bluuebunny/crossref_metadata_2025 huggingface dataset:
Designing and performing experiments for model calibration using an automated iterative procedure
Authors: De Pauw D.J.W. , Vanrolleghem P.A.
Published: July 2007

Optimal experimental design for parameter estimation involves complex mathematical and practical steps in order to obtain a model with sufficiently accurate parameters. This paper proposes a methodology where user interaction is only required at the beginning of the experimental design procedure. All subsequent steps are carried out automatically, including: (1) finding the optimal experiment, (2) performing the experiments in practice, and (3) recalibrating the model. A software extension to an existing modelling and simulation package which performs this automatic procedure is also presented. Finally an illustration for the calibration of a one-step nitrification model using respirometric data is given. In this case, the application of the proposed procedure resulted, after three iterations, in considerably better confidence intervals on the parameter estimates, within the desired boundaries.
Dynamic reasoning to solve complex problems in activated sludge processes: a step further in decision support systems
Authors: Martínez M. , Rodríguez-Roda I. , Poch M. , Cortés U. , Comas J.
Published: July 2007

Decision support systems (DSS) have generated high expectations as a tool to support activated sludge operation because of their ability to represent heuristic reasoning and to handle large amounts of qualitative, uncertain and low-accuracy data. Previous applications have been satisfactory to control simple problems, when static reasoning and literature-based solutions were enough. However to face complex operational problems with biological origin and slow dynamics (e.g. solids separation problems), it is necessary to use dynamic reasoning and apply long-term control strategies, monitoring the evolution of the process and adjusting the action plan according to the feed back of the process. This paper presents a dynamic reasoning DSS to face solids separation problems in the activated sludge system. The DSS is capable of identifying the complex problem affecting the process, determining if the current situation is new or a continuation from the previous one, assessing what is the specific cause of the situation, and recommending a long-term control strategy, which is daily adjusted according to the evolution of the process.
Rule-based fuzzy inference system for estimating the influent COD/N ratio and ammonia load to a sequencing batch reactor
Authors: Kim Y.J. , Bae H. , Ko J.H. , Poo K.M. , Kim S. , Kim C.W. , Woo H.J.
Published: July 2007

A fuzzy inference system using sensor measurements was developed to estimate the influent COD/N ratio and ammonia load. The sensors measured ORP, DO and pH. The sensor profiles had a close relationship with the influent COD/N ratio and ammonia load. To confirm this operational knowledge for constructing a rule set, a correlation analysis was conducted. The results showed that a rule generation method based only on operational knowledge did not generate a sufficiently accurate relationship between sensor measurements and target variables. To compensate for this defect, a decision tree algorithm was used as a standardized method for rule generation. Given a set of inputs, this algorithm was used to determine the output variables. However, the generated rules could not estimate the continuous influent COD/N ratio and ammonia load. Fuzzified rules and the fuzzy inference system were developed to overcome this problem. The fuzzy inference system estimated the influent COD/N ratio and ammonia load quite well. When these results were compared to the results from a predictive polynomial neural network model, the fuzzy inference system was more stable.
Case-based reasoning, a promising tool to face solids separation problems in the activated sludge process
Authors: Martínez M. , Sànchez-Marrè M. , Comas J. , Rodríguez-Roda I.
Published: July 2007

Classical control has serious limitations when faced with solids separation problems in the activated sludge process. Lack of knowledge about the mechanisms involved in the imbalance within the different microbiological communities implies that a general solution to these undesirable situations has not yet been provided. However, operators have to make decisions based on their experience and intuition to solve the problem (or at least to minimise the effects). The acquisition and registration of the knowledge learnt from each new experience can be decisive when solving similar problems in the future. Case-based reasoning (CBR) is an advanced technique for knowledge management in complex systems that uses past experiences to solve brand new situations. Previous simplified proposals in this field have exposed limitations, but this paper describes a new approach to CBR, considering the dynamics and the complexity of solids separation problems.
Knowledge-based control and case-based diagnosis based upon empirical knowledge and fuzzy logic for the SBR plant
Authors: Bae H. , Seo H.Y. , Kim S. , Kim Y.
Published: July 2007

Because biological wastewater treatment plants (WWTPs) involve a long time-delay and various disturbances, in general, skilled operators manually control the plant based on empirical knowledge. And operators usually diagnose the plant using similar cases experienced in the past. For the effective management of the plant, system automation has to be accomplished based upon operating recipes. This paper introduces automatic control and diagnosis based upon the operator's knowledge. Fuzzy logic was employed to design this knowledge-based controller because fuzzy logic can convert the linguistic information to rules. The controller can manage the influent and external carbon in considering the loading rate. The input of the controller is not the loading rate but the dissolved oxygen (DO) lag-time, which has a strong relation to the loading rate. This approach can replace an expensive sensor, which measures the loading rate and ammonia concentration in the reactor, with a cheaper DO sensor. The proposed controller can assure optimal operation and prevent the over-feeding problem. Case-based diagnosis was achieved by the analysis of profile patterns collected from the past. A new test profile was diagnosed by comparing it with template patterns containing normal and abnormal cases. The proposed control and diagnostic system will guarantee the effective and stable operation of WWTPs.
Mass and charge conservation check in dynamic models: application to the new ADM1 model
Authors: de Gracia M. , Sancho L. , García-Heras J.L. , Vanrolleghem P. , Ayesa E.
Published: July 2007

This paper proposes a systematic methodology for the analysis of the mass and charge balances in dynamic models expressed using the Petersen matrix notation. This methodology is based on the definition of the model components via elemental mass fractions and in the estimation of the COD as a function of the redox equations associated with these elements. This approach makes the automatic calculation of all the stoichiometric coefficients under different measuring units and the study of COD, charge or mass fluxes easier. As an example of its application this methodology was applied to the ADM1 in order to illustrate its usefulness for the analysis of organic matter characterisation, nitrogen release or biogas composition in anaerobic digestion. The application of the methodology for a rigorous integration of different IWA models is proposed for further study.
Sensor fault diagnosis in a wastewater treatment process
Authors: Lee C. , Choi S.W. , Lee I.-B.
Published: July 2007

There are many sensors in a wastewater treatment process (WWTP) plant for monitoring process performance and condition. Sensor validation is essential to the success of process monitoring. In this paper, various sensor faults which can occur in WWTP are identified for taking proper remedial action at an early time. A proposed sensor fault isolation method is based on the variable reconstruction using principal component analysis (PCA). Even though several methods have been developed to identify sensor faults, they are only applicable to a static process. In other words, they cannot be successfully used to monitor severe dynamic processes such as WWTPs. We have removed this limitation by developing reconstruction methods based on a dynamic version of PCA. Artificial scenarios of sensor faults generated from the simulation benchmark have been used to validate the proposed sensor identifying methodology. Also, it is compared to a previous method to show its relative superiority in sensor fault validation in the WWTP.
A standard interface between simulation programs and systems analysis software
Authors: Reichert P.
Published: July 2007

A simple interface between simulation programs and systems analytical software is proposed. This interface is designed to facilitate linkage of environmental simulation programs with systems analytical software and thus can contribute to remedying the deficiency in applying systems analytical techniques to environmental modelling studies. The proposed concept, consisting of a text file interface combined with a batch mode simulation program call, is independent of model structure, operating system and programming language. It is open for implementation by academic and commercial simulation and systems analytical software developers and is very simple to implement. Its practicability is demonstrated by implementations for three environmental simulation packages (AQUASIM, SWAT and LEACHM) and two systems analytical program packages (UNCSIM, SUFI). The properties listed above and the demonstration of the ease of implementation of the approach are prerequisites for the stimulation of a widespread implementation of the proposed interface that would be beneficial for the dissemination of systems analytical techniques in the environmental and engineering sciences. Furthermore, such a development could stimulate the transfer of systems analytical techniques between different fields of application.
Effects of soil erosion on water quality and water uses in the upper Phong watershed
Authors: Sthiannopkao S. , Takizawa S. , Wirojanagud W.
Published: July 2007

The main objective of this paper is to simulate the effects of soil erosion on river water quality and on agricultural production as a result of the transformation of forestlands in the catchment of the upstream Phong River. Suspended solids carry down attached nutrients and agricultural chemicals causing water pollution in the downstream. There are four different types of land use in this simulation, namely forestlands, flatland and highland sugarcane plantation areas, and paddy fields. The highest mean annual amount of soil erosion is from paddy fields (585,700 tons/year), followed by highland (73,800 tons/year) and flatland (63,950 tons/year) sugarcane plantation areas and forestlands (41,800 tons/year), respectively. However, as most of paddy fields are located in a low land and are wet type cultivations, the soil erosion occurred has less impact on river water quality and its production compared to the soil erosion from the steeper slopes of highland plantation areas. Under the resource-based agriculture, the sugarcane production is mainly increased by expanding the plantation areas leading to a significant loss of topsoil and a considerable reduction of agricultural production. Soil erosion contributes to an increase in the average annual suspended solids concentration by 72 mg/l.
Long-term fluctuation and regional variation of nutrient loads from the atmosphere to lakes
Authors: Kunimatsu T. , Sudo M.
Published: July 2007

The atmospheric depositions were collected by ordinary bulk-samplers mounted with a glass or polyethylene funnel of 30 cm orifice. A long-term observation was carried out at a site (35°01′30″N, 135°58′07″E) in the urbanized area for 21 years since 1974. The annual volume-weighted average concentrations of total nitrogen (TN) and phosphorus (TP) were 1.02±0.30 and 0.031±0.015 mg l−1, respectively, and the loading rates were 14.5±2.8 and 0.43±0.16 kg ha−1 yr−1. The rates neither had a relationship with the precipitation (1,492±343 mm yr−1) nor showed any diachronic tendencies. In order to obtain the loading rate of TN and TP within 10% uncertainty under the significant level of 0.01, there is no way but to continue the observation for seven and eleven years or more, respectively. In order to clarify the regional variation of the loading amounts of the depositions, the samplers were set at 12 sites distributing throughout the Kinki District for two years. The distance from northernmost (2322 mm yr−1) to southernmost (1242 mm yr−1) is about 150 km. The average loading rates of the 12 sites were 16.2±2.5 kg ha−1 yr−1 of TN and 0.730±0.247 kg ha−1 yr−1 of TP. The depositions of NO3-N, NH4-N, and TN as well as TP showed tendencies with distances neither from a big city nor from Japan Sea.
Characteristics of sediments in a newly constructed reservoir in Japan
Authors: Sakurai Y. , Haruta S.
Published: July 2007

The sediment formation mechanisms of a newly constructed reservoir in Ehime, Japan were evaluated by characterizing the soil particles (SP) and particulate phosphorus (PP) in the runoff and reservoir sediments. The SP and PP loads from the runoffs of the main river in the watershed considerably increased, when the specific discharge rates were over 300 l/s/km2 (high flow conditions). When the specific discharge rates exceeded over 300 l/s/km2, 19% of the watershed generated over 80% of the SP and PP loads. When the specific discharge rates were under 300 l/s/km2 (low flow conditions), the contributions of the previously mentioned 19% area to the SP and PP loads were smaller. Significant amounts of smectite were found in the sediments in the reservoir and in the soil samples obtained at the forest exposed area in this 19% area while it was negligible in citrus orchards and paddy fields that constituted the remaining land surfaces. The forest area exposed by recent landslides was significant for the SP and PP in the reservoir. Judging from the outcomes, land use information alone may not be sufficient to detect critical sources of SP and PP in the runoffs and reservoirs. To identify and confirm crucial areas for the SP and PP in the runoffs, the investigations should be conducted under high flow conditions and the composition of clay minerals in the sediments should be checked against the clay mineral distributions of soils in the watershed.
Study on the potential of farmland soils as non-point sources of nitrogen and phosphorus in Japan
Authors: Ukita M. , Shi X. , Higuchi T. , Arkin Y. , Fukada M.
Published: July 2007

The amounts of N and P accumulated in farmland soils of 50 cm depth were equivalent to the amount of chemical fertilizer supplied for 50–70 years. The values of N/P of surface soils in farmlands were 1.0–4.3, lower than expected. The median diameter of soil particles in run-off waters was generally less than 10 μm. The mean values of particulate fractions over 1 μm and over 0.22 μm were 19% for N, 27% for P, and 39% for N, 64% for P respectively. Fine particles of soil containing concentrated phosphorus should be carefully monitored as potential sources related to eutrophication.
Decrease in herbicide concentrations and affected factors in lagoons located around Lake Biwa
Authors: Sudo M. , Nishino M. , Okubo T.
Published: July 2007

The contamination levels and changes in the concentrations in four lagoons around Lake Biwa of paddy-use herbicide were studied. Four lagoons, Sone-numa (52 days of HRT (hydraulic residence time) estimated from the lagoon volume and the average discharge at the outlet, 21 ha area), Yanagihira-ko (40 days, 5.0 ha), Noda-numa (11 days, 6.0 ha), and Iba-naiko (2 days, 55.5 ha), were selected as monitoring sites. Intensive water sampling was carried out once a week from May to June at the outlet of each lagoon. Although twelve of the monitored herbicides were detected, the maximum concentrations did not exceed the guidelines for water-supply law in Japan. The relation between half-lives in herbicide concentrations and characteristics of a lagoon such as HRT and chlorophyll-a concentrations were examined. The shorter half-lives of herbicide concentrations in lagoons with shorter HRT means that replacement by influent water effectively decreased the pesticide concentrations. Shorter half-lives in lagoons with high chlorophyll-a concentrations between the lagoons with similar HRT suggest that biological degradation during the residence time worked more efficiently in the lagoon with high chlorophyll-a concentrations.
Estimation of pesticide runoff from paddy fields to rural rivers
Authors: Numabe A. , Nagahora S.
Published: July 2007

The runoff characteristics of pesticides from paddy fields to rural rivers were investigated over a period of three years in Hokkaido Prefecture, Japan. High pesticide concentrations were usually observed in rivers during pesticide application periods. In one year, the growth of rice seedlings slowed down after transplantation owing to low temperatures and lack of sunshine, and many farmers delayed herbicide application. In that year, high-concentration runoff of herbicides in rivers was observed 1–3 weeks later than in average years. The pesticide runoff rates ranged from 0.3% for fenthion to 42% for benfuresate. The runoff rates of pesticides applied post-flood were large. Furthermore, the larger the water solubility of the pesticide, the larger the runoff rate. The highest concentrations of herbicides in paddy water were observed on the day of application or 1–2 days later, and the concentrations decreased exponentially afterwards. The half-lives of the herbicides ranged from 1.2 days for pretilachlor and esprocarb to 5 days for simetryn; the concentrations of the herbicides in paddy water had decreased to 1/10 of their initial concentrations by about 7 days after application. Therefore, the runoff amounts of pesticides from paddy fields could be decreased by improving irrigation-water management.
Economic valuation of reduction in nitrogen outflow from a paddy field area equipped with a recycling irrigation facility
Authors: Feng Y.W. , Shiratani E. , Yoshinaga I. , Hitomi T.
Published: July 2007

We estimated the reduction in nitrogen outflow load from a paddy field that had a recycling irrigation facility and, by using a replacement cost method, evaluated the economic effect of nitrogen removal by the paddy field during the irrigation period in the Yoshinuma region of Tsukuba City, Japan. The recycling ratio of outflow water (proportion of outflow reused) was 13.5%. The nitrogen (N) outflow load was reduced by about 45 kg ha−1 by the N removal function of the paddy field and by about 39 kg ha−1 by the recycling irrigation facility. The paddy field equipped with a recycling irrigation facility as an N removal facility was valued at 32.6 million Japanese yen (JPY) ha−1 and 0.72 million JPY ha−1 per year, which compare it with the construction and maintenance costs, respectively, of a water quality improvement facility. The recycling irrigation facility was costed at 17.3 million JPY ha−1 for construction and 0.21 million JPY ha−1 for maintenance per year. The cost for constructing and maintaining a recycling irrigation facility was 53% of the value of the paddy field area equipped with a recycling irrigation facility as an N removal facility.
On-site treatment of turbid river water using chitosan, a natural organic polymer coagulant
Authors: Sekine M. , Takeshita A. , Oda N. , Ukita M. , Imai T. , Higuchi T.
Published: July 2007

Chitosan, acetylate of chitin, is a biodegradable cationic polymer. The objective of this study is to assess the applicability of chitosan as an on-site treatment agent of turbid water caused by river construction works and other diffused pollutions. The results of jar-tests indicate that floc of chitosan is much larger than that of aluminium sulfate, and turbidity treated by chitosan under moving water conditions is much lower than that of aluminium sulfate. Chitosan is applied to Imou River in Yamaguchi prefecture, where river construction work is going on. St.1 is located just below the construction work, St.2 is located about 250 m downstream from St.1, and St.3 is located about 350 m downstream from St.2. Initial turbidity of each station is 1,100, 937 and 313 NTU, respectively. By applying chitosan at St.1, turbidity of each station is drastically reduced to 1,100, 12 and 0 NTU. Chitosan could be helpful to reduce problems caused by turbidity in rivers.
Trace metal levels in sediments deposited in urban stormwater management facilities
Authors: Marsalek J. , Watt W.E. , Anderson B.C.
Published: July 2007

Characteristics of solids recovered from stormwater best management practice (BMP) facilities, including stormwater ponds, constructed wetlands, an infiltration basin, a biofilter, a stormwater treatment clarifier, and three-chamber oil and grit separators were described with respect to their metal chemistry. The reported trace metal concentrations in BMP sediments were assessed against the Ontario Sediment Quality Guidelines. Between 80 to 100% of all samples were marginally-to-intermediately polluted by Cd, Cr, Cu, Fe, Pb, Mn, Ni and Zn. Severe pollution of sediments was noted for Cr (122 μg/g), Cu (151 and 196 μg/g), Mn (1,259 and 1,433 μg/g), and Zn (1,116 μg/g), at several facilities studied, and even higher levels of metals were reported in the literature for certain oil and grit separators. With respect to individual BMPs, the severe pollution was found in sediments from oil and grit separators (for Cd, Cr, Cu, Pb and Zn), the stormwater clarifier sludge (Cu, Mn and Zn), a biofilter (Cu and Mn), an industrial area stormwater pond (Cu only), and a commercial/residential pond (Cr only). Finally, the chemical pollution of pond sediment triggered toxicity testing at some of the facilities studied, and sediment toxicity was confirmed at several sites.
Runoff and loads of nutrients and heavy metals from an urbanized area
Authors: Shirasuna H. , Fukushima T. , Matsushige K. , Imai A. , Ozaki N.
Published: July 2007

To investigate the run-off characteristics of dissolved and particulate substances from a heavily urbanized area (basin area: 95 ha, percentage of impervious surfaces: 60%), sensors for measuring water level, water temperature, DO, pH, electric conductivity (EC), turbidity and ammonium ion were placed in the channel connecting storm sewers and natural river, together with water sampling for analyzing SS, nutrients and metals. While both turbidity and EC showed apparent “first flush”, the peaks of EC were always earlier than those of turbidity. In a similar manner, dissolved nutrients and metals exhibited earlier “first flush” compared with particulate nutrients and acid-extractable metals. Significantly positive correlations between EC and dissolved substances as well as those between turbidity and particulate (acid-extractable minus dissolved) substances were usually observed, and two distinct different regressions were found between the two datasets separated before and after the concentration peaks. Using these relationships, the total loads during the respective rainfall events were calculated on the basis of EC and turbidity changes.The total loads of nitrogen, zinc, etc. were nearly proportional to the lengths of non-rainfall periods before the events, indicating that these loads derived from the atmospheric deposition.
Dispersion and dry and wet deposition of PAHs in an atmospheric environment
Authors: Ozaki N. , Nitta K. , Fukushima T.
Published: July 2007

The atmospheric concentration and dry and wet deposition were measured for particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) from August to December in Higashi-Hiroshima City, Japan. PM concentration of fine particles (0.6–7 μm) was 5.7–75.1 μg m−3, and coarse particles (>7 μm) was 2.2–22.3 μg m−3. Total PAHs concentration of fine particles was 0.14–16.3 ng m−3, and coarse particles was 0.01–0.77 ng m−3. Their concentration increased on non-rainy days and decreased rapidly on rainy days. For seasonal fluctuations of PAHs, their concentrations decreased from summer to winter, and the rate of decrease was more distinct for fine particles. For total (dry+wet) depositions, the PM flux was 1.9–11.2 mg m−2 d−1, and the total PAHs flux was 1.9–97.2 ng m−3 d−1. From these measurements, the yearly total loading of PAHs was estimated for the particle phase. Total loading was 28 μg m−2 y−1 for the dry deposition and 52 mg m−2 y−1 for the wet deposition. The loading of the wet deposition was comparable to those of the dry deposition for all ring numbers.
Characteristics of litter waste in highway storm runoff
Authors: Kim L.-H. , Kang J. , Kayhanian M. , Gil K.-I. , Stenstrom M.K. , Zoh K.-D.
Published: July 2007

Litter characterization is an integrated part of the Caltrans First Flush Characterization Study. These data will provide a basis to develop potential treatment technologies and best management practices to control pollutants in runoff from freeways. During monitoring periods in Southern California areas, the first flush phenomenon was evaluated and the impacts of various parameters such as rain intensity, drainage area, peak flow rate, and antecedent dry period on litter volume and loading rates were evaluated. First flush phenomenon was generally observed for litter concentrations, but was not apparent with litter mass loading rates. Total captured gross pollutants, defined as larger than 0.5 cm, was 90% vegetation with only 10% being litter. The normalized cumulative litter loadings were determined from 1.25 to 13.39 kg/ha for dry litter weight and 0.40 to 8.99 kg/ha for dry biodegradable litter weight. The portions of biodegradable litter to non-biodegradable litter were roughly the same across the entire event. Event mean concentrations were ranged 0.0021 to 0.259 g/L for wet gross pollutants, 0.0001 to 0.027 g/L for wet litters and 0.00007 to 0.018 g/L for dry litters. The mass emission rates should be useful to estimate total litter production for developing total maximum daily loads.
Water quality modeling to evaluate BMPs in rice paddies
Authors: Jeon J.H. , Yoon C.G. , Hwang H.S. , Jung K.W.
Published: July 2007

A water quality model applicable to rice paddies was developed using field data from 1999–2002. Use of the Dirac delta function efficiently explained the nutrient-concentration characteristics of ponded water. The model results agreed reasonably well with the observed data. The ponded-water quality was influenced primarily by fertilization; nutrient concentration was especially high during early cultivation periods. Reducing surface drainage during the fertilization period may substantially reduce nonpoint source loading from paddies. Increased weir heights and shallow irrigation methods were evaluated by the model as practical methods for reducing nutrient loading from paddies. These methods were effective in reducing surface drainage and are suggested as “best management practices” (BMPs) if applied based on site-specific paddy conditions.
Comparative study of two watershed scale models to calculate diffuse phosphorus pollution
Authors: Kovacs A.
Published: July 2007

The aim of this study was to compare and assess models having different principles to calculate diffuse phosphorus emissions on a selected watershed. The empirical MONERIS model and the physically based SWAT model were evaluated for comparative purposes. The approaches were applied for a sub-basin of the Hungarian Zala River watershed for five years. The calculated river loads were checked by the measured values at the catchment outlet. Due to the dissimilar results of water balance and erosion calculations, a highly different phosphorus emission was computed. It was also concluded that in the case of transport-limited watersheds, the SWAT model calculates phosphorus river loads slightly inaccurately, since it does not include the description of fate of inorganic phosphorus interacting with sediment during the channel transport. When these processes are taken into account, modeling results fit better the measured loads. The MONERIS model calculates acceptable river load by assuming very intensive in-stream retention. Additionally, the empirical method can be useful for long-term investigations as a decisions support tool for preliminary design. However, for detailed emission assessment and scenario development the physically based approach seems to be more appropriate.
Indicator of risk of water contamination by phosphorus from Canadian agricultural land
Authors: van Bochove E. , Thériault G. , Dechmi F. , Rousseau A.N. , Quilbé R. , Leclerc M.-L. , Goussard N.
Published: July 2007

The indicator of risk of water contamination by phosphorus (IROWC_P) is designed to estimate where the risk of water P contamination by agriculture is high, and how this risk is changing over time based on the five-year period of data Census frequency. Firstly developed for the province of Quebec (2000), this paper presents an improved version of IROWC_P (intended to be released in 2008), which will be extended to all watersheds and Soil Landscape of Canada (SLC) polygons (scale 1:1, 000, 000) with more than 5% of agriculture. There are three objectives: (i) create a soil phosphorus saturation database for dominant and subdominant soil series of SLC polygons – the soil P saturation values are estimated by the ratio of soil test P to soil P sorption capacity; (ii) calculate an annual P balance considering crop residue P, manure P, and inorganic fertilizer P – agricultural and manure management practices will also be considered; and (iii) develop a transport-hydrology component including P transport estimation by runoff mechanisms (water balance factor, topographic index) and soil erosion, and the area connectivity to water (artificial drainage, soil macropores, and surface water bodies).
Estimation of particulate nutrient load usingturbidity meter
Authors: Yamamoto K. , Suetsugi T.
Published: July 2007

The “Nutrient Load Hysteresis Coefficient” was proposed to evaluate the hysteresis of the nutrient loads to flow rate quantitatively. This could classify the runoff patterns of nutrient load into 15 patterns. Linear relationships between the turbidity and the concentrations of particulate nutrients were observed. It was clarified that the linearity was caused by the influence of the particle size on turbidity output and accumulation of nutrients on smaller particles (diameter <23 μm). The L-Q-Turb method, which is a new method for the estimation of runoff loads of nutrients using a regression curve between the turbidity and the concentrations of particulate nutrients, was developed. This method could raise the precision of the estimation of nutrient loads even if they had strong hysteresis to flow rate. For example, as for the runoff load of total phosphorus load on flood events in a total of eight cases, the averaged error of estimation of total phosphorus load by the L-Q-Turb method was 11%, whereas the averaged estimation error by the regression curve between flow rate and nutrient load was 28%.
Use of immobilised bacteria for the wastewater treatment – examples from the sugar industry
Authors: Jördening H.-J. , Hausmann K. , Demuth B. , Zastrutzki M.
Published: July 2007

This work focuses on the implementation of high performance systems to the wastewater treatment of sugar factories. For this purpose, systems with immobilised bacteria were studied. For the hydrolysis of organic matter and denitrification, fluidized bed reactors were used. The nitrification was studied with an airlift reactor system. Both hydrolysis and nitrogen elimination were investigated on laboratory and pilot scales in sugar factories.

Although with porous materials higher biomass concentrations are attainable for the hydrolysis (up to 55 kg/m3), for economical reasons sand was used (22.5 kg/m3) for the pilot scale-study. With a pilot-scale reactor (volume 1 m3) the maximum sucrose conversion rate achieved with sand in the first campaign was 52 kg/(m3 d).

For the nitrogen elimination on the pilot scale, a system with denitrification and nitrification was combined. The highest performance for the nitrification (reactor volume: 0.68 m3) with pumice as support material was 1.2 kg NH4-N/(m3 d), limiting the whole system. The denitrification rate (reactor volume: 0.12 m3) was four times higher (3.5–5 kg NO3-N/(m3 d). Rules of the modelling of the system are discussed.
Modification of ASM3 for the determination of biomass adsorption/storage capacity in bulking sludge control
Authors: Makinia J. , Rosenwinkel K.-H. , Phan L.-C.
Published: July 2007

The selector activated sludge (SAS) systems are known to prevent excessive growth of filamentous microorganisms responsible for bulking sludge, but these systems were hardly ever modelled. This study aimed to develop a model capable of predicting rapid substrate removal in the SAS systems. For this purpose, the Activated Sludge Model No. 3 (ASM3) was extended with three processes (adsorption, direct growth on the adsorbed substrate under aerobic or anoxic conditions). The modified ASM3 was tested against the results of batch experiments with the biomass originating from two full-scale SAS systems in Germany. The endogenous biomass was mixed with various readily biodegradable substrates (acetate, peptone, glucose and wastewater) and the utilisation of substrate (expresses as COD) and oxygen uptake rates (OURs) were measured during the experiments. In general, model predictions fitted to the experimental data, but a considerable number of kinetic (5) and stoichiometric (2) parameters needed to be adjusted during model calibration. The simulation results revealed that storage was generally a dominating process compared to direct growth in terms of the adsorbed substrate utilisation. The contribution of storage ranged from 65–71% (Plant A) and 69–92% (Plant B).
Activated sludge modelling: past, present and future
Authors: Gujer W.
Published: July 2007

Model complexity in activated sludge modelling has increased over 30 years in parallel with the computational power of computers. Today, the complexity of biokinetics has reached a practical limit. Future advances may be in the direction of enhanced spacial resolution (CFD, single organisms) respectively, in repetitive computations (MC simulation, parameter identification). Further model development may be in niches such as population dynamics, micropollutants, etc.
Plant-wide control: dream, necessity or reality?
Authors: Olsson G. , Jeppsson U.
Published: July 2007

Instrumentation, control and automation (ICA) are key technologies in modern water and wastewater systems. Despite the variability of the influents the system outputs have to be satisfactory. Economic realities and new water directives encourage the application of ICA to make a maximum use of plant and other storage capacities. The final goal of protecting the environmental resources necessitates an integrated view of several interdependent systems, including the collection, transport and treatment processes. In this integrating development ICA will be a decisive technology.
Phosphorus removal and recovery from wastewaterby tobermorite-seeded crystallisation of calcium phosphate
Authors: Berg U. , Donnert D. , Weidler P.G. , Kaschka E. , Knoll G. , Nüesch R.
Published: July 2007

Investigations were focused on the development of a technology for phosphorus (P) recovery straight from wastewater. Facing the finiteness of the natural resources of this essential nutrient, the declared goal must be the sustainable use of available phosphorus sinks such as wastewater treatment plants (WWTP) for the generation of P rock substitutes. A feasible method for simultaneous elimination and recovery of phosphorus from wastewater proved to be the P-RoC process – the phosphorus recovery from wastewater by induced crystallisation of calcium phosphate, applying tobermorite-rich waste compounds of the construction industry. The experiments were performed in fixed bed-, stirred- and expanded bed reactors in laboratory- as well as in pilot-scale experiments. The efficiency and longevity of the P-RoC process was determined by the supply of Ca ions and the initial P concentration. Total P (P-tot) contents in the generated crystallisation products of up to 13% P-tot (30% P2O5) were achieved. Mineralogical investigations proved the formation of a hydroxy-apatite-(HAP)-like coating onto the seed material's surface. Reuse options for the generated crystallisation products, such as substitute for phosphate rock or as new fertiliser, were assessed.
Treatment of source-separated urine by a combination of bipolar electrodialysis and a gas transfer membrane
Authors: Pronk W. , Biebow M. , Boller M.
Published: July 2007

Urine contains nutrients which can be applied usefully as a fertiliser in agriculture, but the relatively high pH can lead to ammonia evaporation. Electrodialysis with bipolar membranes was combined with an additional mass transfer unit in order to render a product containing ammonium and phosphate at a low pH. In one case, the additional mass transfer unit consisted of bubble columns placed in acid and basic concentrate streams, connected with a circulating gas phase. In the other case, the unit consisted of a gas-filled (hydrophobic) membrane placed in between the circulating acid and basic concentrate streams. The results showed that ammonia was transferred through the gas phase, but also carbonate, which is present in stored urine originating from the hydrolysis of urea. Although the pH in the product stream decreases initially, it rises above pH 7 at longer operation times. This pH increase can be attributed to a combination of proton compensating effects. The use of ammonia-selective membranes for the transfer into the acid concentrate could provide a solution to generate an ammonium phosphate product at low pH and high recoveries.
Leachate detoxification by combination of biological and TiO2-photocatalytic processes
Authors: Wiszniowski J. , Robert D. , Surmacz-Gorska J. , Miksch K. , Weber J.-V.
Published: July 2007

Landfill leachates are a problematic wastewater due to their variable concentration, volume changing in time and presence of refractory and hazardous components. In this paper, the results of a new approach to photocatalysis assisted by biological process for the detoxification of stabilised landfill leachate are presented. The biologically pre-treated leachate still contained a significant amount of non-biodegradable COD and TOC amounting to 500 and 200 mg/L, respectively. The 300 min of photocatalytic treatment (UVC/TiO2) brought about a significant decrease in more than 80% refractory organics remaining in leachate. The effect of pH and catalyst loading on mineralisation, colour removal rate and biodegradability (BOD/COD) improvement in the photoreactor were discussed. The bio-accessibility of formed photocatalytic oxidation intermediates was confirmed by oxygen uptake rate (OUR) measurements. Consequently, a part of COD was successfully removed in post-biological treatment.
Model-based evaluation of struvite recovery from an in-line stripper in a BNR process (BCFS)
Authors: Hao X.-D. , van Loosdrecht M.C.M.
Published: July 2007

Phosphate removal and recovery can be combined in BNR processes. This may be realised by struvite precipitation from the supernatant of the sludge in anaerobic compartments. This can be beneficial for either improving bio-P removal effluent quality or lowering the influent COD/P ratio required for bio-P removal. For this reason, a patented BNR process, BCFS®, was developed and applied in The Netherlands. Several questions relating to P-recovery and behaviour of the system remain unclear and need to be ascertained. For this purpose, a modelling technique was employed in this study. With the help of a previous developed model describing carbon oxidation and nutrient removal, three cases were fully simulated. The simulations demonstrated that there was an optimal stripping flow rate and P-recovery would increase in costs and bio-P activity might be negatively affected due to decreased bio-P efficiency if this value was exceeded. The simulations indicated that the minimal CODbiod/P ratio required for the effluent standard (1 g P/m3) could be lowered from 20 to 10 with 36% of P-recovery. A simulation with dynamic inflow revealed that the dynamic influent loads affected slightly the anaerobic supernatant phosphate concentration but the effluent phosphate concentration would not be affected with regular P-recovery.
Copper and zinc removal from roof runoff: from research to full-scale adsorber systems
Authors: Steiner M. , Boller M.
Published: July 2007

Large, uncoated copper and zinc roofs cause environmental problems if their runoff is infiltrated into the underground or discharged into receiving waters. Since source control is not always feasible, barrier systems for efficient copper and zinc removal are recommended in Switzerland. During the last few years, research carried out in order to test the performance of GIH-calcite adsorber filters as a barrier system. Adsorption and mass transport processes were assessed and described in a mathematical model. However, this model is not suitable for practical design, because it does not give explicit access to design parameters such as adsorber diameter and adsorber bed depth. Therefore, for e.g. engineers, an easy to use design guideline for GIH-calcite adsorber systems was developed, mainly based on the mathematical model. The core of this guideline is the design of the depth of the GIH-calcite adsorber layer. The depth is calculated by adding up the GIH depth for sorption equilibrium and the depth for the mass transfer zone (MTZ). Additionally, the arrangement of other adsorber system components such as particle separation and retention volume was considered in the guideline. Investigations of a full-scale adsorber confirm the successful application of this newly developed design guideline for the application of GIH-calcite adsorber systems in practice.
Combining UASB and the “fourth generation” down-flow hanging sponge reactor for municipal wastewater treatment
Authors: Tandukar M. , Uemura S. , Ohashi A. , Harada H.
Published: July 2007

A “fourth generation” down-flow hanging sponge (DHS) Reactor has been developed and proposed as an improved variant of post-treatment system for UASB treating domestic wastewater. This paper evaluates the potential of the proposed combination of UASB and DHS as a sewage treatment system, especially for developing countries. A pilot-scale UASB (1.15 m3) and DHS (0.38 m3; volume of sponge) was installed in a municipal sewage treatment site and constantly monitored for 2 years. UASB was operated at an HRT of 6 h corresponding to an organic load of 2.15 kg-COD/m3 per day. Subsequently, the organic load in DHS was 2.35 kg-COD/m3 per day, operated at an HRT of 2 h. Organic removal by the whole system was satisfactory, accomplishing 96% of unfiltered BOD removal and 91% of unfiltered COD removal. However, nitrification decreased from 56% during the startup period to 28% afterwards. Investigation on DHS sludge was made by quantifying it and evaluating oxygen uptake rates with various substrates. Average concentration of trapped biomass was 26 g-VSS/L of sponge volume, increasing the SRT of the system to 100–125 d. Removal of coliforms obtained was 3–4 log10 with the final count of 103 to 104 MPN/100 ml in DHS effluent.
The membrane biofilm reactor: the natural partnership of membranes and biofilm
Authors: Rittmann B.E.
Published: July 2007

Many exciting new technologies for water-quality control combine microbiological processes with adsorption, advanced oxidation, a membrane or an electrode to improve performance, address emerging contaminants or capture renewable energy. An excellent example is the H2-based membrane biofilm reactor (MBfR), which delivers H2 gas to a biofilm that naturally accumulates on the outer surface of a bubbleless membrane. Autotrophic bacteria in the biofilm oxidise the H2 and use the electrons to reduce NO3−, ClO4− and other oxidised contaminants. This natural partnership of membranes and biofilm makes it possible to gain many cost, performance and simplicity advantages from using H2 as the electron donor for microbially catalysed reductions. The MBfR has been demonstrated for denitrification in drinking water; reduction of perchlorate in groundwater; reduction of selenate, chromate, trichloroethene and other emerging contaminants; advanced N removal in wastewater treatment and autotrophic total-N removal.
Instrumentation, control and automation in the water industry – state-of-the-art and new challenges
Authors: Olsson G.
Published: July 2007

Instrumentation, control and automation (ICA) are key technologies in modern water and wastewater systems. Ever present disturbances make it necessary to automatically attenuate their consequences. A wastewater treatment system is load driven, while a water distribution system is demand driven. Despite the variability the system outputs have to be satisfactory. Economic realities encourages the application of ICA to make a maximum use of plant capacities. An increasing complexity of competing processes in a modern nutrient removal plant makes more elaborate control necessary. The final goal of protecting the environmental resources necessitates an integrated view of several interdependent systems, the collection, transport and treatment processes. In this integrating development ICA will be a decisive technology.
Improvement of ammonia removal in activated sludge process with feedforward-feedback aeration controllers
Authors: Vrečko Darko , Hvala Nadja , Stare Aljaž , Burica Olga , Stražar Marjeta , Levstek Meta , Cerar Peter , Podbevšek Sebastjan
Published: July 2007

In the paper three linear aeration controllers that can be easily implemented are presented and evaluated on the activated sludge process pilot plant. Controllers differ according to the information that is used about the process, which can be oxygen in the last aerobic reactor, ammonia in the last aerobic reactor and ammonia in the influent. The aeration controllers that are addressed are: oxygen cascade PI controller, ammonia cascade PI controller and ammonia feedforward-cascade PI controller. Experiments show that, in comparison with the oxygen cascade PI controller, the ammonia cascade PI controller allows better control of effluent ammonia and airflow savings of around 23%, while the ammonia feedforward-cascade PI controller gives the best reduction of ammonia peaks and can save up to 45% of the airflow.
New process control strategy for wastewater chlorination and dechlorination using ORP/pH
Authors: Kim H. , Kwon S. , Han S. , Yu M. , Gong S. , Colosimo M.F.
Published: July 2007

Due to its efficiency and relatively low capital demanding, many wastewater treatment plants have applied chlorination for disinfection of treated wastewater before discharging it. However, determination of optimal doses of chlorine for chlorination and sulfite for dechlorination, which removes residual chlorine, should made to guarantee complete destruction of microorganisms in treated wastewater and to protect aquatic life in a receiving stream. In this study, a new ORP/pH based approach to determine endpoints of breakpoint chlorination and of dechlorinating titration and to optimize doses of chlorine and sulfite. In this new method, significant points on the ORP and pH profiles occurring during the titrations for chlorination and dechlorination were utilized to determine chlorine demand and sulfite dosage.