bluuebunny/crossref_metadata_2025 huggingface dataset:
Anaerobic biodegradability and digestion in accumulation systems for concentrated black water and kitchen organic-wastes
Authors: Elmitwalli T.A. , van Leeuwen M. , Kujawa-Roeleveld K. , Sanders W. , Zeeman G.
Published: July 2007

The feasibility of two accumulation-systems (AC) for anaerobic digestion and storage of concentrated black water with (AC1) or without (AC2) urine + kitchen organic-wastes was investigated. The waste(water) was collected by two vacuum toilet/transport systems. The influent-total COD of the AC2 (53,000 mg/L) was more concentrated by four times than that of the AC1. The suspended COD represented the major part (71–73%) of influent total COD of the two systems. The batch-experiments results showed a high anaerobic biodegradability of the waste(water) (>85%). The AC systems demonstrated stable performance. There was no inhibition effect of NH4 and VFA concentration decreased in time. Total COD removal of 58% was achieved in both systems, after 105 days at 20 °C. Moreover, if only the supernatant in AC1 is withdrawn and the settled sludge stays for the next runs, only 20% of the influent total COD will be in the supernatant. In AC2, 74% of influent ortho-P was removed by precipitation. Therefore, the settled sludge in the AC2 had a high total-P concentration of 1,300 mg/L. The C:N:P ratios of the supernatant and the sludge were 26:13:1 and 35:4.5:1, respectively, in the AC1, and were 28:14:1 and 32:2.4:1, respectively, in AC2.
Anaerobic digestion of space mission wastes
Authors: Chynoweth D.P. , Owens J.M. , Teixeira A.A. , Pullammanappallil P. , Luniya S.S.
Published: July 2007

The technical feasibility of applying leachbed high-solids anaerobic digestion for reduction and stabilization of the organic fraction of solid wastes generated during space missions was investigated. This process has the advantages of not requiring oxygen or high temperature and pressure while producing methane, carbon dioxide, nutrients, and compost as valuable products. Anaerobic biochemical methane potential assays run on several waste feedstocks expected during space missions resulted in ultimate methane yields ranging from 0.23 to 0.30 L g-1 VS added. Modifications for operation of a leachbed anaerobic digestion process in space environments were incorporated into a new design, which included; (1) flooded operation to force leachate through densified feedstock beds; and (2) separation of biogas from leachate in a gas collection reservoir. This mode of operation resulted in stable performance with 85% conversion of a typical space solid waste blend, and a methane yield of 0.3 Lg per g VS added after a retention time of 15 days. These results were reproduced in a full-scale prototype system. A detailed analysis of this process was conducted to design the system sized for a space mission with a six-person crew. Anaerobic digestion compared favorably with other technologies for solid waste stabilization.
Quantification of Cryptosporidium parvum in anaerobic digesters treating manure by (reverse-transcription) quantitative real-time PCR, infectivity and excystation tests
Authors: Garcés G. , Effenberger M. , Najdrowski M. , Wackwitz C. , Gronauer A. , Wilderer P.A. , Lebuhn M.
Published: July 2007

The survival of Cryptosporidium parvum oocysts in anaerobic digesters treating manure was investigated for mesophilic, thermophilic, and a combined treatment (mesophilic–thermophilic–mesophilic) under different retention times of oocysts in the reactors. C. parvum DNA was extracted with an optimised protocol, and its amount determined by quantitative real-time PCR (qPCR). Results indicated noteworthy differences in DNA content after the different treatments. DNA was not degraded during the process. However, excystation and infectivity tests showed a reduction of viable oocyst numbers of ≥2 and ≥5 log units after the thermophilic treatment in two different experiments. Thus qPCR-targeting DNA can overestimate the number of oocysts that survive and remain viable after anaerobic digestion. However, targeting DNA is suitable to indicate the presence or absence of oocysts. Reverse transcription qPCR (RT-qPCR) targeting C. parvum hsp70 mRNA successfully indicated the presence of viable fraction of oocysts.
Optimised anaerobic treatment of house-sorted biodegradable waste and slaughterhouse waste in a high loaded half technical scale digester
Authors: Resch C. , Grasmug M. , Smeets W. , Braun R. , Kirchmayr R.
Published: July 2007

Anaerobic co-digestion of organic wastes from households, slaughterhouses and meat processing industries was optimised in a half technical scale plant. The plant was operated for 130 days using two different substrates under organic loading rates of 10 and 12 kgCOD.m−3.d−1. Since the substrates were rich in fat and protein components (TKN: 12 g.kg−1) the treatment was challenging. The process was monitored on-line and in the laboratory. It was demonstrated that an intensive and stable co-digestion of partly hydrolysed organic waste and protein rich slaughterhouse waste can be achieved in the balance of inconsistent pH and buffering NH4-N. In the first experimental period the reduction of the substrate COD was almost complete in an overall stable process (COD reduction >82%). In the second period methane productivity increased, but certain intermediate products accumulated constantly. Process design options for a second digestion phase for advanced degradation were investigated. Potential causes for slow and reduced propionic and valeric acid degradation were assessed. Recommendations for full-scale process implementation can be made from the experimental results reported. The highly loaded and stable co-digestion of these substrates may be a good technical and economic treatment alternative.
Co-digestion of manure and biowaste according to the EC Animal By-Products Regulation and Finnish national regulations
Authors: Paavola T. , Syväsalo E. , Rintala J.
Published: July 2007

The objective of this study was to compare methane production and characteristics of digested material in anaerobic digestion concepts according to the Animal By-Products Regulation (ABP-Regulation) of the EC (hygienisation of biowaste for 1 hour at 70 °C, particle size <12 mm) and Finnish national regulations (treatment temperature 55 °C, feeding interval 24 h, hydraulic retention time (HRT) 20 d, particle size <40 mm) and with small variations in treatment methods for treating manure and biowaste. Moreover, the survival of three different salmonella bacteria in these processes was studied. Hygienisation of biowaste prior to digestion at 35 °C enhanced methane production by 14–18% compared to similar treatment without hygienisation. The differences in treatment temperature, HRT and hygienisation of biowaste prior to digestion did not significantly affect the characteristics of digested material. The concepts according to the ABP-Regulation and Finnish national regulations were effective in destroying salmonella bacteria to an undetectable level.
Towards new indicators for the prediction of solid waste anaerobic digestion properties
Authors: Buffiere P. , Loisel D. , Bernet N. , Delgenes J-P.
Published: July 2007

The biochemical composition can be seen as a good indicator of both the biodegradability and the methane potential of a given waste. The work presented here is an attempt to elaborate a typology of wastes and to compare it to the anaerobic degradation characteristics. The first data indicate that there is a link between the ligno-cellulosic content of the waste and the biodegradability. When dealing with application to anaerobic digestion processes, having a tool to predict the ability of the waste to be degraded could be of the greatest interest for preventing failures, estimating biogas production, methane content, or for the management of co-digestion processes.
Enhancing waste decomposition and methane production in simulated landfill using combined anaerobic reactors
Authors: Sanphoti N. , Towprayoon S. , Chaiprasert P. , Nopharatana A.
Published: July 2007

The design of leachate recirculation to enhance municipal solid waste decomposition, methane production and microbial activities was taken into account in this study by using the combined anaerobic reactors of a simulated high organic content landfill reactor and a stabilized fixed film anaerobic reactor. The latter aimed to treat high strength leachate from the simulated landfill reactor before recirculation back to the former reactor. The results showed the possibility to apply this technique to high organic waste landfill where rapid and accumulative acids formed in the leachate were removed and treated by a fixed film anaerobic reactor. In addition, the treated leachate when circulated back to the simulated bioreactor landfill helps accelerate waste decomposition and methane production by providing buffer capacity as well as diluting organic content in the leachate to achieve the favourable conditions for acidogen and methanogen, respectively, to rapidly enter into the methanogenesis phase.
Ultrasonic treatment to improve anaerobic digestibility of dairy waste streams
Authors: Palmowski L. , Simons L. , Brooks R.
Published: July 2007

The dairy-processing industry generates various types of organic wastes, which are utilised as stock feed, for anaerobic digestion, spread on land or alternatively land-filled at high costs. Owing to the generation of renewable energy, anaerobic digestion is an attractive option for many factories. To enhance the biological degradation process, a mechanical disintegration of various waste dairy streams was undertaken. While the successful application of ultrasonic treatment has been reported for various municipal waste streams, limited information was available for dairy industry applications. The results of this study showed that ultrasonic treatment can improve the digestibility of the more problematic dairy waste streams, such as sludges, by breaking down micro-organisms' cell walls and releasing soluble cell compounds. For more soluble streams, such as dairy factory effluent, an increased gas production was observed and attributed to the reduced particle size of the fat globules.
Status of ADSW 2005
Authors: Hartmann H. , Ahring B.K.
Published: July 2007

The status of the recent developments in anaerobic digestion of solid waste (ADSW) is outlined on the basis of a selection of papers presented at the 4th International Symposium on ADSW 2005.
Linking environmental and economic sustainability in establishing standards for wastewater re-use in Israel
Authors: Lawhon P. , Schwartz M.
Published: July 2007

Israel is one of the world's leaders in agricultural re-use of wastewater, currently re-using over 60% of produced wastewater. The effects of arid climate, intensive irrigated agriculture and limited water resources make re-use necessary to conserve fresh water for domestic use. Quality standards for wastewater re-use are needed to protect public health and prevent environmental and agricultural damage. This paper examines the environmental and economic sustainability of the proposed upgrade of wastewater quality standards. A tertiary treatment standard was proposed, but has not been approved due to objections from local authorities and farmers. An upgrade will require higher treatment costs, which will be divided between farmers and local authorities through the pricing of the wastewater. Farmers oppose the upgrade because they will not be able to pay higher prices for wastewater, which they use to irrigate low-profit crops. If the price is too high, these farmers may be forced out of business and a substantial reduction in cultivated lands may result. If the price is too low, the poorer local authorities may not be able to comply with the standards, and may discharge improperly treated wastewater, causing environmental damage. A successful policy balances the needs for environmental protection with the economic realities of farmers and local authorities and may require compensation for local authorities or farmers in order to achieve maximum environmental protection.
Enhanced primary treatment of concentrated black water and kitchen residues within DESAR concept using two types of anaerobic digesters
Authors: Kujawa-Roeleveld K. , Elmitwalli T. , Zeeman G.
Published: July 2007

Anaerobic digestion of concentrated domestic wastewater streams – black or brown water, and solid fraction of kitchen waste is considered as a core technology in a source separation based sanitation concept (DESAR – decentralised sanitation and reuse). A simple anaerobic digester can be implemented for an enhanced primary treatment or, in some situations, as a main treatment. Two reactor configurations were extensively studied; accumulation system (AC) and UASB septic tank at 15, 20 and 25°C. Due to long retention times in an AC reactor, far stabilisation of treated medium can be accomplished with methanisation up to 60%. The AC systems are the most suitable to apply when the volume of waste to be treated is minimal and when a direct reuse of a treated medium in agriculture is possible. Digested effluent contains both liquid and solids. In a UASB septic tank, efficient separation of solids and liquid is accomplished. The total COD removal was above 80% at 25°C. The effluent contains COD and nutrients, mainly in a soluble form. The frequency of excess sludge removal is low and sludge is well stabilised due to a long accumulation time.
Optimization analysis of decentralised sanitation and re-use system
Authors: Huang Ting-Lin , Xu Zhi-Qiang , Wang Xiaochang C , Zhang Hui
Published: July 2007

With the application of system dynamics, a dynamic nonlinear model reflecting the relationship between decentralised water use and reclaimed water supply and demand has been established. Through a system analysis, the model has been applied to a small residential district to predict and analyse the situation of future use of fresh water, demand and supply of re-used water, and treatment scale of reclaimed water. It is illustrated in this paper that wastewater decentralised treatment and re-use can decrease the consumption of fresh water without lowering the standard of living water for the district residents. On this basis, a rational scale and construction time of the decentralised sanitation and re-use system have been determined. Also, the paper predicts the influencing factors of the increasing water cost and changes in consumers' acceptability to re-use water in the decentralised sanitation and re-use system.
Comparison of nutrient removal efficiency between pre- and post-denitrification wastewater treatments
Authors: Hamada K. , Kuba T. , Torrico V. , Okazaki M. , Kusuda T.
Published: July 2007

A shortage of organic substances (COD) may cause problems for biological nutrient removal, that is, lower influent COD concentration leads to lower nutrient removal rates. Biological phosphorus removal and denitrification are reactions in which COD is indispensable. As for biological simultaneous nitrogen and phosphorus removal systems, a competition problem of COD utilisation between polyphosphate accumulating organisms (PAOs) and non-polyphosphate-accumulating denitrifiers is not avoided. From the viewpoint of effective utilisation of limited influent COD, denitrifying phosphorus-removing organisms (DN-PAOs) can be effective. In this study, DN-PAOs activities in modified UCT (pre-denitrification process) and DEPHANOX (post-denitrification ptocess) wastewater treatments were compared. In conclusion, the post-denitrification systems can use influent COD more effectively and have higher nutrient removal efficiencies than the conventional pre-denitrification systems.
Implementation of the IWA anaerobic digestion model No.1 (ADM1) for simulating digestion of blackwater from vacuum toilets
Authors: Feng Y. , Behrendt J. , Wendland C. , Otterpohl R.
Published: July 2007

The IWA anaerobic digestion model No.1 (ADM1) is applied to the blackwater anaerobic digestion (BWAD) plant in this work. In order to verify the biochemical kinetics, batch experiments were executed. According to the Monod type kinetics, the maximum uptake rates (km) of butyric acid (HBu), propionic acid (HPr) and acetic acid (HAc) are testified as 18, 14, 13 d−1, and their half saturation concentrations (KS) are 110, 120, 160 g COD/m3, respectively. Afterwards, the model was calibrated based on the performance of a laboratory scale BWAD plant (under mesophilic conditions) by three scenario studies, i.e. the reference conditions, different feeding frequencies and high NH4+ concentration. The model successfully simulated three scenarios. The further two virtual scenario studies were achieved based on the calibrated model. First, the performance of BWAD plant was predicted with different hydraulic retention times (HRT); second, the kitchen refuse (KR) was added into the BWAD plant as additional organic loading. The model predicted the perspective of BW plus KR digestion and generated valuable suggestions for the operation of the real BWAD plant.
Towards a healthy water cycle in China
Authors: Zhang J. , Xiong B.Y.
Published: July 2007

Water shortage and water environment deterioration are becoming the bottleneck of the continuous socioeconomic growth of China in the 21st Century. Based on the development of water utilisation and the natural matter cycle rule, the authors argued that the fundamental approach to resolve the water crises and achieve the sustainable utilisation of water resource is to establish a healthy water cycle. The key strategy to establish this is advanced wastewater treatment and recycling to entire cities. The successional researches and practices of sustainable water utilisation and water environment restoration in Dalian, Shenzhen, Beijing and the north-east region were presented. These projects were the initial applications of the primary healthy water cycle theory, and indicated that the Chinese water industry gradually tends to the water environment restoration and water recycling.
Agronomic aspects and environmental impact of reusing marginal water in irrigation: a case study from Egypt
Authors: El-Mowelhi N.M. , Abo Soliman S.M.S. , Barbary S.M. , El-Shahawy M.I.
Published: July 2007

Egypt produces approximately 2.4 million m3 of secondary treated wastewater (TWW) annually, used for irrigation directly or indirectly by blending with agricultural drainage water (BDW). The annual re-use of (BDW) is approximately 4 million m3. The safe and efficient use of marginal water (BDW and TWW) is a core objective of this study which has been operating from 1997 to date. After six growing seasons the main results can be summarized as follows: Maximizing crop production: TWW can be used for high production of oil crops (canola, soybean sunflower or maize) compared to fresh water, while BDW can be used for high production of tolerant crops (cotton and sugar beet). Crop quality: using marginal water increases the concentration of elements (Pb, B, Ni, Co) in all crops but these elements were under critical levels (there were no toxicity hazards). It is better to use alternative irrigation with fresh water under a drip irrigation system to maximise crop production and minimise the adverse effects of such water in field crops quality. Soil pollution and salinity build up: A drip irrigation system under alternative irrigation by fresh with TWW or BDW reduces salinity build up risks and the levels of elements (Pb, B, Ni, Co) in soil compared to re-use marginal water. Soil pathogens: using marginal water slightly contaminated the soil with total faecal coliform (TFC), mites, shigella and salmonella Plant anatomy: No great changes in anatomical disturbance where induced in different structures of plants which were reduced at maturity stage. Primary guidelines for re-using marginal water: From obtained results it can be recommended to use marginal water with salinity content ranged between 1.1 to 3. 64 dS/m, and elemental contents (Pb 3.0–3.51 ppm), (B 0.05–1.67 ppm), (Co 0.04–0.07 ppm), (Ni 0.08–0.15 ppm) for safe (field, vegetable and medicinal) crops production. Reuse bio solids for crop production: Sewage sludge produced from treated wastewater can be safely used by mixing with rice straw (1:1 w/w) for economic crop production and saving mineral fertilisers. General conclusion: In the North Nile Delta, marginal water (especially BDW) can be safely used without significant negative impact on the environment, but there is a need for multi-disciplinary, long-term research to investigate irrigation with marginal water in terms of the environment, public health and agricultural productivity.
Anaerobic digestion potential for ecological and decentralised sanitation in urban areas
Authors: Elmitwalli Tarek , Feng Yucheng , Behrendt Joachim , Otterpohl Ralf
Published: July 2007

The potential of anaerobic digestion in ecological and decentralised sanitation has been investigated in this research. Different anaerobic digestion systems were proposed for the treatment of sewage, grey water, black water and faeces. Moreover, mathematical models based on anaerobic digestion model no.1 (ADM1) were developed for determination of a suitable design for each system. For stable performance of an upflow anaerobic sludge blanket (UASB) reactor treating sewage, the model results indicated that optimisation of wastewater conversion to biogas (not COD removal) should be selected for determination of the hydraulic retention time (HRT) of the reactor. For the treatment of sewage or black water in a UASB septic-tank, the model results showed that the sludge removal period was the main parameter for determination of the HRT. At such HRT, both COD removal and wastewater conversion are also optimised. The model results demonstrated that for treatment of faeces in an accumulation (AC) system at temperature ≥25 °C, the filling period of the system should be higher than 60 days. For maximisation of the net biogas production (i.e. reduction of biogas losses as dissolved in the effluent), the separation between grey water, urine and faeces and reduction of water consumption for faeces flushing are required. Furthermore, the faeces and kitchen organic wastes and grey water are digested in, respectively, an AC system and UASB reactor, while the urine is stored.
Aerobic granular sludge: a promising technology for decentralised wastewater treatment
Authors: Li Z.H. , Kuba T. , Kusuda T.
Published: July 2007

In order to evaluate the characteristics of aerobic granular sludge, a sequencing batch reactor, feeding with synthetic wastewater at the organic loading rate of 8 kg COD/m3 d, was employed on the laboratory scale. Granules occurred in the reactor within 1 week after the inoculation from conventional flocculent sludge. Aerobic granular sludge was characterised by the outstanding settling properties and considerable contaminates removal efficiencies. The SVI30 values were in the range of 20 to 40 ml g−1. However, the sludge volume index of short settling time (e.g. SVI10 – 10 min) is suggested to describe the fast settling properties of aerobic granular sludge. The potential application in the decentralised system is evaluated from the point view of footprint and high bioactivity. The occurrence of sloughing, resulting from the outgrowth of filamentous organisms, would be responsible for the instability of aerobic granules. The starvation phase should therefore be carefully controlled for the maintenance and stability of aerobic granular sludge system.
Effect of denitrification type on pH profiles in the sequencing batch reactor process
Authors: Peng Yong-zhen , Shao-po Wang , Shu-ying Wang , Jian-ge Hu , Hai-Bing Qiao
Published: July 2007

Laboratory batch experiments were conducted to investigate pH profiles during partial and complete denitrification with sufficient organic carbon source. Five stirred tank-type glass vessels, with a 7 L working volume for each, were used as SBR reactors that were all operated in denitrification mode. Five levels of initial proportion of nitrogen substances, i.e. nitrate and nitrite, were used in five reactors, respectively. Results showed that, at given temperature and mixed liquor suspended solids (MLSS), partial denitrification could attain a higher pH value than complete denitrification at the end of denitrification with the same initial NOx− concentration. The larger proportion the nitrite took in initial NOx− concentration, the higher pH peak would be obtained on pH profiles during denitrification despite the same total alkalinity produced. It was found that different types of alkalinity were produced during biological denitrification with different nitrogen substances. Partial denitrification could more carbonate alkalinity produce than complete denitrification. Furthermore, some characteristic points were identified on pH profiles which could indicate the disappearance of not only nitrate, but also nitrite in system. When computers are used to detect these features, they can provide rapid, real-time information, regarding the biological state of the system.
Application of a membrane bioreactor for the treatment of low loaded domestic wastewater for water re-use
Authors: Fatone F. , Battistoni P. , Pavan P. , Cecchi F.
Published: July 2007

This paper describes the demonstrative scale application of a membrane biological reactor (MBR) for low loaded domestic wastewater with low attitude to biological treatment (carbon/nitrogen ∼ 5). The biological process was managed by the automatically controlled alternate cycles allowing for re-use purposes with a remarkable reduction of the operational costs. The global process evaluation revealed the system capability of obtaining high nitrogen removal (effective nitrogen removal of 69%) thanks to its high flexibility related to the hourly loading fluctuation. Moreover, high removal of heavy metals and polycyclic aromatic hydrocarbons (PAH) was obtained due to the perfect retention capability of the membranes. In-depth studies were conducted to determine the process behaviour for activated sludge over aeration and with addition of exogenous carbon. Limitation of sludge over aeration and energy savings were observed with a gradient air supplying method. The addition of exogenous carbon (acetic acid up to carbon/nitrogen ∼ 9) led to complete nitrogen removal (Ed = 96%) and permitted biological phosphorus uptake. In conclusion, it was been found that the coupled process alternated cycles-MBR had the capacity to remove COD, BOD, N, P and suspended solids, as well as heavy metals and organic micropollutants, resulting in high quality effluent suitable for re-use purposes.
Innovations in wastewater treatment: –the moving bed biofilm process
Authors: Ødegaard Hallvard
Published: July 2007

This paper describes the moving bed biofilm reactor (MBBR) and presents applications of wastewater treatment processes in which this reactor is used. The MBBR processes have been extensively used for BOD/COD-removal, as well as for nitrification and denitrification in municipal and industrial wastewater treatment. This paper focuses on the municipal applications. The most frequent process combinations are presented and discussed. Basic design data obtained through research, as well as data from practical operation of various plants, are presented. It is demonstrated that the MBBR may be used in an extremely compact high-rate process (<1 h total HRT) for secondary treatment. Most European plants require P-removal and performance data from plants combining MBBR and chemical precipitation is presented. Likewise, data from plants in Italy and Switzerland that are implementing nitrification in addition to secondary treatment are presented. The results from three Norwegian plants that are using the so-called combined denitrification MBBR process are discussed. Nitrification rates as high as 1.2 g NH4-N/m2 d at complete nitrification were demonstrated in practical operation at low temperatures (11 °C), while denitrification rates were as high as 3.5 g NO3-Nequiv./m2.d. Depending on the extent of pretreatment, the total HRT of the MBBR for N-removal will be in the range of 3 to 5 h.
Fate and transport of endocrine-disrupting compounds (oestrone and 17β-oestradiol) in a membranebio-reactor used for water re-use
Authors: Chang Seojin , Jang Namjung , Yeo Younghyun , Kim In S.
Published: July 2007

Oestrogens have been detected in the effluents of sewage treatment plants (STPs) in several countries, as well as in surface water. This occurrence is fundamentally attributed to the excretion of oestrogen from humans and mammalian bodies, and the incomplete removal of these compounds from wastewater treatment plants. These micro-pollutants are causing great concern when it comes to water re-use. There is a lack information on endocrine-disrupting compounds (EDCs) such as oestrogen in water re-use systems, e.g. a membrane bioreactor (MBR). It is clear that there is a strong need for “EDCs in MBR for water re-use”. This study examined an E1 and E2 biodegradation batch test by an activated sludge and hollow fibre membrane filtration test with and without a bio-cake. E2 was effectively removed, even in high initial concentrations (1,000 ppb). E2 was oxidised into E1, and E1 had a lower adsorption rate than E2. The membrane with the bio-cake provided better removal than the virgin membrane.
Low-temperature post-treatment of anaerobically treated-sewage in anaerobic filter with cationic-polymer addition
Authors: Elmitwalli T.A. , Raimundo R. , Kujawa-Roelevel K. , Zeeman G.
Published: July 2007

The post-treatment of domestic sewage pretreated in a 6 m3 UASB was investigated in two high-rate anaerobic filter (AF) reactors operated in parallel. The difference between the two AF reactors was only the addition of cationic polymer to the second reactor (AF + P). The reactors were operated at low temperatures, ranged between 13 and 20 °C. The media in each AF reactor consisted of vertical sheets of reticulated-polyurethane foam (RPF) with knobs. The results demonstrated that the AF + P reactor (HRT = 3 h) with cationic polymer addition (2 mg/L) was an efficient system for post-treatment. The removal efficiencies for total, suspended, colloidal and dissolved COD were, respectively, 41, 86 and 76 and 12% in the AF + P reactor and they were, respectively, 80, 97, 77 and 66% in the UASB+ (AF + P) system. The removal of total, suspended and colloidal COD in the UASB+(AF + P) system were significantly higher than those achieved in the UASB + AF system. As hardly any nutrient was removed in the UASB+(AF + P) system, the effluent after pathogen removal is a valuable product for irrigation and fertilisation to close the water and nutrients cycle.
Estimation of reduced and increasing health risks by installation of urban wastewater systems
Authors: Aramaki T. , Galal M. , Hanaki K.
Published: July 2007

This paper aims to propose a methodological framework for quantifying the reduction and increase of health risks associated with urban wastewater systems. A risk assessment model was used to quantify reduction in disease burden while a life cycle assessment approach was used to quantify increasing risks by environmental loading. Disability adjusted life years (DALYs) was used to quantify health risks. This framework was applied to a hypothetical watershed to evaluate health risks by installation of wastewater treatment systems. In this hypothetical case, 55 DALYs per year of health risk would be reduced for 200,000 people in the downstream community by constructing wastewater systems for 200,000 people, while a range from 1.9 to 22 DALYs per year of health risks would be generated by materials and energy consumption for construction and operation of wastewater systems. However, this result would significantly change, depending on the parameters used in this analysis. The proposed methodology should be improved to obtain more precise results, but it will suggest useful information to discuss the overall effects due to the installation of various types of urban wastewater systems.
Biological phosphorus removal with nitrite as election acceptor
Authors: Zhang Xiaoling , Wang Zhiying , Zhao Qing
Published: July 2007

Biological phosphorus removal was studied in a sequencing batch reactor (SBR). The results showed that nitrite could be used as electron acceptor in denitrifying phosphorus removal. Feed mode of nitrite had significant influence on denitrifying phosphorus removal. Anoxic phosphorus assimilation rate could reach 10.44 mgP/gSS.h and the percentage of anoxic phosphorus assimilation amount was more than 97% with continuous feed mode. Granular sludge with denitrifying phosphorus removal activity was found in the SBR. The effects of different operational conditions, such as COD loading, settling time, HRT etc., on the formation of granules were also studied.
Historical climate and stream flow trends and future water demand analysis in the Calgary region, Canada
Authors: Chen Z. , Grasby S.E. , Osadetz K.G. , Fesko P.
Published: July 2007

The city of Calgary has been one of fastest growing cities in Canada in recent years. Rapid population growth and a warming climate trend have raised concerns about sustainable water supply. In this study, historic climate, stream flow and population data are analyzed in order to develop models of future climate trends and river-water resource availability. Daily water demands for the next 60 years were projected using the relationship between daily maximum temperature and water demand under simulated climate and population growth scenarios. To maintain sustainable growth Calgary will require water conservation efforts that reduce per capita water use to less than half of the current level over the next 60 years, an interval when the civic population is expected to be doubled.
Kinneret watershed analysis tool: a cell-based decision tree model for watershed flowand pollutants predictions
Authors: Preis A. , Tubaltzev A. , Ostfeld A.
Published: July 2007

This paper presents the methodology and application underlying the Kinneret Watershed Analysis Tool (KWAT), developed for flow and contaminant predictions for Lake Kinneret (the Sea of Galilee) watershed located in northern Israel. Lake Kinneret watershed is about 2,730 km2 (2,070 in Israel, the rest in Lebanon), inhabited by about 200,000 people organized in 25 municipalities, and three cities (the Israeli part). The model aims to predict flow and contaminant transports within the watershed, down to its outlet – Lake Kinneret, the most important surface water resource in Israel. The model is comprised of two sections: quantity and quality. The objective of the quantity section is to tune the values of a vector of coefficients α that multiply the average rainfall time series intensity I(t) (the input) imposed on given sub-sets (i.e., cells) of the basin so as to calibrate their outlet flows Q(t); the quality section then uses these optimal flows Q(t) and the effective optimal rainfall intensities to adjust the values of a vector of coefficients β so as to calibrate the sub-watersheds outlet concentrations C(t). The model uses decision trees coupled with a genetic algorithm for optimally tuning the KWAT coefficients for each of the watershed cells, which taken together comprise the flow and contamination amounts measured at the watershed outlet.
Application of WetSpa model for assessing land use impacts on floods in the Margecany–Hornad watershed, Slovakia
Authors: Bahremand A. , De Smedt F. , Corluy J. , Liu Y.B. , Poórová J. , Velcická L. , Kunikova E.
Published: July 2007

The spatially distributed hydrologic model WetSpa combines elevation, soil and land use data within GIS, to predict flood hydrographs and spatial distribution of hydrologic characteristics in a watershed. The model is applied to the Margecany–Hornad river basin (1,131 km2) in Slovakia. Daily hydrometeorological data from 1991–2000, including precipitation data from nine stations, temperature data from four stations and evaporation data measured at one station are used as input to the model. Three base maps, i.e. DEM, land use and soil type are prepared in GIS form, using 100 × 100 m cell size. Results of the simulations show good agreement between calculated and measured hydrographs. The model predicts the daily/hourly hydrographs with 75–80% accuracy according to the Nash–Sutcliff criteria. For assessing the impact of land use changes on floods, the calibrated model is applied for a reforestation scenario, which considers a 50% increase of forest areas. The model results show that the reforestation scenario decreases the peak discharge by 12%. Investigation of peak discharges from the whole simulation period, shows that the scenario results are reduced by 18% on average, while for small discharges the reduction is even about 34%. The time to peak of the simulated hydrograph of the reforestation scenario is 20 hours longer than for the present land use.
A case study of regional catchment water quality modelling to identify pollution control requirements
Authors: Crabtree B. , Seward A.J. , Thompson L.
Published: July 2007

There are four ecologically important river catchments that contain candidate Special Areas of Conservation (cSACs) under the Habitats Directive in the Lake District National Park located in the North of England. These are the rivers Ehen, Kent, Derwent and Eden. For each cSAC, there are defined ecological criteria that include water quality targets to protect the designated species. Stretches of the riverine cSACs in each catchment are failing to meet these and other water quality targets. The Environment Agency commissioned a study of each catchment to provide the underpinning scientific knowledge to allow it to deliver its statutory obligations under the Habitats Directive. SIMCAT river water quality models were produced and used to predict the water quality impacts resulting from a number of water quality planning scenarios aimed at achieving full compliance with the Habitats Directive and other national and EEC water quality targets. The results indicated that further controls on effluent discharges will allow the majority of targets to be met but other sources of pollution will also need to be controlled. The outcome of the study also recognised that water quality improvements alone will not necessarily produce the required improvement to the ecological interest features in each cSAC.
Integrated modelling for river basin management: the influence of temporal and spatial scale in economic models of water allocation
Authors: Cutlac I.M. , He L. , Horbulyk T.M.
Published: July 2007

The increasing use of integrated optimization or simulation models to guide river basin management has placed greater attention on the roles that the temporal and spatial scale of each model play in determining a model's suitability and effectiveness. This is especially the case in “economic” models that incorporate monetary incentives and the optimizing behaviour of economic agents to address decisions about the sources and levels of consumptive and non-consumptive water usage within the basin. With respect to spatial scale, models that aggregate behaviour over entire river basins may prove useful for examining inter-sectoral allocations of water, but are unlikely to provide useful information about how these water allocations influence–and are influenced by–choices of crops or of technologies in irrigation, for example. With respect to temporal scale, very short-run models can illustrate options for water management within an irrigation season should unforeseen water surpluses or deficits arise. Conversely, long-run models can allow adjustment time for investments in machinery, infrastructure and changes in land uses and cropping patterns. The basin management alternatives and choices generated by models on each scale are likely to vary considerably. The paper provides specific illustrative examples from recent models of Alberta's Bow River Basin.
The risk assessment of heavy metals in the ecosystem of urban creeks
Authors: Komínková D. , Nabělková J.
Published: July 2007

This paper is focused on risk assessment of heavy metals in freshwater ecosystems of urban creeks. The paper reports changes in an aquatic ecosystem leading to remobilization of heavy metals and consequently to changes of bioavailability. Concentrations of metals in water, bed sediment and benthic organisms from several small urban streams are monitored and evaluated. In the small urban streams studied copper, zinc and lead were determined as the most significant hazard metals. Although concentrations of these metals in water are very low (often below the detection limit of analytical equipment), concentrations in sediment were found in risky levels mainly in sampling sites affected by CSOs and SSOs from industrial and heavy traffic areas. The benthic organisms showed different ability to accumulate heavy metals (HM). The feeding type collector gatherer had in most cases the highest body concentration of HM and the predator species cumulate, to a high level, only zinc which has a high tendency to release from sediment, hence it is the most bio-available. The collector-filterer had mostly low values. The differences among species are due to the different feeding habits of each trophic level.
Application of SEBAL approach and MODIS time-series to map vegetation water use patterns in the data scarce Krishna river basin of India
Authors: Ahmad M.-D. , Biggs T. , Turral H. , Scott C.A.
Published: July 2007

Evapotranspiration (ET) from irrigated land is one of the most useful indicators to explain whether the water is used as “intended”. In this study, the Surface Energy Balance Algorithm for Land (SEBAL) was used to compute actual ET from a Landsat7 image of December 29, 2000 for diverse land use in the Krishna Basin in India. SEBAL ETa varies between 0 to 4.7 mm per day over the image and was quantified for identified land use classes. Seasonal/annual comparison of ETa from different land uses requires time series images, processed by SEBAL. In this study, the Landsat-derived snapshot SEBAL ETa result was interpreted using the cropping calendar and time series analysis of MODIS imagery. The wastewater irrigated area in the basin has the highest ETa in the image, partly due to its advanced growth stage compared to groundwater-irrigated rice. Shrub and forests in the senescence phase have similar ETa to vegetable/cash crops, and ETa from grasslands is a low 0.8 mm per day after the end of the monsoon. The results indicate that wastewater irrigation of fodder and rice is sufficient to meet crop water demand but there appears to be deficit irrigation of rice using groundwater.
Neural networks modelling of streamflow, phosphorus, and suspended solids: application to the Canadian Boreal forest
Authors: Nour M.H. , Smith D.W. , Gamal El-Din M. , Prepas E.E.
Published: July 2007

Sediment has long been identified as an important vector for the transport of nutrients and contaminants such as heavy metals and microorganisms. The respective nutrient loading to water bodies can potentially lead to dissolved oxygen depletion, cyanobacteria toxin production and ultimately eutrophication. This study proposed an artificial neural network (ANN) modelling algorithm that relies on low cost readily available meteorological data for simulating streamflow (Q), total suspended solids (TSS) concentration, and total phosphorus (TP) concentration. The models were applied to a 130-km2 watershed in the Canadian Boreal Plain. Our results demonstrated that through careful manipulation of time series analysis and rigorous optimization of ANN configuration, it is possible to simulate Q, TSS, and TP reasonably well. R2 values exceeding 0.89 were obtained for all modelled data cases. The proposed models can provide real time predictions of the modelled parameters, can answer questions related to the impact of climate change scenarios on water quantity and quality, and can be implemented in water resources management through Monte Carlo simulations.
Water quality assessment of rivers in Mongolia
Authors: Kelderman P. , Batima P.
Published: July 2007

A study was made on the water quality of the rivers in Mongolia over the years 1949–1990 for the three river basins in the country. In most of the 72 monitoring stations, the water quality is governed by geological and hydrological characteristics; bicarbonate and calcium are the most abundant major ions. No significant trends were observed between river discharges and total dissolved solids contents. The sediment yields (expressed in the run-off of total suspended solids, TSS) were always low, viz. between 0.02 and 20 × 103 kg TSS/km2.yr. In general, the rivers in Mongolia showed low pollution levels for organic pollution, phosphorus, nitrogen, etc., and no time trends were observed in this respect. This does not hold, however, for the northern Tuul River, where especially high BOD and ammonium values were found. This can probably be ascribed to the presence of industries and larger cities, as well as agricultural practices. The rivers in Mongolia can generally be classified as “clean” or “of acceptable quality”. In contrast, the Tuul River was shown to be “moderately polluted”, with a deteriorating trend in water quality over recent years.
Monitoring and assessment of oil pollution in the Danube River during the transnational Joint Danube Survey
Authors: Literathy P.
Published: July 2007

An extensive river basin monitoring exercise of 2581 km of the river Danube was carried out in 2001 under of the aegis of the transnational Joint Danube Survey (JDS). Water, suspended and bottom sediment, and biota samples were collected from 76 cross-sections in the Danube main stream and 22 major tributaries during the 39-day cruise, and analysed for chemical and biological variables. During the JDS, oil pollution was characterised with GC-FID and fluorescence measurements. Fluorescence fingerprints of the cyclohexane extracts of water, suspended and bottom sediment samples allowed characterization and quantification of the type and level of oil pollution. The results revealed that the oil pollution in the water varied in the range 1–300 μg/l. Gasoline type contamination was found at the higher concentration levels and diesel oil type in the lower concentrations. Oil contamination was similar in the suspended and bottom sediment (the less than 63 μm grain-size fraction) and varied between 2–140 mg/kg. A higher contamination level was found along the middle Danube reach. The highest concentrations were observed in the suspended sediment upstream of the Danube delta. Weathered crude oil characteristics were observed in the upper Danube basin, whereas between crude and diesel oil characteristics were dominant along most of the middle and the lower Danube reaches.
Regionalization of rainfall–runoff processes in rice agriculture dominated watersheds
Authors: Rajyalakshmi N.V. , Dutta S.
Published: July 2007

An approach for computing the instantaneous unit hydrograph of rice agriculture dominated watesheds is proposed using the topology and hydraulic charcterstics of its stream network and the hydrologic behaviour of the rice agriculture area. The effect of rice agriculture on the watershed response is considered as partial sink areas. The sink factor, a time-variant weight factor for a particular storm event, is computed from the daily water balanace equation of the rice field. The critcal features of the simulated instantaneous unit hydrographs in three gauged watersheds located in the river Mahanadi, India were then compared with that of the observed 24-hr unit hydrograph. The comparison shows a significant correlation between the two results.