bluuebunny/crossref_metadata_2025 huggingface dataset:
New challenges for the management of plant nutrients and pathogens in the Waikato River, New Zealand
Authors: Vant W. N.
Published: May 2018

The water quality of the Waikato River is currently much better than it was in the 1950s. Major improvements in the treatment of the sewage and industrial wastewaters which are discharged to the river mean that levels of indicator bacteria in the lower reaches of the river are now many times lower than in the past. Eve so, conditions are still not suitable for swimming, and blue-green algal blooms occur at times. Non-point or diffuse sources of contaminants now dominate the nutrient and pathogens budgets. Progressively-intensifying farming, particularly in lowland areas, is thought to contribute the majority of the contaminants found in the river. Future improvements in water quality will therefore depend more on activities like changes to farming practice – such as retiring the riparian margins of lowland tributaries of the river – than on further advances in wastewater treatment.
Ethers as pollutants in groundwater: the role of reaction parameters during the aquasonolysis
Authors: Lifka J. , Hofmann J. , Ondruschka B.
Published: May 2018

Methyl tertiary butyl ether (MTBE) is one of the most used fuel oxygenates. Oxygenates improve combustion, thereby reducing CO and hydrocarbon emissions in motor vehicle exhaust. MTBE is highly soluble in water and poorly sorbed to carbon based substrates such as soil. An important property of MTBE is its poor biodegradability. The treatment of contaminated groundwater and wastewater by means of conventional biological, chemical and physical techniques turned out to be inefficient. As a matter of principle the degradation of organic compounds by ultrasound in water (aquasonolysis) is practicable as an advanced technology for remediation of waters contaminated with MTBE. The degradation reactions mainly occur in the cavitation bubbles as pyrolytical processes. Under the test conditions, the frequency range between 300 and 800 kHz leads to acceptable degradation values at a power density of 5 W/cm2. The degradation was not suppressed by radical scavenger (n-butanol). With concentrations above 25 mg/L MTBE in water, significantly influence of concentration on degradation could be observed.
Water quality response to riparian restoration in an agricultural watershed in Vermont, USA
Authors: Meals D. W.
Published: May 2018

Achievement of management goals for Lake Champlain (Vermont/New York, USA and Quebec, Canada) will require reduction of agricultural phosphorus loads, the dominant nonpoint source in the Basin. Cost-effective phosphorus reduction strategies need reliable treatment techniques beyond basic cropland and waste management practices. The Lake Champlain Basin Agricultural Watersheds National Monitoring Program (NMP) Project evaluates the effectiveness of livestock exclusion, streambank protection, and riparian restoration practices in reducing concentrations and loads of nutrients, sediment, and bacteria in surface waters. Treatment and control watersheds in northwestern Vermont have been monitored since 1994 according to a paired-watershed design. Monitoring consists of continuous stream discharge recording, flow-proportional sampling for total P, total Kjeldahl N, and total suspended solids, grab sampling for indicator bacterial, and land use/agricultural monitoring. Strong statistical calibration between the control and treatment watersheds has been achieved. Installation of riparian fencing, protected stream crossings, and streambank bioengineering was completed in 1997. Early post-treatment data suggest significant reduction in P concentrations and loads and in bacteria counts in the treated watershed. Monitoring is scheduled to continue through 2000.
Kinetics and mechanisms of EDTA photocatalytic degradation with TiO2
Authors: Babey P.A. , Emilio C.A. , Ferreyra R.E. , Gautier E.A. , Gettar R.T. , Litter M.I.
Published: May 2018

A complete study on the photocatalytic degradation of ethylenediaminetetraacetic acid (EDTA) over TiO2 has been initiated, to establish the influence of several parameters on the reaction rate, the nature of the intermediates and the kinetic regime. TiO2 (Degussa P25) suspensions containing EDTA at pH 3 at different concentrations were irradiated under near UV light. A Langmuirian behavior was observed, from which kinetic constants have been obtained. Experiments with 5.0 mM EDTA (zero order kinetic regime) were performed for 3 hours irradiation under different conditions. Under N2 bubbling, depletion of EDTA was very low. Under O2 bubbling, the concentration of EDTA decreased around 90%. However, the corresponding decrease of TOC ranged only between 4.5% and 9%. A higher TOC reduction (22% or more) was obtained by keeping the pH constant by HClO4 addition, or by hydrogen peroxide addition. Addition of 0.5 mM Fe(III) caused a dramatic increase on the initial rate of EDTA depletion and approximately a 32% TOC decrease. Analysis of the filtered solution was performed by ion chromatography and capillary electrophoresis to monitor the disappearance of EDTA and the formation of degradation products after different irradiation times. So far, glycine, ethylenediamine, formic acid, ammonium, iminodiacetic acid, oxalic acid and glyoxylic acid have been identified.
Relating oxygen demand to flow: development of an in situ sediment oxygen demand measurement device
Authors: Jubb S. , Guymer I. , Licht G. , Prochnow J.
Published: May 2018

This paper describes the continuation of an investigation into the effects of increased flow on the dissolved oxygen concentration in the River Maun, UK. A previous investigation indicated that an oxygen demand additional to that in the water phase is observed during and directly after intermittent discharges. Simplified modelling of the river indicated that the additional oxygen demand was possibly linked to the disturbance of sediment during such events. A device has been developed which can be used in situ to measure the effect of flow velocity (shear stress) on the additional demand. Preliminary tests have shown that the inferred demand is significant. It is proposed that the in situ device now be used to measure the oxygen demand of the bed material at a number of locations and flow speeds and that a relationship between the additional demand and velocity be established, with the aim of incorporating such a relationship into a simplified model.
Characteristics of primary production in a eutrophicated bay
Authors: Nakashima M. , Lee I.-C. , Kusuda T.
Published: May 2018

The primary production of phytoplanktons provides organic matter in high concentration in eutrophicated Hakata bay in Japan, even during the winter season in spite of low water temperature. Phytoplanktons may have the biological capabilities to maintain activities of photosynthesis under unfavorable conditions, and these capabilities affect water quality in the bays. In this study, characteristics of primary production were analyzed with a simple box-type ecosystem model. We introduced a concept of efficiency for absorption of sunlight energy to our simulation model of water quality to explain rather high growth rates of phytoplanktons in low sunlight intensity. Through simulation with a box model, we found that the efficiency of primary production in winter is higher than that in summer. It was suggested that the organic pollution comes from dissolved organic carbon (DOC) throughout the year and that the DOC is originated from the primary production of phytoplanktons in biological response of the seasonal change of ambient conditions.
Abatement of the major contaminants present in olive oil industry wastewaters by different oxidation methods: ozone and/or UV radiation versus solar light
Authors: Miranda M.A. , Amat A.M. , Arques A.
Published: May 2018

Four different cinnamic acids (caffeic acid, ferulic acid, p-coumaric acid and cinnamic acid) present in olive oil wastewaters, were treated with advanced oxidation methods: ozone and/or UV radiation. Basic and acid media were tested. Differences between all four acids were found, both in the reaction times and the intermediates formed. Based on a careful study of these intermediates and the variation of their concentrations all along the reaction time, a general mechanism for the degradative oxidation of cinnamic acids is proposed. These results are compared with those obtained with solar light, using a pyrylium salt as a catalyst.
Teaching future professors how to teach
Authors: Bishop P. L. , Yu T. , Kupferle M. J. , Moll D. , Alonso C. , Koechling M.
Published: May 2018

This paper describes a course designed to provide hands-on teaching experience to future professors and to incorporate techniques for more effective teaching. A team of Ph.D. candidates, under the direction of a senior faculty member, prepared a new course from beginning to end and then offered it to a class of graduate students. The course was developed using the unit map concept so that the presentations by the five student-instructors complemented and built upon one another. Immediately after each class, feedback was given to the student-instructors by the faculty advisor and the other student-instructors. Review of video tapes of the lecture reinforced this feedback. At the completion of the course, both students and student-instructors were surveyed as to the effectiveness of the course and the student-instructors. This teaching experience and the feedback obtained from the surveys will be invaluable to the student-instructors in their future development.
A long-term water quality management model for a lignite mining affected river catchment area
Authors: Schlaeger F. , Köngeter J.
Published: May 2018

The paper presents a program system which is used for long-term planning and control of water management of an open-cast mining affected river catchment area. This contribution gives insight into the development of a coupled stochastic water management - water quality model. Simplified algorithms to describe water quality are presented. Finally, applicability of the model is verified by some results which are interpreted with regard to the special water quality situation in the Lusatian mining district.
Modelling and simulation of the steady-state of secondary settlers in wastewater treatment plants
Authors: Queinnec I. , Dochain D.
Published: May 2018

This paper discusses the steady-state modelling of thickening in circular secondary settlers of activated sludge processes. The limitations of the solid flux theory basic models to represent steady-state operating conditions serve as a basis to introduce more sophisticated models derived from computational fluid dynamics. Parameter identification and sensitivity studies have been performed from lab-scale continuous experiments.
Water and soil pollution in vineyards of central Thailand
Authors: Joannon G. , Poss R. , Korpraditskul R. , Brunet D. , Boonsock P.
Published: May 2018

Very intensive cultivation systems have been developed in the delta of the Chao Phraya River for about a century. The objective of the study was to determine the fate of the fertilisers and pesticides applied to vineyards grown on raised beds. Water samples were collected from the outlet of a vineyard to determine the discharge of pollutants in the canal. The accumulation of elements in the soil was investigated by analysing soil samples from different fields. Fertilisation was estimated at 670 kg N, 300 kg P, and 560 kg K year−1 ha−1. Insecticides and fungicides were applied every four days on average, using up to 23 different molecules. Little N and no P were discharged in the canals in solution and discharge in suspension was minor. Pesticides were detected in 36% of the water samples. The topsoil contained 1600 mg kg−1 Bray II P, 936 mg kg−1 exchangeable K, 170 mg kg−1 total Cu, and 167 mg kg−1 total Zn. Pesticides were detected in 62% of the fruits after peeling. Overuse of fertilisers did not lead to water pollution, but overuse of pesticides resulted in pollution of the water bodies and of the fruits. Most applied elements accumulated in the soil, resulting in high values of P, K, Cu, and Zn.
Operational control of storm sewage at an activated sludge process
Authors: Chen J. , Beck M. B.
Published: May 2018

Operational control of storm sewage at a wastewater treatment plant has attracted intensive concern over the last decade in the context of river basin management. The focus is on the exploitation of the full capacity of the wastewater treatment plant in attenuating storm sewage, and minimizing a direct storm sewage bypass to the river. Attention is particularly paid to the surge of storm water on the activated sludge process. Based on two typical rain events, this paper discusses the performance of several practical controllers in achieving an optimal effluent performance under storm loadings, without risking internal biomass stability and sludge overflow. The control algorithms tested include various controls of recycle rate, step-feed and step-sludge. Prediction errors of influent characteristics and process responses are also under consideration in the assessment. The results illustrate well the desirability, effectiveness and robustness of the tested controllers.
Nitrogen leaching from soil treated with sludge
Authors: Sukreeyapongse O. , Panichsakpatana S. , Thongmarg J.
Published: May 2018

The amount of sludge generated from urban centers is increasing more and more, so wastewater treatment plants are being constructed. Recycling of sludge by application to agricultural land can alleviate the disposal pressure, and, at the same time, utilize the plant nutrients in the waste. Organic nitrogen in sludge is mineralized to inorganic forms such as nitrate and ammonium that can be taken up by plants. The inorganic forms of nitrogen, especially nitrates, can easily be leached because of its negative charge. Not only do nitrates cause eutrophication, but, at high concentration in drinking water, can also cause chemical suffocation disease in babies. This work is meant to quantify nitrate and ammonium nitrogen leached from soil treated with sludge. In order to obtain information on the composition of leachate from sludge, Kandiustults and a lysimeter study were used. Municipal and industrial sludge were applied to completely random design plots at different rates: 125, 250 and 375 kg N/ha. Each control lysimeter was treated with chemical fertilizer (N-P2O5-K2O : 20-10-10) at the rate of 125 kg N/ha. After the Chinese kale (Brassica oleracea L.) was planted in each lysimeter, leachate was collected every week and analyzed for NO3− and NH4+. The experiment was conducted at Kasetsart University, Bangkhen Campus, Bangkok, Thailand. Average nitrogen leach in the form of NO3− was 25 times more concentrated than the NH4+. Nitrate concentrations in the leachate exceeded the drinking water standard. Nitrate and ammonium leaching were measured to be between 1.50-3.00 % and 0.03-0.14% of the total treated nitrogen, respectively. Total nitrogen losses found in this study were 44.88%, 77.24% and 77.91% of the total nitrogen applied by chemical fertilizer, Huay Kwang sludge and Bangpa In sludge, respectively.
Runoff characteristics of nutrients in the forest streams in Hyogo Prefecture, Japan
Authors: Umemoto S. , Komai Y. , Inoue T.
Published: May 2018

Nutrients and other pollutant runoffs from streams in artificial forest areas in central Hyogo Prefecture in southwest Japan have been investigated to estimate pollutant loads since 1995. The orthophosphate and ammonium nitrogen contents were usually low and constant during the investigation. When the flowrates of the streams were normal, the concentrations of suspended solids, CODMn, TOC and total phosphorus were very low, and did not change much. However, when stream flows were increased by rainstorms or other precipitation, higher concentrations of these parameters occurred. Otherwise, the average concentrations of nitrate nitrogen and total nitrogen were 0.26 mg/l and 0.31 mg/l, respectively, and they were often increased by precipitation events. They changed at the same time because the ratio of nitrate nitrogen per total nitrogen was high, about 80%. The fluctuation of concentrations of total phosphorus was similar to SS concentrations, which suggested that phosphorus was discharged in the types of suspended solids from forest areas. The specific loads of the nutrients and some other pollutants did not differ among the three watersheds investigated. However, the difference among them between fine days and rainy days was fairly large. It was presumed that pollutant runoff from forest areas is strongly dependent on precipitation events.
Advanced monitoring and control of anaerobic wastewater treatment plants: software sensors and controllers for an anaerobic digester
Authors: Bernard O. , Polit M. , Hadj-Sadok Z. , Pengov M. , Dochain D. , Estaben M. , Labat P.
Published: May 2018

A mass balanced based model representing the dynamical behaviour of anaerobic digester has served as a basis for the design of software sensors for the concentration of inorganic carbon, alkalinity and volatile fatty acids. The predictions of the sensors are close to the actual off-line measurements. The model has also been used to design a model-based adaptive linearizing controller and a fuzzy controller whose objective is to regulate the ratio of the intermediate alkalinity over the total alkalinity below some desired value (0.3) under which the process is assumed to remain in stable conditions and avoid VFA accumulation. Both controllers were calibrated via extensive numerical simulations and implemented. The controllers proved successful in maintaining the ratio of TA over PA below 0.3, even in presence of large variations of the organic load.
Diffuse pollution: lessons from soil conservation policies
Authors: Warkentin B. P.
Published: May 2018

Diffuse pollution of water from various land uses requires a control approach different from the uniform regulations that were successful for point sources. Local solutions, designed by local watershed councils, are preferred over national directives. Soil erosion control policy, based on voluntary measures coordinated by local conservation districts, provides a guide for improvement of water quality in watersheds. Local planning and action are supplemented by government provision of free technical advice, economic incentives and public education programs. There are no national standards, because land use decisions are a guarded prerogative of individual landowners. Among the lessons that can be transferred to diffuse pollution control are the practicality of the voluntary approach, the need for continuing financial incentives, local solutions to local problems, the wide range of effectiveness of local groups, the uncertainty whether the most critical problems are resolved and the need for education to foster a normative attitude of what we ought to do for watershed health.
Sensitivity analysis and calibration of the parameters of ESWAT: application to the River Dender
Authors: Vandenberghe V. , van Griensven A. , Bauwens W.
Published: May 2018

The paper deals with the sensitivity analysis and parameter calibration of a complex river water quality model, implemented in ESWAT. The Extended SWAT includes a QUALIIE-based river quality simulator, in view of an integrated analysis of water quantity and quality management practises. The sensitivity analysis uses Latin Hypercube Sampling and criteria related to the duration of low concentrations of dissolved oxygen and the occurrence of high algae concentrations. The analysis on the river Dender shows that parameters related to the growth and die-off of the algae have the largest impact, while also the BOD decay constant and the benthic oxygen demand are important. A subsequent calibration of these most important parameters shows however that the optimal values of the parameters related to the activity of the algae are statistically not significant. This apparent contradiction is due to the poor information content of the measurements. It is concluded that the application illustrates the complementarity of the sensitivity analysis and the parameter calibration.
A numerical identifiability test for state-space models - application to optimal experimental design
Authors: Hidalgo M. E. , Ayesa E.
Published: May 2018

This paper describes a mathematical tool for identifiability analysis, easily applicable to high order non-linear systems modelled in state-space and implementable in simulators with a time-discrete approach. This procedure also permits a rigorous analysis of the expected estimation errors (average and maximum) in calibration experiments. The methodology is based on the recursive numerical evaluation of the information matrix during the simulation of a calibration experiment and in the setting-up of a group of information parameters based on geometric interpretations of this matrix. As an example of the utility of the proposed test, the paper presents its application to an optimal experimental design of ASM Model No.1 calibration, in order to estimate the maximum specific growth rate μH and the concentration of heterotrophic biomass XBH.
The use of dissolved air flotation in municipal wastewater treatment
Authors: Ødegaard H.
Published: May 2018

Flotation can be used in municipal wastewater treatment plants in different ways. Since the pollutants in wastewater to such a large extent are associated with particles, a very substantial treatment efficiency can be reached at a very small space, by using flotation in a chemical (or enhanced primary) treatment scheme. This is demonstrated in this paper with reference to results from small, prefabricated chemical plants based on flotation, which are frequently used in Norway. If used in connection with biological plants (for instance for nitrogen removal), the combination of biofilm reactors and flotation is especially advantageous because coagulation/flocculation/flotation can be placed directly after the bioreactor. Results from two such plants in Norway are presented. Recommendations with respect to design and operation of flotation plants in wastewater treatment are given.
Modelling of floc-bubble aggregate rise rates in dissolved air flotation
Authors: Haarhoff J. , Edzwald J. K.
Published: May 2018

The use of relatively simple, but conceptually sound mathematical models, is a powerful tool to identify and understand parameters that are critical to a process. In this paper, a model is presented which addresses the rise rate of floc-bubble aggregates in the DAF separation zone. The model uses Stoke's Law as a point of departure, which is then progressively extended to incorporate the non-sphericity of the aggregates, the non-laminar nature of their movement, the fractal nature of the flocs, the physical constraints of attaching bubbles to a floc, and the limit on bubble numbers imposed by a typical air dosing system. The main findings are:There are two distinctly different DAF domains, namely a small floc domain and a large floc domain. In the small floc domain, the bubble size, the air volume, chemical dosing and the degree of flocculation have to be optimized and accurately controlled, while the large floc domain is less sensitive to these parameters.The calculated rise rates are significantly lower than some of the latest pilot testing results reported from the USA; a surprising finding at first. There are, however, numerous modelling simplifications that may explain this discrepancy. The most probable reasons are the further agglomeration of the aggregates in the separation zone due to differential rise rates or the recirculating flow within the white-water blanket, and the complex and poorly understood flow patterns within the separation zone.
Applicability of sniffing team observations: experience of field measurements
Authors: Van Langenhove H. , Van Broeck G.
Published: May 2018

Sniffing measurement campaigns are a commonly used technique in Flanders to estimate the impact of an odour emission source. The Department of Organic Chemistry at Ghent University has developed its own sniffing strategy throughout the last ten years. The method uses, in essence, the technique of plotting odour perception areas and calculation of total odour emission rates based on maximum odour perception distance. 566 sniffing measurements, executed from 1990 until 1999 around industrial and agricultural odour sources were collected in a database for statistical analysis. Short-term dispersion modelling was executed using four different models, two of them based on Bultynck-Malet dispersion parameters, and two based on Pasquill dispersion parameters. Results from this analysis demonstrate some causes of variance in calculated emissions and show the fitness of each model. From the results of the sniffing teams, which are expressed as sniffing units (SU) instead of odour units (OU, OUE) to underline the difference in methodological approach, the overall odorous emission can be calculated, using short-term atmospheric dispersion models. In a second step, long-term dispersion models can be used to calculate isopercentile contour plots. According to our experience the short-term atmospheric model is a source of “noise” in the method since calculated standard deviations on calculated emissions are larger than standard deviations in the observed maximum distance for odour perception. This will be illustrated by presenting results from the evaluation of composting plants and animal farm houses.
Improving odour assessment by using better dispersion models: some examples
Authors: Ormerod R.
Published: May 2018

A critical aspect of odour assessments is modelling to define exposure characteristics in affected communities, and to examine the effects of odour control options. In many cases, odour dispersion is influenced by complex or non steady-state meteorology that cannot be represented by the commonly used dispersion models, such as ISC3 and AUSPLUME. These models are based on a steady-state Gaussian plume assumption, which is often inaccurate. Recent developments in modelling of local meteorology and plume dispersion have enabled far more realistic predictions of odour dispersion. Three-dimensional models have been successfully applied to improve the predictions of odour impact and to better define the parameters for odour control options. These models more accurately represent features such as drainage flows along valley floors and around hills, and strong wind shear that can develop in stable conditions. Such conditions are often critical for a proper assessment of odour impact. Second-by-second fluctuations in odour concentrations can now be simulated using the KSP model developed by Yamartino et al. This model avoids the use of arbritrary methods of determining peak-to-mean ratios. New models can also provide detailed microscale wind fields, suitable for odour modelling in urban areas where odour dispersion is affected by very complex flows.
Informing river management policies and programs with science
Authors: Edgar B. , Schofield N. , Campbell A.
Published: May 2018

Conventional wisdom has it that we already have enough science to address the problems causing degradation of our environment, including rivers. This is not true. However it is the case that we could be using existing knowledge better, and that we could be doing more to learn the lessons from the huge sums being spent on river restoration and management. Informing good policy and practical on-ground management with R&D outputs has proven to be is difficult, but essential.

This paper reviews some of the history of water and river management in Australia and how perceptions of rivers have evolved. It discusses the challenge of enhancing the linkages between science, policy and practice in river management. It outlines the knowledge exchange, R&D and capacity building strategies of the National Rivers Consortium - a new initiative whose founding partners are LWRRDC, the MDBC, CSIRO Land and Water and the Western Australian Waters and Rivers Commission. This strategic collaboration between policy makers, river managers and scientists brings together organisations with responsibility and expertise to improve the health and management of Australian rivers. The National Rivers Consortium is making a major investment in knowledge exchange and capacity building, based on direct personal contact and learning by doing. The Consortium is establishing a program of training activities targeting river managers and policy makers, based on the best available science and high quality information products. It will support river managers as they plan and implement river restoration and protection projects.

The paper concludes with a discussion of the key knowledge gaps that remain impediments to the better management of Australia's unique and diverse river landscapes.
Development of a procedure to determine odour emissions from animal farming for regulatory purposes in Flanders
Authors: Van Langenhove H. , De Bruyn G.
Published: May 2018

The purpose of the project described in this paper was to develop a procedure to determine odour emissions at existing and new intensive animal farming houses. The procedure should be scientifically valid and preferably applicable on a large scale at reasonable costs. In this project odour emissions were measured during one year at the same farm. Measurements included 20 olfactometric sampling days and 50 sniffing measurements, all spread over one year. For each olfactometric sampling day, samples were taken in duplicate for the different pig categories. The olfactometric analysis resulted in the determination of odour emission factors for growing/fattening pigs, weaned piglets, dry sows and farrowing sows. The influence of external parameters (ventilation rate, inside temperature, outside temperature, pen dirtiness, number of pigs and their weight) was examined. Good correlation between the odour emission and an external parameter could only be found for the ventilation rate (r = 0.98) and outside temperature (r = 0.87). The sniffing measurements resulted in maximal odour perception distances and odour emissions calculated with short and long term dispersion models. No significant influence of the outside temperature (season) could be found here. The results of the olfactometric and sniffing measurements will be presented, including a combination of both techniques to determine the odour emission of an agricultural construction.
Technologies to address air quality issues impacting animal agriculture
Authors: Williams C.M.
Published: May 2018

The continued productivity, profitability and sustainability of animal production agriculture in most parts of the world will be dependent upon implementation of effective technologies and management practices to mitigate perceived and documented environmental impacts resulting from confined animal operation emissions. North Carolina State University Animal and Poultry Waste Management Center (APWMC) program efforts to identify such technologies through support of research, development and demonstration projects involve collaborative efforts with approximately 20 other universities (nationally and internationally). Many of these projects are well beyond the laboratory developmental stage and some are yielding encouraging results. Performance data, to date, has shown that swine manure treatment systems including a covered in-ground anaerobic digester, a sequencing batch reactor, and an upflow biological aerated filter system significantly improved odor emission variables.
Biosolids management - sustainable development status and future direction
Authors: Englande A. J. , Reimers R. S.
Published: May 2018

The role of biosolids management continues to gain priority in terms of holistic waste management/reuse. Recommended options should lead to simple and safe management alternatives that stress reclamation of resources. This paper addresses current sustainability strategies, priorities and future direction of waste management as it relates to residuals and in particular to sludges/biosolids. Sludge management and resource recovery approaches must be diversified and flexible. They should be based on actual needs of the affected society and community. It is also important that the chosen strategy be appropriate to the conditions of the site under consideration. Processes which promote sustainability will become viable options for resource management if conversion into a “value-added product” can be realized.
Heavy metal removal from wastewater and leachate co-treatment sludge by sulfur oxidizing bacteria
Authors: Aralp L. C. , Erdincler A. , Onay T. T.
Published: May 2018

Heavy metal concentration in sludge is one of the major obstacles for the application of sludge on land. There are various methods for the removal of heavy metals in sludge. Using sulfur oxidizing bacteria for microbiological removal of heavy metals from sludges is an outstanding option because of high metal solubilization rates and the low cost. In this study, bioleaching by indigenous sulfur oxidizing bacteria was applied to sludges generated from the co-treatment of municipal wastewater and leachate for the removal of selected heavy metals. Sulfur oxidizing bacteria were acclimated to activated sludge. The effect of the high organic content of leachate on the bioleaching process was investigated in four sets of sludges having different concentrations of leachate. Sludges in Sets A, B, C and D were obtained from co-treatment of wastewater and 3%, 5%, 7% and 10% (v/v) leachate respectively. The highest Cr, Ni and Fe solubilization was obtained from Set A. Sulfur oxidizing bacteria were totally inhibited in Set D that received the highest volume of leachate.
Chemical and biological removal of arsenic from sewage sludge
Authors: Ito A. , Takachi T. , Aizawa J. , Umita T.
Published: May 2018

Chemical and biological leachings of As and metals from sewage sludge were carried out using a batch reactor under an aerobic condition. Addition of phosphate to the sludge was ineffective for the elution of As from the sludge at neutral pH. Akalization of the sludge to pH 11 eluted sufficient As, whereas it was ineffective for Al, Cd, Mn and Zn. Furthermore, the effectiveness of ferric sulfate and iron oxidizing bacteria was investigated under acidic conditions. The application of ferric iron and/or iron oxidizing bacteria eluted As from the sludge more effectively than that of sulfuric acid only at pH 2. However, at pH 3, addition of ferric acid decreased significantly the amount of As eluted. It was found that the optimum pH was 2 for removing simultaneously As and metals from the sludge utilizing ferric iron or iron oxidizing bacteria.
Development of a routine analytical procedure for nonylphenol polyethyoxylates and their biodegradation products in sludge from sewage treatment plants
Authors: Tateda M. , Hung N.V. , Kaku H. , Asano M. , Ike M. , Fujita M.
Published: May 2018

A method of quantitative analysis of nonylphenol polyethoxylates (NPnEOs) and their biodegration products (NPE-BDPs) in sewage sludge, which is effective, economical, and applicable to a high performance liquid chromatography was developed and actual sludge samples collected from Japanese sewage treatment plants (STPs) were analyzed using the method to confirm its effectiveness. Soxhlet extraction showed better recovery in a spike and recovery test than shaking extraction. Among the four pretreatments for Soxhlet extraction tested, the condition in which samples were freeze-dried, ultrasonicated, and extracted with methanol showed the best recovery efficiency. Quantitative analysis of NPE-BDPs in STP sludge resulted in 6.1 μg/g, 4.3 μg/g, and 8. μg/g in average concentration for NPnEOs (n=1-3), NPnEOs (n=4-18), and nonylphenol ethoxycarboxylates (NPnECs (n=1-3)), respectively, and the values of concentration were 100-1000 times higher than those in effluent at Japan's STPs. The results implied importance of quantitation of NPE-BDPs in sewage sludge to assess the risk to the environment.
Ammonia removal in a deep reclaimed wastewater reservoir before agricultural reuse
Authors: Delgado S. , Elmaleh S. , Díaz F. , Rodríguez-Sevilla J. , Marrero M. C.
Published: May 2018

An experimental study has been carried out to determine the ammonia removal in a deep reclaimed wastewater reservoir of 50,000 m3. The reservoir is part of the Reuse System of Reclaimed Wastewater of South Tenerife (Spain). The study has been conducted under batch mode operation, in three different periods (winter, spring-summer and winter-spring), with an average storage time of 85 days. Vertical profiles of temperature, dissolved oxygen and pH were determined together with NH3-N, NO2-N and NO3-N concentrations at different points and different depths in the reservoir. Maximum removal efficiency was obtained during the winter periods, in absence of stratification and with good mixing conditions throughout the water column. During these periods, nitrification took place in some extension, favoring the ammonia removal. Average NH3-N concentrations in the reservoir were calculated and apparent first-order rate constants were determined for different stratification conditions. Although ammonia nitrogen could be used as nutrient in the agricultural reuse, its removal from reclaimed wastewater could be useful in order to diminish the chlorine needs for disinfection.
Wet oxidation of domestic sludge and process integration: the Mineralis® process
Authors: Lendormi T. , Prévot C. , Doppenberg F. , Spérandio M. , Debellefontaine H.
Published: May 2018

Wet oxidation (WO) in subcritical conditions is a new alternative to usual routes for sewage sludge treatment that complies with environmental standards. This paper presents tests carried out using a batch reactor and continuous pilot and industrial units, treating municipal sewage sludge. The main products after oxidation are CO2, water, VFA and ammonia. The results highlight the considerable influence of the treatment temperature and of the type of sewage sludge which is treated. At temperatures around 240°C, VFA fraction present in WO supernatant is limited to 50% because of the presence of non-degraded fatty compounds and surfactants. Moreover, the COD reduction is limited to 70%. On the contrary, at 300°C, COD removal efficiencies greater than 80% are achieved without any catalyst addition and, in addition, only highly biodegradable compounds remain in the oxidised liquor. In order to treat the residual ammonia nitrogen by biological processes, it is therefore necessary to obtain a VFA fraction as high as possible for achieving denitrification and then to operate the WO process at high temperature and without catalyst addition.
Effect of particle size on the performance of batchwise centrifugal filtration
Authors: Hwang K.-J.
Published: May 2018

The effect of particle size distribution on the performance of batchwise centrifugal filtration is studied. By analyzing the velocity of particles in a filter, a numerical program is designed for simulating the migration and deposition of particles. The particle size distributions and the average specific filtration resistances of cake are then estimated under various rotating speeds of the centrifuge. A large deviation of particle concentration profiles in the filter chamber will occur if the particle size distribution is not taken into consideration. A more heterogeneous cake will form under a lower rotating speed due to the sedimentation effect of particles. The predicted results of particle size distribution and average specific filtration resistance of cake agree well with the available experimental data.
Parallel studies on dewatering and conditioning of an alum sludge and an aluminium hydroxide suspension
Authors: Papavasilopoulos E.N. , Bache D.H.
Published: May 2018

The paper shows a comparison between properties of an alum sludge gained from the coagulation of a coloured water with those of a suspension of aluminium hydroxide at a concentration equivalent to the coagulant fraction within the sludge. Background information is provided on composition and aspects of the source floc. The comparisons embraced floc size, polymer adsorption, and dewatering parameters including specific resistance to filtration, capillary suction time and the equilibrium moisture content under pressure. In all cases, there were strong similarities in the behaviour of the two suspensions. It is suggested that such features emanate from a common fractal structure within the source floc, whose fractal index (= 1) has been found to be insensitive to the composition of the floc.
Evaluation of refractory organic removal in combined biological powdered activated carbon - microfiltration for advanced wastewater treatment
Authors: Seo G. T. , Ohgaki S.
Published: May 2018

Biological powdered activated carbon (BPAC) was incorporated with a microfiltration (MF, 0.2 μm pore size) system to remove the refractory organic matter contained in secondary sewage effluent. A synthetic secondary sewage effluent was used as influent in this study, containing both non-biodegradable organic substances (such as humic acid, lignin sulfonate, tannic acid and arabic gum powder) and biodegradable ones. These refractory organic materials were possibly degraded in contact with microorganisms for 20-27 days. Although humic acid and arabic gum were weakly adsorbed on the activated carbon, they could be effectively removed in the BPAC reactor. The TOC removal at a powdered activated carbon (PAC) concentration of 20 g/L was higher than at 0.5-2 g PAC/L (83% and 66-68%, respectively). The higher removal efficiency was due to the increased rejection at the membrane module in which most of the PAC was accumulated. More than 90% of non-biodegradable compounds removal (detected as E280 , UV absorption at 280 nm) occurred in the BPAC reactor. The biological growth parameter b/Y, used in system design, was estimated to be 0.017 d-1. Relatively high permeate flux of 1.88 m/d could be obtained even at higher PAC concentration of 20 g/L.
Impact of cold and dilute sewage on pre-fermentation - a case study
Authors: Bixio D. , van Hauwermeiren P. , Thoeye C. , Ockier P.
Published: May 2018

The municipal sewage treatment plant (STP) of the city of Ghent (Belgium) has to be retrofitted to a 43%-increase in the nitrogen treatment capacity and to phosphorus removal. Cold weather, dilute sewage and a critical COD over N ratio make the retrofit a challenge for full biological nutrient removal. The potential for fermentation of primary sludge to alter those critical feed sewage characteristics was experimentally evaluated. The idea was that the pinpoint introduction of fermentate could optimise the available reactors by achieving high-rate denitrification and enhanced biological phosphorus removal.

The fermentation process was evaluated with a bench scale apparatus. At 20°C (heated process), the hydrolysis yield - expressed in terms of soluble COD - varied from 11% to 24% of the total sludge COD. The fermentation yield expressed in VFA COD varied from 8% to 13% of the total sludge COD. The efficiency of heated fermentation of primary sludge was lower during cold and wet weather, due to the different sewage characteristics, as a result of extended dilution periods and low temperature.

The raw sewage, the primary effluent and the fermentate were fractionated according to the requirements for the IAWQ Activated Sludge Model No. 2d. The results clearly show that fermentation in the sewer played an important role and temperature was the driving parameter for the characteristics of the dissolved COD. Instead, the weather flow conditions were the driving parameter for the characteristics of the suspended COD.

The results of the detailed fractionation were used as background for process evaluation. The final scenario choice for the retrofit depends on a cost-efficiency calculation.
Abattoir effluent treatment and protein production
Authors: de Villiers G. H. , Pretorius W. A.
Published: May 2018

A modified SBR process was evaluated for biological pretreatment of abattoir effluent. One of the main objectives was to produce a biomass with low SVI that can be used as a protein feed addition for animals. A pilot plant was used with reactor working volume of 60 kl. The process was easy to operate and adapted readily to changes in raw effluent generation. COD removal was in excess of 85%. A biomass was produced with SVI lower than 80 ml/g that included aerobic granular sludge. Filamentous organism growth could be limited by controlling the dissolved oxygen concentration in the reactor. Crude protein values of 27 to 37% were obtained. The optimum cell residence time to maximise protein production was between 4 and 5 days. The process can be described as a protein recovery and production process.
Marine-based waste stabilisation ponds: an evaluation of the hydraulic viability
Authors: Burrows R. , Ali K. H. M. , Tickell R. G. , Hedges T. S. , Pearson H. W. , Mara D. D.
Published: May 2018

Marine-Based Waste Stabilisation Ponds, formed by floating boom/skirt curtain enclosures anchored in sheltered waters, have recently been proposed for provision of low-cost effluent treatment facilities where land availability is limited in rapidly expanding coastal cities in the Third World. This paper outlines findings from a viability assessment, which drew on a preliminary site evaluation and baseline environmental survey (for a site in sheltered waters in the Far East), laboratory studies involving scale model tests in wave/wind/current flumes, and a structural and design loading study. It focuses on hydraulic and hydrodynamic considerations and reports the study's conclusions.
Control measures for wastewater treatment plants during storm flow
Authors: Niemann K. , Orth H.
Published: May 2018

In the context of the development of treatrnent plant control techniques, three measures for maintaining a high efficiency of treatment plants during rainfall events were tested. The three measures are increasing the nitrification volume by operating a facultative aeration, bypassing the primary sedimentation and adding flocculants before secondary sedimentation. Ammonia concentrations and ammonia loads were used in combination with rainfall forecasts as the criteria for putting the measures into operation. A simulation based on the Activated Sludge Model No.1 and a pilot scale plant were used for testing the measures. The results show that all three measures may be suitable to cope with peak loads of treatment plants during rainfall events.
Performance evaluation of a UASB - activated sludge system treating municipal wastewater
Authors: von Sperling M. , Freire V. H. , de Lemos Chernicharo C. A.
Published: May 2018

Recent research has indicated the advantages of combining anaerobic and aerobic processes for the treatment of municipal wastewater, especially for warm-climate countries. Although this configuration is seen as an economical alternative, is has not been investigated in sufficient detail on a worldwide basis. This work presents the results of the monitoring of a pilot-scale plant comprising of an UASB reactor followed by an activated sludge system, treating actual municipal wastewater from a large city in Brazil. The plant was intensively monitored and operated for 261 days, divided into five different phases, working with constant and variable inflows. The plant showed good COD removal, with efficiencies ranging from 69% to 84% for the UASB reactor, from 43% to 56% for the activated sludge system only and from 85% to 93% for the overall system. The final effluent suspended solids concentration was very low, with averages ranging from 13 to 18 mg/l in the typical phases of the research. Based on the very good overall performance of the system, it is believed that it is a better alternative for warm-climate countries than the conventional activated sludge system, especially considering the total low hydraulic detention time (4.0 h UASB; 2.8 h aerobic reactor; 1.1 h final clarifier), the savings in energy consumption, the absence of primary sludge and the possibility of thickening and digesting the aerobic excess sludge in the UASB reactor itself.