bluuebunny/crossref_metadata_2025 huggingface dataset:
Watershed monitoring to address contamination source issues and remediation of the contaminant impairments
Authors: Barnes P. L. , Kalita P. K.
Published: May 2018

The Big Blue River Basin is located in southeastern Nebraska and northeastern Kansas and consists of surface water in the Big Blue River, Little Blue River, Black Vermillion River, and various tributaries draining 24,968 km2. Approximately 75% of the land area in the basin are cultivated cropland. The Big Blue River flows into Tuttle Creek Reservoir near Manhattan, Kansas. Releases from the lake are used to maintain streamflow in the Kansas River during low flow periods, contributing 27% of the mean flow rate of the Kansas River at its confluence with the Missouri River. Tuttle Creek Reservoir and the Kansas River are used as sources of public drinking water and meet many of the municipal drinking water supply needs of the urban population in Kansas from Junction City to Kansas City. Elevated concentrations of pesticides in the Big Blue River Basin are of growing concern in Kansas and Nebraska as concentrations may be exceeding public drinking water standards and water quality criteria for the protection of aquatic life. Pesticides cause significant problems for municipal water treatment plants in Kansas, as they are not appreciably removed during conventional water treatment processes unless activated carbon filtering is used. Pesticides have been detected during all months of the year with concentrations ranging up to 200 μg/l. If high concentration in water is associated with high flow conditions then large mass losses of pesticides can flow into the water supplies in this basin. This paper will investigate the use of a monitoring program to assess the non-point source of this atrazine contamination. Several practices will be examined that have shown ability to remediate or prevent these impairments.
Evaluation of pH inhibition effect on activated sludge by the pseudo toxic concentration (CPT) concept model
Authors: Ko J. H. , Choi K. S. , Woo H. J. , Lee H. I. , Kim C. W.
Published: May 2018

It is generally accepted that the inhibition effect of pH on activated sludge follows the non-competitive inhibition kinetics. But the non-competitive inhibition kinetic equation cannot be directly applied to pH inhibition, due to the difficulty in quantification of pH as a term of inhibitor concentration. So, many empirical equations were developed especially for acidic condition to describe pH inhibition effect. In this research, the pseudo toxic concentration (CPT) concept model to quantify pH inhibition effect on activated sludge was proposed and compared with other existed models. Prediction of performance, presented by Prediction Accuracy and Prediction Accuracy Index, showed that the CPT concept model can explain the reduction of the maximum specific growth rate (μmax) more accurately than any other models do at a wide range of pH. The CPT concept model was applicable not only to activated sludge but also to specific microorganism groups, such as nitrifier, less acidophilic species and nitrifying biofilm.
Stochastic structures between quantity and quality responses of rainfall-runoff at an upland agricultural watershed
Authors: Kim S. H. , Delleur J. W.
Published: May 2018

The causality between hydrologic parameters and water quality variations has been studied for a small upland agricultural watershed using a time-series analysis approach. The stage at the outlet of the watershed, which is a proxy for the outflow, and the average saturation deficit, which is a surrogate for the groundwater level, were used as hydrologic variables. The stages were measured at a triangular weir at the watershed outlet. The saturation deficits were obtained by means of a rainfall-runoff simulation model for agricultural upland watersheds (an extended version of TOPMODEL). Sequential water quality data were also collected at the watershed outlet. A systematic procedure for testing the causality between the hydrologic and water quality time-series is presented and used to investigate possible relationships between the two systems. The stochastic structure of a causality between hydrologic and water quality systems is shown. This stochastic structure is associated not only with the transport pathways (surface or subsurface) of each water quality parameter but also with the characteristics of the rainfall events.
Water quality of a reservoir as affected by agriculture in the east of Thailand: a preliminary study
Authors: Tonmanee N. , Wada H.
Published: May 2018

A preliminary study on the water quality of a reservoir, affected by agriculture, in the east of Thailand was conducted during 1996-1997. Monitoring water quality of a reservoir is important because the sloping lands surrounding the reservoirs are mainly utilized for cultivating cash crops (pineapple, cassava, etc). A lot of fertilizers and agrochemicals were applied to soil and crops which can polluted the water . The results from the preliminary studied will be applied for the monitoring of the water quality in other reservoirs in the 16 pilot areas.
Supervisory control of wastewater treatment plants by combining principal component analysis and fuzzy c-means clustering
Authors: Rosen C. , Yuan Z.
Published: May 2018

In this paper a methodology for integrated multivariate monitoring and control of biological wastewater treatment plants during extreme events is presented. To monitor the process, on-line dynamic principal component analysis (PCA) is performed on the process data to extract the principal components that represent the underlying mechanisms of the process. Fuzzy c-means (FCM) clustering is used to classify the operational state. Performing clustering on scores from PCA solves computational problems as well as increases robustness due to noise attenuation. The class-membership information from FCM is used to derive adequate control set points for the local control loops. The methodology is illustrated by a simulation study of a biological wastewater treatment plant, on which disturbances of various types are imposed. The results show that the methodology can be used to determine and co-ordinate control actions in order to shift the control objective and improve the effluent quality.
Advanced monitoring and control of anaerobic wastewater treatment plants: fault detection and isolation
Authors: Steyer J-Ph , Genovesi A. , Harmand J.
Published: May 2018

In this paper, a fault detection and isolation approach using fuzzy logic is described for on-line analysis of problems occurring in anaerobic digestion processes. The measurements available on the process are preprocessed to build a vector of fault residuals indicating the magnitude of the problems. This vector is classified into a prespecified category (i.e., a class) which is a state of the system, according to discrimination fuzzy rules. Three different types of classes were defined in a hierarchical structure : sensors faults, sub-process faults and process faults. This approach was developed to handle in real time both technical and biological problems. Demonstration of the practical interest of this study was made using real life experiments and large improvement of the reliability and safety of the process was obtained, thus optimizing the overall wastewater treatment.
Water quality management planning zone development by introducing a GIS tool in Kathmandu valley, Nepal
Authors: Ha S.-R. , Pokhrel D.
Published: May 2018

This research was conducted to identify the critical pollution (BOD, TN, TP) areas and to develop the priority mitigation zone for the Bagmati River pollution in the Kathmandu valley, Nepal. A GIS tool was used to define and identify the critical pollution areas and sources. Pollution source information such as population, livestock, industry and land use were collected on the basis of the individual village boundary. The industrial, land use and living pollution were aggregated by the GIS overlay analysis capability to obtain the combined pollution load within the watershed. Priority areas for the mitigation of the pollution were defined considering the pollution loading rate, distance of stream from pollution source, and political, religious, and touristic values of the area. This research noticed that Kathmandu, Lalitpur and Bhaktapur municipalities are the major polluting areas and living beings are the major factors of Bagmati River pollution. Delivery ratio for the watershed was found to vary from 40-69% for BOD and nitrogen but the delivery of phosphorus was exceptionally high (92% at Gaurighat and 77% at Chovar) due to cremation activity of the Hindu religion on the riverbanks. Thus, the priority areas for the mitigation of the carbonaceous and nutrient source pollution were identified. At present the land use and industry impaired a very low contribution compared to the huge pollution load from the municipalities to the river system.
Identification of model structure for aquatic ecosystems using regionalized sensitivity analysis
Authors: Osidele O. O. , Beck M. B.
Published: May 2018

The Regionalized Sensitivity Analysis (RSA) was developed in 1978, for identifying critical unknown processes in poorly defined systems, thus directing the focus of further scientific investigations. Here, we demonstrate its application to model structure identification, by ranking the constituent hypotheses and identifying the critical elements for progressive revision of the model. Our case study is Lake Oglethorpe - a small monomictic impoundment in South-eastern Georgia, USA. Recent studies indicate that the warm temperate regional climate affords an extended growing season - typically from March to October - which promotes bacterial productivity in the lake. The result is a summer food web dominated by microbial processes, in contrast to the conventional phytoplankton-dominated food chains typically observed in the cold temperate lakes of Europe and North America. Starting with a simple phytoplankton-based food web model and a qualitative definition of system behaviour, we use the RSA procedure to establish the critical role of bacteria-mediated decomposition in Lake Oglethorpe, thus justifying the inclusion of microbial processes. Further analysis reveals the importance of size-dependent selective consumption of phytoplankton and bacteria. Finally, we discuss important practical implications of this novel application of the RSA regarding sampling efficiency and statistical robustness.
A systematic approach to error isolation in computerized wastewater simulation models
Authors: Lennox J. A. , Yuan Z. , Harmand J.
Published: May 2018

Activated sludge models are used extensively in the study of wastewater treatment processes. While various commercial implementations of these models are available, there are many people who need to code models themselves using the simulation packages available to them. Quality assurance of such models is difficult. While benchmarking problems have been developed and are available, the comparison of simulation data with that of commercial models leads only to the detection, not the isolation of errors. To identify the errors in the code is time-consuming.

In this paper, we address the problem by developing a systematic and largely automated approach to the isolation of coding errors. There are three steps: firstly, possible errors are classified according to their place in the model structure and a feature matrix is established for each class of errors. Secondly, an observer is designed to generate residuals, such that each class of errors imposes a subspace, spanned by its feature matrix, on the residuals. Finally, localising the residuals in a subspace isolates coding errors. The algorithm proved capable of rapidly and reliably isolating a variety of single and simultaneous errors in a case study using the ASM1 activated sludge model. In this paper a newly coded model was verified against a known implementation. The method is also applicable to simultaneous verification of any two independent implementations, hence is useful in commercial model development.
An overview of the posters presented at Watermatex 2000. III: Model selection and calibration/optimal experimental design
Authors: Nopens I. , Hopkins L. N. , Vanrolleghem P. A.
Published: May 2018

This paper presents an overview of the posters presented in sessions 7 and 8 of the Watermatex 2000 conference. These posters present two aspects of modelling biological processes - model selection and calibration. Special attention is given to the papers on OED (Optimal Experimental Design), which is a method of optimising the data collection for model selection and calibration. The presence of these presentations at the conference highlights the continuing significance of modelling and stresses the requirement of improvements in modelling techniques. The papers provide some contribution to this end.
Using lessons learned and advanced methods to design a 1,500 Ml/day DAF water treatment plant
Authors: Crossley I. A. , Valade M. T. , Shawcross J.
Published: May 2018

The paper describes the method that led to the design of the 1,500 Ml/day dissolved air flotation (DAF) water treatment plant for Boston's water supply. In particular, the topics of flocculation techniques, floated solids removal and DAF recycle as they relate to very large capacity plant design are covered in detail. The use of mathematical models, including computational fluid dynamics (CFD) software, to refine the design is described.
Industrial applications of new sulphur biotechnology
Authors: Janssen A.J.H. , Ruitenberg R. , Buisman C.J.N.
Published: May 2018

The emission of sulphur compounds into the environment is undesirable because of their acidifying characteristics. The processing of sulphidic ores, oil refining and sulphuric acid production are major sources of SO2 emissions. Hydrogen sulphide is emitted into the environment as dissolved sulphide in wastewater or as H2S in natural gas, biogas, syngas or refinery gases. Waste streams containing sulphate are generated by many industries, including mining, metallurgical, pulp and paper and petrochemical industries.

Applying process technologies that rely on the biological sulphur cycle can prevent environmental pollution. In nature sulphur compounds may cycle through a series of oxidation states (-2, 0, +2, +4, +6). Bacteria of a wide range of genera gain metabolic energy from either oxidising or reducing sulphur compounds. Paques B.V. develops and constructs reactor systems to remove sulphur compounds from aqueous and gaseous streams by utilising naturally occurring bacteria from the sulphur cycle. Due to the presence of sulphide, heavy metal removal is also achieved with very high removal efficiencies. Ten years of extensive laboratory and pilot plant research has, to date, resulted in the construction of over 30 full-scale installations. This paper presents key processes from the sulphur cycle and discusses recent developments about their application in industry.
Dissolved air flotation treatment of concentrated fish farming wastewaters
Authors: Jokela P. , Ihalainen E. , Heinänen J. , Viitasaari M.
Published: May 2018

Fish farming wastewaters contain nutrients, phosphorus and nitrogen, which promote eutrophication in the typically shallow farming sites in Finland. Fish farming wastewater treatment is problematic because of large quantities of very dilute wastewater (200 – 600 m3/kg fish produced). In practice wastewater treatment is concentrated on suspended solids removal. Treatment can be done in two steps: concentration of the very dilute wastewater and subsequent treatment of the concentrated wastewater. Dissolved air flotation pilot trials were conducted using two types of concentrated wastewaters: settled solids from a sludge hopper of a cultivation basin and swirl separator concentrate. Two different pilot plants were used and performances compared. Both mechanical treatment and precipitation by ferric salts were applied. Depending on the influent quality, 70 to 90% phosphorus reductions were achieved without chemicals. Chemical precipitation and flotation produced 90% phosphorus reductions and effluent concentrations at the level of 0.05 mgP/l when 13 m3/(m2h) hydraulic loading was used.
Experimental and modeling evaluation of upward and downward velocities in the coaxial flotation column
Authors: Park K. , Cho J.-M. , Oh J. , Chung K.
Published: May 2018

This study was conducted to show the influence of upward velocity in the inner column and downward velocity in the outer column of the coaxial cylinder-type flotation column on the solids removal efficiency, solids concentration in the treated water, and so on. The SIMPLE (Semi-Implicit Method for Pressure Linked Equation) solution was applied to the coaxial flotation column to simulate the velocity vectors of the elements of water flowing in the column. The effects of solids loading and residence time in the agglomerate separation zone on the solids removal efficiency were also tested.

In the pilot scale coaxial DAF column experiments with solids concentration of 1,000–2,000 mg of SS per liter and solids loading less than 350 kg/m2/day, approximately 90% of the solids removal efficiencies were obtained using the upward velocity of up to 110 cm/min in the contact zone of the inner column and the downward velocity of up to 30 cm/min in the outer column. In the simulation, similar results were observed as in the experiments. The solids loading in the excess of 350 kg/m2/day caused the instability of the sludge float layer and aggravated the quality of the treated water.
Interlaboratory comparison of dynamic olfactometry in Central Europe 2000
Authors: Mannebeck D. , Mannebeck H.
Published: May 2018

This paper presents the results of an interlaboratory comparison (ringtest) on olfactometry with 31 participants from four countries in Central Europe. The aim was to give evidence of the performance of dynamic olfactometry on the basis of the European Standard prEN 13725 (Draft) “Determination of odour concentration with dynamic olfactometry”. The test included the analysis of three individual substances (n-butanol, hydrogen sulphide, tetrahydrothiophen) as well as a natural odour mixture (coffee flavour) to compare mean values and the standard deviations of results for the investigated samples. It was confirmed that laboratories working in compliance with the requirements of the new standard achieve a significantly better repeatability and reproducibility than those that are not compliant.
Community and connectivity: summary of a community based monitoring program set up to assess the movement of nutrients and sediments into the Great Barrier Reef during high flow events
Authors: Devlin M. , Waterhouse J. , Brodie J.
Published: May 2018

The Great Barrier Reef (GBR) system encompasses the largest system of corals and related life forms anywhere in the world. The health of this extensive system, particularly the inshore area, is dependent on the relationship between the GBR and adjacent coastal catchments. The major impact of agricultural practices on the GBR is the degradation of water quality in receiving (rivers) waters, caused by increased inputs of nutrients, suspended sediments and other pollutants. For the past three years, the Great Barrier Reef Marine Park Authority (GBRMPA) has been involved with the co-ordination of a river-monitoring program, specifically targeting the sampling of rivers during flood events. Representative sites were set up along two North Queensland rivers, the Russell-Mulgrave and Barron Rivers. This monitoring program is run in conjunction with the Queensland Department of Natural Resources' Waterwatch program. The program involves intensive sampling of first flush, extreme flow and post flood conditions over the two rivers. Extreme flow conditions are sampled over a limited time span (48 hours) with trained volunteers at 4-hour intervals. Concentrations measured in the flood events are dependent on landuse characteristic, and extent of flow. Concentrations of dissolved and particulate nutrients are higher if the extreme flow event is part of the first flush cycle. Concentrations of DIN and DIP measured before, during and after a major flood event suggest that there is a large storage of inorganic material within the Barron and Russell-Mulgrave agricultural subcatchments that move over a period of days, and perhaps weeks. This program created a forum in which GBRMPA liased with the Barron and Russell-Mulgrave community about the connectivity existing between the river and the Great Barrier Reef lagoon.
Predicting odour impact using the Austrian odour dispersion model (AODM)
Authors: Schauberger G. , Piringer M.
Published: May 2018

Using a dispersion model to calculate ambient odour concentrations, the separation distance between livestock buildings and residential areas is defined by the odour impact criteria using a combination of a pre-selected odour threshold and an exceeding probability. The dynamic Austrian Odour Dispersion Model (AODM), a Gaussian model, is used to calculate the direction-dependent separation distances for several combinations of these two values, which represent the protection level of various land use categories. The calculated direction-dependent separation distances are a function of the prevailing wind velocity and atmospheric stability conditions. At a site in the Austrian North-alpine foreland, the direction-dependent separation distance (calculated on the basis of a two year time series of meteorological data) for pure residential areas (3% exceeding probability over the year for an odour threshold of 1 OU/m3) lies between 99 m (for northerly winds with a probability of less than 3%) and 362 m (for westerly winds with a probability of 34%). For west and east the main wind directions, odour sensation can be expected more often for higher wind velocities and a neutral or stable atmosphere around sunset. Northerly and southerly winds show the typical diurnal variation of a local valley wind system with predominantly northerly daytime up-valley and southerly night-time down-valley winds.
Influence of different pig housing systems on odor emissions
Authors: Gallmann E. , Brose G. , Hartung E. , Jungbluth T.
Published: May 2018

The odor emissions from two different housing systems were determined during three fattening periods from October 1999 to November 2000 by analyzing weekly samples by means of dynamic olfactometry. The objects of the investigations were a standard housing system with fully slatted floor and forced ventilation (FF) compared with a kennel housing system with natural shaft ventilation (KN) in parallel operation. Only little data but with a wide range of odor emission values are available from the literature and these are difficult to compare and interpret, because of missing standards in presenting the results and experimental conditions. Therefore minimum requirements for measuring odor emissions from livestock buildings have been derived. In the scope of the measurements during the first two fattening periods (October 1999 to June 2000), no differences in odor emissions could be determined with mean values related to the livestock units (1 LU = 500 kg life weight) of 85 (FF) / 87 (KN) in period A and 60 (FF) / 61 (KN) (OU/s)LU−1 in period B. The overall range of the results of all measurements in periods A and B was 4 to 355 (OU/s)LU−1. In period C (August-November 2000), the system FF showed higher odor emissions with 193 (28-550) compared to system KN with 105 (25-218) (OU/s)LU−1. The air flow rates and odor concentrations at the three different naturally ventilated exhaust shafts of system KN differed considerably from each other. Odor measurement techniques with a higher temporal resolution than olfactometry are necessary to give evidence for the main factors influencing the odor formation and release.
Biofilters - the influence of different filter materials and different operating conditions on the reduction efficiency
Authors: Hartung E. , Martinec M. , Jungbluth T.
Published: May 2018

A series of biofilter materials were tested for performance efficiency in treating ventilation air from pig sheds. Two different phases were conducted. In phase A five different biofilter materials were tested with the aim of selecting the best material regarding the odor reduction and over all efficiency. In conclusion of phase A, biochips, a new filter material, was selected due to its high average odor reduction (81%) in combination with a very low flow resistance (less than 30 Pa for filter volume loads of 600 m3 h−1 m−3). In phase B, biochips and coconut fiber peat were tested under different operating conditions. Biofilters number 3 and 4 each with down-flow air supply could realize a higher average odor reduction than biofilter 5 with up-flow air supply. All three filter materials had the same moisture, however the two biofilters with down-flow air supply showed a more homogenous moisture distribution but they also used approximately three times more water than biofilter 5. Like in phase A the specific odor cleaning efficiency was mainly influenced by the specific odor loading rate and showed only slight differences between the five biofilters differing in bulk layer height (0.5 m and 1.0 m) and air supply mode. All in all the investigation showed that the efficiency of biofilters can be optimized by using an new filter material and a appropiate operating mode.
Laboratory investigation of supported permeable organic covers for the management of odour emissions from anaerobic piggery waste ponds
Authors: Hudson N. , Casey K. , Melvin S. , Nicholas P.
Published: May 2018

Australian research has linked much of the odour arising from intensive livestock operations to pond treatment systems. A reduction in emissions from treatment ponds would therefore generally reduce odour emissions from intensive livestock operations. Published data indicates that the application of straw and other biological materials to effluent pond surfaces as a continuous cover reduces odour emissions. The effectiveness of these covers has not, however, been researched under controlled conditions. Using locally available materials, the efficacy of supported covers has been investigated using a series of laboratory anaerobic digesters treating typical piggery effluent. Research to date has focused on:•identifying effective cover and cover support materials;•quantifying odour reduction;•• identifying the impact use these covers may have on greenhouse gas emissions;•• devising practical and effective methods for constructing these covers.Results have confirmed that a variety of cover materials are effective in reducing pond odour emissions. Supporting the pond cover appears to extend the cover life expectancy. While greenhouse gas emissions appear to vary according to cover type, the overall significance of these emissions is not yet clear. The impact of permeable pond covers on overall pond performance requires additional research.
Possibilities to improve the quality of wastewater sludges
Authors: Balmér P.
Published: May 2018

Falling heavy metal concentrations in wastewater sludges are an indicator of the improvements in sludge quality achieved over the past thirty years. Studies of the sources of heavy metals in wastewater sludges, particularly the loads introduced by domestic and industrial wastewater and storm water, show the potential improvement that may still be made.
Strategies for development of industrial wastewater reuse in Thailand
Authors: Visvanathan C. , Cippe A.
Published: May 2018

Majority of the industrial activities in Thailand are concentrated around Bangkok Metropolitan Area. The ever increasing industrial activities have led to over exploitation of water resources and discharge of significant pollution load. Therefore, it is important to identify the wastewater reuse potentials and develop strategies for its promotion within the industrial sector. Although technological advances have made it possible to treat effluents for industrial re-use, in practice, the Thai industries do lack in implementation of such technologies. Promotion of cleaner production concepts and advanced new technologies such as membrane technologies could assist the industry for the implementation of wastewater reuse projects in Thailand. This paper discusses various technical, institutional and management related issues to promote industrial wastewater reuse, with few case studies.
Small scale water recycling systems - risk assessment and modelling
Authors: Diaper C. , Dixon A. , Butler D. , Fewkes A. , Parsons S. A. , Strathern M. , Stephenson T. , Strutt J.
Published: May 2018

This paper aims to use quantitative risk analysis, risk modelling and simulation modelling tools to assess the performance of a proprietary single house grey water recycling system. A preliminary Hazard and Operability study (HAZOP) identified the main hazards, both health related and economic, associated with installing the recycling system in a domestic environment. The health related consequences of system failure were associated with the presence of increased concentrations of micro-organisms at the point of use, due to failure of the disinfection system and/or the pump. The risk model was used to assess the increase in the probability of infection for a particular genus of micro-organism, Salmonella spp, during disinfection failure. The increase in the number of cases of infection above a base rate rose from 0.001% during normal operation, to 4% for a recycling system with no disinfection. The simulation model was used to examine the possible effects of pump failure. The model indicated that the anaerobic COD release rate in the system storage tank increases over time and dissolved oxygen decreases during this failure mode. These conditions are likely to result in odour problems.
A methodology to evaluate water and wastewater treatment plant reliability
Authors: Eisenberg D. , Soller J. , Sakaji R. , Olivieri A.
Published: May 2018

Evaluating the reliability of treatment processes and treatment facilities should be an important part of the planning and design process for water resource, wastewater treatment, and particularly wastewater reuse projects. With the recent developments in technology, particularly the development of membrane processes and alternative disinfection processes for water and wastewater treatment, there is an increasing need for a common methodology to evaluate the reliability of alternative processes and treatment facilities that utilize different combinations of those processes. To assess the reliability of a treatment facility, several aspects of treatment must be considered including a methodical evaluation of both mechanical reliability and plant performance. A straightforward method for conducting these types of analyses is described herein along with a description of applications of this methodology. A discussion is provided highlighting the value of such a methodology for both the water quality engineer and the risk manager.
Sludge pipeline design
Authors: Slatter P.T.
Published: May 2018

The need for the design engineer to have a sound basis for designing sludge pumping and pipelining plant is becoming more critical. This paper examines both a traditional text-book approach and one of the latest approaches from the literature, and compares them with experimental data. The pipelining problem can be divided into the following main areas; rheological characterisation, laminar, transitional and turbulent flow and each is addressed in turn. Experimental data for a digested sludge tested in large pipes is analysed and compared with the two different theoretical approaches. Discussion is centred on the differences between the two methods and the degree of agreement with the data. It is concluded that the new approach has merit and can be used for practical design.
Removal of microorganisms in different stages of wastewater treatment for Mexico City
Authors: Jiménez B. , Chávez A. , Maya C. , Jardines L.
Published: May 2018

In this study the removal of a diversity of microorganisms during different stages of treatment was evaluated. The process scheme consisted of Advanced Primary Treatment (APT), sand filtration, and chlorine disinfection. During the first 2 stages, fecal coliforms were reduced from 1.24×109 to 1.2×108 MPN/100 mL and helminth ova were reduced to less than 1 ova/L. Nevertheless, to obtain an effluent water quality that meets the microbiological standards recommended by the World Health Organization (1989) and the Mexican norm for water destined for agricultural reuse it was necessary to disinfect the effluent with a chlorine dose of 12 mg/L for a 3 hour contact time. Under these conditions, fecal coliforms were reduced from 1.2×109 to 5.8×101 MPN/100 mL, Salmonella spp. from 5.0×108 MPN/100 mL to below the detection limit, Pseudomonas aeruginosa from 2.0×105 MPN/100 mL to below the detection limit, and protozoan cysts from 1052 to 31 cysts/L. Regrowth of bacteria was never observed during the 48 hours period following disinfection. The active chlorine was primarily in the form of chloramines thus reducing the formation of other potentially carcinogenic disinfection byproducts.
Increasing the fertilizer value of palm oil mill sludge: bioaugmentation in nitrification
Authors: Onyla C.O. , Uyub A.M. , Akunna J.C. , Norulaini N.A. , Omar A.K.M.
Published: May 2018

Malaysia is essentially an agricultural country and her major polluting effluents have been from agro-based industries of which palm oil and rubber industries together contribute about 80% of the industrial pollution. Palm oil sludge, commonly referred to, as palm oil mill effluent (POME) is brown slurry composed of 4-5% solids, mainly organic, 0.5-1% residual oil, and about 95% water. The effluent also contains high concentrations of organic nitrogen. The technique for the treatment of POME is basically biological, consisting of pond systems, where the organic nitrogen is converted to ammonia, which is subsequently transformed to nitrate, in a process called nitrification. A 15-month monitoring program of a pond system (combined anaerobic, facultative, and aerobic ponds in series) confirmed studies by other authors and POME operators that nitrification in a pond system demands relatively long hydraulic retention time (HRT), which is not easily achieved, due to high production capacity of most factories. Bioaugmentation of POME with mixed culture of nitrifiers (ammonia and nitrite oxidizers) has been identified as an effective tool not only for enhancing nitrification of POME but also for improving quality of POME as source of liquid nitrogen fertilizer for use in the agricultural sector, especially in oil palm plantations. Nitrate is readily absorbable by most plants, although some plants are able to absorb nitrogen in the form of ammoniun. In this study, up to 60% reduction in HRT (or up to 20% reduction in potential land requirement) was achieved when bioaugmentation of POME was carried out with the aim of achieving full nitrification.
Determination of the critical pressure drop for filtration of super-compactible cakes
Authors: Tiller F.M. , Li W.P. , Lee J.B.
Published: May 2018

In accord with Darcy's law, the flow rate through a porous bed depends upon the pressure drop Δpc. In general, increasing Dpc leads to increased values of flow rate and average percentage solids in filtration operations. When cakes become super-compactible, their behavior undergoes an unexpected change in which both the flow rate and the percentage solids reach maximum values and thereafter are unaffected by increasing Δpc. The critical pressure drop ΔpcR is defined as that value at which the flow rate reaches 90% of its ultimate value. When Δpc is greater than DpcR and is doubled or tripled, the cake resistance approximately doubles or triples leaving the rate virtually unchanged. The super-compactibility problem is analyzed theoretically, and is verified by stepped pressure filtration experiments on different materials from Houston and Korea.
Properties of flocs produced by water treatment coagulants
Authors: Gregory J. , Dupont V.
Published: May 2018

Hydrolyzing coagulants are extensively used in water and wastewater treatment, often under conditions where hydroxide precipitation is important, giving “sweep flocculation”. Pre-hydrolyzed coagulants, such as polyaluminium chloride (PACl) are also widely used and have several advantages over traditional additives, such as aluminium sulfate. Their action is usually discussed in terms of cationic species and charge neutralization. However, precipitation may also be important and this aspect has not been considered in detail. The present work has compared the action of alum and three commercial PACl products on model clay suspensions. The conventional jar test procedure has been used, along with measurements of settled floc volume and dynamic monitoring of floc formation and break-up by an optical technique. The latter method gives very useful information on the nature of the flocs produced and their response to different shear conditions. It is clear from the results that the PACl products form larger and stronger flocs than alum. With all coagulants floc breakage appears to be essentially irreversible. Sediment volumes are slightly lower for flocs produced by PACl than by alum, but the value is proportional to the dosage in all cases.
Water recycling at the Millennium Dome
Authors: Hills S. , Smith A. , Hardy P. , Birks R.
Published: May 2018

Thames Water is working with the New Millennium Experience Company to provide a water recycling system for the Millennium Dome which will supply 500m3/d of reclaimed water for WC and urinal flushing. The system will treat water from three sources:rainwater - from the Dome roofgreywater - from handbasins in the toilet blocksgroundwater - from beneath the Dome site

The treatment technologies will range from “natural” reedbeds for the rainwater, to more sophisticated options, including biological aerated filters and membranes for the greywater and groundwater. Pilot scale trials were used to design the optimum configuration. In addition to the recycling system, water efficient devices will be installed in three of the core toilet blocks as part of a programme of research into the effectiveness of conservation measures. Data on water usage and customer behaviour will be collected via a comprehensive metering system. Information from the Dome project on the economics and efficiency of on-site recycling at large scale and data on water efficient devices, customer perception and behaviour will be of great value to the water industry. For Thames Water, the project provides vital input to the development of future water resource strategies.
Particle size analysis as a tool for performance measurements in high rate effluent filtration
Authors: van der Graaf J. H. J. M. , de Koning J. , Tang J.
Published: May 2018

In the Netherlands almost all wastewater treatment plants have been redesigned and adapted in order to remove nitrogen, phosphorus and suspended solids to a very low level. The improved effluent quality leads to a growing interest in the reuse of effluent of the modernised wastewater treatment plants. This again results in investigations on filtration techniques as deep bed filtration and membrane filtration. At the wastewater treatment plant Ede research was done on deep bed filtration in order to develop relations between particle removal and filter performance and to explore ways of optimization.

The results of the experiments are rather typical for effluent of modern Dutch wastewater treatment plants. The very low concentrations of suspended solids and precipitable substances result in poor flocculating properties.

From turbidity measurements it may be concluded that the best results were obtained with a dosage of flocculant. However, the particle size measurements indicated the opposite. Suspended solids calculations, based on the particle volume distributions, showed a better removal without a dosage of flocculant. From this it is concluded that a dosage of coagulant (Fe3+ or Al3+) has an adverse effect on the removal efficiencies even at low dosages (1 mg/l).
A modification to the Activated Sludge Model No. 2 based on the competition between phosphorus-accumulating organisms and glycogen-accumulating organisms
Authors: Manga J. , Ferrer J. , Garcia-Usach F. , Seco A.
Published: May 2018

A modification to the ASM2 is proposed which permits representation of the competition between phosphorus accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) in a nutrient removal activated sludge system. Some important aspects, which are not considered in ASM2, are discussed. The proposed modification includes denitrification by PAOs, PAO glycogen storage capability and GAO metabolism model. It is shown that the proposed modification is capable of describing pilot plant data using a single set of stoichiometric and kinetic parameters over three different sludge ages (16, 14 and 12 days). The modified ASM2 may be applicable to a wide range of situations where PAOs and GAOs can compete. This modification may well provide a better understanding about GAO behaviour.
State estimation for a biological phosphorus removal process using an asymptotic observer
Authors: Larose A. , Jørgensen S. B.
Published: May 2018

This study investigated the use of an asymptotic observer for state estimation in a continuous biological phosphorus removal process. The estimated states are the concentration of heterotrophic, autotrophic and phosphorus accumulating organisms, polyphosphate, glycogen and PHA. The reaction scheme describing the process was simplified from a combined ASM1-Delft model. Three examples were investigated: operation at steady state, operation at steady state with a random white-noise in the measurements and operation with a ramp disturbance. In each case, the estimation was quite accurate even if the convergence, driven by the dilution rate, was slow (from 15 to 60 days). The propagation of the measurement noise and a bias in the estimation of glycogen and PHA could be the result of the high condition number of one of the matrices used in the algorithm of the asymptotic observer for the aerated tanks.
Duckweed based wastewater treatment (DWWT): design guidelines for hot climates
Authors: Smith M. D. , Moelyowati I.
Published: May 2018

Conventional wastewater treatment systems are expensive in either investment or running costs. On the other hand, waste stabilisation ponds may be unable to meet effluent standards for nutrients. Wastewater treatment using duckweed therefore becomes more significant as an option capable of achieving effluent standards and generating revenue from selling the duckweed. However existing duckweed based wastewater treatment (DWWT) systems have high land requirements despite being able to reduce concentrations of organic compounds and pathogens to acceptable levels. Improved guidelines for the design of DWWT are necessary to obtain a reliable and cost-effective wastewater treatment plant using duckweed. This guideline provides a DWWT design program using spreadsheets for different configurations of wastewater treatment units using duckweed. The design program developed suggests that a combination of anaerobic ponds, DWWT systems and maturation ponds can minimise land requirements and capital costs while achieving specified effluent standards. In order to achieve effluent standards, the land required is typically from 1.5 to 1.8 m2/capita (excluding associated facilities), capital costs are in the range from 7.9 to 9.7 USD/capita, with a retention time from 15 to 18 days. Income generation is dependent mainly on the social and cultural acceptability of duckweed use within the community.
Moving-bed biological treatment (MBBT) of municipal wastewater: denitrification
Authors: Maurer M. , Fux C. , Graff M. , Siegrist H.
Published: May 2018

Denitrification in a full-scale installation and a pilot plant for moving-bed biological treatment (MBBT) was subject to detailed investigation. Two different types of carriers were used in conventional activated sludge reactors: foam cubes and plastic tubes (Kaldnes®).

Both investigated carriers showed the same behavior with regard to denitrification capacity, temperature dependency and maximum COD and nitrate turnover. In contrast to the plastic tubes (Kaldnes®), the sponge cubes stored remarkable amounts of substrate. The maximum denitrification rate with acetate as a substrate was 420 gNm-3d-1 at 10°C and 730 gNm-3d-1 at 20°C. An average denitrification rate of 240 gNm-3d-1 (10°C) was achieved with wastewater. A maximum of 37% of the COD in the influent was denitrified with a volumetric loading rate in the anoxic zone of 2.2 kgCODm-3d-1.
Setting microbiological water quality standards for sea bathing - a critical evaluation
Authors: Mugglestone M. A. , Stuff E. D. , Rushton L.
Published: May 2018

The World Health Organization (WHO) recently produced draft guidelines for safe recreational water environments. The microbiological standards proposed in the guidelines are expected to over-estimate the degree of water quality required to provide given levels of public health protection. The WHO standards were obtained by means of a risk assessment which featured a dose-response model derived from a series of randomised controlled trials. The trials have many strengths but biases and problems with statistical analysis are likely to have led to over-estimation of the risks from bathing in the dose-response model. In addition, the WHO risk assessment failed to consider the effects of uncertainty and variability in risk estimates and sensitivity to model assumptions. Improved standards could be obtained by extending the risk assessment to examine these effects and by incorporating a suitably revised dose-response model.
Climatic effects on Salmonella survival in plant and soil irrigated with artificially inoculated wastewater: preliminary results
Authors: Palacios M. P. , Lupiola P. , Tejedor M. T. , Del-Nero E. , Pardo A. , Pita L.
Published: May 2018

The use of wastewater to replace other water resources for irrigation is highly dependent on whether the health risk and environmental impacts entailed are acceptable or not. Total count and species of microorganisms found in wastewater vary widely because of climatic conditions, season, population sanitary habits and disease incidence. Salmonella, one of the genera associated with waterborne diseases, lives in the intestine. Thus, it is widely accepted that they have a limited survival period under environmental conditions. Wastewater management practices and the ability of Salmonella to survival under field conditions would determine the health risk associated with its presence in wastewater. Although chlorination is widely used, there are situations in which Salmonella is able to survive the sudden stress imposed by this technique. The aim of this experiment was to contribute to the study of the climatic and soil effects on pathogen survival under agricultural field conditions in order to assess which were the best wastewater management practices from both health and economic points of view. Five pots filled with soil seeded with Medicago sativa and an automatic weather station were used. A secondary effluent was artificially inoculated with Salmonella. In addition, open plates (filled with sterilised soil) and ultraviolet radiation isolated plates (filled with non-sterilised soil) were used. As soil heat emission contributes to the environmental conditions around the bacteria, standardised meteorological temperature data had to be carefully used in the bacterial survival studies under agricultural conditions. Radiation was the main cause of Salmonella mortality as its effect was more important than natural soil bacteria competence. Higher reduction of Salmonella counts could have been associated with longer spring days. Soil was able to effectively remove Salmonella. Subsurface drip irrigation methods could provide an effective tool to prevent health risk associated with wastewater irrigation.