.
The utility of the AC/TC ratio for watershed management: a case study
Authors: Booth J. , Brion G.M.
Published: May 2018

A human-impacted watershed was monitored during the dry summer seasons in 2002 and 2003 to investigate the impact of providing access to sewer mains to local village residences. Faecal coliform concentrations were monitored at select sites along the 30-mile stretch of creek, together with faecal streptococci, enterococci and total coliforms. Analysis of the results found that levels of faecal coliforms were inadequate at identifying significant known influxes of human and animal sewage established by sanitary survey. However, the bacterial ratio of atypical colonies to total coliform colonies (AC/TC), obtained from the total coliform membrane filter assay on m-Endo media, correctly indexed human faecal impact of inadequately sewered villages located along the creek. In addition, the AC/TC ratio correctly classified the predominant source of faecal runoff in the creek headwaters as agricultural, and indicated when aged agricultural faecal material was introduced by tributaries. An approach for watershed management that uses the AC/TC ratio in addition to levels of bacteria is proposed.
Identification of cytopathogenic isolates from environmental matrices: application of analytical protocols
Authors: Casini B. , Stefani L. , Giuntini A. , Verani M. , Sigari G. , Carducci A.
Published: May 2018

This work was aimed at studying cytopathogenic agents isolated from the environment by adopting, in parallel, various techniques currently used in clinical virology. The purpose of this research was not only to identify the viral species isolated but also to verify the most reliable protocols for environmental applications.
Series of surveys for enteric viruses and indicator organisms in Tokyo Bay after an event of combined sewer overflow
Authors: Katayama H. , Okuma K. , Furumai H. , Ohgaki S.
Published: May 2018

Combined sewer overflows (CSOs) have been recognised as one of the serious sources of pollution to the water environment during rain events, although field surveys to investigate the effect of their magnitude and duration on receiving waters have been very limited. The fates of enteric viruses (norovirus G1, G2, enteroviruses) and coliforms were determined in the wastewater treatment plant on a fine day and on a rainy day. Not all microorganisms were reduced in the primary treatment, but were reduced in the secondary treatment. Occurrences of enteric viruses and levels of coliforms were surveyed in the receiving coastal area after a CSO event, with the profiles of the enteric viruses in the coastal seawater being almost at the same positive ratio for 4 d after the CSO event.
Combining direct viable count (DVC) and fluorescent in situ hybridisation (FISH) to enumerate viable E. coli in rivers and wastewaters
Authors: Garcia Armisen T. , Servais P.
Published: May 2018

In this study, a combination of the direct viable count procedure (DVC) and the FISH method was used to monitor by epifluorescence microscopy the abundance of viable E. coli in river water and wastewater samples. The DVC procedure consisted of exposing bacterial cells to a resuscitation medium containing antibiotics preventing cellular division and, thus, inducing an elongation of the viable cells. The FISH was performed using the “Colinsitu” probe specific for E. coli 16S r-RNA. Accuracy and detection limit of the epifluorescence microscopic DVC-FISH procedure were investigated. The method was then applied to river-water and wastewater samples. A good correlation was found in a log-log plot between the abundance of E. coli enumerated by a classical culture-based method (MPN method) and the DVC-FISH procedure. However, the DVC-FISH procedure gave consistently higher numbers. The ratio between both enumerations (DVC-FISH/MPN), which also indicated the ratio between viable and culturable E. coli, ranged between 2 and >30. It increased with decreasing abundance of culturable E. coli.
Salt reduction in municipal sewage allocated for reuse: the outcome of a new policy in Israel
Authors: Weber B. , Juanicó M.
Published: May 2018

Israel is presently reusing about 70% of its sewage and the buildup of salts in soils has been detected in some areas of the country. Prevention of sewage salt enrichment is one of the most immediately available solutions. The discharge of brines to municipal sewers is now prohibited and they are discharged to the sea. Discharge of brines to the sea has increased from 580,000 m3 in 1999 to more than 700,000 m3 in 2002. These salts are thus definitively taken out of the reuse cycle, year after year. The concentration of salts in industrial effluents is presently limited by the national water law and a unique regulation limiting the Boron and Sodium content in detergents has been implemented. Israeli industry has undergone a radical change in recent years. Many factories and all the hospitals have adopted K or Ca for softening and neutralization, while others have shifted to reverse osmosis. The concentration of Cl and Na in the sewage reaching treatment plants is declining. The addition of Cl to sewage has dropped from 120 mg/l to 70 mg/l. The average Boron concentration in sewage has dropped from 0.6 mg/l to 0.3 mg/l and should reach 0.2 mg/l by 2008.
Surface analysis and depth profiling of corrosion products formed in lead pipes used to supply low alkalinity drinking water
Authors: Davidson C.M. , Peters N.J. , Britton A. , Brady L. , Gardiner P.H.E. , Lewis B.D.
Published: May 2018

Modern analytical techniques have been applied to investigate the nature of lead pipe corrosion products formed in pH adjusted, orthophosphate-treated, low alkalinity water, under supply conditions. Depth profiling and surface analysis have been carried out on pipe samples obtained from the water distribution system in Glasgow, Scotland, UK. X-ray diffraction spectrometry identified basic lead carbonate, lead oxide and lead phosphate as the principal components. Scanning electron microscopy/energy-dispersive x-ray spectrometry revealed the crystalline structure within the corrosion product and also showed spatial correlations existed between calcium, iron, lead, oxygen and phosphorus. Elemental profiling, conducted by means of secondary ion mass spectrometry (SIMS) and secondary neutrals mass spectrometry (SNMS) indicated that the corrosion product was not uniform with depth. However, no clear stratification was apparent. Indeed, counts obtained for carbonate, phosphate and oxide were well correlated within the depth range probed by SIMS. SNMS showed relationships existed between carbon, calcium, iron, and phosphorus within the bulk of the scale, as well as at the surface. SIMS imaging confirmed the relationship between calcium and lead and suggested there might also be an association between chloride and phosphorus.
MIC mitigation in a 100 MW district heating peak load unit
Authors: Olesen B.H. , Lorenzen J. , Kjellerup B.V. , Ødum S. , Nielsen P.H. , Frølund B.
Published: May 2018

During inspection of AISI316 stainless steel plate heat exchangers in a district heating peak load unit, localised corrosion attacks along with indications of microbiological activity were found on the boiler side beneath patches of sturdy black deposits. Bacteria and sulphide were detected within black deposits. Thorough investigation of the boiler system revealed several incidents of localised corrosion on low alloy steel along with deposits of organic matter and bacteria primarily in places with stagnant water or places operating at a low flow rate. A relatively large amount of bacteria was detected within the system, primarily in deposits and around corrosion sites. The observations suggested the combination of deposits and bacterial activity, being the major reason for the observed corrosion. Prior to the investigation, the boiler system had operated with cat-/anion-exchanged, de-aerated water for 3 years, during which the water fulfilled strict chemical limits set to minimise corrosion. Based on these findings, the system has been modified in order to minimise the risk of microbiologically influenced corrosion and a monitoring program for fouling and corrosion has been established.
Scaling in domestic heating equipment: getting to know a complex phenomenon
Authors: Brink H. , Slaats P.G.G. , van Eekeren M.W.M.
Published: May 2018

Excessive scaling is one of the main nuisances in relation to the use of drinking water. Ever more water companies try to minimise scaling. Although scaling is an old problem, prediction of scaling has been proven to be very tricky. Traditionally, the (Langelier) Saturation Index is used to evaluate scaling properties of drinking water. From experience it is well known that this parameter is not suitable for proper prediction. New parameters have been developed and standardised for scaling prediction, namely the Calcium Carbonate Precipitation Potential, calculated at a temperature of 90°C (CCPP90); the Saturation Index, also calculated at a temperature of 90°C (SI90); the Nucleation Index (NI) and the Measured Calcium Carbonate Precipitation (MCCP). These parameters are currently successfully used in The Netherlands. The development of new parameters to predict scaling in domestic heating equipment has resulted in a better understanding of processes involved. Even now unexpected and at first sight contradictory results are obtained frequently. With the use of the developed measuring techniques, solutions may be found to combat excessive scaling.
Decontamination of wastewater contaminated by polychlorinated biphenyls (PCBs)
Authors: Kastanek F. , Kastanek P. , Demnerová K. , Maléterová Y.
Published: May 2018

Wastewater contaminated by PCBs obtained from three different sources was treated at both laboratory and pilot plant scale conditions by ultraviolet oxidation of organics at the presence of hydrogen peroxide after partial adsorption of impurities and PCBs on activated carbon and/or activated bentonite. The procedure was conducted both with and without a Fe(II) catalyst and considerable reduction of PCB concentration was achieved in both cases. In pilot plant scale experiments, activated carbon polishing step followed UV oxidation. The following three types of contaminated waste water were examined: a) aqueous extracts originated in the course of clean-up of contaminated soil by extraction with aqueous solvents. Concentrations of PCBs in extracts were between 1 μg/L to 3,000 μg/L; b) wastewater condensates originated in the process of thermal desorption of PCB from soils. Concentrations of PCBs in condensates were between 300 μg/L and 5,000 μg/L. c) underground water contaminated by PCBs extracted from the sites of old contamination. The content of PCBs was up to 50,000 ng/L. Biodegradation of PCBs with a mixture of indigenous soil bacteria (selected strains of Pseudomonas and Acitenotobacter) was also tested. It was carried out in a reactor with volume of 1.5 m3 by application of the bacteria in a slurry of bentonite with adsorbed PCBs.
Domestic wastewater reclamation by submerged membrane bioreactor with high concentration powdered activated carbon for stream restoration
Authors: Seo G.T. , Ahan H.I. , Kim J.T. , Lee Y.J. , Kim I.S.
Published: May 2018

This study focuses on the practical application of high concentration powdered activated carbon coupled membrane bio-reactor to domestic wastewater reclamation. The study was conducted in three parts, such as analysis of secondary domestic wastewater effluent, design and operation parameter evaluation and reclaimed water quality estimation for stream restoration. The organic concentration was 25.2-80.2 mgCODCr/L for the effluent of three domestic wastewater treatment plants. Around 50-75% of the COD was low molecular substances less than 1,000 which were quite biodegradable. The sawdust PAC was estimated to be proper adsorbent for the organics in the secondary effluents. Its Freundlich constant, K value was 5.847 and 1/n, 0.36. Using a system consists of single reactor with high concentration PAC (80 g/L) and submerged hollow fiber MF membrane module with nominal pore size of 0.1 μm, design and operation parameters were obtained, such as HRT of the bioreactor (2.5 hr), PAC concentration (80 g/L), the initial ßux (less than 0.5 m/day) and intermittent suction cycle (12 min. suction and 3 min. idling). Organic removal by the system was high enough to produce reclaimed water for urban stream restoration The effluent organic concentration was at the level of 2 mg/L in terms of TOC (around 5 mg/L as CODCr). Substances with molecular weight cut off <1,000 were removed mostly by adsorption and biodegradation. Those above 1,000 were rejected at PAC cake layer on the membrane and gradually degraded by microorganisms during extended contact.
Scaling of process equipment by saline streams - challenges ahead
Authors: Sheikholeslami R.
Published: May 2018

Scaling is a major problem and bottleneck in operation of all types of equipment used for handling and/or processing saline streams. The challenge is to be able to determine the criteria to define and predict the onset and rate of scale formation. Even though precipitating salts co-exist in industrial water systems, due to the complexity of the fouling process, research has primarily been concentrated on a single salt precipitation. And solubility concentrations obtained for single salt crystallization have been used as a measure of scaling potential in actual practical situations and usually not with much success. This paper critically assesses the current practices and shows based on the recent work by the author's research group that the thermodynamics and kinetics of single salt crystallization are not applicable to practical conditions of feed water when a mixture of salts is present. Presence of other species, salinity effects and even presence of trace components could have a detrimental effect on scaling potential of given water and cannot be ignored. Application of Debye Huckle theory or a modified version of that though essential, is not sufficient.
Contribution of the colmation layer to the elimination of coliphages by slow sand filtration
Authors: Dizer H. , Grützmacher G. , Bartel H. , Wiese H.B. , Szewzyk R. , López-Pila J.M.
Published: May 2018

River bank or slow sand filtration is a major procedure for processing surface water to drinking water in central europe. In order to model the performance of river bank and slow sand filtration plants, we are studying the different mechanisms by which the elimination of pathogens is realized. An important question concerning the mode of action of slow sand filters and river bank filtration units is the role of the colmation layer or “schmutzdecke” on the elimination of human pathogens. The schmutzdecke is an organic layer which develops at the surface of the sand filter short after the onset of operation. We have inoculated a pilot plant for slow sand filtration with coliphages and determined their rate of breakthrough and their final elimination. In the first experiment, with a colmation layer still missing, the breakthrough of the coliphages in the 80 cm mighty sandy bed amounted to ca. 40%. In contrast, less than 1% of coliphages escaped from the filter as the same experiment was repeated two months later, when a substantial colmation layer had developed. Our preliminary conclusions are that the colmation layer is extremely efficient in eliminating of viruses.
Water reuse in the Apatlaco River Basin (México): a feasibility study
Authors: Moeller-Chavez G. , Seguí-Amórtegui L. , Alfranca-Burriel O. , Escalante-Estrada V. , Pozo-Román F. , Rivas-Hernández A.
Published: May 2018

The aim of this work is to determine the technical and economic feasibility of implementing different reclamation and reuse projects that improve the quality of the Apatlaco river basin located in the central part of Mexico. A special methodology based on a decision support system was developed. This methodology allows to decide if it is convenient or not to finance a reclamation or reuse project for the most common water uses in the basin. This methodology is based on the net present value criteria (NPV) of the effective cash flow during the useful life of the project. The results obtained reveal a technical and economical feasibility for industrial reuse in Jiutepec and for agricultural reuse in Zacatepec and Emiliano Zapata. On the other hand, sanitation projects are not feasible in all cases analyzed. Therefore, Mexican Regulation (Ley Federal de Derechos en Materia de Agua) as currently implemented, does not promote and support this kind of projects.
Modelling nutrient fluxes from diffuse and point emissions to river loads: the Estonian part of the transboundary Lake Peipsi/Chudskoe drainage basin (Russia/Estonia/Latvia)
Authors: Mourad D. , van der Perk M.
Published: May 2018

First results are presented of a large-scale GIS-based nutrient transport modelling for the 1985-1999 period in the Estonian part of the transboundary drainage basin of Lake Peipsi (Estonian)/Chudskoe (Russian), one of the largest lakes in Europe, shared by Russia and Estonia. Although the lake is relatively undisturbed by human pollution, it is vulnerable for eutrophication by increased river loads, as shown in the past, when the north-eastern part of the former Soviet Union suffered from intensive agriculture. The collapse of the Soviet Union caused a dramatic decline in fertilizer application rates and widespread abandonment of agricultural land. Although concentration measurements and modelling results indicate a general decrease in nutrient loads, modelling is complicated by the transfer of nutrients from diffuse emissions, which is strongly governed by retention and assumed periodic release from storages within the river basin, like the root zone, tile drains, ditches, channels, bed sediments, floodplains and lakes. Modelling diffuse emission contribution to river loads can be improved by better knowledge about the spatial and temporal distribution of this retention and release within the drainage basin.
The fate of metals in forest industry wastewater treatment systems
Authors: Bryant C.W. , Pagoria P.S.
Published: May 2018

The capture/removal of a range of metals was estimated for a number of pulp and paper wastewater treatment systems. Both long-term wastewater data and accumulated sludge data were examined. Only copper and lead were effectively captured (greater than 50%) by all sites and estimate methods. Zinc capture exceeded 50% in all but one case. Qualitatively, iron, aluminium, cadmium, and cobalt were usually captured to a significant extent. The sludge inventory-based approach and the wastewater system inlet-outlet approach gave reasonably similar capture estimates.
Impact of nitrogen reduction measures on nitrogen surplus, income and production of German agriculture
Authors: Gömann H. , Kreins P. , Müller C.
Published: May 2018

Among the numerous non-point sources of diffuse water pollution with nitrogen, agriculture is counted one of the main sources. The agricultural policies of the Agenda 2000 and a decoupling of direct payments for farmers from their production decisions are exemplarily evaluated as nitrogen reduction measures using the Regional Agricultural and Environmental Information System RAUMIS. The results show that until the target year 2010 the risk of diffuse pollution of water bodies with nitrogen is a regional problem in Germany. These problems are neither mitigated by the policies of Agenda 2000 nor by a decoupling of direct payments from production decisions of farmers. While total nitrogen surplus reduces considerably after a decoupling of direct payments due to decreases of land-use the nitrogen surplus on the remaining cultivated area increases resulting from structural changes. Granting the same amount of direct payments to farmers in both policy alternatives the agricultural sector income would be higher after a decoupling of direct payments opposed to the Agenda 2000 resulting from a more efficient allocation of inputs.