bluuebunny/crossref_metadata_2025 huggingface dataset:
Predicting the risk to permit compliance of new sewage treatment works
Authors: Dunn A. J. , Frodsham D. A. , Kilroy R. V.
Published: May 2018

The privatised water industry in England and Wales has the requirement to construct a substantial number of new assets to meet new national and European legislation. In order to do so economically, the risk of performance of new assets has to be matched to the cost of construction. To undertake such risk management, a risk technique has been developed that allows the performance against permit compliance of new processes to be established. The technique is based on statistical analysis of data effectively creating a pure black box model to determine performance.

The technique has been further developed to take into account the dependency between influent quality and process performance. The dependency factor selected is the Spearman's Rank Coefficient which is a convenient way to define complex relationships. It can be used to define many dependent variables referring to the same independent variable and as such removes the need for complex mechanistic equations. This technique has been calibrated using two years, existing data and then validated for the next 6 months data of a wastewater treatment works in the North West of England. The results of the validation illustrate the ability of the technique to be used as a predictive tool.

The output from the model allows the direct comparison of different process options and permits executive management to make informed decisions about investment against risk to permit compliance.
A keypoint of nitrification in an upflow biofiltration reactor
Authors: Pujol R. , Lemmel H. , Gousailles M.
Published: May 2018

The wastewater treatment plant Seine Aval at Achères is the largest plant in France, with an average flowrate of 25 m3/s. For the moment, this plant consists of an activated sludge process for organic carbon removal. However, due to the recent European water regulations, it will soon be necessary to remove nitrogen pollution. For this reason, tertiary nitrification prototype reactors were installed and tested, in order to examine a future upgrading of the plant. This article presents the results obtained, during the last two years, with an upflow BAF reactor utilizing a granular media with a density > 1. The objective will be to examine a key parameter of the process: the water velocity (part of the applied loading rate. The removal rate depends directly and linearly on the applied loading rate, as long as the nitrification conditions (aeration, temperature, etc …) are not limiting. The highest loading rates for nitrification, as well as for BOD5 removal and SS retention, were obtained at high water velocity (10 m3/m2.h). These results demonstrate that the hydraulic retention time, even when extremely short (10 minutes), does not influence the reactor performance. The high water velocities in this kind of filter positively influence and improve the mass transfer between the liquid environment and the bacteria.
Binding constants of chlorobenzenes and polychlorobiphenyls for algal exudates
Authors: Koelmans Albert A. , Heugens Evelyn H. W.
Published: May 2018

In eutrophic ecosystems, primary production may significantly affect the behaviour of toxicants or the accumulation in the aquatic food chain. Little is known about the potential of extracellular carbon, e.g., exudates, to scavenge hydrophobic chemicals. In a laboratory Selenastrum capricornutum culture with 30% extracellular carbon, phytoplankton-water bioconcentration factors (BCF) and exudate-water association factors (KDOC) were measured for two chlorobenzenes and 4 PCBs (total log Kow range 4.6-7.4). The apparent logBCFs were measured after 3 day batch equilibration and varied linearly with logKow with a slope of 0.63. The KDOC values for exudates from the same batch were measured using a gas purge method and were very high and more or less equal to Kow: logKDOC=logKow −0.057 (r2=0.926, n=6). The strong association with exudates limits the bioavailability of PCBs in laboratory cultures and natural aquatic systems.
Models for water quality management: the problem of structural change
Authors: van Straten Gerrit
Published: May 2018

This paper challenges the common belief that a calibrated and validated model is sufficient to warrant technically sound application to guide water quality planning measures. The reason is that the planning of measures intrinsically implies that the present situation is going to be changed. Consequently, the model is going to be used outside its original domain, which from a strict systems theoretic point of view is not allowed, unless experience shows that the underlying laws are universal. Due to the complexity of water systems and their contained ecology, the structure of the developed models is almost surely not universal enough to cover changed conditions, and the prediction ability will deteriorate. Various remedies to mitigate the situation are discussed, among them over-specification combined with knowledge from similar systems, cybernetic modelling, educated speculation, and flexibility by feed-back.
Nitrification in partially aerated flocculation filters - a full-scale approach
Authors: Kolisch G.
Published: May 2018

In a full-scale approach, we investigated whether nitrification can be carried out in partially aerated flocculation filters without compromising the removal of suspended solids. The objective is an aerated filter in addition to an advanced nitrification in the main biological treatment step to reduce low NH4-N concentrations in the effluent to very low concentrations. In two separate sets of experiments with an aerated filtering layer of 0.7 m and 1.4 m, nitrification rates up to 14 g N/(m3/h) were achieved. Compared to unaerated chambers, there was approximately the same removal of particulate COD and of precipitated phosphorus compounds. Due to the formation of anoxic zones, nonspecific denitrification occurred in the chambers under both conditions. Decay products are suspected to be the endogenous H-donors.
Low cost procedure for nutrient removal in small rural wastewater treatment plants
Authors: Rolf F. , Grabowski F. , Burde M.
Published: May 2018

Nutrient removal in small wastewater treatment plants is often beneficial especially if the effluent must be discharged into sensitive or guarded waters or into groundwater. The presented studies optimised an inexpensive method of subsequent enhanced wastewater treatment. The developed reactor is similar to a concentrated subsoil passage. The fixed bed reactor is divided in two sections to achieve aerobic and anoxic conditions for nitrification/denitrification processes. To enhance phosphorus removal, ferrous particles are addedto the aerobic zone. Two series of column tests were carried out and a technical pilot plant was built to verify the efficiency of the process. The results show that this method can be implemented successfully. The aerobic processes, nitrification and phosphorus removal by absorption, were not problematic. Elimination rates higher than 90 % were measured. The capacity of phosphorus removal is principally limited. After consumption of the ferric ions the reactor filling must be renewed. Denitrification strongly depends on the availability of a degradable organic substrate. To balance the substrate load and the nitrate flow a simple device was created. Weekly monitoring of the BOD and nitrate effluent concentration seems to be sufficient to find an appropriate adjustment. A technical-scale pilot plant was built and the first test drives have been started.
First results of the restoration of Lake Geerplas
Authors: van Duin E. H. S. , Frinking L. J. , van Schaik F. H. , Boers P. C. M.
Published: May 2018

In 1986 lake restoration was started in the Langeraar lakes, three small connected lakes in the western part of The Netherlands. In one of the lakes, Lake Geerplas, both the internal and external phosphorus load to the lake was reduced. Water quality parameters have been monitored six years after the measures were taken, in both Lake Geerplas and in one of the other Langeraar lakes. Water quality improved in Lake Geerplas during four years, indicated by decreased phosphorus concentrations and turbidity. At the end of the third fourth summer, phosphorus concentrations increased rapidly, presumably due to excessive phosphorus release from the lake sediment. Phytoplankton biomass and phytoplankton composition changed as well. In the sixth year phosphorus concentrations decreased slowly without any additional measures taken. Chlorophyll-a concentrations and turbidity are at the same level now as shortly after the measures were taken. At this moment, the effects of the measures are evaluated and additional measures are considered. Though the changes in water quality variables during the years are clearly related, the driving forces are not yet identified.
Simple feedback logic, genetic algorithms and artificial neural networks for real-time control of a collection system
Authors: Hajda Pavel , Novotny Vladimir , Feng Xin , Yang Ruoli
Published: May 2018

This paper describes a pilot-scale implementation of a simple, real-time control (RTC) algorithm based on feedback and also outlines the development and simulation testing of a new RTC methodology that combines genetic algorithms (GAs) and artificial neural networks (ANNs). Computer simulations indicated that the simple feedback logic could reduce pumping by 50 to 80 percent if used to replace the existing RTC system in the test area. Experience with the algorithm after its implementation has confirmed the potential of the algorithm to reduce pumping. Additional simulations with an emerging approach to control (based on GAs) indicated possibilities of reducing pumping still further. Although relatively simple flow routing was used in the GAs, these algorithms do not restrict flow routing to any particular method. If highly accurate flow routing is incorporated, GAs are likely to be rendered too slow for on-line applications. Nevertheless, GAs can still be used, because they can be combined with fast executing on-line algorithms, such as ANNs. This possibility was demonstrated by training a multi-layer ANN to approximate one of the GAs developed. In verification runs the trained ANN provided virtually the same control decisions as did the GA used as the source of the training data.
Applying real-time control to enhance the performance of nitrogen removal in the continuous-flow SBR system
Authors: Yu Ruey-Fang , Liaw Shu-Liang , Chang Cheng-Nan , Cheng Wan-Yuan
Published: May 2018

Conventional operations of wastewater treatment systems use the concepts of steady-state control, and often lead to unnecessary resource consumption for maintaining system functions. Real-time control was examined as a useful approach for improving the operation of wastewater treatment systems. This paper presents the application of real-time control to enhance the performance of nitrogen removal in a continuous-flow SBR system. A real-time control system combining on-line measurement of ORP and pH with Artificial Neural Network (ANN) model was proposed to carry out unsteady-state regulation of the hydraulic retention time of different operation phases. The result of this study shows that the performance of nitrogen removal was enhanced under real-time operation. Compared with fixed-time operation, the retention time of aerobic and anoxic phases can be reduced by approximately 45% and 15.5% in real-time operation respectively, also meaning that 45% aeration energy can be saved. The real-time operation also reveals a higher total nitrogen removal in a relative short retention time. Moreover, some dynamics and kinetics of nitrogen were investigated. These indicate the occurrence of nitrite-type nitrification under real-time operation. This nitrite-type nitrification results in the enhancement of denitrification performance with less carbon resource requirement and higher denitrification efficiency.
Process state evaluation of alternating oxic-anoxic activated sludge using ORP, pH and do
Authors: Paul E. , Plisson-Saune S. , Mauret M. , Cantet J.
Published: May 2018

Better control of wastewater treatment requires the development of pertinent sensors. For Alternating Aerobic-Anoxic Activated Sludge, the relatively simple sensors measuring ORP, DO and pH appeared to be useful for managing the aeration. Bending-points on the ORP and pH curves are linked to the major biological activities playing a role in nitrification and denitrification. In this work, it is shown that the appearance or the absence of these bending-points and the pH variation slope allow the operating state of the biological system to be identified. Case studies of over- and under-loaded conditions and over- and under-aerated systems are examined. The diagnosis procedure can be used to regulate the aeration flow rate, to optimize the ORP thresholds and the timers, and to evaluate the organic load and the potentials of the bacterial populations involved in nitrogen elimination.
Characterization of the municipal wastewaterpart human urine and a preliminary comparison with liquid cattle excretion
Authors: Fittschen Imke , Hahn Hermann H.
Published: May 2018

In separation toilets, human urine and faeces are separated at source in order to keep them away from the aquatic environment and to enable recycling. 24-hour urine samples of 19 individuals were analysed for several wastewater parameters. The daily loads and their mean variation are presented, and the contribution of human urine to the total daily load in municipal wastewater is calculated.

The concentration of plant nutrients in human urine was compared with those of liquid cattle excretion as traditional organic fertilizer. Nearly all investigated chemical parameters showed great differences. Cations and anions could not be balanced. During storage, the urea in both human urine and cattle urine was quickly converted to ammonium. During 41 days, storage of human urine with passive gas transfer did not lead to significantly higher nitrogen losses than closed storage. Cattle urine reached highly significantly better results than human urine in a germination test with summer barley and in most of the cases highly significantly or significantly worse results in a germination test with cress. The results indicate that the effects of liquid cattle excretion on plant growth are not the same as those of human urine.
Evaluation of faecal contamination and microbial die-off in urine separating sewage systems
Authors: Höglund C. , Stenström T. A. , Jönsson H. , Sundin A.
Published: May 2018

An important feature for recirculated products from a sewage system is that the risk for transmission of disease is low. In a urine source separating system faeces may contaminate the collected urine through the toilet. The concentrations of faecal indicator organisms were measured in 14 urine collection tanks. The survival of these and some pathogenic microorganisms in source separated human urine was studied. Total coliforms, E. coli and clostridia were found in low concentrations while faecal streptococci occurred in concentrations up to 105/ml urine solution. The results from phenotyping of faecal streptococci and the high counts indicate growth within the system. The majority of the pathogenic microorganisms investigated had a rapid die-off. A higher temperature, a low degree of dilution and a pH far from neutral had a negative effect on survival. E. coli had a rapid die-off and is not suitable for indicating faecal contamination of the collected urine. Quantification of faecal sterols is a possible alternative to microbial analysis for this purpose. The amounts of coprostanol showed that the faecal contamination varied from not detected to up to 13.3 mg/ml urine solution with a concentration in the urine sludge of up to 417.5 mg/kg.
Pilot-scale SBR and MF operation for the removal of organic and nitrogen compounds from greywater
Authors: Shin Hang-Sik , Lee Sang-Min , Seo In-Seok , Kim Goo-Oung , Lim Kyeong-Ho , Song Jun-Sang
Published: May 2018

A pilot plant of SBR (Sequencing Batch Reactor) and MF (microfiltration) process was operated in order to treat and reuse the greywater produced from an office building. The performance of SBR for greywater was satisfactory as the effluent had 20 mg/l, 5 mg/l, and 0.5 mg/l of SCOD, BOD, and ammonia, respectively. The cyclic operation of SBR used in this study proved more effective in nitrification and denitrification than the conventional SBR operation. However, the most effective mode was step-feed SBR for denitrification. The decanting system of this SBR discharged the effluent fairly well without sludge washout. However, it was difficult to maintain constant concentration of suspended solid from the SBR process. Thus, additional filtration was needed to get adequate water quality for water reuse. MF could remove residual suspended solids and pathogens as well from the SBR effluent. The suspended solids of final effluent were around 1 mg/l and allowed using the treated water for some purposes.
The effect of dissolved silica on the action of hydrolysing metal coagulants
Authors: Gregory J. , Duan J.
Published: May 2018

Using a simple continuous optical technique, coupled with measurements of electrophoretic mobility, the effect of silicic acid or dissolved silica on the coagulation of kaolin suspensions has been examined. The results show that the presence of dissolved silica greatly affects the coagulation process at both low and high coagulant concentrations. The effect depends on the silica concentration and solution pH. Dissolved silica can improve, suppress or even prevent coagulation, and these effects may be due to the modification of hydrolysis species and precipitates due to the interaction between the metal ions and dissolved silica.
Control of biological iron removal from drinking water using oxidation-reduction potential
Authors: Tremblay Catherine V. , Beaubien André , Charles Philippe , Nicell James A.
Published: May 2018

Biological removal of iron to produce drinking water was established in a pilot plant treating raw water with a pH of 5.7. The objective was to evaluate the use of oxidation-reduction potential (ORP) as a control tool and determine its relationship to dissolved oxygen (DO) and residual iron concentration in filtered water from an operating biological filter. Results showed that above a low minimum value of DO, residual iron concentration and ORP were not affected by varying the DO level. A non-linear regression was established to correlate total residual iron concentration to ORP with an R2 of 0.8848. This correlation can be used to predict iron concentration when ORP is in the range 300 to 470 mV. Below this range, total residual iron is greater than or equal to 3 mg/l and above, total residual iron is less than the French regulation limit of 0.2 mg/l. Pilot plant operating conditions were implemented in the primary filter of an industrial plant in France, improving iron elimination and doubling the length of the filtration cycle.
Influence of ageing on the catalytic activity of ferric sludge for oxidation of fe(II)
Authors: Tufekci Nese , Sarikaya Hasan Z.
Published: May 2018

The catalytic effect of freshly formed or added ferric iron on the Fe(II) oxidation has been demonstrated by previous studies. High Fe(III) concentrations significantly accelerate the oxygenation rate. High Fe(III) concentrations can be maintained only by sludge recycle which eventually leads to sludge ages as high as 10 days. Therefore, the aim of this study was to determine whether ageing of ferric hydroxide sludge affects its catalytic effect on the oxidation of ferrous iron by aeration.

In order to reach this aim four different groups of experiments were carried out using ferric hydroxide sludge aged for a period of 0 to 10 days. Initial Fe(III) concentrations were varied within the range of 50 mg/l to 200 mg/l. It has been demonstrated that the catalytic effect of ferric hydroxide sludge on the oxidation of ferrous iron by aeration increases with increasing sludge age contrary to what is commonly expected. It has been concluded that, catalytic oxidation rate constant kcat obtained from the batch systems can safely be used in design of continuous flow iron oxidation reactors with sludge recycle.
The performance of an ozonation-biological activated carbon process under long term operation
Authors: Nishijima Wataru , Kim Woo Hang , Shoto Eiji , Okada Mitsumasa
Published: May 2018

The objective of this study is to evaluate removal of DOC and THMFP during long term operation of an ozonation-biological activated carbon (BAC) process. A pilot scale plant with raw water in an eutrophic reservoir for drinking water supply was operated for 910 days. High DOC and THMFP removal were maintained at 36% and 57%, respectively, in the ozonation-BAC process even after saturation of BAC by DOC. DOC and THMFP removal by ozonation were only 8% and 24%, respectively. High DOC and THMFP removal after saturation was due to the increase in biodegradable DOC by ozonation from 7% to 32% and the subsequent biodegradation by bacteria attached on BAC. Although water temperature changed in the range from 5 to 30°C, seasonal changes in DOC and THMFP removal were not observed in the ozonation-BAC process.
Biological stability of drinking water in new York City
Authors: Jolis D. , Faber W. W. , Diyamandoglu V.
Published: May 2018

A study was carried out to determine the degree of biological activity in the drinking water supplied to New York City by the Croton and Catskill/Delaware systems, as measured by the Attached Growth Rate Estimate (AGRE) method. Also, possible relationships between AGRE results and standard water quality parameters were examined. The AGRE results for both the systems ranged between 0 and 0.5 d−1, indicative of biologically stable water. These results suggest that excessive bacterial growth in the New York City distribution system would be rare. The Croton results were temperature and alkalinity dependent. The Catskill/Delaware results revealed that growth rates decreased with travel time in the distribution system. These differences emphasize the complexity of biological activity monitoring in drinking water distribution systems.
Microbial oxidation and bioluminescence response for toluene and trichloroethylene
Authors: Robinson Kevin G. , Pieters Jan G. , Sanseverino John , Cox Chris D. , Wright Charles L. , Cheng Catherine L. , Sayler Gary S.
Published: May 2018

Two Pseudomonas strains, P. putida F1 and P. putida TVA8, were used to evaluate biodegradation of toluene and cometabolism of trichloroethylene (TCE) in batch systems. Both organisms effectively utilized toluene although at different rates. The extent of TCE cometabolism was dependent upon the initial mass of toluene present. A relationship between toluene/TCE degradation and bioluminescence production for P. putida TVA8 was explored. A linear relationship between the total amount of toluene degraded and total bioluminescence was found. The slope of this straight line, however, was found to vary between experiments. To overcome this problem, a normalization method was proposed and successful tested.
Anaerobic/aerobic biodegradation of pentachlorophenol using GAC fluidized bed reactors: optimization of the empty bed contact time
Authors: Wilson Gregory J. , Khodadoust Amid P. , Suidan Makram T. , Brenner Richard C. , Acheson Carolyn M.
Published: May 2018

An integrated reactor system has been developed to remediate pentachlorophenol (PCP) containing wastes using sequential anaerobic and aerobic biodegradation. Anaerobically, PCP was degraded to approximately equimolar concentrations (>99%) of chlorophenol (CP) in a granular activated carbon (GAC) fluidized bed reactor (FBR) at empty bed contact times (EBCTs) ranging from 18.6 to 2.3 hr. However, at lower EBCTs, chlorophenol concentrations decreased to less than 10% of the influent PCP concentration. The optimal EBCT was determined to be 2.3 hr based on PCP conversion to CPs and stable reactor operation. Decreasing the EBCT fourfold did not inhibit degradation of PCP and its intermediates, and thus, removal of PCP is possible at lower detention times providing a significant cost advantage.

Analytical grade PCP was fed via syringe pumps into a GAC FBR at an influent concentration of 200 mg/L. Acting as the primary substrate, ethanol was also fed at a concentration of 1388 mg/L. Effluent PCP and chlorinated phenolic compounds were analyzed weekly to evaluate reactor performance. Biodegradation pathways were also identified. 3-chlorophenol (3-CP) was the predominant CP. Concentrations of 3-CP follow the same trends as 3,5-dichlorophenol (DCP) concentrations. In a similar manner, 4-chlorophenol concentrations correlate with 3,4-DCP concentrations.

A second stage aerobic GAC FBR was added after the anaerobic bioreactor which removed the remaining CP and phenols. No phenol or CP has been observed in the effluent or on the GAC. Overall, the influent chemical oxygen demand (COD) loading was reduced from 34 g/L*d to less than 1.36 g/L*d.
Impact of biodegradable trenching slurry on iron treatment wall performance
Authors: Navon D. , Loehr R. C. , Liljestrand H. M. , Daniel D. E.
Published: May 2018

Biodegradable trenching slurries have been proposed as a cost effective method for the emplacement of reactive treatment barriers. In this study, the impact of a bio-polymer slurry on the ability of zero-valent iron to reductively dehalogenate trichloroethene was measured. First-order trichloroethene degradation rates were determined for three types of iron, with and without slurry in batch reactions. For the commercial grade iron, a significant difference was determined between the surface area normalized rate without slurry (1.78E-4 L m−2 hr−1) and with slurry (1.23E-4 L m−2 hr−1). However, no significant difference was determined with or without bio-slurry for the reagent grade irons.
Groundwater remediation by anionic surfactant micelles - an innovative double layer model applied to Na+ and Mg2+ association with dodecylsulfate micelles
Authors: Yuan Ching , Hung Chung-Hsuang , Jafvert Chad T.
Published: May 2018

The association reactions involving counterions, Na+ and Mg2+, and micelles composed of the anionic surfactant, dodecylsulfate (DS−), were investigated in ultrafiltration experiments. To access the data, an innovative model was developed that considered specific counterion binding within a Stern layer, with binding constant dependent upon the electrical potential as derived by the Poisson-Boltzmann equation and with calculation of the cmc as a function of counterion binding (or association). The experimental and model results both show that magnitude of counterion binding is greater for divalent species, Mg2+, than that for the monovalent species, Na2+. However, high concentration of Na+ compete for surface area diminishing the ability of the DS− to bind either divalent species. At experimental conditions from 0 to 100 mM NaCl addition, the binding ratio (BR) varied only from 0.58 to 0.63. The optimum binding constants, KMg and KNa, were determined to be 0.4 and 1.0 L mol−1, respectively, for the model. The experimental data and model calculated results were generally in good agreement.
Metal toxicity on the dechlorination of monochlorophenols in fresh and acclimated anaerobic sediment slurries
Authors: Kong I.-C.
Published: May 2018

The biotransformation of 2- and 3-chlorophenol(CP) was examined in anaerobic fresh and acclimated sediments in the presence and absence of CuCl2, CdCl2 and K2Cr2O7 ranging from 10 to 200 mg/l. Differing inhibitory effects of specific metals were observed on dechlorination of CPs in sediment slurries. In case of fresh unacclimated slurry, addition of 20 mgCu/l resulted in no appreciable inhibition of dechlorination for tested CPs. In contrast, 20 mg/l of Cd and Cr moderately affected lag periods prior to dechlorination. In this case, Cd was more inhibitory than either Cu or Cr (Cd > Cr ≥ Cu), which illustrated nearly similar effect.

In case of acclimated slurry, the dechlorination activity of 2- and 3-CP was inhibited in the presence of 20 mg/l of three tested metals. Metals amended to 2- and 3-CP acclimated sediments exhibited inhibition degree in the order of Cd > Cu > Cr, which are different patterns compare to fresh slurry.
Comparison of ozonation and AOPs combined with biodegradation for removal of THM precursors in treated sewage effluents
Authors: Ito Kazuaki , Jian Wen , Nishijima Wataru , Baes Aloysius U. , Shoto Eiji , Okada Mitsumasa
Published: May 2018

The efficiency of ozonation (O3) and advanced oxidation processes (AOPs) such as O3/UV, O3/H2O2, H2O2/UV and O3/H2O2/UV was examined for removal of trihalomethane (THM) precursors in treated sewage effluents. A low-pressure mercury (Hg) lamp (maximum wavelength 253.7 nm; intensity 2.6 × 10−6 Einstein s−1) was employed for AOPs using ultraviolet light. The efficiency of the processes employed was examined by both direct mineralization of target compounds and the formation of biodegradable compounds, based on the removal of dissolved organic carbon (DOC), UV absorbance at 260 nm (UV260), and THM formation potential (THMFP). The contribution of ozonation was relatively small for mineralization of DOC, but was larger for the increase in biodegradability of residual DOC. On the other hand, AOPs were effective for both mineralization and increase in biodegradability. A longer reaction time with AOPs resulted to an increase in mineralization but not to an increase in biodegradable components possibly because the biodegradable components were also decomposed by AOPs. The removal of UV260 was obtained by chemical/photolytic processes and not by biodegradation. The rate of THMFP removal by ozonation, AOPs, and biodegradation was higher than that of DOC removal.
Effect of cadmium on the embryos and juveniles of a tropical freshwater snail, Physa acuta (Draparnaud, 1805)
Authors: Cheung C. C. C. , Lam P. K. S.
Published: May 2018

The effects of cadmium on early life stages of a freshwater snail, Physa acuta (Draparnaud), were investigated. The 24- and 48-hour LC50 for embryos were 1.27 mg/l (95% confidence interval: 1.13 - 1.42) and 0.85 mg/l (0.71 - 1.01), respectively. The 24- and 48-hour LC50 for juveniles were 1.32 mg/l (1.13 - 1.54) and 1.05 mg/l (0.81 - 1.36), respectively. An increase in cadmium concentrations at sublethal levels resulted in a significant reduction in embryo growth rate and embryo hatchability. Developmental deformities of the embryos were also observed. The NOEC and LOEC for embryonic growth were 0.32 and 0.50 mg/l, respectively, and the LOEC for hatchability was 0.13 mg/l. These results suggest that embryonic growth and hatchability are useful endpoints in chronic toxicity tests. In addition, the potential use of early life stages of pulmonate snails in ecotoxicological tests is discussed.
Stimulation of reductive dechlorination for in situ bioremediation of a soil contaminated with chlorinated ethenes
Authors: Middeldorp Peter J. M. , van Aalst Martine A. , Rijnaarts Huub H. M. , Stams Fons J. M. , de Kreuk Han F. , Schraa Gosse , Bosma Tom N. P.
Published: May 2018

A soil from a former chemical redistribution company, contaminated with mainly chlorinated aliphatics, was studied for bioremediation purposes. Groundwater analyses revealed that the original pollutants, i.e. tetrachloroethene (PCE) and trichloroethene (TCE), were present at levels ranging from 2.3 to 122 mg/L. Dichloroethene (DCE), vinylchloride (VC), ethene and ethane were also detected at significant concentrations although they had never been introduced to the soil. Relatively high concentrations of cis-DCE as compared to trans-DCE and 1,1-DCE indicated that a slow in situ biodegradation had taken place by reductive dechlorination. Laboratory experiments with flow-through soil columns were performed to determine the optimal conditions for the enhancement of reductive dechlorination by the indigenous dechlorinating population. The addition of single electron donors to artificial groundwater resulted in the dechlorination of PCE to TCE and cis-DCE, whereas complete dechlorination to ethene was solely achieved with compost extract added to native groundwater.
Possibilities of reduction of recipient loading of tannery wastewater in Slovenia
Authors: Roš Milenko , Gantar Anton
Published: May 2018

The leather industry is well known as a high consumer of water (30 to 80 m3 for 1 ton of processed raw skins). At the same time this industry is known for the high specific pollution of wastewater. The main characteristics of tannery wastewater are: high salinity, high organic loading (COD, BOD5), high content of ammonia and organic nitrogen, and presence of specific pollutants (sulphide, chromium).

The largest Slovenian tannery (IUV Vrhnika) processing 40 to 50 t of pig skins daily has a good system of physico-chemical pre-treatment of their wastewater (coagulation and flocculation with Al-sulfate and anionic polyelectrolyte). In pre-treatment, about 60% of organic substances are removed (COD and BOD5) and above 95% of sulfide and chromium. Concerning Slovenian regulations and taking into consideration the fact that this tannery is located on the relatively small and slowly running river Ljubljanica such pre-treatment is not sufficient. The company would like to supplement pre-treatment with biological treatment.

Laboratory and pilot scale feasibility experiments including conventional biological treatment with activated sludge and combined anaerobic-anoxic-aerobic treatment with fixed biomass using mechanical pretreated wastewater and pretreated wastewater with flotation were performed. It became clear that effective biological treatment requires long retention times (several days) for applicable effluent.
Applicability of UASB sludge to agricultural lands
Authors: Yükselen Mehmet Ali
Published: May 2018

Investigation of dewaterability and applicability of UASB sludge to agricultural lands were the objectives of this study. Under laboratory conditions, 90% of sludge moisture percolated in 4 days. Desorption of metals such as copper and lead did not occur under normal conditions. Desorption of metals occurred only at pH 1 or less. UASB sludges have strong affinity for metals. The nutrient value of these sludges are small compared to commercial fertilizers.
Upgrading our inherited urban water systems
Authors: Harremoës P.
Published: May 2018

Environmental issues have to be discussed in the largest possible context. It is all too frequent that a miniature vision creates solutions with unanticipated detrimental effects in neighbouring fields of interest. It is noteworthy that the society has so few options, which may be identified by five verbs: no use, reuse, convert, contain and disperse. The future lies in analysis of the environmental issues in the context of total mass balance of important substances through society. Water is scarce only as long as it is lost by evaporation. The purpose of water usage is to pollute it, because the success of the past century has been to use water as a means of transport out of cities. It is a key issue that water usage can be diminished by demand control. There will still be polluted water to be purified. It is within the technological and economical range to purify water to a degree that would make it fit for urban reuse - to the point where the flow of water withdrawn from the environment can be diminished to a very small fraction of the present day withdrawal.
Upgrading of Borås wastewater treatment plant based on intelligent process and operation control
Authors: Thornberg Dines E. , Nielsen Marinus , Eriksson Jöran
Published: May 2018

Borås wastewater treatment plant is being upgraded to comply with the new effluent standards for nitrogen. Three different configurations have been tested in parallel in full scale in the existing activated sludge plant. The Biodenitro operated line showed the best performance because of the flexible adjustment of the nitrification and denitrification capacity. The adjustment was made off-line with the aid of continuous ammonia and nitrate measurements. On-line sensors are now installed permanently at Borås wastewater treatment plant and will be used for on-line dynamic control of the nitrogen removal in a Biodenitro configuration. The plant capacity will be further increased by settling in the aeration tanks in situations with high hydraulic load.
Development of an air removal system for dissolved air flotation
Authors: Hedberg Torsten , Dahlquist Jan , Karlsson Dick , Sörman Lars-Ove
Published: May 2018

Dissolved Air Flotation (DAF) is often used as a separation step in drinking water treatment. An increasing use of high rate processes has become a trend in chemical treatment. When increasing the loading rate for a flotation process, an increasing head loss built up occurs in the following filter process due to dispersed air carry over. This paper describes the development of an air removal system by using a lamella plate separation system for the dispersed air. Pilot plant experiments showed that the surface load for the combination Lamella Dissolved Air Flotation, the LDAF-unit can be considerably increased in comparison with a conventional DAF-unit.
Up-flow roughing filtration: rehabilitation of a water treatment plant in Tarata, Bolivia
Authors: Ingallinella Ana María , Stecca Luis María , Wegelin Martin
Published: May 2018

This paper presents the methodology used for the rehabilitation of the pretreatment stage in a water treatment plant for a village located in Bolivia which has 3500 inhabitants. The treatment plant was initially composed by horizontal-flow roughing filters and slow sand filters, but due to the high contents of colloidal turbidity of the providing source, it did not work properly. A plan of rehabilitation was made which comprised laboratory tests, pilot tests and proposal of modifications based on the results of previous stages. The laboratory tests were made in order to find the optimum conditions to coagulate the raw water. It was found that horizontal-flow roughing filters must be turned into up-flow roughing filters, so a pilot plant was built and was operated for three months in order to find suitable design parameters. The results obtained obtained during the operation of the pilot plant and the proposal of modifications are presented. The results of operation of the final plant, which are also reported, demonstrated the advantages of the up-flow roughing filtration as a pretreatment stage when it is necessary to add chemical products in small treatment plants.
Implementing biofilm carriers into activated sludge process-15 years of experience
Authors: Müller N.
Published: May 2018

Seven full-scale hybrid systems have been operating in waste water treatment plants in Southern Germany since the early eighties. The aerobic submerged biofilm technology applied is known as Bio-2-Sludge process. The plants have originally been designed for carbon removal and were modified later on to allow nitrogen removal. For this purpose, the age of the operating sludge had to be raised. This was achieved without any addition of reactor volume by installation of submerged biofilm carriers. The use of the submerged, fixed bed devices results in a very efficient sludge, allowing MLSS of up to 11 g/l. Operational results show both a purification improvement of BOD and ammonia and the existence of simultaneous denitrification. Practical experiences of long-term operations are being reported.
Upgrading of waste water treatment processes for integrated nutrient removal-the BCFS® process
Authors: van Loosdrecht M. C. M. , Brandse F. A. , de Vries A. C.
Published: May 2018

In the past years extensive experience has been gained in the upgrading of waste water treatment processes for efficient nutrient removal. Hereby especially the integration of denitrification and biological P-removal has been focused upon on these experiences a new process configuration (the BCFS®-process) was developed. This process is specially designed to optimise the activity of denitrifying P-removing bacteria. If the biological P-removal process needs to be supplemented an integrated ‘P-stripper’ is designed. This paper reviews the upgrading of three wastewater treatment plants by the new process.
Clinoptilolite and multipurpose filters for upgrading effluent ammonia quality under peak loads
Authors: Baykal B. Beler
Published: May 2018

Peak loads of ammonia can not always be handled with success in the biological process of nitrification and compliance with standards may be a problem. Ion exchange with clinoptilolite may be used as a second stage unit to polish the effluent and to assure compliance. Within this context, the use of clinoptilolite in an ion exchange unit or alternatively in filters together with filter material, without a significant loss of capacity, may be possible, providing substantial reductions in terms of land requirement for the upgrade. Results from units of clinoptilolite only, and in combination with (i) burned clay and (ii) sand filters have revealed that all configurations are successful as upgrades for dampening ammonia peaks. Among the configurations investigated, the combined scheme where clinoptilolite is added to a filter unit which is aerated to enhance biological activity, has given the best results, provided that enough time is allowed for the adaptation of the nitrifiers.
Combined sewer overflow treatment – knowledge or speculation
Authors: Geiger W. F.
Published: May 2018

The stochastic behaviour of rainfall and the uncertainties in land use development as well as the limited knowledge on efficiency of CSO-treatment measures yield the most difficult conditions for design. Therefore less emphasis should be given to regulations for sizing individual structures and more ingenuity must be used for flexible designs and integration of CSO-facilities in the overall system. More emphasis should be paid to observe and monitor the effectiveness of constructed facilities. The greatest potential in achieving more protection for less money is seen in better using the tradeoff potential between decentral and central treatment and between storage and treatment level.
Modelling the total ammonia impact of CSO and WWTP effluent on the receiving water
Authors: Holzer Peter , Krebs Peter
Published: May 2018

For 25 rain events test runs were performed on a catchment of a small town, where 40% of the person equivalents are connected to a separate sewer system and 60% to a combined one. We investigate the effects of rain events with regard to NH4-loads discharged by the wastewater treatment plant and by a combined sewer overflow. NH4-concentrations in the river caused by these loads are also discussed. NH4 is important as (i) it closely interrelates with NH3 – a fish poison – and (ii) it stands for dissolved compounds that mainly origin from the wastewater. The sewer system is simulated with three different options: with a combined water retention tank connected to the CSO structure, with a sewage retention tank at the interface between the separate and the combined system, and without any retention structure. While the sewage retention tank performs better concerning the integrated load discharged into the river, the combined sewer retention tank is more efficient in decreasing peak values and duration of high concentrations in the river. We also show that NH4 peak concentrations in the river are largely due to a wash-out effect in the main sewer at the beginning of a rain event.
Estimation of urban nonpoint source pollution in Lake Biwa Basin
Authors: Ichiki Atsushi , Ohnishi Toshiyuki , Yamada Kiyoshi
Published: May 2018

This study aims to simulate pollutant runoff into Lake Biwa using the Macro Model and examine the runoff characteristics of pollutants from urban nonpoint sources. As a result of the simulations of all rivers flowing into Lake Biwa, the characteristics of urban nonpoint source pollution and the basic units of urban nonpoint pollutants in the Lake Biwa basin became clear. It was shown that the control of pollutant runoff from nonpoint sources during storm events was significant in order to protect the water quality of Lake Biwa. From these results, valuable data concerning the environmental management of the Lake Biwa basin was obtained.
A renovated model for spatial analysis of pollutant runoff loads in agricultural watershed
Authors: Ha Sung Ryong , Jung Dhong Il , Yoon Cho Hee
Published: May 2018

Runoff loads of pollutant in agricultural watersheds were spatially analyzed by using geographic information system(GIS) technology. The topological relationship between pollution sources in the watershed was, first of all, identified by using the developed digital map of land use and then the pollutant loads generated from each source was estimated by applying a conventional unit loading factor on the obtained digital information of pollution sources. To evaluate the loads delivered from spatially distributed pollution sources to monitoring stations in down stream via surface of watershed, a renovated empirical model incorporated with the information of pollutant discharge path was developed through introducing a digital terrain model(DTM) technique. In this model, the function of degradation of pollution loads during delivery process was simplified so that each watershed could have a basin-wide self-purification capacity which would be considered to be possessed inherently in each watershed and could retard the discharge of pollutants from sources generated to stream water. Model credibility showed good consistency with comparing the simulated values with observed data. Monte Carlo optimizing technique made it possible to estimate the basin-wide self-purification coefficients.
Marine sewage outfall assessment for the capital regional district, British Columbia, using nested three-dimensional models
Authors: Hodgins D. O. , Tinis S. W. , Taylor L. A.
Published: May 2018

Nested three-dimensional, prognostic hydrodynamic and coupled transport-diffusion models were developed to simulate the dispersion of contaminants from two large marine outfalls discharging untreated sewage effluent into the estuarine waters of Juan de Fuca Strait. The modelling system is comprised of a 200-m fine grid model nested inside a 1-km large area model incorporating all estuarine circulation processes, and an embedded version of the UM buoyant diffuser plume model. Predictions for fecal coliform distributions were successfully verified using observations obtained during a monitoring program in December 1996.
Sustainable waste management - a case study from the UK water industry
Authors: Burton J. M.
Published: May 2018

Waste disposal practices were developed at a time before the implementation of waste regulation. When the first control came the industry found that it was its own waste regulator and so its own practices were not closely examined. Privatisation of the water industry overturned this situation and the disposal practices of the past came under the full spotlight of regulatory control. This was just at a time when waste disposal legislation itself was going through a process of revision to take account of European and Global environmental initiatives. North West Water's response to this was to instigate a thorough review of waste management practice across the Company. This has resulted in a totally new approach to waste management and the creation of a dedicated waste management organisation. The primary role of this organisation is to manage, to the best financial and environmental benefit of the Company, all its waste streams. This management must provide a high level of protection for the receiving environment, take account of cost, and strive to achieve the aims of sustainable development.