bluuebunny/crossref_metadata_2025 huggingface dataset:
Attitudes to traditional and alternative sustainable sanitary systems
Authors: Hedberg Torsten
Published: May 2018

The sanitary system is the most important supply system in a society. A central problem today is the provision of a future urban system which meets the requirements clearly borne out in environmental documents and action plans at local and global levels. The conventional water and wastewater systems have been questioned whether they can be considered as sustainable or not. Other small, decentralized systems have been implemented and a short description of different systems is shown. The attitudes, at different administrative levels in the society, to traditional and alternative sanitary systems are discussed. The general conclusion is that there is a strong driving force and an interest in changing the systems. However, the evaluation of the systems implemented so far shows that it is important to have time for careful and thorough investigations of new but also of existing systems in the light of the criteria for sustainability.
Closed soilless growing systems: a sustainable solution for dutch greenhouse horticulture
Authors: Van Os Erik A.
Published: May 2018

Dutch greenhouse growers are obliged to invest in environmental friendly cropping systems, in order to comply with new legislation. Closed soilless growing systems may lead to environmental friendly systems and thus to a sustainable horticultural sector. This paper encompasses the change from general to specific legislation, the availability of good water and the developments in disinfection of nutrient solutions. For the latter, the interest of growers in the possibilities of slow sand filtration to disinfect the nutrient solution will be discussed.

In the last ten years there has been an awakening of environmental consciousness in society. Agriculture and horticulture have had to face their polluting aspects too, such as the discharge of nutrients, the emission of pesticides and the waste of materials such as plastics and substrates for cultivation. Initial legislation was rather rough and not based on research. Later, forced by court judgments and social pressure, new regulations have set a timetable for all nurseries to adopt specific measures in order to decrease the leaching of water and fertilisers into the environment. A recent covenant between horticultural employers and the Dutch government for a sustainable development of greenhouse horticulture between 2000 and 2010 enables the growers to achieve the environmental targets in their own way, if they make a specific plan for their nurseries.

Closed growing systems prevent the leaching of chemicals into the environment; in Dutch situations leaching into ground and surface water. Studies showed savings of up to 30% of water and up to 40% of fertilisers in closed systems compared to traditional open systems. A 100% efficiency of water and nutrients often cannot be achieved, because of the relatively poor water quality of the supply water. Mostly the sodium content of the water eventually becomes too high, and, consequently, part of the nutrient solution should be discharged.

Closed growing systems bear the risk of dispersal of pathogens all over the nursery. Therefore, it is always said in the Netherlands that disinfection of the recirculating nutrient solution is a necessity for long-term crops to avoid a disaster due to an outbreak of root-borne diseases. However, existing, active, sterilisation systems are not always applied, mainly because of the high costs. Now, developments in passive disinfection equipment focus on the removal of pathogens without a complete sterilisation of the nutrient solution. Investigations into the prospects of slow sand filtration as a cheap, robust disinfection method for a number of major pathogens have proved its feasibility on a small scale.

Future trends are scaling-up and inter-farm co-operation to achieve a sustainable use of water and nutrients to minimise contamination of ground and surface water. Economic prospects are still the most important motive to change the traditional way of growing.
A cost-sustainability analysis of urban water management
Authors: Icke J. , van den Boomen R. M. , Aalderink R. H.
Published: May 2018

A simple model for the urban water cycle is presented, based on mass balances for water and phosphorus. This model is used for the evaluation of the sustainability rate of the urban water cycle. This type of model is to be used in an early stage of town planning, to compare several possible measures. In general, contributing to achieving a more sustainable urban water management. A sensitivity analysis was performed to rank the management options and additional measures to their contribution to the sustainability rate of the urban water cycle. A module for the calculation of cost was linked to the model, revealing the relation between cost and the sustainability rate for a wide range of scenarios. The results show that an improved separated sewer system and the use of a local ground water source have the biggest impact on the sustainability rate. A slightly positive correlation between investment cost and the sustainability rate was found as well.
Denitrification kinetics in biological N and P removal activated sludge systems treating municipal wastewaters
Authors: Ekama George A. , Wentzel Mark C.
Published: May 2018

The denitrification kinetics at 12, 20 and 30°C in nitrification denitrification biological excess phosphorus removal (NDBEPR) systems were delineated in batch tests on sludge harvested from laboratory scale M/UCT systems. In some investigations, it was found that the P release and uptake were confined exclusively (>95%) to the anaerobic and aerobic reactors respectively and the observed P removal conformed to the BEPR model of Wentzel et al. In these investigations, due to an absence of anoxic P uptake (substantiated by PHB measurements), it could be inferred that the phosphate accumulating organisms (PAOs) did not significantly contribute to the denitrification. The ordinary heterotrophic organism (OHO) and PAO groups were separated with the aid of the BEPR model of Wentzel et al. Ascribing the denitrification to the OHO group performing this process, the specific rates of denitrification associated with the utilization of slowly biodegradable COD (SBCOD) in the primary (K′2) and secondary (K′3) anoxic reactors were calculated and compared with the rates in ND systems (K2 and K3). In other investigations it was found that P release and uptake were not confined exclusively to the anaerobic and aerobic reactors respectively and the observed P removal was only about 60% of that expected from the BEPR model of Wentzel et al. In these investigations significant P uptake under anoxic conditions was observed so the PAOs may have been involved with the denitrification. However, the denitrification rates were calculated as before by attributing it exclusively to the OHOs. Widely varying K'2 rates were observed at 20°C, ranging from 0.071 to 0.335 mgNO3-N/(mgAHVSS.d). The variation in K' rate is mainly due to widely varying OHO active fraction estimates for NDBEPR systems.
Formation of Dimethyloligo-Sulfides in Lake Kinneret
Authors: Ginzburg B. , Chalifa I. , Hadas O. , Lev O.
Published: May 2018

Dimethyloligosulfides were recently identified as a primary source of mild malodorous emissions from Lake Kinneret, Israel. The seasonal odor episodes coincide with a bloom of Peridinium gatunense algae. The possibility that the dimethyloligosulfides are formed by bacterial degradation of Peridinium gatunense lysis products, under oxygen rich conditions was investigated. Several bacterial strains were isolated from the lake. Addition of Peridinium cells to the isolated bacteria cultures yielded dimethyldisulfide and dimethyltrisulfide. One of the bacteria strains, identified as Acinetobacter lwoffii, an obligatory aerobe was singled out for detailed investigation. Addition of Peridinium cells or methionine to the Acinetobacter culture yielded, under aerobic conditions dimethyldisulfide and dimethyltrisulfide. Cystein feed yielded only inorganic oligosulfides, which were converted to dimethylsulfides by addition of d3-methyliodide.
Advanced process control for biological nutrient removal
Authors: Islam K. Ashraf , Newell Bob , Lant Paul
Published: May 2018

We introduce an Australian collaborative research and development project aimed at implementing advanced process control strategies to biological nutrient removal wastewater treatment plants. We show why process control is a key technology for the future of this industry and present several control ‘tools’ which we have developed.
Odors Arising from Ammonia and Amino Acids with Chlorine During Water Treatment
Authors: Kajino M. , Morizane K. , Umetani T. , Terashima K.
Published: May 2018

Odor produced by breakpoint chlorination in a drinking water purification process was researched. Ammonia and six amino acids (glycine, alanine, valine, leucine, arginine, proline) were chlorinated and production of odor and its change were investigated. An intense odor which was different to the odor of residual free chlorine was detected after the chlorination of ammonia. The production of the odor was affected by pH and chlorine dose rate. While the intense odor was not produced in the breakpoint chlorination at pH 8.3, a weak odor before the breakpoint and the intense odor after the breakpoint were produced at pH 6.5. At pH 3.0, the intense odor was detected even in a sample of low chlorine dose rate. An identification of the intense odor substance was done using a gas chromatograph-mass spectrometer and trichloramine or a dimer of dichloramine was suspected as the odor causing substance. In chlorination of the six amino acids, the intense odor and its change were different according to each amino acid. Production of chlorinated intermediate and final products which had a different odor were suspected as one of the reasons.
Effect of the Cyanobacterial Metabolite Geosmin on Growth of a Green Alga
Authors: Sklenar K. S. , Horne A. J.
Published: May 2018

Geosmin (trans-1,10-dimethyl-trans-decalol) is an odorous compound produced by some species of cyanobacteria. It was found to enhance the growth of Selenastrum 1648, a green alga. Chlorophyll a concentrations of unialgal Selenastrum cultures differed significantly in cultures (p<0.001) with different geosmin concentrations. Chlorophyll a concentrations were highest in flasks with geosmin concentrations of 480 ng/l, and lowest in flasks to which no geosmin was added. Significantly higher chlorophyll a concentrations in flasks with higher geosmin concentrations indicate that geosmin may be functioning as some kind of growth enhancer or antibiotic, possibly reducing populations of parasitic bacteria or fungi that antagonize algae.
Controlled biomass removal - the key parameter to achieve enhanced biological phosphorus removal in biofilm systems
Authors: Morgenroth Eberhard , Wilderer Peter A.
Published: May 2018

In contrast to enhanced biological phosphorus removal (EBPR) in activated sludge systems mass transfer processes have a major influence on overall phosphorus removal in biofilm reactors. Based on results from a laboratory scale sequencing batch biofilm reactor (SBBR) and from a mathematical model the influence of the following processes on EBPR in biofilms was evaluated: (1) mass transfer limitation for oxygen, (2) mass transfer limitation for organic substrate, (3) lack of controlled removal of biomass from the system. It was shown that mass transfer of soluble components (oxygen and organic substrate) had only a minor effect on overall phosphorus removal. Soluble components fully penetrate the biofilm at certain times during the SBBR cycle as a consequence of SBBR operation with large concentration variations over the cycle time. The limiting processes for EBPR is the efficient removal of phosphorus rich biomass from the reactor. Biomass at the base of the biofilm that is not removed during backwashing will release accumulated phosphorus due to lysis or endogenous respiration and will not contribute to net phosphorus removal. For efficient operation of EBPR in biofilm systems regular and intensive backwashing resulting in thin biofilms is suggested.
Environmental Management of Coastal Development, State of Kuwait
Authors: Marmoush Y. R.
Published: May 2018

The impact of coastal development in Kuwait is to be assessed as per the following environmental conditions: water circulation, sediment behavior, water quality, and marine ecology and fisheries. The objectives of this assessment are to identify and predict the environmental impact associated with coastal development and the various activities involved in any coastal project. These activities and their associated impact can be grouped into two categories: those that occur during construction (short-term effect), and those that occur after construction (long-term effect). This paper attempts to present the fundamental issues related to the environmental measures and the practical experience required to evaluate the potential environmental impact of coastal development in Kuwait. The conclusions and general considerations regarding the environmental feasibility of coastal development are given, and measures to minimize the adverse impact on the environment are recommended.
Distribution of Volatile Liquid Hydrocarbons in the Vicinity of Power/Desalination Plants in Kuwait
Authors: Saeed Talat , Khordagui Hosny , Al-Bloushi Amal
Published: May 2018

Volatile liquid hydrocarbons (VLHs) represent some 40% of crude oil and are considered to be the most toxic compounds of petroleum other than the carcinogenic polycyclic aromatic hydrocarbons. The distribution of these compounds in Kuwait's coastal waters in the vicinity and at the inlets of power plants was assessed. About 200 samples were collected from selected sampling stations over the four seasons. The VLHs in the samples were concentrated using Grob's closed-loop technique and analyzed by GC using FID and confirmed by GC/MS. The results showed that VLHs were ubiquitous in the coastal water of Kuwait. The detected levels (ranged from 307 to 7882 ng/l in Kuwait Bay and from 331 to 5017 ng/l in the south) were comparable to the levels found in other parts of the world and were not alarming. However, the spotty higher levels encountered gave reason for some concern. Benzenoids (originating from petroleum) predominated, representing roughly 70% of the total VLHs. The levels were relatively low at the intake of the power plant located in the Kuwait Bay (annual average 677 ng/l) while higher levels (annual average 3006 ng/l) were encountered at the intake of the plant located at the south of oil the loading terminals and refineries.
Simulation of multispecies biofilm development in three dimensions
Authors: Noguera Daniel R. , Pizarro Gonzalo , Stahl David A. , Rittmann Bruce E.
Published: May 2018

A mathematical model to simulate the three-dimensional growth of multispecies anaerobic biofilms is developed and tested with a two-species biofilm composed of sulfate-reducing bacteria and methanogens. The numerical approach is based on the separation of biological, physical, and chemical phenomena so that quasi-steady-state conditions can be used in the solution. Simulations with Desulfovibrio vulgaris and Methanobacterium formicicum result in the formation of a biofilm heterogeneous in structure and composition. The model predicts different biofilm structures in the absence of sulfate, when a syntrophic association between the two organisms develops, and in the presence of sulfate, when the two organisms compete for the available hydrogen.
Mathematical model for the biodegradation of VOCs in trickle bed biofilters
Authors: Alonso C. , Zhu X. , Suidan M. T. , Kim B. R. , Kim B. J.
Published: May 2018

The objective of this work is to develop a fundamental mathematical model that describes the biodegradation of volatile organic compounds (VOCs) in gas phase trickle-bed biofilters, and to estimate the unknown model parameters. The mathematical model considers a three-phase system (biofilm, water, and gas phase), non-uniform bacterial population, and one limiting substrate. Two pilot-scale trickle-bed biofilters were operated to remove the VOC diethyl ether from a waste gas stream. Experimental results from this system were used to estimate the unknown parameters of the steady-state model: the maximum rate of substrate utilization μmXf/Y, the Monod constant, Ks, and the ether biofilm/water diffusivity ratio, rd. While the value of μmXf/Y was uniquely determined, the values of Ks and rd were highly correlated. High values of the Monod constant and the ether diffusivity in the biofilm gave similar predictions to those corresponding to low values of both parameters. Batch studies were used to estimate the value of Ks without mass transfer limitations showing that Ks < 1 mg/L=2.6 mg COD/L. Using this information and biofilter operating data the true values of Ks and rd were determined.
Periodicity of Coliform Bacteria in an Aquatic Environment
Authors: Bagde U. S. , Rangari A. K.
Published: May 2018

The present study deals with enumeration and seasonal distribution of total and faecal coliform bacteria, the indicators of microorganisms causing faecal pollution of the aquatic ecosystem by a multiple tube technique. A lake called Upvan lake of Thane city, India was investigated during 1996-97 for the purpose. Bacterial population varied with seasonal variations in the water body. Bacterial counts increased during summer months and lowered during winter months. Highest coliform counts were reported in monsoon and lowest in winter season. Samples collected from different sites of the lake showed wide variations in the counts of bacteria. Positive correlation was established between faecal and total coliform. Bacteriological analysis of lake water indicated that water was polluted by faecal contaminants to the extent that it was unportable for drinking purposes and unsuitable from the recreation point of view and hence needed thorough impoundment.
Improvement of Tertiary Wastewater Quality by Soil Aquifer Treatment
Authors: Viswanathan M. N. , Al Senafy M. N. , Rashid T. , Al-Awadi E. , Al-Fahad K.
Published: May 2018

Treatment of wastewater by the high rate land infiltration system is known as soil aquifer treatment (SAT). SAT is a proven technique for the improvement of wastewater quality. The quality of wastewater produced after SAT is suitable for unrestricted irrigation. The experimental study undertaken at Sulaibiyah proved that the method could be successfully used in Kuwait. The gatch layers within the subsurface region posed no major problems for the infiltration of the wastewater. The groundwater conditions at Sulaibiyah are suitable for the storage of large volumes of wastewater. The cost of treatment by SAT is considerably less than that of conventional methods.
RP4 plasmid transfer among species of pseudomonas in a biofilm reactor
Authors: Ehlers Laura J. , Bouwer Edward J.
Published: May 2018

Conjugation, the most prevalent mechanism of horizontal gene transfer, has been extensively studied for its role in the dissemination of antibiotic resistance and catabolic genes among bacteria. Very little research on conjugation has been conducted in natural biofilm systems, although over 99% of bacteria in nature are attached to surfaces. Previous studies suggest that rates of conjugation on surfaces elevated compared to rates in liquid media. The goal of this research was to observe conjugation between bacteria growing in a biofilm reactor. Conjugation of the broad host range plasmid RP4 between two species of Pseudomonas occurred in the biofilm reactor at high frequencies. The most important environmental para-meter was the shear stress at the biofilm-liquid interface. Conjugation was only observed below a shear of 0.0851 N/m2, corresponding to a laminar flow regime. Increasing temperature from 15°C to 28°C increased conjugation frequencies 10,000-fold. Conjugation frequency was unchanged in experiments conducted with 3.5, 7, and 35 mg/l acetate, though total cell concentration in the biofilm increased as expected. These data suggest ways to manipulate environmental parameters to affect plasmid transfer rates among biofilm bacteria.
Micro-environments and mass transfer phenomena in biofilms studied with microsensors
Authors: de Beer Dirk , Schramm Andreas
Published: May 2018

Direct observations on chemical micro-environment and microbial composition in biofilms are rare. The combination of microsensor and molecular techniques is highly useful for studies on the microbial ecology of biofilms. We shortly describe some applications of microsensors to study mass transfer phenomena and microbial processes in biofilms. It has recent been recognized that biofilms are not always flat layers of cells, but can consist of complex structures allowing liquid flow. Thus the classical view, that transport in biofilms is diffusional, is challenged. In laboratory grown biofilms the effect of convection on mass transfer was demonstrated. The microsensor technique has improved, so that direct in situ measurements in living biofilms are possible. By direct measurements of liquid flow with microsensors we show that in biofilms grown in bioreactors heterogeneity and convectional transport must also be taken into account. For the description of the microbial population we use molecular techniques, such as in situ hybridisation with 16S rRNA-targeted oligonucleotide probes. In a nitrifying-denitrifying biofilm we found a complex nitrifying community consisting of members of the genera Nitrosomonas, Nitrosospira, Nitrobacter and Nitrospira. Their occurrence was correlated with nitrification activity as determined by microsensor measurements.
Mathematical modeling and simulation of methane gas production in simulated landfill column reactors under sulfidogenic and methanogenic environments
Authors: Pareek Sandeep , Matsui Saburo , Kim Seog Ku , Shimizu Yoshihisa
Published: May 2018

A mathematical model was developed to simulate methane and carbon dioxide production from simulated landfill column reactors operated under sulfate reducing and methane producing conditions. The model incorporated governing equations which describe the chemical and biochemical processes responsible for the degradation of organic waste materials. These processes were hydrolysis, acidogenesis, methanogenesis and sulfidogenesis. The differential equations were numerically solved using Stella Researcher Software. The model was calibrated and verified using 700 days of gas production data from the simulated landfill column reactors. The calibrated hydrolysis rate constants for newspaper and sludge were found to be higher in sulfate reducing reactors as compared to methane producing reactors. The simulated methane production was quite accurate in all the reactors, but the predicted carbon dioxide production in the sulfate reducing reactors was not so accurate for the first 100 days, which may be attributed to the necessity of further governing equations. According to the sensitivity analysis, hydrolysis rate constants and moisture factors were the two most sensitive parameters controlling the gas production.
Impact of Bulgarian rivers on heavy metal pollution of the Black Sea
Authors: Mirinchev G. A. , Tzankov Tz. V. , Kostova I. S. , Mirincheva M. G.
Published: May 2018

In the Bulgarian part of the Black Sea coast there are seventeen rivers and three lakes which contribute to the pollution and eutrophication of the Black Sea. The hydrophysical and hydrological characteristics of these rivers are described. The variation in the concentration of heavy metals during recent years (data up to 1996) has been determined. The total annual quantity of some pollutants and their percentage distribution are presented. Conclusions are made based on the variation of water quality of the rivers and their impact on the heavy metal pollution of the Black Sea.
Evaluation of the impact from the discharge of treated sewage on the south-east Saronicos Gulf through mathematical water quality modelling
Authors: Noutsopoulos C. , Gavalaki E. , Andreadakis A.
Published: May 2018

The paper presents the results of a study of the impact caused by the discharge of treated sewage from the south-west Attiki area to the south-east coast of the Saronicos Gulf. The study involved the application of a eutrophication-dissolved oxygen model which, following validation on the basis of field measurements, was applied to predict the impact of three different biological treatment configurations, with and without nutrients removal, as well as three alternative disposal sites on the quality of the receiving waters. The simulation results show that nitrogen is the limiting nutrient and that its removal during treatment results in a substantial improvement of the quality of the recipient. The disposal site is a critical factor in the case of a biological treatment scheme exhibiting carbon removal, but it is of limited importance in the case of treatment systems with nitrogen removal.
Comparison of the Behaviour of Expanded Granular Sludge Bed (EGSB) and Upflow Anaerobic Sludge Blanket (UASB) Reactors in Dilute and Concentrated Wastewater Treatment
Authors: Jeison D. , Chamy R.
Published: May 2018

In the present study an upflow anaerobic sludge blanket (UASB) reactor and an expanded granular sludge bed (EGSB) reactor were operated with different substrates under the same conditions. Ethanol, diluted beer (as a brewery effluent model) and wastewater from a coffee industry were tested. Ethanol was fed at two different concentrations: 0.5 and 10 gCOD/l. Beer was diluted to a concentration of 3gCOD/l and coffee wastewater had a concentration of approximately 7 gCOD/l. During the operation, samples of sludge were taken from both reactors to measure TSS, VSS, size distribution and methanogenic activity. Batch assays were performed in a third reactor using ethanol at two different superficial velocities to measure substrate uptake. The overall COD removal for ethanol at 500 gCOD/l in EGSB and UASB reactors was similar (around 80% for a sludge loading rate of 0.8 gCOD/day/gVSS). Granular sludge experienced an important development in its characteristics during the operation with ethanol. Superficial velocity showed a positive effect on COD removal for ethanol below 5m/h. There were no big differences in the removal rates during the operation with coffee wastewater. Probably in this effluent the process is limited by the reaction kinetics instead of by the mass transfer, due to the complex nature of the waste. With diluted beer, EGSB reactor showed a better performance than the UASB.
Combined filter for ammonia removal – part I: Minimal zeolite contact time and requirements for desorption
Authors: Dimova G. , Mihailov G. , Tzankov Tz.
Published: May 2018

The minimal contact time in removal of ammonia ions by ion-exchange with zeolite, Na-form, is determined using the method of differential element. The relationship between the contact time, the water velocity, the effect of removal and the initial ammonia concentration is investigated. The obtained data serve as a basis for mathematical modeling of the ion exchange kinetics and give valuable information about some design parameters of ion-exchange facilities. Some basic analyses, concerning the desorption of ammonia from zeolite, induced mainly from the cations naturally present in surface waters are made. The influence of water velocity and water hardness on such desorption is investigated. These experimental data and analyses are an essential part of a study, the purpose of which is to investigate the possibilities for ammonia removal and biological regeneration of zeolite in a combined facility, using the processes: ion-exchange, desorption induced by small concentrations of cations and biological nitrification.
Use of a Fungal Bioreactor as a Pretreatment or Post-Treatment Step for Continuous Decolorisation of Dyes
Authors: Palma C. , Moreira M. T. , Mielgo I. , Feijoo G. , Lema J. M.
Published: May 2018

A continuous decolorisation system is proposed as a pretreatment or post-treatment step in an integrated treatment system, combining the use of fungi and anaerobic bacteria. The system consisted of a pulsing packed-bed bioreactor operating with white-rot fungi. This methodology was effective to achieve high decolorisation of a coloured compound, the polyanthraquinone dye Poly R-478, which was degraded up to percentages exceeding 70%. Moreover, a stable operation was maintained for an extended period of time (more than 100 days). The proposed system deserves consideration as a combined bacterial-fungal system to be applied in decolorisation and possibly detoxification of industrial coloured effluents.
A relatively less polluted drinking water reservoir of metropolitan Istanbul near the black sea coast
Authors: Baykal B. B. , Tanik A. , Gonenc E.
Published: May 2018

Located near the Black Sea coast of Turkey, Lake Terkos is one of the six main drinking water reservoirs of Metropolitan Istanbul, providing 25% of the water demand. With very limited industrial activities and only 1% of its catchment area being devoted to settlements, it is a relatively less populated and comparatively less destroyed catchment of the metropolis. In contrast to other drinking water reservoirs of Istanbul, the water quality of Lake Terkos is still of overall second class, implying that it can be used as a safe drinking water resource following a conventional water treatment scheme. The most critical group of pollutants was determined to be nutrients, which somewhat exceed Class 2. Presently, phosphorous load is found to originate from point sources of domestic origin, whereas approximately half of the nitrogen load arises from forests and meadows. An appropriate management strategy, concentrating especially on the future population densities, land use and an effective protection practice is needed to maintain the sustainability of the lake as a drinking water resource.
Environmental study of the alternatives for the sewer system of a small coastal community in the bay of Biscay
Authors: Alvarez C. , Juanes J. A. , Revilla J. A. , Koev K. , Roldan A. , Ivanov V.
Published: May 2018

Zumaia is a small tourist community on the northern coast of Spain, situated along the estuary of the Urola river. This ecosystem has been affected by urban discharges coming from the villages surrounding the estuary. According to the 91/271 European Community Directive, regarding wastewater treatment, this situation should be addressed in order to achieve the quality objectives established for the restoration of the natural values of the area. The local Water Authorities of the Basque Country (Spain) have adopted an integrated model for the design of the sewer system of this community. The model was developed specifically for the study of coastal sewerage under dominant wet weather conditions and includes: 1) Establishment of the site specific statutory requirements and environmental objectives; 2) Design of sewer system components with specific reference to influences on marine water quality; 3) Development of monitoring programs.

The construction of a sewer pipe alongside the river to collect the foul and the stormwater flow will prevent a large proportion of the discharges of contaminants into the receiving waters. However, the presence of overflows in the system during storms leads to the release of a great deal of pollutants into these waters. The main problems related to this type of discharge in the littoral zone arise from the bacteriological contamination of the bathing waters and from the oxygen depletion over the estuary. These two topics have been the predominant issues conditioning the consideration of different schemes of management of the sewer system. The aim of this paper is to analyze, from an environmental point of view, the structural and functional scheme considered for the sewage management of this community.
Wastewater management strategies for the black sea coast of Turkey
Authors: Ozturk I. , Yuksel E. , Tanik A.
Published: May 2018

The Black Sea, surrounded by six riparian countries, is under the threat of severe pollution, giving rise to the need of taking precautions to protect it from further deterioration. In this paper, an effort putting forth a wastewater treatment and management strategy is outlined for the Black Sea coast of Turkey, including both the technical and financial aspects. The present situation of the coast in terms of land-based pollution and infrastructure is stated, followed by an applicable management strategy. The strategy developed for the coastal settlements involves various stagewise treatment schemes based on population distribution and densities along the coastline, and on the availability of land in a specified period of thirty years. Similar strategies are proposed for the control of pollution originating from industries, for those carried by rivers joining the sea, and for leachate of solid waste landfills. The cost estimations of various treatment schemes are also given in terms of population equivalents.
Treatment of Anthranilic Acid in an Anaerobic Expanded Granular Sludge Bed Reactor at Low Concentrations
Authors: Razo-Flores Elías , Smulders Patrick , Prenafeta-Boldú Francesc , Lettinga Gatze , Field Jim A.
Published: May 2018

The mineralization of anthranilic acid (2AB) as the only carbon and energy source was studied in batch and continuous conditions using methanogenic granular sludge. Under batch conditions in serum vials, 2AB (300 mg/l) was completely mineralized to methane within 55 days time. The experiment with the anaerobic continuous expanded granular sludge bed (EGSB) reactor was initially conducted at an upflow velocity (Vup) of 5 m/h, a hydraulic retention time (HRT) of 12 h and an organic loading rate (OLR) of 1.5 g chemical oxygen demand (COD)/l-d. After 102 days, 2AB was not degraded at all and the reactor operation was shifted to batch mode by recycling the effluent. After some days, 2AB was completely mineralized and accumulation of flocculent sludge was observed. Batch biodegradability assays demonstrated that this flocculent biomass had a higher specific biodegradation rate compared to the granular sludge. During EGSB reactor operation, the flocculent biomass which was not attached to the granules probably washed-out under the applied hydrodynamic conditions. When the EGSB reactor was operated at Vup of 2 m/h to favour the retention of the flocculent biomass, 2AB was mineralized even at influent concentrations as low as 140 mg COD/L. Kinetic calculations indicated that the sludge had an apparent Ks value for the mineralization of 2AB as low as 24 mg COD/l.
Modelling in-sewer changes in wastewater quality under aerobic conditions
Authors: Almeida M. C. , Butler D. , Davies J. W.
Published: May 2018

In the present paper a model for the simulation of in-sewer transformation processes occurring during the transport of wastewater under aerobic conditions is presented. The basic approach is to use a detailed description of the transport processes to separate the effect of advection-dispersion in the variations of concentration (of a certain pollutant in a certain pipe length) from those due to transformation processes. The focus is on dry weather flow and free surface flows. Processes such as reaeration, heterotrophic growth and decay, hydrolysis, ammonification and biofilm consumption of substrate and oxygen are considered. Transformation processes are modelled using a similar approach to that of the IAWQ Activated sludge model n°1. Results of tracer experiments are presented showing the relevance of dispersion in pipe flow. The results of sensitivity analysis on the model parameters are presented. The model results are especially sensitive to variations in yield and maximum growth rate for heterotrophs. Thus, these parameters should be determined experimentally for a given system. Less precise estimates for the other parameters have less impact on the model results. This aspect is especially relevant due to the lack of established methods for the estimation of these parameters for sewer systems modelling.
Sediment behaviour in grass filter strips
Authors: Deletic Ana
Published: May 2018

Sediment transport was studied in non-submerged overland flow over grass in a laboratory. Artificial turf (astro-turf) was used to simulate natural grass and no infiltration was allowed at this stage of the investigation. Experiments were conducted for different grass densities, flow rates, sediments inflows, and sediment types. It was observed that concentration of sediment in runoff decreases exponentially with the distance and reaches asymptotically a constant value. Measured sediment deposition was compered with the results calculated by the Kentucky model (tollner et al., 1976). The model over-predicted grossly the trapping efficiency of all particle fractions, but it is unreliable particularly for small particles. A new simplified relationship was established between particle fall number, Nf, and percentage of particles trapped in the grass. The relationship should be verified on natural grass before it is used in practice. Finally, infiltration of water and particles should be studied on natural turf, as well as, influence of grass blades bending, before the complex model of sediment behaviour in grass is established.
Hydraulic design of intake structures of deeply located underground tunnel systems
Authors: Toda K. , Inoue K.
Published: May 2018

This paper deals with hydraulic effects of intake structures of underground storage or tunnel systems from the aspect of energy dissipation and entrained air control. First, through the literature reviews, the advantage of vortex-flow dropshaft type is confirmed. Next, with the analytical solutions of free-surface swirling flows in vertical dropshaft, the energy dissipation effects of vortex-flow dropshaft are examined and some results of practical use are obtained. Also, the relation between the dropshaft shape and air entrainment is studied and the excellent of the helicoidal-ramp dropshaft is clarified. Based on the above results, the directions of the hydraulic designs of drop structures are proposed.
Modifications of rainfall runoff and decision finding models for on-line simulation in real time control
Authors: Cassar Andreas , Verworn Hans-Reinhard
Published: May 2018

Most of the existing rainfall runoff models for urban drainage systems have been designed for off-line calculations. With a design storm or a historical rain event and the model system the rainfall runoff processes are simulated, the faster the better. Since very recently, hydrodynamic models have been considered to be much too slow for real time applications. However, with the computing power of today - and even more so of tomorrow - very complex and detailed models may be run on-line and in real time. While the algorithms basically remain the same as for off-line simulations, problems concerning timing, data management and inter process communication have to be identified and solved.

This paper describes the upgrading of the existing hydrodynamic rainfall runoff model HYSTEM/EXTRAN and the decision finding model INTL for real time performance, their implementation on a network of UNIX stations and the experiences from running them within an urban drainage real time control project. The main focus is not on what the models do but how they are put into action and made to run smoothly embedded in all the processes necessary in operational real time control.
Modelling drainage performance in slums of developing countries: how good is good enough?
Authors: Kolsky P. , Butler D. , Cairncross S. , Blumenthal U. J. , Hosseini M.
Published: May 2018

A model for the dual drainage system in a flat 20 hectare slum in Indore, India was developed to evaluate the factors which influence drainage performance. Performance was defined by the depth, extent, duration, and frequency of flooding during the 1994 monsoon. This paper reports on the conceptual problem of model validation, particularly for “flooding” or “not flooding”. The model's predictions for maximum depth during verification were reasonable, as 72% of maximum depth predictions were within +/− 0.10 m of observed values. The predictions for the binary variable of flooding at a point were, however, poor. The model gave good predictions of freeboard violation, where the freeboard level was set at 50 mm below the lowest kerb. The paper offers some intuitive reasons as to why prediction of freeboard violation may be expected to be better than prediction of flooding. The authors conclude that where models cannot be validated for flooding prediction, it may be better to redefine performance criteria and validate the model for freeboard violation.
Paddling Enforceable Approaches Upstream to EU Standards: Water Quality Management and Policy Implementation in Central and Eastern Europe
Authors: Smith Mark Griffin , De March Carlo , Jolma Ari
Published: May 2018

Rivers in Central and Eastern Europe are highly polluted as a result of over-industrialization, resource intensive production processes and lax environmental enforcement. At the beginning of the economic transition, great optimism abounded within the region that environmental problems would be dealt with early and that the West would offer significant financial help. It is now clear that achieving significant improvement in environmental quality will require many years and will be largely financed from internal resources. Moreover, the region's goal of joining the European Union dominates the environmental policy agenda. Drawing upon the results of a three year study conducted at the International Institute for Applied Systems Analysis (IIASA), cost-effective strategies for eventually achieving this goal are identified. The paper discusses recommendations for implementing these strategies within the evolving political and economic environment of Central and Eastern Europe.
Strategies for Approximating EU Legislation in Hungary: The Sajó River Case
Authors: Somlyódy L. , Buzás K. , Clement A. , Melicz Z.
Published: May 2018

The Hungarian watershed of the Sajó River (a shared river basin with Slovakia), representing about 5% of the country's population and territory was used as a case study to analyze issues of EU accession with special regard to drinking water supply and urban wastewater management. In the past the Sajó was one of the most contaminated Hungarian rivers due to industrial, transboundary and municipal emissions. For today its quality became acceptable due to industrial transformation and municipal wastewater management. The uniqueness of the problem stems from the fact that 30% of the population lives in small settlements of low level of water service. In the frame of the present study large number of water supply, sewerage and wastewater treatment strategies were developed to study the solution of existing problems and to meet EU requirements. For transboundary loads several scenarios were prepared. The investment costs of alternatives were evaluated on the basis of a detailed comparison of international and national estimation techniques. Water quality impacts in terms of traditional components were assessed by using models. Affordability was analyzed and a phased development policy was recommended.
Calibration of QUAL2E Model for the Sava River (Slovenia)
Authors: Drolc A. , Končan J. Zagorc
Published: May 2018

The use of mathematical models is a good decision making tool in river basin management for selection of wastewater treatment technologies and for estimation of the impact of discharged wastewater on the quality of receiving streams. In rivers mostly polluted with degradable organic matter, the major effect of wastewater discharge results in a substantial decrease of dissolved oxygen. The model QUAL2E developed by the United States Environmental Protection Agency was applied to wastewater impact assessment in the Sava river (Slovenia). We present the procedures for the determination of input data for the QUAL2E model. The sediment oxygen demand rate constant was determined experimentally in situ using an specially designed device; the degradation rate constant was determined in a river laboratory model; hydrological characteristics were evaluated on the basis of empirical coefficients; while the reaeration rate constant was calculated on the basis of an energy dissipation model. The mathematical water quality model QUAL2E was calibrated on the basis of field and laboratory measurements and validated with an independent set of data for critical summer low flow conditions when the dissolved oxygen concentrations are low. A sensitivity analysis of the model was also performed. The validated model was then used to estimate the impact of municipal and industrial wastewater discharges on dissolved oxygen concentrations in the Sava river near Ljubljana. The model was used to simulate various conditions in the river and various degrees of treatment of discharged wastewaters. It is estimated according to the model predictions that at critical summer low flow conditions, wastewater should be treated to reach a BOD under 30 mg l−1 with the goal that Slovenian water quality standards are not violated, meaning a dissolved oxygen concentration above 5 mg l−1.
Analysis of Water Quality Criteria in Mexico
Authors: Jiménez B. , Ramos J. , Quezada L.
Published: May 2018

During the last decade, it has been acknowledged that, at national level, the availability of water is a trade-off between its temporary and spatial distribution as well as contamination problems. This situation has urged the Mexican Government to revise the plans and programs for the integrated management of hydric resources by analysing the institutional system, the legal frame and its effectiveness. Within this context, an essential aspect is to ensure the ordering of the uses and exploitation of water resources.

This paper shows that a revision of the effectiveness and applicability of the current water standards and laws is essential to satisfy the demands, and to have control over the different uses of water (drinking water for human consumption, the use of water for agricultural, municipal, industrial related activities and other purposes). Therefore, in this work, a redefinition of the Ecological Criteria of Water Quality has been proposed. The proposal establishes the Quality Criteria under a new perspective, wherein the set of parameters and their values constitute the goal of quality, in the sense that any type of water with such characteristics or better ones, cannot only be used as it is, but constitutes the most suitable water for such use.
Ecotechnological Measures to Control Nutrient Losses from Catchments
Authors: Kuusemets Valdo , Mander Ülo
Published: May 2018

Ecotechnological measures allow to use different natural and seminatural ecosystems to control nutrient losses from intensively used watersheds. The most effective means are buffer strips, buffer zones and constructed wetlands. In southern Estonia a 31 m wide buffer zone of wet meadow and grey alder forest removed 50% nitrogen and 78% phosphorus, while in a 51 m buffer zone, also containing a grassland strip in addition to wet meadow and alder forest, 87 % N and 84 % P was retained. The outflow of total – N was 4.9% and outflow of total – P was 4.8% lower in well-buffered watershed in comparison to similar watershed with lower buffering ability. Three constructed wetlands in southern Estonia were studied. The removal efficiency was 76 – 84% for BOD5, 39 – 70% for total-N, 73 – 83% for total-P. All results show that compared to other seasons the winter performance was not reduced.