bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphorus release from sediments of a deep wastewater stabilization pond
Authors: Ortuño J. F. , Sáez J. , Llorens M. , Soler A. 
Published: May 2018

The fractional composition and potential mobility of particulate phosphorus was investigated in sediment from a deep wastewater stabilization pond. The predominant phosphorus fractions were Fe- and Al-bound P (NaOH-RP) and Residual-P (consisting mainly of organic P), which amounted to 35 and 34% of total phosphorus, respectively. A laboratory study was conducted to determine the influence of various environmental parameters (pH, redox conditions, biological activity and temperature) on phosphorus release from lagoon sediment. Phosphorus release was observed under both anaerobic and aerobic conditions. Anaerobic release was about 1.4-5 times greater than aerobic release. Phosphorus release was redox-sensitive and favoured by high pH values, up to 17.4% of total phosphorus being liberated anaerobically and at high pH. Biological activity favoured phosphorus release, since the amount released under non-sterile conditions exceeded that observed under sterile conditions.
Sediment phosphorus was fractionated before and after the release experiments. The NaOH-RP fraction was sensitive to pH and redox environmental changes, and was readily released under reduced conditions and at high pH. The mobility of the Residual-P fraction was enhanced in incubations involving biological activity due to the decomposition of the organic matter in the sediments, and NaOH–nRP (organic phosphorus) decreased by up to 45% during the incubation of non-sterile suspensions.
Tracer studies on a New Zealand waste stabilisation pond and analysis of treatment efficiency
Authors: Shilton A. , Wilks T. , Smyth J. , Bickers P. 
Published: May 2018

This paper presents data collected from tracer studies undertaken at a facultative waste stabilisation pond in New Zealand. The dye used was rhodamine WT. The tracer studies were conducted using the stimulus-response technique to produce normalised curves of the hydraulic retention time distribution.
Two studies were undertaken. Comparison of the results shows a rapid rise to a high peak, followed by a slow, steady decrease with a long tail. The curves are similar to what would be expected from a mixed reactor suffering from short-circuiting. Although very similar for the majority of the study period, the two runs vary during the initial period.
The method described by Levenspiel, for analysis of non-linear reactions in reactors having non-ideal flow, was used to calculate treatment efficiencies from the tracer data.
It is evident from these calculations that the initial period of the tracer data, corresponding to small amounts of flow exiting with very short retention periods, accounts for the majority of the pollutant that escapes treatment in the pond system. For example, over half of the coliforms discharged untreated are due to the fraction of flow that exits the pond in a retention time of 24 hours or less. This highlights the potentially severe impact that short-circuiting has on attempts to achieve high treatment efficiencies. More generally it illustrates the importance of sound hydraulic pond design that avoids premature release of the wastewater. Further, in the context of pond hydraulics research it shows the importance of acquiring adequate data from the initial stages of a tracer study.
Improved fecal coliform decay in integrated duckweed and algal ponds
Authors: van der Steen P. , Brenner A. , Shabtai Y. , Oron G. 
Published: May 2018

Algal growth in wastewater ponds has two contradicting effects on fecal coliforms (FC) decay. On the one hand, algal photosynthesis increases the FC decay due to increased pH and DO. However, on the other hand, attenuation of solar radiation by algal matter reduces the decay rate. It was therefore investigated if suppressing algal development could enhance the FC removal efficiency. Limiting the algal growth was accomplished by inserting duckweed ponds in between a series of algal ponds. Duckweed ponds are modified stabilization ponds, covered with a mat of small floating plants, that are known to remove algal from algal pond effluent.
The FC decay in a series of five shallow algal ponds was compared to FC decay in an integrated system of algal and duckweed ponds. The integrated system consisted of five mini-ponds (30 cm depth) in series: duckweed pond – algal pond – duckweed pond – algal pond – duckweed pond. The environmental factors that are known to affect FC decay were monitored and related to FC decay rates.
In the algal ponds of the conventional system the light attenuation by algal matter became rate-limiting for the FC decay. In the integrated system, the algal concentration in the algal ponds was reduced by the intermediary duckweed ponds. This was shown to increase the FC decay in the algal ponds of the integrated system considerably, compared to the FC decay in the algal ponds of the conventional system. An improved system of duckweed and algal ponds is proposed, that is expected to reduce significantly the area requirements of pond systems.
Implementation of EU discharge guidelines at IVAR's Regional Wastewater Treatment Plant of North Jaeren, Stavanger, Norway
Authors: Tornes O. 
Published: May 2018

Norway is a leading country on wastewater treatment comprising chemical precipitation processes. This is because Norwegian effluent standards to the North Sea have traditionally focused on phosphorus removal. In most cases, chemical treatment therefore has been considered to give lower investment and operating costs than biological treatment. Norwegian wastewater policy and management is based on the EU guidelines resulting from the EEA (European Economic Area) Agreement. According to the 1991 Urban Wastewater Treatment Directive, this will in most cases require secondary treatment. However, primary treatment can be accepted for plants larger than 10,000 PT with effluents to less sensitive coastal areas, if no negative environmental impacts can be proved.
The main objective of the Regional Water, Sewerage and Waste Company (IVAR) is to comply with the prevailing effluent limits at lowest possible cost. During the past four years, IVAR has therefore undertaken comprehensive optimising of the precipitation process including full-scale experiments with different coagulant dosing control systems and different types of coagulants. IVAR also accomplished a feasibility study of introducing biological treatment as an alternative to chemical treatment. Under the prevailing frame conditions of discharge requirements and sludge deposit costs, it is not economically feasible to change to organic coagulants or biological treatment. This conclusion might have to be altered later resulting from the implementation of new EU regulations and increasing sludge deposit costs.
This paper presents results from full-scale experiments, extracts from the feasibility study and a comparison of costs. Furthermore, the practical consequences of implementing the EU-guidelines are discussed.
Development and verification of design and operation criteria for the step feed process with nitrogen removal
Authors: Larrea L. , Larrea A. , Ayesa E. , Rodrigo J. C. , Lopez-Carrasco M. D. , Cortacans J. A. 
Published: May 2018

The step feed process with three stages of denitrification-nitrification reactors has been studied using simulations in order to develop criteria for the optimum selection of the design parameters and to propose efficient operational strategies. To verify the simulation results experimental studies in a pilot plant of 1100 litres were carried out.
The simulation studies showed that the optimum influent flow distribution to the three anoxic reactors is in the range of 40-40-20% and 33-33-34% depending on the wastewater characteristics and effluent requirements. These two latter conditions and in turn the influent flow distribution determine the anoxic and aerobic reactor volumes. The reduction of the dissolved oxygen in the two first aerobic reactors and the use of facultative zones in the final D-N stage are proposed as operational strategy. The experimental results proved the validity of the criteria developed for design and operation. A high capacity of the IAWQ activated sludge model No. 1 to predict the performance of the step feed process was observed.
Implementation, study and calibration of a modified ASM2d for the simulation of SBR processes
Authors: Marsili Libelli s. , Ratini P. , Spagni A. , Bortone G. 
Published: May 2018

An enhanced process model for SBRs has been developed. Though the basic mechanism largely draws on the Activated Sludge Model n. 2d, its new features are the splitting of the nitrification stage in a two-step process, according to the well known Nitrosomonas - Nitrobacter oxidation sequence, and an improved XPAO dynamics, involved in the anaerobic/aerobic phosphorus removal process.
The model was implemented through the DLL technique allowing complied C++ modules to be linked to an ordinary Simulink block diagram. The static sensitivity study revealed that if the parameter vector is partitioned into subsets of biologically related parameters and calibrated separately, the calibration procedure does not present particularly difficult aspects. Trajectory sensitivity showed also to which extent data collection could be optimised in order to improve calibration accuracy.
The study of the shape of the error functional generated by parameters couples allows a much more effective calibration strategy.
Domestic sewage treatment in full-scale UASBB plant at Mangueira, Recife, Pernambuco
Authors: Florencio L. , Kato M. Takayuki , Cardoso de Morais J. 
Published: May 2018

The anaerobic technology application for domestic sewage treatment in Pernambuco State (Brazil) is relatively recent. Some UASB reactors of less than 250 m3 were built in the Recife Metropolitan Region (RMR) in the 1990s. Mangueira (18,000 inhabitants) was the first neighborhood where the municipality built a plant with a bigger UASB reactor of 810 m3. It was intended to evaluate the performance and verify if such technology would be feasible. The objective would be the possible application of UASB reactors to the RMR, according to the new sewage master-plan under elaboration that would benefit about 3 million inhabitants.
The monitoring of the Mangueira UASB reactor over 30 months showed that satisfactory results were obtained. Three distinct operational phases occurred, in which efficiency varied from 60% up to 90% based on COD removal. The results were very dependent on the operation and maintenance, either in the plant or in the sewage collection. Significant amount of inert solids was measured inside the reactor. Despite the operational problems, the UASB was shown to be very robust and stable. Under high fluctuation of influent concentrations (150-750 mg COD/L) during the period, resulting in applied organic loading rate of 0.5 to 2.5 kg COD/m3.d, the average values of COD removal efficiency did not change significantly. An active biomass with specific methanogenic activity varying from 0.18 to 0.25 gCOD/gVSS.d was measured at the end of the period.
Anaerobic digestion of a nonionic surfactant: inhibition effect and biodegradation
Authors: Jiménez-González A. , Salazar-González M. , Gutiérrez-Rojas M. , Monroy O. 
Published: May 2018

Nonionic surfactants are used worldwide in various industrial and household applications. Since these compounds are used in aqueous solutions, they primarily enter the environment through sewage and industrial wastewater treatment plants. The objective of this work was to evaluate the inhibitory effect of Triton X-100, a commercial nonionic surfactant, on the anaerobic digestion of lactose. Thus non-ionic surfactants acts as a non-competitive inhibitor with KI = 250 mgL−1 and a inhibition order of 2.4.
Nonetheless if give enough time the sludge was able to degrade 79% of Triton at 0.1 gL−1 d−1 in a UASB reactor. An activity test of this sludge showed that Triton inhibited the acetogenic (both propionic and butyric) and acetoclastic activities, while there were high fermentative and hydrogenotrophic activities (80% and 95%, respectively).
Feasibility of a pilot-scale UASB/trickling filter system for domestic sewage treatment
Authors: Chernicharo C.A.L. , Nascimento M.C.P. 
Published: May 2018

This paper presents the results of pilot system comprised of one UASB reactor followed by one trickling filter (TF). The UASB reactor had a volume of 416 litres, being operated at an average hydraulic retention time (HRT) of 4 hours. The trickling filter had a useful volume of 60 litres, being operated at hydraulic and organic loading rates varying from 3.4 to 30.6 m3/m2.d and 0.3 to 3.9 kgBOD/m3.d, respectively. These different operational conditions characterised eight research phases. Both reactors were fed with domestic sewage pumped directly from the main interceptor of Belo Horizonte City, Brazil.
After almost 16 months of continuous monitoring, the UASB/TF system produced very good results in terms of COD and BOD removal, and also very low solids concentration in the final effluent. The average results of COD and BOD removal varied from 74 to 88% and from 80 to 94%, respectively, sufficient to maintain the COD concentration in the final effluent in the range of 60 to 120 mg/L and the BOD values systematically below 60 mg/L. The overall averages of SS in the final effluent were kept below 30 mg/L.
The UASB/TF system is a very promising alternative for the treatment of domestic sewage in Brazil and other developing countries, since the system can be designed with very short hydraulic retention times, resulting in a very compact and low cost treatment unit. Besides, the energy consumption and the labour costs are minimal.
Domestic sewage treatment in a pilot system composed of UASB and SBR reactors
Authors: Torres P. , Foresti E. 
Published: May 2018

The results obtained from the operation of a treatment system composed of an anaerobic (up-flow sludge blanket - UASB) reactor followed by an aerobic (sequencing batch - SBR) reactor treating domestic sewage are presented and discussed. The pilot plant was monitored during 6 months, aiming to obtain performance data on organic matter, nitrogen and phosphate removal under different operating conditions.
The UASB reactor was operated at a constant hydraulic detention time (θ) of 6 h while the SBR performance was monitored in four different duration cycles (24, 12, 6 and 4 h) corresponding to aeration times (AT) of 22, 10, 4 and 2 h, respectively.
COD and TSS overall removal efficiencies (Eo) up to 91% and 84%, respectively, were achieved independently on the aeration time applied to the SBR. In respect to nitrification and phosphate removal, AT was found to be a determinating operating parameter. TKN removal of approximately 90% was achieved for AT equal to or higher than 10 h; complete nitrification occurred for AT higher than 4 h; significant phosphate removal (72%) occurred only at the AT of 2 h. It was not possible to achieve simultaneous efficient removal of nitrogen and phosphate, under the operating conditions imposed on the treatment system.
Ozone treatment of textile wastewaters for reuse
Authors: Ciardelli G. , Capannelli G. , Bottino A. 
Published: May 2018

Treatment of textile wastewaters by means of an ozonation pilot plant are described. Wastewaters used were produced by a dyeing and finishing factory and were first treated in an active sludge plant and filtrated through sand. In the appropriate conditions very high colour removal (95-99%) was achieved and the effluent could be reused in production processes requiring water of high quality as dyeing yarns or light colorations. Even if the chemical oxygen demand of treated waters was still in a range (75-120 mg/l, a decrease of up to 60%) that was usually considered to be too high for recycling purposes, recycling experiments were successful. The economical viability of the techniques implementation was also demonstrated and the industrial plant is currently under realisation under an EU financed project.
The paper considers also the possible improvement of ozone diffusion by means of membrane contactors realised in a second pilot plant, in order to further reduce operating costs of the technique. With respect to traditional systems, the gas/liquid contact surface is much higher being that of the membrane. Ozone at the interface is therefore immediately solubilized and potentially consumed with no additional resistance to the mass transfer.
Modelling the structure and function of extracellular polymeric substances in biofilms with new numerical techniques
Authors: Horn H. , Neu T. R. , Wulkow M. 
Published: May 2018

The objective of this study is the mathematical description of the structure and function of the extracellular polymeric substances (EPS) in biofilms. The basic assumptions of the EPS biofilm model are:the production of EPS in biofilms is coupled to the growth of micro-organismsthe production of EPS is additionally coupled to the substrate conditions-the EPS represent a considerable volume fraction of the matrix in biofilms and thus the density of the biofilms is strongly influenced by the EPS-sorption of biocides and pollutants in biofilms occurs mainly to EPSthe EPS can be used as an energy source during substrate limited phases.
The mathematical model has been derived as a system of partial differential equations. The numerical solution of these complex balance equations has been done by a self-adaptive Galerkin-h-p-method. It can be shown, that on the one hand the simulation of substrate conversion and biofilm growth with the EPS-biofilm model yields similar results as the known biofilm models without consideration of the EPS fraction. On the other hand the advantage of the EPS-biofilm model is a better understanding of biofilm structure, which is mainly influenced by the EPS fraction in the biofilm. Furthermore, the sorption of pollutants, such as heavy metals and chlorinated organic substances, can be simulated in more detail.
Managing water supply and sanitation services to developing communities: key success factors
Authors: Schutte C.F. 
Published: May 2018

A number of key success factors in the management of organisations responsible for the provision of water supply and sanitation services to developing communities have been identified as critical to the sustained success of such organisations. These factors have to receive specific and sustained attention from management. They should form the focus of management attention in addition to the many other important factors requiring management input.
The key success factors which are critical to ensure a sustained water supply and the provision of sanitation services to developing communities centre around two main areas, i.e. the credibility of the organisation with the community it serves and the creation of an organisation culture of focusing on service to the community, on income generation and on minimising of losses.
Water harvesting techniques for small communities in arid areas
Authors: Yuen E. , Anda M. , Mathew K. , Ho G. 
Published: May 2018

Limited water resources exist in numerous remote indigenous settlements around Australia. Indigenous people in these communities are still living in rudimentary conditions while their urban counterparts have full amenities, large scale water supplies and behavioral practices which may not be appropriate for an arid continent but are supported by extensive infrastructure in higher rainfall coastal areas. As remote indigenous communities continue to develop, their water use will increase, and in some cases, costly solutions may have to be implemented to augment supplies.
Water harvesting techniques have been applied in settlements on a small scale for domestic and municipal purposes, and in the large, broadacre farm setting for productive use of the water. The techniques discussed include swales, infiltration basins, infiltration trenches and “sand dam” basins.
This paper reviews the applications of water harvesting relevant to small communities for land rehabilitation, landscaping and flood control. Landscaping is important in these communities as it provides shelter from the sun and wind, reduces soil erosion and hence reduced airborne dust, and in some cases provides food and nutrition. Case studies of water harvesting systems applied in the Pilbara Region, Western Australia for landscaping around single dwellings in Jigalong and Cheeditha, in a permaculture garden in Wittenoon and at a college and carpark in Karratha are described.
Sustaining our rivers in crisis: setting the international agenda for action
Authors: Petts G. 
Published: May 2018

The history of streams and rivers is as much a social and technological history as it is a scientific one. Rivers are the lifeblood of nations and the control of their waters has been fundamental to the building of human civilisations. The control or regulation of rivers embodied the advancement of institutions, administration and co-ordination; it was a manifestation of military and economic power.
Yet the history of human development is also characterised by the degradation of the basic resource - polluted water, increased flooding, and the loss of biological diversity. Many early civilisations collapsed in the face of environmental degradation, manifest by flood, drought, famine and plague. The Industrial Revolution upon which modern societies are founded was based upon a short-term vision that has left rivers in crisis, marked by a legacy of pollution, slums, a loss of confidence in civic life, and a loss of ownership of places and spaces - once seen to be at the heart of civilised society.
Within this global or international context of water management, this paper examines the impacts and future of rivers and water within the United Kingdom, establishing some principles for such management in other settings.
Improving the efficiency of a wastewater treatment plant by fuzzy control and neural networks
Authors: Bongards M. 
Published: May 2018

One of the main problems in operating a wastewater treatment plant is the purification of the excess water from dewatering and pressing of sludge. Because of a high load of organic material and of nitrogen it has to be buffered and treated together with the inflowing wastewater.
Different control strategies are discussed. A combination of neural network for predicting outflow values one hour in advance and fuzzy controller for dosing the sludge water are presented. This design allows the construction of a highly non-linear predictive controller adapted to the behaviour of the controlled system with a relatively simple and easy to optimise fuzzy controller. Measurement results of its operation on a municipal wastewater treatment plant of 60,000 inhabitant equivalents are presented and discussed. In several months of operation the system has proved very reliable and robust tool for improving the system's efficiency.