bluuebunny/crossref_metadata_2025 huggingface dataset:
Removal of pharmaceutically active compounds in nitrifying–denitrifying plants
Authors: Suárez S. , Ramil M. , Omil F. , Lema J.M.
Published: May 2018

The behaviour of nine pharmaceutically active compounds (PhACs) of different diagnostic groups is studied during a nitrifying–denitrifying process in an activated sludge system. The compounds selected cover a wide range of frequently used substances such as anti-epileptics (carbamazepine), tranquillisers (diazepam), anti-depressants (fluoxetine and citalopram), anti-inflammatories (ibuprofen, naproxen and diclofenac) and estrogens (estradiol and ethinylestradiol). The main objective of this research is to investigate the effect of acclimation of biomass on the removal rates of these compounds, either by maintaining a high sludge retention time or at long-term operation. The removal rates achieved for nitrogen and carbon in the experimental unit exceed 90% and were not affected by the addition of PhACs. Carbamazepine, diazepam and diclofenac were only removed to a small extent. On the other hand, higher removal rates have been observed for naproxen and ibuprofen (68% and 82%), respectively.
Applying science to conservation and restoration of the world's wetlands
Authors: Mitsch W.J.
Published: May 2018

The world has an estimated 7 to 9 million km2 of wetlands which can be defined through their hydrology, physiochemical environment, and biota. Many human cultures have lived in harmony with wetland environments for centuries. Many others have not, resulting in drainage or severe impact of wetlands throughout the world. Conservation of wetlands needs to be a priority for the cultural and ecological values they provide. But a more optimistic note is that large-scale restoration and re-creation of wetlands and riverine systems is beginning to happen throughout the world through ecological engineering. Examples of large-scale wetland restoration projects are presented for Delaware Bay, the Skjern River (Denmark), Florida Everglades, Louisiana Delta, the Mississippi River Basin, and the Mesopotamian Marshlands of Iraq.
Elution and adsorptive concentration of Japanese cedar (Cryptomeria japonica) pollen allergen in environmental water
Authors: Sagehashi M. , Fukuda T. , Fujii T. , Sakai Y. , Sakoda A.
Published: May 2018

Elution of Japanese cedar pollen allergens (Cry j I and others) from pollen grains and its adsorptive concentration onto hydrophobic and hydrophilic surfaces were investigated using the surface plasmon resonance technique. Results showed that the allergen elution was obviously enhanced when the ion concentration was higher than that within the human body, indicating that the pollen tend to release its allergen in environmental water having a high ion concentration. However, higher adsorption capacity was observed on hydrophobic surface than hydrophilic surface. These results indicate that water puddles on roadsides beside heavy traffic including large amounts of ion compounds and hydrophobic diesel exhaust particles (DEPs) are a pollen allergen-DEP complex generator. DEPs are easily absorbed into the living body; therefore these mechanisms may be responsible for causing the highest incidence of pollinosis among residents living alongside roads with heavy automobile traffic.
Degradation of parathion and the reduction of acute toxicity in TiO2 photocatalysis
Authors: Zoh K.D. , Kim T.S. , Kim J.G. , Choi K.H.
Published: May 2018

Photocatalytic degradation of methyl parathion was done using a circulating TiO2/UV and TiO2/solar reactor. Indoor experimental results showed that, under the photocatalysis conditions, parathion was more effectively degraded than under the photolysis and TiO2 only conditions. Parathion (38μM) was completely degraded under photocatalysis within 90min, and more than 80% TOC decrease after 150 minutes. The main ionic byproducts during the photocatalysis were measured, and almost complete nitrogen recovery was achieved as mainly NO3− NO2−, and NH4+, and 80% of sulfur as recovered as SO42−. Organic intermediates such as nitrophenol and methyl paraoxon were also identified during the photocatalysis of parathion, and these were further degraded after 90 minutes. Microtox bioassay using Vibrio fischeri was used in evaluating the toxicity of solutions treated by photocatalysis and photolysis of parathion. The results showed that the acute toxicity expressed as EC50 almost reduced after 90min under the photocatalysis condition whereas only 40% reduction of toxicity as EC50 was achieved in photolysis condition. The outdoor results using a TiO2/solar system were similar to the TiO2 indoor system, indicating the possibility of applying TiO2/solar system for the treatment of parathion-contaminated water.
Role of hydrophilic organic matter on developing toxicity in decay process of activated sludge
Authors: Narita H. , Funamizu N. , Takakuwa T. , Kunimoto M.
Published: May 2018

It is known that the toxicity of effluent is more intensive than that of influent in the activated sludge process. In this study, we applied bioassay using cultured human cell lines to the decay process of activated sludge to evaluate the toxicity of organic matter generated and/or released from activated sludge bacteria. We also applied this bioassay to hydrophilic fraction of samples. The bioassay results showed that: (1) the variation in the dose–response relation obtained from assay with original samples was observed during decay; (2) on the other hand, the response curves of only hydrophilic fraction at each time show the same relationship between TOC and viability of MCF7 cells; (3) this trend was confirmed by plotting the time course of EC50. These results imply that: (1) the hydrophilic organic matter controlled for developing toxicity during decay process of activated sludge; and (2) the character of hydrophilic organic matter is not changed during the experimental period.
Environmental impact and health risks associated with greywater irrigation: a case study
Authors: Gross A. , Azulai N. , Oron G. , Ronen Z. , Arnold M. , Nejidat A.
Published: May 2018

There is an increasing trend to use greywater for irrigation in households. This is partly due to the notion that greywater is of better quality than wastewater and therefore does not need extensive treatment beyond addressing public health issues. The aim of the study was to evaluate the environmental impact and health risks associated with the use of greywater for irrigation on a small private farm. Over a three-year period, each of three plots on a farm was irrigated with either freshwater, fertilized water, or greywater. Irrigation water and soil from the plots were analyzed for a wide range of chemical and microbial variables. Results suggest that greywater may be of similar quality to wastewater in several parameters such as BOD and faecal coliforms. For some other variables such as boron and surfactants, greywater may even be of worse quality than wastewater. Long-term irrigation of arid loess soil with greywater may result in accumulation of salts, surfactants and boron in the soil, causing changes in soil properties and toxicity to plants. Faecal coliforms did not survive in the soil. Treating greywater before using it for irrigation is recommended, even in places where this is not a requirement.
Summary and conclusions from the SIWI Seminar for Young Water Professionals: Food and urban security – breaking the urban/rural division in water management
Authors: Magnusson T. Sjömander
Published: May 2018

At the Seminar for Young Water Professionals, a group of young people from different parts of the world met to discuss and debate:the interface between the urban and rural environment – how can water management see to the interest of both the farmer and the urban citizen;how the spatial boundaries within water resources management will develop in the future due to changing population patterns.

Three key themes crystallized during the day: the challenges of the urban/rural interface, the need for new boundaries in water resources management and the importance of site-specific, appropriate solutions in relation to water re-use.
Evaluation of heavy metal inhibition of activated sludge by TTC and INT-electron transport system activity tests
Authors: Yin J. , Tan X.J. , Ren N.Q. , Cui Y.B. , Tang L.
Published: May 2018

TTC and INT-electron transport system activity tests were compared for assessing heavy metal inhibition of activated sludge. The median inhibitory concentrations (IC50s) of Cu2+, Zn2+, Cd2+, Hg2+, Ni2+, Pb2+ and Ag+ measured via TTC test were lower than those measured via INT test, which indicates that the INT-electron transport system activity test was less sensitive to heavy metal toxicity than the TTC test. Tested heavy metals brought about similar decrease in TTC-electron transport system activity and COD removal rate, but less decrease in INT-electron transport system activity than COD removal rate, which suggests that the TTC-electron transport system activity is a better parameter for reflecting heavy metal inhibition of activated sludge than INT-electron transport system activity. The ranking of tested heavy metals in order of decreasing toxicity based on TTC test was Hg2+, Cd2+, Cu2+, Ag+, Zn2+, Ni2+ and Pb2+, and the ranking based on INT test was Hg2+, Ag+, Cu2+, Cd2+, Zn2+, Ni2+ and Pb2+.
Dinitrogen oxide detection for nitrification failure early warning systems
Authors: Butler M.D. , Stephenson T. , Stokes L. , Stuetz R.M.
Published: May 2018

Experiments were conducted in order to establish whether N2O could be used to predict nitrification failure (through non-invasive means). Previous research had shown a strong correlation between N2O gas and NH3 in the effluent, giving rise to the possibility N2O can be used as an indicator for failure in the nitrification process. Two pilot-scale activated sludge plants were used, each with two lanes. The smaller consisted of a 60l aeration tank and a 20l clarifier; the larger pilot plant had an aeration tank of 315l and a clarifier of 100l. The small pilot plant experiments showed that N2O gas was given off almost immediately from O2 deprivation/NH3 shock loads, but did not follow the expected trend of the time lag of NH3 in the effluent. This led to further investigation in the hydrodynamics and mixing characteristics of aeration basins, where a second larger pilot plant was used. Further experiments were conducted of high NH3 loadings and O2 deprivation, showed that work of was reproducible. However, it was also shown that with partial nitrification failure, a different N2O response of a continual rise was observed.
How to treat raw sewage with constructed wetlands: an overview of the French systems
Authors: Molle P. , Liénard A. , Boutin C. , Merlin G. , Iwema A.
Published: May 2018

The development of vertical flow constructed wetlands treating raw wastewater in France has proved to be very successful over the last 20 years. In view of this a survey was carried out on more than 80 plants in order to study their performance and correct the design if necessary. This study shows that such systems perform well in terms of respecting the goals of both low level outlet COD and SS and nitrification. Pollutant removal performance in relation to the loads handled and the specific characteristics of the plants were investigated. Nitrification is shown to be the most sensitive process in such systems and performance in relation to sizing is discussed. Such systems, if well designed, can achieve an outlet level of 60 mg L−1 in COD, 15 mg L−1 in SS and 8 mg L−1 in TKN with an area of 2–2.5 m2.PE−1. The sludge deposit on the first stage must be removed after about 10–15 years.
Constructed wetlands for CSO treatment: an overview of practice and research in Germany
Authors: Uhl M. , Dittmer U.
Published: May 2018

Vertical flow treatment wetlands have been developed as very useful tools for treatment of combined sewage overflow. Several systems have been in operation for over 15 years. Based on recent research work, new technical guidelines now recommend systems with a drained filter of sand 0/2 mm and a throttled outflow. COD, NH4-N and SS removal rates of 85–99% can be expected from this type of filter. SS loadings that are too high and very long or frequent inundation affect the performance adversely. Information for successful long-term operation were derived from various existing plants.
Using a compact combined constructed wetland system to treat agricultural wastewater with high nitrogen
Authors: Kantawanichkul S. , Somprasert S.
Published: May 2018

The objectives of this study were to find appropriate conditions for nitrogen removal by a compact combined constructed wetland system and to evaluate the removal rate constant in a tropical climate. This study will present suitable operating conditions for a combined system to treat pig farm wastewater containing high ammonia-nitrogen. Four laboratory-scale combined constructed wetland units (0.5 × 1.0 × 1.0 m3): vertical flow vegetated bed over horizontal flow sand bed, were operated under an average temperature of 24 °C. Pig farm wastewater with COD and NH4+-N concentration of 1034 and 448 mg/L in average was fed to the system at different HLR from 2 to 8 cm/day. The performance of the system when operated with a vertical flow bed followed by a horizontal flow bed or vice versa did not show a significant difference but under high HLR, nitrogen removal efficiencies were clearly reduced. Nitrobacter and Nitrosomonas were found in a large number in vertical flow beds and the same for denitrifier bacteria in a horizontal flow beds. Removal rate constants for nitrification (kNH4-N) were 0.0413 m/d for H-Vmode and 0.0339 m/d for V-H mode. Removal rate constants for denitrification (kNOx-N) were 0.0979 m/d for H-Vmode and 0.0399 m/d for V-H mode, respectively.
Influence of surface layer on hydrology and biology of gravel bed vertical flow constructed wetlands
Authors: Chazarenc F. , Merlin G.
Published: May 2018

In France, gravel vertical flow constructed wetlands (gVFCWs) were adapted to treat raw wastewater, which led to important accumulations of matter in filters (organic and mineral). To prevent clogging, large gravel sizes were employed (∅ 2–6 mm). The aim of this paper was to present the influences of matter accumulation on the hydraulic and biological behaviour of the system. A one-year survey of accumulated matter content and potential respiration activities was completed in three gVFCWs (operating for 3, 4 and 8 years). Cores were sampled into filters. Results showed a vertical stratification of accumulated matter and respiration rates. Dry accumulated matter quantities ranged from 20 kg m−2 (3 and 4 years operating) to 80 kg m−2 in the oldest plant (8 years). Potential respiration was larger in the oldest plant (75 g O2 m−2 h−1) than in the most recent one (15 g O2 m−2 h−1). Accumulated matter seemed to play a role both on the water retention (enhancing initial percolation time by 5 times) and biological profile (enhancing microfauna's diversity). Contrary to what is generally proposed in the literature, accumulated matter in French gVFCWs seemed to provide better treatment efficiency without leading to surface clogging compared to systems using sand.
Effluent standards for developing countries: combining the technology- and water quality-based approach
Authors: Ragas A.M.J. , Scheren P.A.G.M. , Konterman H.I. , Leuven R.S.E.W. , Vugteveen P. , Lubberding H.J. , Niebeek G. , Stortelder P.B.M.
Published: May 2018

It is a challenge for developing countries to realize socio-economical development without impairing water resources in an unacceptable way. A possible means for controlling water pollution is through defining, applying and enforcing effluent standards for wastewater discharges. However, in many developing countries the definition of effluent standards is still poor. They are either too stringent because they are based on standards from developed countries, or too relaxed and therefore they do not guarantee the safe intended uses of water. In order to define an approach for setting effluent standards that suits the needs and means of developing counties, water quality management practices in the USA, the EU, the New Independent States (NIS) and the Philippines were analyzed and compared. Four criteria (protection of the environment, technical viability, economic feasibility and institutional capacity requirements) were used to assess the suitability of these practices for developing countries. It is concluded that a combined approach that is based on best available technology not entailing excessive costs and environmental quality standards is the best way to define effluent standards that restrict water pollution against affordable costs.
Vertical flow constructed wetlands for municipal wastewater and septage treatment in French rural area
Authors: Paing J. , Voisin J.
Published: May 2018

This paper presents the purification performance of 20 wastewater treatment plants with vertical reed bed filters (Macrophyltres®), built between 1998 and 2003 by SAS Voisin, for communities of between 150 and 1400 PE. The first stage vertical reed bed (directly fed with raw wastewater by intermittent feeding) achieved high removal of SS, BOD and COD (mean respectively 96%, 98%, 92%). The second stage permitted compliance easily with effluent standards (SS < 15 mg/l, BOD < 15 mg/l, COD < 90 mg/l and mean TKN < 10 mg/l). Performance was not significantly influenced by variations of organic and hydraulic load, nor by seasonal variations. Rigorous operation and maintenance were required to obtain optimal performances. Another application of vertical reed beds is the treatment of septage (sludge from individual septic tanks). The results obtained on two sites operating for 2 and 3 years are presented. The first site achieved complete treatment of septage (solid and liquid fraction), the second permitted a pre-treatment for co-treatment of percolate with wastewater.
Inactivation of algal blooms in eutrophic waterof drinking water supplies with the photocatalysisof TiO2 thin film on hollow glass beads
Authors: Kim S.-C. , Lee D.-K.
Published: May 2018

Photocatalytic inactivation of algae, Anabaena, Microcystis, and Melosira, was carried out with TiO2-coated Pyrex hollow glass beads under the illumination of UV light (370nm wavelength). After being irradiated with UV light in the presence of the TiO2-coated Pyrex glass beads, Anabaena and Microcystis, known as typical cyanobacteria, lost their photosynthetic activity, and the string of Anabaena cells and the colonies of Microcystis cells were completely separated into individual spherical ones. In the case of Melosira, which is a typical diatom, however, somewhat lower photocatalytic inactivation efficiency was obtained, which was believed to be due to the presence of the inorganic siliceous wall surrounding the cells of Melosira. The TiO2-coated hollow glass beads could successfully be employed for the practical application in a eutrophicated river under sunlight. More than 50% of the chlorophyll-a concentration could be reduced by the action of TiO2 photocatalysis.
Treatments of oil-refinery and steel-mill wastewaters by mesocosm constructed wetland systems
Authors: Yang L. , Hu C.C.
Published: May 2018

In this study, two types of industrial wastewater, oil-refining and steel-milling, were selected for investigating their feasibility of treatment by mesocosm constructed wetland systems. The secondly treated effluents from the wastewater treatment plants were directly discharged into the systems controlled at different flow rates. Three wetland mesocosms were installed in the two industries: mesocosms A and B were in the oil refinery, and mesocosm C was in the steel mill. The substratum media used in wetland systems were sand (mesocosm A) and gravel (mesocosms B and C), while the vegetation types selected were reeds (mesocosms A and B) and mixed species of reeds and cattails (mesocosm C). The flow regimes were controlled as free water surface (FWS) and subsurface flow (SSF) for the sand- and gravel-beds, respectively. According to the experimental results, we found that the system treating oil-refining wastewater performed better than that treating steel-milling wastewater learned by comparing the removal efficiencies of COD, total N and total P. In addition, it was found that for oil-refining wastewater treatments, the SSF wetland system (mesocosm B) performed better than FWS (mesocosm A) wetland system when comparing both of their removal of pollutants and growth of vegetation. Besides, the effluents from these two industrial wetland treatment systems might be reclaimed and reused for boiler water, cooling, cleaning and miscellaneous purposes in industries. Further treatments are required if the constructed wetland effluents are thought about being reused for processing in industries.
Simulation of a subsurface vertical flow constructed wetland for CSO treatment
Authors: Dittmer U. , Meyer D. , Langergraber G.
Published: May 2018

Constructed wetlands (CWs) have proved to be a highly effective measure to reduce the ecological impact of combined sewer overflows (CSOs) on receiving waters. Due to the stochastic nature of the loading regime and the multitude of environmental influences, assessment of the performance of such plants requires detailed mathematical modelling. A multi-component reactive transport module (CW2D) was applied to simulate the flow, transport and degradation processes occurring in a CW for CSO treatment. CW2D was originally developed to simulate the treatment of municipal wastewater in subsurface flow CWs. Loading and operational conditions in CSO treatment differ fundamentally from the conditions occurring for wastewater treatment. Despite these differences, first results from the simulation of lab-scale experiments show, that the model is generally applicable to this type of plant. Modelling of adsorption, degradation processes, and influent fractionation, however, require further research.
Treatment of gully pot liquor containing heavy metals with constructed wetlands in Scotland
Authors: Scholz M. , Anderson P. , Forman B.I.
Published: May 2018

The aim of this investigation was to assess the treatment efficiencies for gully pot liquor of 12 experimental vertical-flow constructed wetland filters containing Phragmites australis (Cav.) Trin. ex Steud. (Common Reed) and filter media of different adsorption capacities in a cold climate. Seven of the twelve filters received inflow water spiked with heavy metals. For one year, hydrated copper nitrate and hydrated nickel nitrate were added to sieved gully pot liquor to simulate contaminated primary treated storm water runoff. The inflow concentrations for dissolved copper, nickel and nitrate-nitrogen were approximately 1.0, 1.0 and 1.45 mg/l, respectively, which represent mean loading rates of 0.063 g/m2/d for Filters 2 and 7 to 11, and 0.115 g/m2/d for Filter 12. For these filters receiving metals, an obvious breakthrough of dissolved nickel was recorded after road gritting and salting during winter. Sodium chloride was responsible for nickel leaching. Reductions of copper, nickel, biochemical oxygen demand and suspended solids were frequently insufficient compared to international secondary wastewater treatment standards. Moreover, the overall filtration performance for all filters was similar.
Integration and application of the Rainfall Runoff Library
Authors: Kim S. , Vertessy R.A. , Perraud J-M. , Sung Y.
Published: May 2018

The Rainfall Runoff Library (RRL) provides a convenient platform for implementing environment modelling components such as rainfall runoff models, calibration tools, and objective functions. A rainfall–runoff model widely known and used in South Korea, TANK, is added to the RRL, and used along with the models AWBM and SIMHYD to reproduce the historical time series of daily and monthly runoff at the Soyanggang Dam and Youngcheon Dam catchments located in South Korea. The features of the RRL allow for an easy comparison of different models in a standardised and common framework. Three optimisation methods (Genetic algorithm, Rosenbrock method and Shuffled Complex Evolution algorithm) were applied to calibrate the model parameters using three different objective functions. The applicability of each model to these catchments is discussed based on the resulting statistics.
Optimization of low-cost phosphorus removal from wastewater using co-treatments with constructed wetlands
Authors: Leader J.W. , Reddy K.R. , Wilkie A.C.
Published: May 2018

Eighteen wastewater treatment systems were operated for one year to investigate phosphorus (P) removal. Systems paired co-treatment reactors containing iron or calcium drinking water treatment residuals with vertical-flow constructed wetland mesocosms planted with Schoenoplectus tabernaemontani (K.C. Gmel.) Palla. For secondary municipal wastewater, soluble reactive P (SRP) concentrations were reduced from 0.70 to 0.03 mg L−1 (95%) or 0.01 mg L−1 (98%) by systems with the calcium or iron co-treatments, respectively (compared to 0.09 mg L−1 or 87% by controls). Total P (TP) concentrations were reduced from 1.00 to 0.07 mg L−1 (93%) and 0.05 mg L−1 (95%) by the same treatments (compared to 0.16 mg L−1 or 84% by controls). For anaerobically digested dairy wastewater, SRP was reduced from 7.68 to 6.43 mg L−1 (16%) or 5.95 mg L−1 (22%) by the systems with calcium or iron, respectively (compared to 7.37 mg L−1 or 4% by controls). For this wastewater, the TP was reduced from 48.5 to 22.5 mg L−1 (53%) and 22.7 mg L−1 (53%) by the same treatments (compared to 24.1 mg L−1 or 50% by controls) but performance improved substantially with a design modification tested.
Sediment deposition in constructed wetland ponds with emergent vegetation: laboratory study and mathematical model
Authors: Schmid B.H. , Stephan U. , Hengl M.A.
Published: May 2018

Retention of suspended particles by settling is among the main physical treatment processes in constructed wetland ponds. Laboratory experiments were conducted to study the transport and deposition of suspended particles in the slow, near-stagnant flows typical of constructed wetland ponds with emergent vegetation. The presence of stems was found to create a velocity field which is much more uniform than its counterpart without vegetation. This property was used to obtain an approximate mathematical model, for which an analytical solution could be given to describe sediment transport and deposition. The deposition rates predicted by this formula were compared to the data from the above-mentioned laboratory experiments and found to agree closely.
Small scale sanitation technologies
Authors: Green W. , Ho G.
Published: May 2018

Small scale systems can improve the sustainability of sanitation systems as they more easily close the water and nutrient loops. They also provide alternate solutions to centrally managed large scale infrastructures. Appropriate sanitation provision can improve the lives of people with inadequate sanitation through health benefits, reuse products as well as reduce ecological impacts. In the literature there seems to be no compilation of a wide range of available onsite sanitation systems around the world that encompasses black and greywater treatment plus stand-alone dry and urine separation toilet systems. Seventy technologies have been identified and classified according to the different waste source streams. Sub-classification based on major treatment methods included aerobic digestion, composting and vermicomposting, anaerobic digestion, sand/soil/peat filtration and constructed wetlands. Potential users or suppliers of sanitation systems can choose from wide range of technologies available and examine the different treatment principles used in the technologies. Sanitation systems need to be selected according to the local social, economic and environmental conditions and should aim to be sustainable.
Effective distribution of domestic wastewater effluent between percolation trenches in on-site treatment systems
Authors: Gill L.W. , Hand A. , O'Súlleabháin C.
Published: May 2018

On-site treatment systems discharging to groundwater rely on the effective distribution of effluent across a percolation area to provide an appropriate loading rate for the subsoil. In Ireland, this is achieved in a distribution box which splits the effluent evenly between the requisite number of percolation pipes. The flow regime experienced at four different distribution boxes was monitored continuously over twelve month periods which established that the most common flow rates at the distribution unit were in the range 1–4 litres/minute for a four to five person dwelling. In addition, the average flow rate from the four sites was only 100 litres per person per day, compared to recommended design value of 180 litres per person per day. Two distribution boxes were also tested in the laboratory to assess their distribution efficiency over a range of loading rates. The most commonly installed unit was found to significantly favour two out of the four trenches and both units were shown to perform particularly poorly at a range of different off-level installation angles. Modifications to the boxes were also tested, involving plastic V-notch inserts which were shown to greatly improve the hydraulic distribution and make the unit much less sensitive to off-level installation or subsidence.
Particle and microorganism removal in floating plastic media coupled with microfiltration membrane for surface water treatment
Authors: Chiemchaisri C. , Chiemchaisri W. , Kornboonraksa T. , Dumrongsukit C. , Threedeach S. , Ngo H. H. , Vigneswaran S.
Published: May 2018

Floating plastic media followed by hollow fiber microfiltration membrane was applied for surface water treatment. The performance of the system in terms of particle and microorganisms was investigated. The floating filter was examined at different filtration rates of 5, 10 and 15 m3/m2.h. Treated water was then fed into a microfiltration unit where different filtration rates were examined at 0.6, 1.0 and 1.4 m3/m2.d. It was found that polyaluminum chloride was the best coagulant for the removal of particle, algae and coliform bacteria. Average turbidity in treated water from the floating plastic media filter was 3.3, 12.2 and 15.5 NTU for raw water of 80 NTU and 12.9, 11.7 and 31.2 NTU for raw water of 160 NTU after 6 hours at the filtration rates of 5, 10 and 15 m3/m2.h, respectively. The microfiltration unit could further reduce the turbidity to 0.2–0.5 NTU with low transmembrane pressure development of 0.3–3.7 kPa. Microfiltration membrane could retain most of algae and coliform bacteria remaining in the effluent from the pretreatment unit. It was found that at higher turbidity, algae and coliform bacteria removal efficiencies were achieved at lower filtration rate of the system of 5 m3/m2.h whereas a higher filtration rate of 15 m3/m2.h yielded better coliphage removal.
Evaluation of bipolar electrocoagulation applied to biofiltration for phosphorus removal
Authors: Yu M.J. , Koo J.S. , Myung G.N. , Cho Y.K. , Cho Y.M.
Published: May 2018

To reduce the residual organic matter and phosphorus contained in secondary effluent, a biofiltration system combined with electrocoagulation using bipolar iron elegctrodes was evaluated as a supplementary treatment to existing small-community sewage treatment. Based on the results of batch tests, bipolar electrocoagulation (BEC) was found to be more effective on phosphorus removal than monopolar electrocoagulation (MEC) but energy consumption was less in monopolar electrocoagulation. Optimum conditions of BEC to treat the secondary effluent were current density 15 A/m2, electrode spacing 1 cm and pH < 8. The removals of CODCr and phosphorus by biofiltration system without BEC were 69.1% and 9.6%, respectively. However, biofiltration system combined with BEC showed 76.6–83.7% and 70.7–93.0% removal for CODCr and phosphorus respectively. Extraordinary increase in phosphorus could be achieved by introducing electrocoagulation to biofiltration, and BEC/biofiltration system was evaluated to be applicable to existing small-community sewage treatment plants as a supplementary process.
Clinoptilolite: a possible support material for nitrifying biofilms for effective control of ammonium effluent quality?
Authors: Inan H. , Baykal B. Beler
Published: May 2018

Ammonium selective natural zeolite clinoptilolite is suggested as a possible support material for nitrifying biofilms to help improve effluent ammonium quality through its high capacity of ammonium removal in the process of ion exchange. This will especially be helpful in cases where the biofilter receives peak or variable loads routinely or occasionally. At the time of peak loads or shocks of ammonium, ion exchange capacity will provide a buffer for the effluent ammonium quality. Data to support this suggestion is presented.
BTEX degradation by fungi
Authors: Nikolova N. , Nenov V.
Published: May 2018

Aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylenes (BTEX) are environmental pollutants that cause serious problems in groundwater, in surface water and in soil. Specifically, the coastal area of Bourgas bay (Bulgarian Black Sea coast) is very vulnerable to such pollution as the large petrochemical industry situated there poses a continuing threat to the environment. The potential for degradation of BTEX by fungi was studied. Two fungal strains were used in the experiments carried out in a batch reactor. The fungi were isolated from gasoline-polluted sites and were identified as deuteromycetes belonging to the Cladophialophora (CPH) and Cladosporium (CS) genera. It was found that neither of the fungal strains was able to degrade benzene. Ethylbenzene was easily degraded in all cases; o- and m-xylene were fully degraded by Cladophialophora sp. both as single substrates and in mixtures with toluene, whereas Cladosporium sp. was able to degrade them fully in mixtures with toluene only. p-Xylene was only partially degraded in all tests; however, the experiments with Cladosporium sp. showed better results compared to those with Cladophialophora sp. in this particular case. Ethylbenzene, o- and m-xylene negatively affected toluene removal rate of both fungal strains, which suggests possible competitive substrate interactions. In general, the results obtained with Cladophialophora sp. were better than those with Cladosporium sp., except in the case of p-xylene degradation.
Waste stabilisation ponds in France: state of the art and recent trends
Authors: Racault Y. , Boutin C.
Published: May 2018

Waste stabilisation ponds represent 20% of the total number of wastewater treatment plants in France. Practical expertise acquired during these last 20 years has led to modification in the design of the first facultative basin of WSP systems. Its active surface area is now dimensioned at 6 m2(p.e.)−1 in order to limit the risk of malfunctioning. The cumulated surface of the 2nd and 3rd basin is maintained at 5 m2(p.e.)−1. Another practical point is also that WSPs must receive mainly diluted influents. Globally, the plants are on average far from their nominal loadings, which explains why the first sludge removals took place on average 13 years after being put in operation. Based on a representative sample of plants, i.e. 15% of the French WSPs, it has been possible to estimate the time, material means and cost needed for sludge removal as well as the amount of sludge accumulated. The sludge removed at the 1st yields on average 110 L (p.e.)−1 which represents 12 kg DM (p.e.)−1. The current trend of increasing the quality levels necessary for discharge into sensitive receiving bodies has led to adaptive solutions of polishing treatments by intermittent sand filter systems with or without the plantation of reeds.
Changes in waste stabilisation pond performance resulting from the retrofit of activated sludge treatment upstream: part I – water quality issues
Authors: Cromar N.J. , Sweeney D.G. , O'Brien M.J. , Fallowfield H.J.
Published: May 2018

This paper describes changes in effluent quality occurring before and after an upgrade to the Bolivar Wastewater Treatment Plant in South Australia. Trickling filters (TF) were replaced with an activated sludge (AS) plant, prior to tertiary treatment using waste stabilisation ponds (WSPs). The water quality in the WSPs following the upgrade was significantly improved. Reductions in total and soluble BOD, COD, TKN, suspended solids and organic nitrogen were recorded and the predominant form of inorganic nitrogen changed from NH4-N to NO2/NO3-N. The reduction in ammonium and potentially toxic free ammonia removed a control upon the growth of zooplankton, which may have contributed to decreases in algal biomass in the final ponds and consequently lower dissolved oxygen. Additionally, changes in inorganic nitrogen speciation contributed to a slightly elevated pH which reduced numbers of faecal coliforms in WSPs. The AS pretreated influent recorded significantly lower inorganic molar N:P ratio (10–4:1) compared to those fed with TF effluent (17–13:1). Algae within the WSPs may now be nitrogen limited, a condition which may favour the growth of nitrogen-fixing cyanobacteria. The decrease in algal biomass and in dissolved oxygen levels may enhance sedimentary denitrification, further driving the system towards nitrogen limitation.
Risk management in waste water treatment
Authors: Wagner M. , Strube I.
Published: May 2018

With the continuous restructuring of the water market due to liberalisation, privatisation and internationalisation processes, the requirements on waste water disposal companies have grown. Increasing competition requires a target-oriented and clearly structured procedure. At the same time it is necessary to meet the environment-relevant legal requirements and to design the processes to be environment-oriented. The implementation of risk management and the integration of such a management instrument in an existing system in addition to the use of modern technologies and procedures can help to make the operation of the waste water treatment safer and consequently strengthen market position.

The risk management process consists of three phases, risk identification, risk analysis/risk assessment and risk handling, which are based on each other, as well as of the risk managing. To achieve an identification of the risks as complete as possible, a subdivision of the kind of risks (e.g. legal, financial, market, operational) is suggested. One possibility to assess risks is the portfolio method which offers clear representation. It allows a division of the risks into classes showing which areas need handling. The determination of the appropriate measures to handle a risk (e.g. avoidance, reduction, shift) is included in the concluding third phase. Different strategies can be applied here. On the one hand, the cause-oriented strategy, aiming at preventive measures which aim to reduce the probability of occurrence of a risk (e.g. creation of redundancy, systems with low susceptibility to malfunction). On the other hand, the effect-oriented strategy, aiming to minimise the level of damage in case of an undesired occurrence (e.g. use of alarm systems, insurance cover).
Primary facultative ponds in the UK: the effect of operational parameters on performance and algal populations
Authors: Abis K.L. , Mara D.D.
Published: May 2018

Waste stabilisation pond systems in the UK are used to treat effluents from small rural communities where there are large fluctuations in both BOD load and inflow; the facultative ponds in these systems have a wide range of hydraulic retention times: between 11–86 days. Low hydraulic retention times in UK ponds are sometimes accompanied by a high BOD loading, although some have a low BOD loading due to high inflows of dilute wastewater. It is not certain whether the performance is affected by the short hydraulic retention time or high BOD loading. A pilot-scale experiment tested the effect of hydraulic retention time (20–60 days) on primary facultative pond performance whilst keeping the BOD loading constant at 80 kg/ha d. It was found that no significant loss of performance was experienced at the test range for BOD and ammonia removal; some loss in SS removal was noted at 20 days' retention time. The effect of BOD loading on the maintenance of algal populations during winter (November(February) was tested at loadings of 50 and 80 kg/ha d. Although there was a significant difference in the concentrations of chlorophyll a and dissolved oxygen between the two loadings, there was no effect on performance.
Planning, modelling and assessing source control concepts on catchment scale
Authors: Peters C. , Mühleck R. , Sieker H. , Jekel M.
Published: May 2018

Today's water management practice was identified often not to be consistently structured. Usually the decision space is not clearly depicted and then systematically explored. Often stakeholders are involved too late and many objectives are neglected. An adaptive DSS is being developed to help overcoming these problems. Core of the DSS is a “decision matrix”, which has been implemented as a web based application (www.wsm300.de). The management objectives are represented by the indicators labelling the rows. They will be the result of a discussion of the objectives and problems in the specific sub-basin, which is supported by the catalogue of indicators. The columns of the matrix are specified by the scenarios whose development is supported by the database of measures and a Geographical Information System (GIS). The matrix, once the labels are defined, serves as a plot for the planning process, defining clearly which objectives have to be considered and which indicator-values have to be calculated. The DSS further includes a concept and tools for the combination of existing software components and supports the processing of model-outputs to indicator-values. Filled with the indicator-values the matrix allows a comparison of the scenarios and provides a good base for a decision. Multi-criteria decision aid methods can (if desired) further help to find the optimal scenario and to mediate between stakeholders. Finding the optimal scenario will likely be an iterative process.
Implications for physical design: the effect of depth on the performance of waste stabilization ponds
Authors: Pearson H.W. , Athayde S.T. Silva , Athayde G.B. , Silva S.A.
Published: May 2018

Studies on experimental primary facultative ponds showed that varying the depth from 1.25 m to 2.3 m had no effect on the rates of BOD removal. In contrast k values for FC removal rates were higher in the shallower (1.25 m) facultative ponds. The risk of odour release via H2S production was higher in the 2.2 m ponds than the 1.25 m ponds and NH3 removal was much better in the 1.25 m facultative ponds. A comparison of the efficiency of shallow 5-pond series (1.0 m and 0.61 m deep) with a 2.2 m deep series showed that the shallow systems were more efficient at FC removal, but the deeper series actually saved land area for the same FC final effluent quality under tropical conditions. However, efficient nutrient removal (N and P) only occurred in the shallow series and effluent standards for nutrient concentrations are unlikely to be met by 2.2 m deep 5-pond series in contrast to the norms for pathogen removal.
Performance of very shallow ponds treating effluents from UASB reactors
Authors: von Sperling M. , Mascarenhas L.C.A.M.
Published: May 2018

Polishing ponds are units conceived for the post-treatment of the effluents from anaerobic reactors, are designed as maturation ponds, and aim at a further removal of organic matter and a high removal of pathogenic organisms. The paper investigates the performance of four very shallow (H = 0.40 m) polishing ponds in series, with very low detention times (1.4–2.5 days in each pond), treating anaerobic effluent from the city of Belo Horizonte, Brazil. The system was able to achieve excellent results in terms of BOD and E. coli removal, and good results in terms of ammonia removal, allowing compliance with European standards for urban wastewater and WHO guidelines for unrestricted irrigation. The paper presents the values of BOD and E. coli removal coefficients, which were much higher than those found in conventional pond systems. No statistically significant difference was found in the effluent E. coli concentrations from a pond with low depth and low detention time, and another pond in parallel, with double the depth and approximately double the detention time. The results endorse the applicability of the system composed by UASB reactors followed by very shallow ponds in series, with low detention times.
Aerated rock filters for enhanced nitrogen and faecal coliform removal from facultative waste stabilization pond effluents
Authors: Johnson M. , Mara D.D.
Published: May 2018

Facultative waste stabilization ponds in the UK, loaded at 80 kg BOD/ha day, produce effluents which comply with the European Urban Waste Water Treatment Directive (i.e., ≤25 mg filtered BOD/l and ≤150 mg SS/l). However, the Environment Agency of England and Wales typically requires a higher effluent quality of ≤40 mg/l unfiltered BOD and ≤60 mg/l SS, both on a 95-percentile basis. An ammonium-nitrogen requirement might also be applied. Traditionally, maturation ponds and reedbeds have been used to upgrade facultative pond effluents, requiring large land areas. This paper describes and compares aerated and unaerated rock filter performance for BOD, SS, nitrogen and faecal coliform removals, and highlights the land-saving opportunities as maturation ponds and reedbeds become redundant.
A benchmark study of controlled emptying of equalization basins
Authors: Bolmstedt J. , Olsson G.
Published: May 2018

Storm tanks, or equalization basins, have been used for many years in sewer or wastewater treatment systems to reduce the amount of combined sewer overflows. In this paper, a systematic control of an equalization basin is used not only to dampen or reduce the hydraulic load, but also to systematically improve the effluent quality in a nitrogen removal plant. It is demonstrated that the effluent ammonia concentration is the key component. The Benchmark Simulation Model 1, implemented in MATLAB/Simulink, has been used to perform the evaluations. It has been extended with systematic rainfall generations. Intuitively, it is apparent that the equalization basin should be emptied before a rainfall. This requires a prediction capacity. It is shown that the choice of prediction time is by no means trivial and it is not true that a long prediction horizon is always advantageous.
Performance of a pilot-scale high rate algal pond system treating abattoir wastewater in rural South Australia: nitrification and denitrification
Authors: Evans R.A. , Cromar N.J. , Fallowfield H.J.
Published: May 2018

As part of a study examining the efficacy of high-rate algal pond treatment of high-strength abattoir wastewater, the impact of pond configuration and loading rate on nitrification was determined. The extent of nitrification in all ponds was consistent with mass balance estimates of oxygen demand and availability. Deeper ponds were more stable nitrifying systems, with shallow ponds displaying greater variation in response to changes in nitrogen loading. In a separate experiment the pond system was modified by covering a part of an in-series HRAP to exclude light, providing conditions suitable for denitrification. Specific denitrification rates were often within the range typical for endogenous carbon sources, with mass balance calculations indicating removals of up to 95%.