bluuebunny/crossref_metadata_2025 huggingface dataset:
On the concept of model structural error
Authors: Beven K.
Published: May 2018

A consideration of model structural error leads to some particularly interesting tensions in the model calibration/conditioning process. In applying models we can usually only assess the total error on some output variable for which we have observations. This total error may arise due to input and boundary condition errors, model structural errors and error on the output observation itself (not only measurement error but also as a result of differences in meaning between what is modelled and what is measured). Statistical approaches to model uncertainty generally assume that the errors can be treated as an additive term on the (possibly transformed) model output. This allows for compensation of all the sources of error, as if the model predictions are correct and the total error can be treated as “measurement error.” Model structural error is not easily evaluated within this framework. An alternative approach to put more emphasis on model evaluation and rejection is suggested. It is recognised that model success or failure within this framework will depend heavily on an assessment of both input data errors (the “perfect” model will not produce acceptable results if driven with poor input data) and effective observation error (including a consideration of the meaning of observed variables relative to those predicted by a model).
Biofilm physical structure, internal diffusivity and tortuosity
Authors: Melo L.F.
Published: May 2018

The paper proposes tortuosity as a physical concept particularly useful to interpret internal diffusivities in terms of biofilm structure. Results from different authors are presented showing how average effective diffusivities in biofilms (measured with inert tracers) vary with the fluid velocity: in the case of biofilms formed under turbulent flow conditions, an increase in fluid velocity corresponds to a decrease in the diffusivity, although sometimes this decrease is very slight; however, in laminar flow situations, no common trend is found from research group to research group.
Total nitrogen removal in an aerobic/anoxic membrane biofilm reactor system
Authors: Cowman J. , Torres C.I. , Rittmann B.E.
Published: May 2018

The hydrogen-based membrane biofilm reactor (MBfR) is effective for reducing nitrate-N to N2 gas, but most wastewaters contain ammonium-N. Here, we document that an aerobic/anoxic MBfR system achieves nearly total N removal (<2 mgN/L) when the influent N is ammonium. The aerobic/anoxic MBfR couples two MBfR modules. The aerobic MBfR is supplied O2 and brings about nitrification of ammonium to nitrate or nitrite. The anoxic MBfR is supplied H2 and brings about denitrification to N2 gas. Total N removal is most strongly influenced by the O2 pressure in the aerobic module: too low O2 caused poor nitrification, while too high O2 inhibited denitrification in the anoxic module. Hydrogen pressure does not strongly affect total-N removal, and the best total-N removal occurs when the H2 and O2 pressures are similar.
Acetate and ammonium diffusivity in membrane-aerated biofilms: improving model predictions using experimental results
Authors: Shanahan J.W. , Cole A.C. , Semmens M.J. , LaPara T.M.
Published: May 2018

Membrane-aerated biofilm reactors (MABRs) are advantageous for wastewater treatment because of their ability to achieve both nitrification and denitrification in a single bioreactor. The stratification of membrane aerated biofilms, however, needs to be better understood so that MABRs can be properly designed and implemented. In this study, we present a modified multi-population model that accounts for variation in effective diffusivity in biofilms of variable biomass density. For biofilms grown at a low fluid velocity (2 cm s−1), the variation in effective diffusivity had a profound effect on the predicted stratification and activity of bacterial populations. For biofilms grown at a high fluid velocity (14 cm s−1), biomass density was relatively constant as a function of depth and thus there was less substantial variation in effective diffusivity; our modified model, therefore, predicted a population stratification that was similar to its original version under these conditions.
Start-up of moving bed biofilm reactors for deammonification: the role of hydraulic retention time, alkalinity and oxygen supply
Authors: Gaul T. , Märker S. , Kunst S.
Published: May 2018

Aerobic and anaerobic ammonium oxidation can be combined in a completely mixed moving bed biofilm reactor, allowing for single-stage ammonium removal from wastewater with low COD/N ratio unsuitable for conventional nitrification/denitrification processes (‘deammonification’). Mandatory preconditions are: (a) a low hydraulic retention time to wash out suspended cells competing with mass transfer limited biofilm cells for alkalinity as limiting substrate; and (b) an oxygen flux adapted to the surface loading rate to prevent complete nitrification to nitrate. pH control or ‘NH3 inhibition’ of nitrite oxidation are neither useful nor necessary. By this strategy, oxygen limited biofilms with simultaneous presence of NH4-N and NO2-N were enriched, which allowed for growth of anaerobic ammonium oxidizers. It could be demonstrated that a deammonifying reactor can be purposefully started up within a reasonable span of time and without prior inoculation, if this explicitly described strategy is applied. Depending on surface loading and air flow rate, N removal rates of 4–5 g N/m2 d could be achieved at DO concentrations between 1.0 and 4.0 mg/l.
Growth and structure of phototrophic biofilms under controlled light conditions
Authors: Zippel B. , Neu T.R.
Published: May 2018

Phototrophic biofilms may be defined as interfacial microbial communities mainly driven by light as energy source. Structure, productivity and taxonomic composition of freshwater phototrophic biofilms under different growth conditions were investigated within the EU-project PHOBIA with the following aims: 1) optimisation of wastewater treatment in wetlands, 2) control and prevention of biofouling on submersed objects, and 3) modelling of phototrophic biofilm development. Experiments were carried out in a flow-lane incubator with precise control of external light, temperature, velocity conditions and nutrient-adapted artificial medium. Structure and architecture of phototrophic biofilms at different developmental stages were examined by using multi-channel confocal laser scanning microscopy (CLSM). The development of phototrophic biofilms was clearly light dependent. Fast growing phototrophic biofilms were mostly dominated by single species algae and formed less stable structures of up to 900 μm thickness. Biofilms with these dimensions had to be cryo-sectioned and post-stained for CLSM. Laser microscopy analysis also revealed a stratification of phototrophic organisms which was more pronounced in slow growing biofilms. In contrast, at very low light intensity the development of phototrophic biofilms was strongly delayed. In conclusion, structural features and subsequent functional relationships may be key parameters for exploitation, control and modelling of phototrophic biofilms.
Recent developments in lake modelling
Authors: Jørgensen S.E.
Published: May 2018

The radical variability of ecosystems such as lakes when reacting to prevailing conditions has in many situations found traditional modelling too inflexible. The introduction of eco-exergy, a measure of a system's distance from thermodynamic equilibrium, has enabled models to deal with ecosystems that can show major structural changes resulting from adaptation and shifts in species composition.
Analysis of drugs and personal care products in French source and drinking waters: the analytical challenge and examples of application
Authors: Bruchet A. , Hochereau C. , Picard C. , Decottignies V. , Rodrigues J.M. , Janex-Habibi M.L.
Published: May 2018

This paper illustrates the challenge faced by analytical chemists when trying to measure selected compounds representative of various classes of prescription and hospital drugs. Because hundreds of drugs belonging to a wide variety of chemical groups are allowed for use, an array of analytical methods has to be implemented. As an example, as part of the European Poseidon Project, five different methods were required to measure eight drugs and personal care products. These methods are discussed in detail. Examples of application to surface and ground waters from the Paris area are also reported. The antibiotics roxithromycin and sulfamethoxazole were detected for the first time in the Seine River downstream of Paris. The behaviour of the eight target compounds during aquifer recharge and drinking water treatment is described. An incident involving the detection of micrograms per litre levels of the personal care product Galaxolide in a drinking water distribution system is reported. The value of the pharmaceuticals and personal care products selected as potential indicators is also discussed.
Disinfection by-products and microbial contamination in the treatment of pool water with granular activated carbon
Authors: Uhl W. , Hartmann C.
Published: May 2018

For swimming pools, it is generally agreed that free chlorine levels have to be maintained to guarantee adequate disinfection. Recommended free chlorine levels can vary between 0.3 and 0.6mg/L in Germany and up to 3mg/L in other countries. Bathers introduce considerable amounts of organic matter, mainly in the form of such as urine and sweat, into the pool water. As a consequence, disinfection byproducts (DBPs) are formed. Regulations in Germany recommend levels of combined chlorine of less than 0.2mg/L and levels of trihalomethanes (THMs) of less than 20μg/L. Haloacetic acids (HAAs), haloacetonitriles (HANs), chloropicrin and chloral hydrate are also detected in considerable amounts. However, these compounds are not regulated yet. Swimming pool staff and swimmers, especially athletes, are primarily exposed to these byproducts by inhalation and/or dermal uptake. In Germany, new regulations for swimming pool water treatment generally require the use of activated carbon. In this project, three different types of granular activated carbon (GAC) (one standard GAC, two catalytic GACs) are compared for their long time behaviour in pool water treatment. In a pilot plant operated with real swimming pool water, production and removal of disinfection byproducts (THMs, HAAs, AOXs), of biodegradable substances (AOC), of bacteria (Pseudomonas aeruginosa, Legionella, coliforms, HPC) as well as the removal of chlorine and chloramines are monitored as function of GAC bed depth. Combined chlorine penetrates deeper in the filter bed than free chlorine does. However, both, free and combined chlorine removal efficiencies decrease over the time of filter operation. The decreases of removal efficiencies are also observed for parameters such as dissolved organic carbon, spectral absorption coefficient, adsorbable organic carbon and most of the disinfection byproducts. However, THMs, especially chloroform are produced in the filter bed. The GAC beds were contaminated microbially, especially with P. aeruginosa. The contamination was not removable by backwashing with chlorine concentrations up to 2mg/l free chlorine.
Arsenic contamination of groundwater in Nawabganj, Bangladesh, focusing on the relationship with other metals and ions
Authors: Ohno K. , Furukawa A. , Hayashi K. , Kamei T. , Magara Y.
Published: May 2018

Serious arsenic contamination of groundwater in Bangladesh has been frequently reported and is of great concern. In this research, repeated water sampling from the same 10 tubewells in Nawabganj municipality, Bangladesh, was conducted and analysed, focusing on the seasonal variation of water quality and the relationship among arsenic and other metals and ions. For the seasonal variation of water quality, arsenic and iron concentrations were higher in the rainy season in general although the tendency was not consistent and it depended on the tubewell and the time. Correlation between arsenic and iron could not be observed in this study (r = −0.01) when using all cases. This was because no correlation was observed in the higher arsenic concentration range. Arsenic removal by co-precipitation with coexisting iron is known as one of the locally applicable techniques in Bangladesh, but the result from this study suggests that some additional treatments such as the extra injection of iron should be performed in some cases, especially where the arsenic concentration is high. The correlation between arsenic and other substances was also analysed. As a result, manganese (r = 0.37), molybdenum (r = 0.33) and sulfate ion (r = −0.33) significantly correlated with arsenic (p<0.05). The negative correlation between arsenic and sulfate ion implies the dissolution of arsenic into groundwater under reductive conditions although there are some exceptional cases.
Protecting human and ecological health under viral threats in Asia
Authors: Matsui S.
Published: May 2018

Severe acute respiratory syndrome (SARS) outbroke in 2003, and the avian influenza A (H5N1) also outbroke in 2003 and continued to 2004. These pandemic viral diseases originated in South East Asia. Many human and animal lives were lost. Economic damages due to the pandemics were also very large. The question arises of why did the pandemics originate from South East Asian areas. Human influenza A consists of many sub-types of coronaviruses including the SARS virus and the avian influenza (H5N1) that are all variants of RNA of avian coronavirus. Variants are formed during infection of a coronavirus through not only birds but also mammals, including human beings. There are hot spots where viral infection rates are accelerated among birds, mammals and human beings. Suspicious areas are in South East Asia, where living conditions of birds, mammals and human beings are so close that there are always risks of viral infection. When we see the living conditions of farmers in southern China, northern Vietnam, Laos and northern Myanmar, they commonly raise ducks/chickens with pigs sharing ponds into which they discharge household wastewater, including human excreta, and pig excreta that are significant carriers of viruses. Bird faeces are also key carriers of the viruses. In the ponds, they raise ducks and conduct fish culture. Other important players are migrating birds from North Asia, which are principal vectors of avian influenza viruses. There is an urgent necessity of improving human and ecological health in South East Asia to control viral infection among birds, mammals and human beings. We can hinder the vicious cycle of virus infection through water contamination in ponds by providing good human, pig and chicken sanitation. It is easy to provide good sanitation practices for human, pigs and chickens, introducing collection and treatment of excreta. Our modern water technology can find good solutions for the problem.
Sustainable sanitation and water in small urban centres
Authors: Rosemarin A.
Published: May 2018

The objective of this paper is to review the global trends in urbanization with respect to availability of adequate sanitation and water supply services. Urbanization is unrelenting and rapid increase in the urban population in the less developed countries is of major global concern regarding this topic of sustainable sanitation and water. Most global urban growth is in the smaller cities and in the developing world. Half the urban developing world lacks adequate water and sanitation. Global urban access to waterborne sanitation is not affordable and thus is not a realistic option so alternative approaches are necessary. The treatment of drinking water cannot be a substitute for sanitation. In order to achieve sustainable sanitation, a change in attitude about human excreta and use of water is required. Essential features of a sustainable sanitation system are: containment, sanitisation and recycling. To improve water supply, we need to improve management practices, use full-cost pricing, introduce watershed approaches to protection and provide improved sanitation. Small urban initiatives need to go beyond the traditional sectors and new initiatives are required like on-site urban ecostations, source-separation of urine and faeces, decentralised greywater treatment and integration of sanitation into the cost of housing.
Cometabolic transformation of cis-1,2-dichloroethylene and cis-1,2-dichloroethylene epoxide by a butane-grown mixed culture
Authors: Kim Y. , Semprini L.
Published: May 2018

Aerobic cometabolism of cis-1,2-dichloroethylene (c-DCE) by a butane-grown mixed culture was evaluated in batch kinetic tests. The transformation of c-DCE resulted in the coincident generation of c-DCE epoxide. Chloride release studies showed ∼75% oxidative dechlorination of c-DCE. Mass spectrometry confirmed the presence of a compound with mass-to-charge-fragment ratios of 112, 83, 48, and 35. These values are in agreement with the spectra of chemically synthesized c-DCE epoxide. The transformation of c-DCE required O2, was inhibited by butane and was inactivated by acetylene (a known monooxygenase inactivator), indicating that a butane monooxygenase enzyme was likely involved in the transformation of c-DCE. This study showed c-DCE epoxide was biologically transformed, likely by a butane monooxygenase enzyme. c-DCE epoxide transformation was inhibited by both acetylene and c-DCE indicating a monooxygenase enzyme was involved. The epoxide transformation was also stopped when mercuric chloride (HgCl2) was added as a biological inhibitor, further support a biological transformation. To our knowledge this is the first report of the biological transform c-DCE epoxide by a butane-grown culture.
Improving basin water use in linked agricultural, ecological and urban systems: seeking new flow paths and avoiding dead ends
Authors: Molden D. , Bos M.G.
Published: May 2018

In many river basins, patterns of water withdrawals, deliveries, depletion, return flows, and reuse are prevalent. These cascading systems, often misunderstood, provide opportunities, but also threats to livelihoods and environment. Different ways of thinking about these cascading systems are required.
Excess propagation and biological control of zooplanktonic Cyclops in drinking water sources
Authors: Cui F.-Y. , Lin T. , Liu D.-M. , Zhang L.-Q.
Published: May 2018

Starting with the occurrence of Cyclops in drinking water sources and its danger to drinking water safety, we extensively investigated the nature of its excess propagation by analyzing the effect of living space and predator pressure in the food chain on its survival. Then we developed an ecological project using fish biomanipulation, different to the conventional fishery culture technique, to control excess propagation of Cyclops. The control effects on Cyclops of four species of fish were investigated experimentally at a stocking density of 30g/m3 of water. Results showed that the food habit of the fish had a significant influence on the biological control of Cyclops. The propagation of Cyclops could be controlled effectively and also the water quality improved simultaneously by stocking filter-feeding fish, such as silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis). However, herbivorous Ctenopharyngodon idellus and omnivorous Cyprinus carpio had no obvious biological effects on controlling the growth of Cyclops and restoring water quality. The results further proved that under conditions of proper poly-culture densities of silver carp and bighead carp, the number of Cyclops might be controlled at very low levels and eutrophication might be abated by removing nutrients from the water body.
Free water surface wetlands for wastewater treatment in Sweden: nitrogen and phosphorus removal
Authors: Andersson J.L. , Bastviken S. Kallner , Tonderski K.S.
Published: May 2018

In South Sweden, free water surface wetlands have been built to treat wastewater from municipal wastewater treatment plants. Commonly, nitrogen removal has been the prime aim, though a significant removal of tot-P and BOD7 has been observed. In this study, performance data for 3–8 years from four large (20–28 ha) FWS wetlands have been evaluated. Two of them receive effluent from WWTP with only mechanical and chemical treatment. At the other two, the wastewater has also been treated biologically resulting in lower concentrations of BOD7 and NH4+-N. The wetlands performed satisfactorily and removed 0.7–1.5 ton N ha−1 yr−1 as an average for the time period investigated, with loads between 1.7 and 6.3 ton N ha−1 yr−1. Treatment capacity depended on the pre-treatment of the water, as reflected in the k20-values for N removal (first order area based model). In the wetlands with no biological pre-treatment, the k20-values were 0.61 and 1.1 m month−1, whereas for the other two they were 1.7 and 2.5 m month−1. P removal varied between 10 and 41 kg ha−1 yr−1, and was related to differences in loads, P speciation and to the internal cycling of P in the wetlands.
Blueprint for a greener city: growth need not costthe earth
Authors: Anderson J.M.
Published: May 2018

The current human use of global natural resources exceeds the long-term sustainable capacity of the planet. New and more sustainable ways of building cities and providing urban water services are needed. The Australian city of Sydney is expected to grow by more than 1 million people over the next 30 years. Water use from the Hawkesbury-Nepean River system already exceeds system capacity. Current proposals to allocate a greater proportion of low flows to meet environmental flow needs will limit urban water allocations and require the development of more efficient water and sewerage systems for new and existing urban development. This paper presents a hypothetical case study of how water supply and sewerage services might be provided for an additional 1 million people over a 25-year period. It compares traditional service provision with alternative scenarios incorporating water conservation measures, rainwater harvesting and water reuse. The paper presents both economic and environmental comparisons. The economic comparisons include valuations of environmental externalities in the form of environmental levies. It shows that the extra capital costs of water conservation, alternative water sources and water reuse scenarios are offset by operating savings and environmental benefits. Ecological footprints are reduced because of lower water diversions, discharges, energy use and CO2 emissions. The paper also discusses the implication of alternative infrastructure ownership and water pricing arrangements, and the opportunities to create incentives for additional investment in water conservation and reuse projects.
Optimization of Suzhou Creek Rehabilitation Project Stage I
Authors: Xu Z. , Liao Z.
Published: May 2018

Suzhou Creek is a seriously polluted tidal river in Shanghai, China. With the development of Shanghai, there is more and more concern over the “blackness and stink” phenomenon of Suzhou Creek. Suzhou Creek Rehabilitation Project was launched in 1998, and the planning investment of the Project Stage I was 8.65 billion yuan (about 1.05 billion US dollars). It is important to predict the effectiveness of the project and to optimize it. In this study, the USEPA's WASP model is employed to establish a water quality model of Suzhou Creek by using data from the Third Trial Low Flow Augmentation on Suzhou Creek in 1999 and other monitoring results. Based on this, Suzhou Creek Rehabilitation Project Stage I is optimized and adjusted, so the actual investment of the Project Stage I is reduced to 6.99 billion yuan. By implementing the Project Stage I, the targets of Stage I have been met, the “blackness and stink” phenomenon of the mainstream was eliminated by the end of 2000, and the ecological system was improved step by step.
Estimations of municipal point source pollution in the context of river basin management
Authors: Zessner M. , Lindtner S.
Published: May 2018

Integrated presentation of total emissions on catchment scale is prerequisite for many tasks in integrated management of point and diffuse sources of pollution. This paper will focus on emissions of nutrients from municipal point sources. Based on calculations of discharges of N, P from households into wastewater and on the detailed evaluation of data from 76 municipal wastewater treatments plants, this paper presents ranges of specific loads of inhabitants and population equivalents in the raw wastewater. In addition data of these treatment plants have been evaluated in respect of the treatment efficiency for nitrogen and phosphorus (average reduction rates) dependent on the design characteristic (with or without nitrification, denitrification or enhanced phosphorus removal). The results of the investigation show that the specific N and P loads from households in Austria lie within the range 1.6–2.0gP/(inhabitant.d) and 11–13gN/(inhabitant.d). The specific contribution of industries to municipal wastewater varies between 0.3 and 2.0gP/(pe.d) and 0 and 13gN/(pe.d) with average values of 1.3gP/(pe.d) and 6.5gN/(population equivalent (pe)/d). As average values for municipal wastewater (contributions from household and industry) this leads to specific influent loads of 1.5gP/(pe.d) and 8.8gN/(pe.d). Average treatment efficiencies of treatment plants are for instance 50% nitrogen removal in treatment plants with nitrification and 80% in treatment plants with nitrification/denitrification. For phosphorus a removal of about 85% can be expected where the treatment plant was designed for enhanced phosphorus removal. Finally a method for load estimations based on standard values as mentioned above was tested for the estimation of emission from municipal point sources of selected regions.
Exceeding tertiary standards with a pond/reed bed system in Norway
Authors: Browne W. , Jenssen P.D.
Published: May 2018

At Vidaråsen in Norway sewage from a community consisting of 160 people, including a dairy, a food processing workshop, a bakery and a laundry is treated using a pond/reed bed system. The system consists of sludge settlement, pre-treatment surface/vertical-flow constructed wetlands, a 5 m deep enhanced facultative pond, three stabilization ponds, a planted sand filter and finally two horizontal-flow constructed wetlands filled with lightweight aggregate (Filtralite-P). The enhanced facultative pond and the primary stabilization pond are equipped with Flowform-cascades, which provide year-round aeration, rhythmical treatment and mixing of wastewater in the ponds. Treatment performance during the first five years has been high and unaffected by harsh winter conditions. Average phosphorus discharge from the system is 0.25 mg/l with total nitrogen 4 mg/l, total organic carbon (TOC) 5 mg/l and thermo-tolerant coliforms <100/100 ml. The system is ecologically diverse and supports abundant populations of higher aquatic life such as ducks, amphibians and carp.
From conventional to advanced environmental sanitation
Authors: Schertenleib R.
Published: May 2018

The basic concept of collecting domestic liquid waste in water-borne sewer systems goes back more than 100 years and became in the last century the conventional approach to sanitation in urban areas. Over the years, these sewage disposal systems had to be successively upgraded by additional sewage treatment plants increasing investment, operating and maintenance costs. Although these conventional sanitation systems could improve significantly the public health situation in those countries who could afford to install and operate them, it is highly questionable, if they are economically and ecologically sustainable. The large number of people in the developing world who still do not have access to adequate sanitation is a clear indication that the conventional approach to sanitation is not adapted to the socio-economic condition prevailing in most countries of Africa, Asia and Latin America. Advanced environmental sanitation is aiming not only to protect public health and the integrity of aquatic ecosystems but also to conserve precious freshwater and non-renewable resources. The Bellagio Principles and the Household Centred Environmental Sanitation Approach (HCES) are suggested as guiding principles and a new approach for planing and designing advanced (sustainable) environmental sanitation systems.
Optimal maintenance of constructed wetlands using an environmental decision support system
Authors: Turon C. , Alemany J. , Bou J. , Comas J. , Poch M.
Published: May 2018

Constructed wetlands (CWs) are artificial wastewater treatment systems appropriate for small communities because of their affordability, operability and reliability. These qualities are true whenever CWs are designed and constructed properly, and as long as the necessary operation and maintenance procedures are carried out correctly. Experience shows that the operation and maintenance procedures, and the frequencies with which these procedures are carried out, differ from one CW to another. With this in mind, and along with a projected increase in CWs in Catalonia, the Catalan Water Agency (Agència Catalana de l'Aigua) has developed an Environmental Decision Support System (EDSS) which proposes guidelines for monitoring and maintenance, according to the characteristics of each CW. This EDSS was developed following a methodology based on five steps: (i) problem analysis; (ii) collecting data and knowledge acquisition; (iii) model selection; (iv) model implementation and (v) validation. This paper describes the methodology followed to build the decision support system and presents some examples of the information provided by this EDSS.
Research on wastewater reuse planning in Beijing central region
Authors: Jia H. , Guo R. , Xin K. , Wang J.
Published: May 2018

The need to implement wastewater reuse in Beijing is discussed. Based on the investigation of the built wastewater reuse projects in Beijing, the differences between small wastewater reuse system and large systems were analyzed according to the technical, economical and social issues. The advantages and disadvantages of the small system and the large system were then given. In wastewater reuse planning in Beijing urban region, the large system was adopted. The rations of reclaimed water for difference land use type, including industrial reuse, municipal reuse, grass irrigation, and scenes water reuse were determined. Then according to the land use information in every block in central Beijing, using GIS techniques, the amounts of the reclaimed water needed in every block were calculated, and the main pipe system of reclaimed water was planned.
Recycling of treated domestic effluent from an on-site wastewater treatment system for hydroponics
Authors: Oyama N. , Nair J. , Ho G.E.
Published: May 2018

An alternative method to conserve water and produce crops in arid regions is through hydroponics. Application of treated wastewater for hydroponics will help in stripping off nutrients from wastewater, maximising reuse through reduced evaporation losses, increasing control on quality of water and reducing risk of pathogen contamination. This study focuses on the efficiency of treated wastewater from an on-site aerobic wastewater treatment unit. The experiment aimed to investigate 1) nutrient reduction 2) microbial reduction and 3) growth rate of plants fed on wastewater compared to a commercial hydroponics medium. The study revealed that the chemical and microbial quality of wastewater after hydroponics was safe and satisfactory for irrigation and plant growth rate in wastewater hydroponics was similar to those grown in a commercial medium.
Effluent tracing and the transport of contaminants from a domestic septic system
Authors: Geary P.M.
Published: May 2018

A domestic soil absorption system in a coastal location was instrumented with suction lysimeters and piezometers and monitored between August and December 2002. Using the sandy soils from the site, column leaching experiments were also undertaken and these suggested that bromide would be a suitable conservative tracer which could be added to the wastewater system to determine the direction and rate of groundwater flow. The septic system plume boundaries were identified from the monitoring results and the subsurface fate of the inorganic nutrients determines using ion ratios. The tracing results indicated that groundwater was moving at 0.4 m/day towards a nearby drain. The ion ratios indicated that total inorganic nitrogen and orthophosphate were not substantially lost or diluted in the sandy soils downgradient from the soil absorption system, and that without riparian vegetarian lining the drain, these nutrients would have been largely unattenuated in transport. In the absence of adequate vertical and horizontal setback distances, riparian vegetation is regarded as very important in limiting the subsurface transport of inorganic nutrients from domestic septic systems.
Package plant of extended aeration membrane bioreactors: a study on aeration intensity and biofouling control
Authors: Ujang Z. , Ng S.S. , Nagaoka H.
Published: May 2018

Biofouling control is important for effective process of membrane bioreactor (MBR). In this study, phenomena of biofouling for immersed type extended aeration MBR with two different anti-fouling aeration intensities were studied through a laboratory set up. The objectives of this study were (a) to observe biofouling phenomena of MBR that operates under different anti-fouling bubbling intensity, and simultaneously monitors performance of the MBR in organic carbon and nutrients removal; (b) to compare effectiveness of detergent and detergent-enzyme cleaning solutions in recovering biofouled membranes that operated in the extended aeration MBR. For MBR, which operated under continuous anti-fouling aeration, deposition and accumulation of suspended biomass on membrane surface were prohibited. However, flux loss was inescapable that biofilm layer was the main problem. Membrane cleaning was successfully carried out with detergent-enzyme mixture solutions and its effectiveness was compared with result from cleaning with just detergent solution.
Rehabilitation studies and recovery of a once lifeless estuary: the Golden Horn
Authors: Yüksek A. , Okuş E. , Yılmaz N.
Published: May 2018

Within this study fluctuations in biodiversity of the Golden Horn from past to present are evaluated. Limited studies and observations dating back to 60 years ago pointed out the importance of the Golden Horn as a fishery. Unfortunately, in accordance with increase in unplanned settlements and industry around the Golden Horn in the 1960s, pollution stress became a demanding factor for this unique environment, affecting biodiversity adversely. Preliminary studies in the 1990s indicated survival of only a couple of pollution-resistant species, at the relatively cleaner outer estuary. Following intensification of “still ongoing” rehabilitation studies in 1998, a remarkable day-by-day recovery in marine life has began, in regard to improvements in water quality. Surveys conducted in 2002 using SCUBA, documented the level of diversification of life at the Golden Horn. Extended till Haliç Bridge, all appropriate substratums were intensely covered by macrobenthic forms and particularly filter feeders dominated the plankton-rich ecosystem. Detection of seahorses at the inner-middle parts of the estuary, in addition to numerous fish, invertebrate and macroalgae species, clearly depicted the level of recovery and change in the ecosystem. All results support the existence of a dynamic biological life at the Golden Horn, improving considerably with rehabilitation studies. Achieving the diversity of the 1940s is not possible, since the Black and Marmara seas, highly influencing water quality in the Golden Horn are also suffering from anthropogenic impacts and are far beyond their rich diversity in the 1940s. However, it is obvious that ecosystems should recover when mankind gave a chance to them. Recovery of the recently lifeless Golden Horn in such a short period of time is a very good example.
Nitrogen management in reservoir catchments through constructed wetland systems
Authors: Tunçsiper B. , Ayaz S.Ç. , Akça L. , Samsunlu A.
Published: May 2018

In this study, nitrogen removal was investigated in pilot-scale subsurface flow (SSF) and in free water surface flow (FWS) constructed wetlands installed in the campus of TUBITAK-Marmara Research Center, Gebze, near Istanbul, Turkey. The main purposes of this study are to apply constructed wetlands for the protection of water reservoirs and to reuse wastewater. Experiments were carried out at continuous flow reactors. The effects of the type of plants on the removal were investigated by using emergent (Canna, Cyperus, Typhia spp., Phragmites spp., Juncus, Poaceae, Paspalum and Iris.), submerged (Elodea, Egeria) and floating (Pistia, Salvina and Lemna) marsh plants at different conditions. During the study period HLRs were 30, 50, 70, 80 and 120 L m2 d−1 respectively. The average annual NH4-N, NO3-N, organic N and TN treatment efficiencies in SSF and FWS wetlands are 81% and 68%, 37% and 49%, 75% and 68%, 47% and 53%, respectively. Nitrification, denitrification and ammonification rate constant (k20) values in SSF and FWS systems have been found as 0.898 d−1 and 0.541 d−1, 0.488 d−1 and 0.502 d−1, 0.986 d−1 and 0.908 respectively. Two types of the models (first-order plug flow and multiple regression) were tried to estimate the system performances
Land use change analysis of Beykoz-Istanbul by means of satellite images and GIS
Authors: Musaoglu N. , Coskun M. , Kocabas V.
Published: May 2018

Management and planning of the natural environment requires spatially accurate and timely information on land use patterns. With repetitive satellite coverage, the rapid evolution of computer technology and the integration of satellite and spatial data, the development of land use applications have become ubiquitous. The integration of Remote Sensing (RS) and Geographic Information Systems (GIS) has been widely applied and recognized as a powerful and effective tool in detecting land use change in urban areas. This paper presents the land use change analysis of the Beykoz region, which is the second largest administrative district of Istanbul. Land use changes and their impacts are monitored using Landsat (MSS – TM) and Spot 5 satellite data in the period of 1975–2001. The independent classification of each satellite image was used as a change analysis method and the resulting images were analyzed with GIS techniques. The results showed that forest area of Beykoz decreased from 80.55% to 70.5% between 1975 and 1984 and during the 1984–2001 periods, the forested area decreased from 70.5% to 68.86% and the urban growth rate was 4.65%.
A sustainable approach towards rural development: dry toilets in Nepal
Authors: Regmi M.R.
Published: May 2018

Existing inadequate sewerage systems and direct disposal of household waste into water courses has tremendously increased water pollution. Dry toilets are feasible in rural and peri-urban areas to reduce the consumption of costlier water that is required for flushing. As conventional treatment technologies require high investment, and operation and maintenance costs, dry toilets are the only suitable option left for sanitation in the 21st century when working with limited financial resources. To reduce environmental degradation and overcome this problem, the dry toilet is only the realistic option in Nepal. Two reactors, one exposed to sunrays and the other without sunrays, were constructed. In the model with sunrays, it was found that in 48 days of observation faecal coliform presence depleted to 610 cells per gm from the initial value of 7×1010 and volatile organic matter came down from 98.09% to 70.18%. Similarly, in the other model, the destruction of faecal coliform in 65 days was found to be 920 cells/gm while the destruction of organic matter took 75 days. Also, observing from 313 people in a cluster on the pilot project, the annually recovered value of N, P and K was found to be 1565kg, 125kg, 344kg, respectively. This paper deals with the different types of dry ecological toilet, their performance and feasibility study in Nepal, with the full involvement of local people, based on complete laboratory analysis and regular monitoring. Using dry toilets will save 14 LPCD, which is equivalent to 14 MLD and the resulting demand will become only 80 MLD for the urban area of Kathmandu. The result advocates the implementation of ecological dry toilets to save valuable water wasted in flushing, as well as saving the resources needed to treat the waste.
Improving nitrogen reduction in waste stabilisation ponds
Authors: Archer H.E. , O'Brien B.M.
Published: May 2018

This paper reviews the performance of two waste stablisation ponds (WSP) systems in the South Island of New Zealand that have been upgraded to multiple ponds-in-series to improve effluent quality. Results of monitoring are provided which show that it is possible to achieve relatively low ammonia (approximately 1 g/m3) and total nitrogen (approximately 10 g/m3) effluent concentrations through the use of nitrification filter beds (rock trickling filters) and sand filters. Evidence suggests that the nitrification and denitrification processes in the extra biofilm surface area provided by the rock filters or rock bank protection is primarily responsible for the improved effluent quality. The paper also compares the WSP results with effluent quality predicted by published formulae. It is concluded that these formulae do not reliably predict the performance of WSP systems and the development of universally applicable design guidelines would be useful.
Profiling and modelling of thermal changes in a large waste stabilisation pond
Authors: Sweeney D.G. , Nixon J.B. , Cromar N.J. , Fallowfield H.J.
Published: May 2018

A thermal profiling study was undertaken at four depths at each of nine sites, and at the inlets and outlets of a large waste stabilisation pond (WSP). Results were collected simultaneously using a network of 42 thermistors and dataloggers. Profiles at each site were categorised as either “stratified” or “unstratified”, and persistence analysis was used to determine the frequency and persistence of stratification events at each of the nine sites. Stratification was found to persist most strongly at the site furthest upwind in the WSP, with respect to prevailing wind during the study, leading to the conclusion that stratification induced short-circuiting will be greatest in this region of the WSP. A computational fluid dynamics (CFD) model was constructed of the WSP, including an energy balance to predict the bulk stratification gradient in the pond. Environmental conditions and WSP inlet temperature during one day in June 2001 were used as boundary conditions. The pond thermal profiles measured during the profiling study, together with outlet temperature during the day, were used to validate the CFD model results. The model predicted mean pond temperature with a high degree of accuracy (r2=0.92). However it was evident that even modest winds (≥1.5 m/s) partially broke down stratification, leading to poor prediction of the gradient by the CFD model, which did not directly account for the impact of wind shear stress on mixing in the WSP.
Testing of conductivity/calcium and rubidium/strontium ratios as indicators of the chemical stability of a river: comparison with a biological indicator
Authors: Nirel P.M.V. , Lazzarotto J.
Published: May 2018

It is customary to detect pollution in a water flow by monitoring the increase of sensitive elements concentrations (NH4+, PO43−, NO3−…). However, concentrations are dependent on the flow rate and these compounds are not conservative, implying a concentration decrease downstream leading to false negative diagnosis of pollution impact. The use of elemental ratios of conservative compounds should diminish these pitfalls. We then thought of the χ/Ca (conductivity/calcium) and Rb/Sr (rubidium/strontium) ratios as water chemical stability indicators to clearly identify and discriminate point from diffuse pollutions.

This hypothesis has been tested on 12 brooks located in the basin of Lake Geneva, during 2 hydrological years. The results were compared to the observed land use of the watershed and a biological indicator: the Pollution Sensitivity Index (PSI). The PSI is calculated from diatom taxonomy and evaluates biological quality with a grade ranging from 0 to 20 (bad to excellent). The main results of the research can be summarized as follows. The pollution signal is observable far downstream of the pollution site. Both χ/Ca and Rb/Sr ratios are water quality indicators expressing the stability of water chemistry. They can both be used to detect diffuse and point pollution impact. These indicators provide complementary information: χ/Ca variations increase in case of point pollution; Rb/Sr variations increase when diffuse pollutions occur. The results obtained with the indicators χ/Ca and Rb/Sr agree with biological indicator and observation of the land use. χ/Ca and Rb/Sr ratios represent important tools to identify and discriminate point source pollution from diffuse pollution.
Anaerobic digestion as a core technology in sustainable management of organic matter
Authors: Verstraete W. , Morgan-Sagastume F. , Aiyuk S. , Waweru M. , Rabaey K. , Lissens G.
Published: May 2018

In the past decades, anaerobic digestion (AD) has steadily gained importance. However, the technology is not regarded as a top priority in science policy and in industrial development at present. In order for AD to further develop, it is crucial that AD profits from the current fuel issues emerging in the international arena. AD can provide low-cost treatment of sewage and solid domestic wastes, which represents a vast application potential that should be promoted in the developing world. Furthermore, the developments in the last decades in the domain of anaerobic microbiology and technology have generated some interesting niches for the application of AD, such as anaerobic nitrogen removal and the treatment of chlorinated organics. Recently, AD has also generated some serendipities, such as the use of AD in processes for sulphur and calcium removal and the coupling of AD with microbial fuel cells. The international developments in terms of bio-refineries and CO2-emission abatement are of crucial importance with respect to the impetus that AD will receive in the coming decade. There should be little doubt that by placing the focus of AD on the production of green energy and clean nutrients, the future of AD will be assured.
Microbial characteristics of a methanogenic phenol-degrading sludge
Authors: Zhang T. , Ke S. Z. , Liu Y. , Fang H.P.
Published: May 2018

Microbial properties of a methanogenic granular phenol-degrading sludge were characterized using the 16S rRNA/DNA-based techniques, including polymerase chain reaction (PCR) amplification, cloning, DNA sequencing, and fluorescence in situ hybridization (FISH). The sludge was sampled from an upflow anaerobic sludge blanket reactor, which removed 98% of phenol (up to 1260 mg/l) in wastewater at 26°C with 12 hours of hydraulic retention. Based on DNA analysis, the Eubacteria in the sludge was composed of 13 operational taxonomy units (OTUs). Two OTUs, one resembling Clostridium and the other remotely resembling Desulfotomaculum, were likely responsible for the conversion of phenol to benzoate, which was further degraded by five Syntrophus-resembling OTUs to acetate and H2/CO2; methanogens lastly converted acetate and H2/CO2 into methane. The role of six remaining OTUs remains unclear. Overall, the sludge was composed of 26±6% Eubacteria and 74±9% methanogens, of which 54±6% were acetotrophic Methanosaetaceae, 14±3% and 3±2% were hydrogenotrophic Methanomicrobiales and Methanobacteriaceae, respectively.