bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of the effectiveness of source control sanitation concepts including pre-treatment with Rottebehaelter
Authors: Gajurel D.R. , Li Z. , Otterpohl R.
Published: May 2018

High levels of nutrients recovery can be achieved with source control sanitation - technologies are already available. Separation toilets for example separate urine that can be used in agriculture with some crop restrictions as a fertiliser after about 6 months of storage. The grey water has very low loads of nitrogen and can be treated in different combinations of biological and physical treatment and reused. Faecal matter with flush water from the separation toilet can be discharged into Rottebehaelter (an underground pre-composting tank) that retains solid material and drains liquid to a certain extent. Investigation of Rottebehaelter in the different sites and laboratory experiments showed that retained faecal material still contained a high percentage of water. However, odour was not noticed in those Rottebehaelters that have been examined. One of the major advantages of this system over other forms of pre-treatment as the septic tanks is that it does not deprive agriculture of the valuable nutrients and soil conditioner from human excreta. It has to be stated that maintenance is a crucial factor. As an intermediate result of the intensive research of Rottebehaelter it seems that these systems are rather a way of solids retaining, de-watering and long-term storage before the contents are further treated.
Performance and membrane fouling in a pilot scale SBR process coupled with membrane
Authors: Shin H. , Kang S.
Published: May 2018

The performance of the pilot-scale submerged membrane coupled with sequencing batch reactor (SM-SBR) for upgrading effluent quality was investigated in this study. The reactor was operated with 3-hour cycle with alternating anoxic and aerobic conditions to treat organics, nitrogen and phosphate. Despite various influent characteristics, COD removal was always higher than 95%. Sufficient nitrification was obtained within a few weeks after start-up and during the stable period, complete nitrification occurred despite short aeration time. Total nitrogen (TN) removal efficiency was reached up to 85%. Membrane flux was critical for TN removal so that the decrease of flux by membrane fouling led to increase of HRT, and it caused the endogenous respiration of microorganisms such as nitrifying bacteria. The stirred cell test revealed the significant role of the soluble fraction in membrane permeability and dissolved solids played a major role in the short-term fouling mechanism. The cake resistance by the soluble COD fraction of supernatant or soluble microbial products (SMP) was investigated as a major part of total resistance.
Selected requirements on a sustainable nutrient management
Authors: Lampert C.
Published: May 2018

Nutrients are a limited resource and call for management. A sustainable nutrient management strategy reintegrates nutrients in the environment without accumulating harmful substances above an acceptable level. In this study a methodology to assess the environmental compatibility was developed. For this assessment both the (i) enrichment of pollutants in the soils and (ii) the area specific nutrient demand of the crops were taken into account. The method considers, that products applied on soils also contain stable substances, and as a consequence the accumulation of pollutants diminishes. Additionally, it is considered, that increasing substance concentrations in the soil will lead to an increase of substance flows out of the soil by percolation, plant-removal (and erosion). In practice long term management strategies are restricted by the time span considered, the accepted accumulation of substances, the plants real needs and legal constraints. The rating of various goods can be made with the ratio of the added nutrients, considering the pollution criteria, the legal constraints and the plants real needs.
Features of double chamber bed and case study
Authors: Tian W. , Wen X. , Qian Y.
Published: May 2018

A double chamber bed (DCB) was developed in China in 1980 and has been utilised in more than 500 setups. This paper introduces the structure and operation features of DCB, and also the unique structure of DCB leads to its perfect operation features. It can be also considered as the best option in reconstruction projects which can replace other types of ion exchangers, such as fixed bed, double cell fluidized-bed, multi-bed. Four reconstruction project cases were introduced, which were selected from more than twenty plants designed by us. Through the case study, it is concluded that DCB can not only be used to treat different sources of water (river and well), but can also be used to treat water with the ratio of transient hardness to total cation to be less than 0.5 and the ratio of strong to weak anion to be more than 7.0. These findings enlarge the scope of application of DCB.
Transforming data into information
Authors: Beck M.B. , Lin Z.
Published: May 2018

In spite of a long history of automated instruments being deployed in the water industry, only recently has the difficulty of extracting timely insights from high-grade, high-volume data sets become an important problem. Put simply, it is now relatively easy to be “data-rich”, much less easy to become “information-rich". Whether the availability of so many data arises from “technological push” or the “demand pull” of practical problem solving is not the subject of discussion. The paper focuses instead on two issues: first, an outline of a methodological framework, based largely on the algorithms of (on-line) recursive estimation and involving a sequence of transformations to which the data can be subjected; and second, presentation and discussion of the results of applying these transformations in a case study of a biological system of wastewater treatment. The principal conclusion is that the difficulty of transforming data into information may lie not so much in coping with the high sampling intensity enabled by automated monitoring networks, but in coming to terms with the complexity of the higher-order, multi-variable character of the data sets, i.e., in interpreting the interactions among many contemporaneously measured quantities.
Disinfection in a pilot-scale “advanced” pond system (APS) for domestic sewage treatment in New Zealand
Authors: Davies-Colley R.J. , Craggs R.J. , Nagels J.W.
Published: May 2018

“Advanced” pond systems (APS) have the potential for improving treatment, including disinfection, over conventional WSPs. Disinfection in a pilot scale APS at Ngatea, New Zealand was studied. This system comprises a high-rate algal pond (HRP) that optimises growth of settleable colonial green algae, followed by an algal settling pond (ASP) that removes much of the nutrients and solids as non-noxious algal sludge, and then a maturation pond (MP) for effluent polishing. Monitoring of this pilot-scale system over 2 years showed excellent overall removal of E. coli (average of 2000-fold reduction), with approximately 1 log removal in each of the three stages. Experiments in the pilot scale HRP suggest that most E. coli removal in this stage is inactivation by sunlight exposure, but with an important contribution from continuous dark processes. Preliminary experiments on the pilot scale algal settling pond (APS) suggest the combined effect of sedimentation of bacteria and sunlight disinfection of the (clarified) supernatant water.
Progress in sensor technology - progress in process control? Part II: results from a simulation benchmark study
Authors: Alex J. , Rieger L. , Winkler S. , Siegrist H.
Published: May 2018

To show the impact of sensor behaviour on the control result, four strategies for aeration control are tested using different sensor characteristics. It is demonstrated, on the one hand, how an increasing response time will limit the achievable control quality and, on the other hand, how a given sensor characteristic can be taken into account for the controller design. The presented tests show that an improvement potential by control for WWTPs is available but this potential is limited compared to proper DO control with fixed set-points. To activate this control potential, sufficient control authority must be available and a careful control design is required. It can be shown that using feedback control, sensors with a small response time have significant advantages compared to conventional sensors. Using feed forward control, the improvement potential by control is considerably higher and additionally, the sensor delay can be integrated into the controller design. The presented discussion is based on simulation studies performed on a standardised benchmark case. For these tests it was necessary to include sensor models into the simulation model. It can be stated that the usage of sensor models is necessary for the application of dynamic simulation for the design and evaluation of WWTP control and in general to achieve realistic results.
An integrated sensor for the monitoring of aerobic and anoxic activated sludge activities in biological nitrogen removal plants
Authors: Sin G. , Malisse K. , Vanrolleghem P.A.
Published: May 2018

An integrated sensor is developed as a tool for monitoring the activated sludge activity on which the performance of the treatment plant depends. The sensor provides information-rich data of high frequency obtained from respirometric-titrimetric and nitrate measurements in one single set-up. The sensor is shown to successfully monitor and provide in-depth insight into nitrification, denitrification and carbon source degradation processes occurring in BNR plants. Based on the experimental results it is hypothesized that the ratio of NUR to OUR rather reflects the rate of carbon source uptake (storage) under anoxic and aerobic conditions than growth process.
Reducing hydraulic short-circuiting in maturation ponds to maximize pathogen removal using channels and wind breaks
Authors: Lloyd B.J. , Vorkas C.A. , Guganesharajah R.K.
Published: May 2018

This paper reports the impact of four sequential maturation pond interventions on the removal of thermotolerant “faecal” coliform bacteria at a full scale WSP system in tropical Colombia. Each intervention was designed to increase hydraulic retention time and was followed by continuous physico-chemical logging and meteorological monitoring, and simultaneous tracer studies to define hydraulic retention time, flow paths and dispersion. Inlet and outlet monitoring showed that, primarily due to hydraulic short-circuiting, the open maturation pond only achieved a 90% reduction in thermotolerant “faecal” coliforms. By contrast, an in-pond batch decay rate study for thermotolerant faecal coliforms showed that a 1 log (90%) reduction was achieved every 24 hours for 4 days at 26°C, so that the maximum theoretical efficiency would be a 2.6 log reduction (99.7%) if hydraulic efficiency was perfect for plug flow. The second intervention was the conversion of the maturation pond to a parallel series of three open channels to attempt to control short-circuiting and convert to plug flow. The channels raised performance to 96%. The introduction of top baffles, at the end of the first and second channels, to attempt to further reduce the effect of surface and sub-surface flow on short-circuiting, actually reduced performance to 92.64%, and were removed. The final intervention, a 2.1 m high wind break around the maturation channels raised efficiency to 98.13%; this performance is almost a half log (0.47) greater than the efficiency (95.1%) predicted from Marais' equation for a completely mixed reactor, and 0.77 log greater than recorded in the open pond. The results have fundamental implications for improving WSP efficiency, for meeting re-use guidelines, for savings in land area and improvement of design of WSPs; they also highlight short-comings in the indiscriminate use of the Marais design equation for faecal coliform removal.
Improvement of mixing patterns in pilot-scale anaerobic ponds treating domestic sewage
Authors: Peña M.R. , Mara D.D , Piguet J.M.
Published: May 2018

Anaerobic ponds are customarily designed as completely mixed reactors. However, evidence from experiments on full-scale facilities shows large deviations from ideal flow models, which in turn cause a reduced process performance. Thus, modified pilot scale anaerobic ponds receiving domestic sewage were developed and studied in parallel. A factorially designed experiment evaluated horizontal and vertical baffling, ponds fitted with cross-sectional plastic nets and a pond with a mixing pit. The hydrodynamic behaviour and process performance of these modified configurations were monitored for four flow rates (1.0, 1.2, 1.5 and 2.0 l/s). The results showed that baffling (vertical and horizontal) and the mixing pit configuration had the best hydrodynamic behaviours and removal efficiencies. Consequently, the development of high-rate anaerobic ponds, through improvements of hydrodynamic behaviour, seems feasible.
Dairy farm wastewater treatment by an advanced pond system
Authors: Craggs R.J. , Tanner C.C. , Sukias J.P.S. , Davies-Colley R.J.
Published: May 2018

Waste stabilisation ponds (WSPs) have been used for the treatment of dairy farm wastewater in New Zealand since the 1970s. The conventional two pond WSP systems provide efficient removal of wastewater BOD5 and total suspended solids, but effluent concentrations of other pollutants including nutrients and faecal bacteria are now considered unsuitable for discharge to waterways. Advanced Pond Systems (APS) provide a potential solution. A pilot dairy farm APS consisting of an Anaerobic pond (the first pond of the conventional WSP system) followed by three ponds: a High Rate Pond (HRP), an Algae Settling Pond (ASP) and a Maturation Pond (which all replace the conventional WSP system facultative pond) was evaluated over a two year period. Performance was compared to that of the existing conventional dairy farm WSP system. APS system effluent quality was considerably higher than that of the conventional WSP system with respective median effluent concentrations of BOD5: 34 and 108 g m-3, TSS: 64 and 220 g m-3, NH4-N: 8 and 29 g m-3, DRP: 13 and 17 g m-3, and E. coli: 146 and 16195 MPN/100 ml. APS systems show great promise for upgrading conventional dairy farm WSPs in New Zealand.
An evaluation of duckweed-based pond systems as an alternative option for decentralised treatment and reuse of wastewater in Zimbabwe
Authors: Nhapi I. , Dalu J. , Ndamba J. , Siebel M.A. , Gijzen H.J.
Published: May 2018

A study was carried out in Zimbabwe to evaluate the performance of duckweed ponds as an option for treating and reusing wastewater in small, decentralised communities. The study focused on nitrogen and phosphorus removal, operational problems, and duckweed application. Two full-scale trial plants at Nemanwa and Gutu-Mupandawana growth points were used. Sewage samples were collected and analysed monthly from September 2000 to August 2001 for NO3, NH4-, TKN, TP, COD, and other field measurements. The duckweed was harvested daily and fed to chickens. The Nemanwa plant had high nutrient levels due to nil outflows caused by water rationing in the area. The Gutu effluent had averages of 38.7 ± 23.1 mg/l TN and 7.5 ± 2.4 mg/l TP which are above the respective Zimbabwean standards of 10 mg/l TN and 1 mg/l TP. COD removal efficiency at Gutu was poor at 45%. The performance of Gutu and Nemanwa plants suffered from inappropriate design especially pond depth and short-circuiting. The duckweed died off in the November-January period, this being attributed to excessive levels of ammonia. It was concluded that the duckweed pond systems would offer a good alternative for managing and reusing wastewater at community level provided due regard is paid to appropriate design criteria.
The use of chemical and molecular microbial indicators for faecal source identification
Authors: Gilpin B. , James T. , Nourozi F. , Saunders D. , Scholes P. , Savill M.
Published: May 2018

Identifying the source of faecal pollution is important to enable appropriate management of faecal pollution of water. We are developing and evaluating a combination of these microbial and chemical indicators better able to identify the source of faecal pollution. These assays make use of a combination of direct PCR, culturing, and colony hybridisation to identify source specific species of Bifidobacterium, Rhodococcus and Bacteroides. In conjunction with assays for (a) fluorescent whitening agents and (b) faecal sterols and stanols, these indicators were able to identify human derived faecal pollution in river water containing inputs from septic tanks, municipal oxidation ponds, farmed animals and feral animals. Differentiating amongst the animal sources was more difficult and will require development of molecular assays for organisms specific to each animal group.
Removal of trichloroethylene from waste gases via the peroxone process
Authors: Van Craeynest K. , Dewulf J. , Vandeburie S. , Van Langenhove H.
Published: May 2018

In dealing with chlorinated organic compounds in waste gases, traditional treatment techniques show some severe shortcomings. Thermal oxidation may lead to the formation of dioxins, active carbon adsorption does not degrade the pollutants and biotechnological treatment is difficult since microorganisms do not always possess efficient degradation pathways for these compounds. These drawbacks explain the growing interest of the waste gas treatment sector for Advanced Oxidation Processes (AOPs) which were initially developed as water treatment techniques. AOPs generate highly reactive hydroxyl radicals that efficiently oxidise organic pollutants. In the peroxone process, this is done by a combination of ozone and hydrogen peroxide. In this work, the peroxone process is applied in an oxidative scrubber for the removal of trichloroethylene (TCE). Rapid oxidation of absorbed TCE in the liquid phase enhances TCE absorption. Practically, a gas stream contaminated with TCE is mixed with an ozone loaded gas stream. The mixture is led through a bubble column that is fed with a buffered hydrogen peroxide solution. The effect of different process parameters (flow rates, buffer concentration, pH, hydrogen peroxide/ozone dosage ratio, TCE dosage) on TCE removal was investigated. Depending on the operating conditions, removal efficiencies up to 98% could be attained.
Detection of Naegleria spp. and Naegleria fowleri: a comparison of flagellation tests, ELISA and PCR
Authors: Behets J. , Seghi F. , Declerck P. , Verelst L. , Duvivier L. , Van Damme A. , Ollevier F.
Published: May 2018

To detect Naegleria spp, in particular Naegleria fowleri, the causative agent of human primary amoebic meningoencephalitis, a flagellation test (FT) is routinely used followed by a specific ELISA. A positive FT indicates the presence of Naegleria spp although some false negatives are likely to occur since parameters for enflagellation vary greatly. As negative FTs are not routinely screened any further for the presence of N. fowleri, this could result in an underestimation of the presence of this pathogen. Therefore, amoebae were further analysed using ELISA and standard PCR not only after a positive but also after a negative FT. In this study 39 cultures containing amoebae were tested with FT, ELISA and the two PCR assays with 11 positive for FT. These were submitted to ELISA and four confirmed as N. fowleri. PCR with the common primer-set on these 11 positive FTs revealed all as Naegleria spp. The specific PCR used on these cultures detected four positive for N. fowleri, corresponding totally with the ELISA results. The 28 negative flagellation tests were also submitted to ELISA and PCR. Of these, 11 were identified as Naegleria spp with common PCR and six as N. fowleri as well as with ELISA and the specific PCR. When the detection of Naegleria spp is based on intermediary processes, such as flagellation tests, false negatives are likely to occur leading to severe underestimations. This study has shown that amoebae taken from negative FTs can be identified as Naegleria spp and N. fowleri when using PCR and ELISA. The application of at least one of the specific N. fowleri tests is recommended for routine screening. The heterogeneous distribution of the false negative results between the different power plants suggested the presence of different genotypes.
Efficiency of autothermal thermophilic aerobic digestion and thermophilic anaerobic digestion of municipal wastewater sludge in removing Salmonella spp. and indicator bacteria
Authors: Zábranská J. , Dohányos M. , Jeníček P. , Ružičková H. , Vránová A.
Published: May 2018

The study is focused on the comparison of autothermal thermophilic aerobic digestion, thermophilic and mesophilic anaerobic digestion, based on long term monitoring of all processes in full-scale wastewater treatment plants, with an emphasis on the efficiency in destroying pathogens. The hygienisation effect was evaluated as a removal of counts of indicator bacteria, thermotolerant coliforms and enterococci as CFU/g total sludge solids and a frequency of a positive Salmonella spp. detection. Both thermophilic technologies of municipal wastewater sludge stabilisation had the capability of producing sludge A biosolids suitable for agricultural land application when all operational parameters (mainly temperature, mixing and retention time) were stable and maintained at an appropriate level.
Evaluation of Bacillus subtilis and coliphage MS2 as indicators of advanced water treatment efficiency
Authors: Huertas A. , Barbeau B. , Desjardins C. , Galarza A. , Figueroa M.A. , Toranzos G. A.
Published: May 2018

The assessment of water treatment facilities for their efficiency using alternate indicators is of paramount importance. Current methods for assessing efficiency are limited by the specific characteristics of the microorganisms, such as their different sensitivities to disinfectants. A pilot study was carried out to compare different treatment scenarios for the future upgrade of the Sergio Cuevas Water Treatment plant (the largest in the Caribbean) in San Juan, Puerto Rico. The treatment units under investigation included a coagulation-flocculation-sedimentation unit, dual-media filters, micro-filtration units, intermediate ozone injection and contact columns as well as a biological filtration unit. The plant was challenged at different stages of treatment with Bacillus subtilis spores and MS2 coliphages in an attempt to test them as possible alternate indicators of treatment plant performance. These organisms were chosen because of their resistance to disinfection and desiccation, their low analysis costs and ease of detection. The removal of spores and coliphages by each treatment unit tested was calculated by seeding a known concentration (5-7 log10) of spores and coliphages and following the removal or disinfection rates. The seeded indicators were detected using traditional culture techniques. Ballasted clarification was shown to be highly efficient at removing 99.1% (∼3 log10) of the spores and 85.1% (∼0.86 log10) of MS2. Ozone treatment inactivated 80.37% (∼1.4 log10) spores and 99.95% (∼3.07 log10) coliphages. The coliphage inactivation rate obtained confirmed data obtained by previous studies indicating that MS2 was less resistant to ozonation than B subtilis spores. The membrane technology had the best efficiency in terms of physical removal of spores achieving over 99.9% (>3 log10) removal. Coliphage removal mechanisms remain to be determined and will be a future focus of the study. Preliminary results indicate that aerobic spores and coliphages may be useful as indicators to determine the efficiency of different drinking water treatment technologies.
Experimental studies of sewer exfiltration
Authors: Ellis J.B. , Revitt D.M. , Lister P. , Willgress C. , Buckley A.
Published: May 2018

The effects of joint openings and in-pipe sediment on exfiltration losses in an experimental sewer are reported and the influence of flow and head on loss rates are also evaluated. Exfiltration rates tend to be exponential with changes in head for clean-water tests but exhibit power functions when the pipe is subject to sedimentation. In-pipe sediment leads to an effective sealing of joints especially if the invert deposits are both organic in nature and contain saturated adhesive material such as shredded toilet tissue. Simple tracer techniques are described to quantify exfiltration losses and the potential effects of tracer adsorption by in-pipe solids are evaluated.
Exfiltration from gravity sewers: a pilot scale study
Authors: Vollertsen J. , Hvitved-Jacobsen T.
Published: May 2018

Pilot-scale experiments were conducted on exfiltration of wastewater from gravity sewers. The effect of storm events, flushing of pipes and alternating infiltration/exfiltration were simulated. Exfiltration through different types of sewer leaks and into different soils were studied. It was found that the exfiltration rate became constant after some days of exfiltration. It stayed constant for the duration of the experiments, which typically spanned over some weeks. The exfiltration was governed by the development of a clogging zone at the sewer leak and could be characterized by a leakage factor. The leakage factor may then be used to estimate the risk of groundwater pollution from a sewer network.
High-rate anaerobic hydrolysis and acidogenesis of sewage sludge in a modified upflow reactor
Authors: Yu H.-Q. , Zheng X.-J. , Hu Z.-H. , Gu G.-W.
Published: May 2018

Continuous experiments were conducted to study the hydrolysis and acidogenesis of sewage sludge in an upflow reactor with an agitator and a gas-liquid-solid separator. Results of this study showed that 34-78% of volatile suspended solids (VSS) in sewage sludge was hydrolyzed at pH in the range 4.0-6.5, 35°C and 4-24 hours of hydraulic retention time (HRT). About 31-65% of carbohydrate in sewage sludge, 20-45% of protein and 14-24% of lipid were acidified in this reactor. Hydrogen production was favored in lower pH and HRT, whereas methane production was encouraged at higher pH and HRT. Acetate, propionate, butyrate, and i-butyrate were the main aqueous acidogenic products. The distribution of these compounds in the effluent was more sensitive to pH, but was less sensitive to HRT. The maximum specific COD solubilization rate and specific volatile fatty acids production rate were 126 mg-COD/g-VSS·d and 102 mg-VFA/g-VSS·d, respectively. Compared with a CSTR, this modified upflow reactor was shown to be a more promising biosystem for the hydrolysis and acidogenesis of sewage sludge.
Dynamic modelling of pollutants from CSOs
Authors: Schlütter F. , Mark O.
Published: May 2018

In a number of industrialised countries there is an effort made to reduce pollutant discharges from combined sewer overflows. After establishing proper treatment plants the CSO discharges are contributing with a higher percentage of the total pollutant load on the receiving waters. The acknowledgement of this issue has made the authorities in some countries issue requirements for maximum allowed pollutant loads and water quality from individual CSOs. However, in order to make standards for CSO emissions knowledge about the current state is needed and subsequently others needs to be able to document that they are in compliance with the standard. The question is how to calculate the annual pollutant load from a given CSO? The purpose of this article is to present results from calculation of annual loads in different ways.
Cellulosic waste degradation by rumen-enhanced anaerobic digestion
Authors: Barnes S.P. , Keller J.
Published: May 2018

Anaerobic digestion of lignocellulosic material is carried out effectively in many natural microbial ecosystems including the rumen. A rumen-enhanced anaerobic sequencing batch reactor was used to investigate cellulose degradation to give analysis of overall process stoichiometry and rates of hydrolysis. The reactor achieved VFA production rates of 207-236 mg COD/L/h at a loading rate of 10 g/L/d. Overloading of the reactor resulted in elevated production of propionic acid, and on occasion, the presence of succinic acid. With improvements in mixing and solids wasting, the anaerobic sequencing batch reactor system could enable full-scale application of the process for treatment of cellulosic waste material.
Combination of computational techniques - evaluation of CSO efficiency for suspended solids separation
Authors: Pollert J. , Stránsky D.
Published: May 2018

During the last two decades, the use of simulation models has played an increasingly important role in the evaluation of the dynamic behaviour of sewer systems. One of the basic characteristics of these models is the number of dimensions taken into account during simulation. This paper demonstrates the benefits of the combination of two models with a different number of dimensions included. The evaluation of separation efficiency of suspended solids in the combined sewer overflow (CSO) was the basic objective of the project. Two simulation models have been used for the evaluation. The 1D model output was the CSO inflow hydrograph, which was used as an input for the 3D model. With the help of the 3D model, the water flow inside the CSO was simulated. This paper includes the results of case study documenting the proposed methodology. Charts of concentration dynamics of suspended solids on the CSO inflow, outflow and overflow are presented (for particles with different characteristics).
Chemical characteristics and methane potentials of source-separated and pre-treated organic municipal solid waste
Authors: Hansen T.L. , Svärd Å , Angelidaki I. , Schmidt J.E. , Jansen J. , Christensen T.H.
Published: May 2018

A research project has investigated the biogas potential of pre-screened source-separated organic waste. Wastes from five Danish cities have been pre-treated by three methods: screw press; disc screen; and shredder and magnet. This paper outlines the sampling procedure used, the chemical composition of the wastes and the estimated methane potentials.
Sludge drying reed beds
Authors: Nielsen S.
Published: May 2018

Sludge reduction occurs by dewatering (draining, evapotranspiration) and mineralization. Sludge from wastewater treatment plants (2,500-125,000 PE) is treated in sludge reed basin systems with 1-18 basins with loading rates of 25-2,200 tons dry matter/year for 10 years. In general, the sludge type is surplus activated sludge or a mix of mesophile digested sludge and surplus activated sludge. Dimensioning and design of reed basin systems for 10-year periods of operation depends on how the sludge is produced, rate of production (tons of dry matter/year), sludge type, quality and regional climate. Loading cycles are related to the sludge type and the age of the sludge reed systems. The period can be divided into a number of operating phases: commissioning, full operation, emptying and re-establishment of the system. Experience shows that efficiency makes special demands on the design of the systems and on the operational control in order to obtain a final dry matter content in the sludge residue of approximately 40% and the number of operating years. Sludge loadings with surplus activated sludge and surplus activated sludge mixed with anaerobically digested sludge amount to a maximum of 60 and 50 kg dry matter/m2.year, respectively.
Comparison of detection specificity of nitrifying bacteria in biofilm using fluorescence in situ hybridization and in situ fluorescent antibody methods
Authors: Noda N. , Ebie Y. , Matsumura M. , Tsuneda S. , Hirata A. , Inamori Y.
Published: May 2018

The in situ fluorescent antibody and fluorescence in situ hybridization (FISH) methods are very useful in the in situ detection of specific bacteria like nitrifiers in a biofilm. In this study, simultaneous staining using the FISH and in situ fluorescent antibody methods was examined. As a result, no specific fluorescence was observed with either method when FISH was performed followed by the in situ fluorescent antibody method; however, when the in situ fluorescent antibody method was performed first followed by FISH, specific fluorescence was observed in both cases. Moreover, it was suggested that the detection specificities of FISH and the in situ fluorescent antibody method are almost identical.
Horizontal sub-surface flow constructed wetland with pulsing water level
Authors: Vymazal J. , Masa M.
Published: May 2018

A constructed wetland with horizontal sub-surface flow at Dolni Mesto (Czech Republic) was put into operation in 1999 and treats municipal wastewater from 522 PE. The total area of vegetated beds of 2,646 m2 is divided into two parallel sections of equal size, each with two beds in series. Between two periods of water discharge there is no outflow from the bed. During the period of September 1999-September 2000 one bed was operated with a pulsing water level while the other one was not pulsing, i.e., was operated as regular sub-surface flow in order to evaluate the effect of pulsing on treatment efficiency, especially on removal of NH4-N. Between September 1999 and February 2000 the pulse was 8 cm, for the rest of the experimental period the pulse was 15 cm. The results indicate a positive effect of pulsing on removal of BOD5 (annual average of 53%), COD (30%) and NH4-N (27%) as compared to non-pulsing beds. For SS, a decrease in removal effect by 30% was observed. This is probably due to the higher outflow velocity of discharged water from pulsing beds which can flush out settled particles. The results also indicate that a pulsing level of 15 cm was more efficient than 8 cm.
Nutrient removal and plant biomass in a subsurface flow constructed wetland in Brisbane, Australia
Authors: Browning K. , Greenway M.
Published: May 2018

Four native plant species (Baumea articulata, Carex fascicularis, Philydrum lanuginosum and Schoenoplectus mucronatus) are being investigated for their suitability in subsurface flow wetlands. The pilot scale Oxley Wetland, Brisbane, consists of 4 cells with different sized gravel (5 mm and 20 mm). The project aims to investigate nutrient removal rates and removal efficiency; nutrient storage in plant biomass; effect of cropping on plant regrowth, and the effect of gravel size on both water treatment and plant growth. Average daily mass removal rates ranged from 7.3 Kgha-1d-1 NH4-N in Cell D to 4.6 Kgha-1d-1 in Cell C i.e. 37%-22% removal efficiency respectively; 5.2 Kgha-1d-1 NOx-N in Cell C to 1.3 Kgha-1d-1 in Cell A (i.e. 75%-22% removal efficiency) and 0.8 Kgha-1d-1 PO4-P in Cell A to 0.1 Kgha-1d-1 in Cell C (i.e. 10%-1% removal efficiency). Cell A was the youngest wetland with new 5 mm gravel. Plant biomass was highest for Baumea and Carex. Gravel size does not appear to have affected biomass and recovery following cropping. Carex consistently had the highest harvested above ground biomass with high re-growth following cropping. Cropping appears to have retarded growth of the other three species with Schoenoplectus consistently having slowest regrowth. Plant biomass and nutrient storage was highest in Cell A and accounted for 11% of nitrogen removal and 3% of phosphorus removal.
Preliminary investigation of the potential of four tropical emergent macrophytes for treatment of pre-treated pulp and papermill wastewater in Kenya
Authors: Abira M.A. , Ngirigacha H.W. , van Bruggen J.J.A.
Published: May 2018

The potential of four aquatic macrophytes for treatment of wastewater in constructed wetlands was investigated in bucket mesocosms at Pan African Paper Mills (E.A) Limited. The buckets were operated as semi-continuous batch reactors with reversed vertical flow for a period of 3 months. Four treatments were applied involving two hydraulic retention times (HRT) and two wastewater concentrations. Plants appeared healthier and greener in treatments at HRT5 than at HRT10. Cyperus immensus and Typha domingensis had higher biomass gain compared to the other two species. Plant nitrogen and phosphorus content, based on dry weight, was lower at the end of the experiment than at the beginning in all treatments for all species.

The removal efficiency achieved for COD ranged from 10 to 55% for planted buckets at HRT5 and 15 to 65% at HRT10 for similar buckets. The mean percentage COD removal in unplanted buckets was significantly lower than in planted ones. TSS removal efficiency ranged from 44-86%. Buckets planted with Typha exhibited the highest removal efficiency in all treatments. Those at HRT5 showed significantly higher removal efficiencies than those at HRT10 for all species. The results indicate that the plants are suitable for use in constructed wetlands for treatment of the wastewater provided the appropriate treatment is applied.
Adhesion of Escherichia coli, Citrobacter freundii and Klebsiella pneumoniae isolated from milk: consequence on the efficiency of sanitation procedures
Authors: Faille C. , Fontaine F. , Lelièvre C. , Bénézech T.
Published: May 2018

The effects of adhesion and of biofilm development on the efficiency of cleaning and disinfection procedures were investigated on three strains belonging to the E. coli, C. freundii and K. pneumoniae species, which were able to raise more or less complex biofilms. Resistance to a rinsing procedure was strain dependent but not related to the biofilm structure: E. coli was poorly adherent although embedded in an organic matrix. Conversely, a similar increase in the heat- and disinfectant-resistance was observed, regardless of the complexity of the biofilm (more or less significant organic matrix). These results suggested the essential role of the bacterial physiological state in resistance to sanitation procedures.
Hydrocarbon removal in an experimental gravel bed constructed wetland
Authors: Omari K. , Revitt M. , Shutes B. , Garelick H.
Published: May 2018

Two outdoor subsurface flow beds (control and experimental, 10 m × 1 m) were filled with a substrate of pea gravel (3-6 mm) to a depth of 60 cm. The experimental bed or small-scale constructed wetland was originally planted with Typha seedlings at a density of 7.5 plants/m2. Both beds (experimental and control) were treated with the same aqueous concentrations of diesel oil under identical dosing conditions. The average overall hydrocarbon removal efficiencies at the three monitored depths (top, middle and bottom) in the subsurface systems were 80.1 ± 9.8%, 78.0 ± 9.1% and 71.6 ± 10.0% in the experimental bed and 72.3 ± 11.9%, 69.1 ± 10.3% and 63.4 ± 9.4% in the control bed. The differences in the hydrocarbon removal efficiencies between corresponding months in 1999 and 2000 were statistically analysed and are generally not significant. The individual hydrocarbon removal efficiencies exceeded 60% in the top sections of both beds except for C-11 and C-25 with C-23 and C-26 also reduced in the control bed. Overall differences in the removal efficiencies of the planted and the unplanted beds as well as at different depths in both systems, indicate that Typha related removal processes complementing adsorption onto the gravel substrate are occurring.
Transport and transformation of de-icing urea from airport runways in a constructed wetland system
Authors: Thorén A.-K. , Legrand C. , Herrmann J.
Published: May 2018

Urea, NH2-CO-NH2, is used as a de-icing agent at Kalmar Airport, southeast Sweden. During 1998-2001, urea contributed on average 30% of the yearly nitrogen (N) transport of 41,000 kg via Törnebybäcken stream to the coastal zone of the Baltic Sea. In order to reduce stream transport of N from airport, agricultural and other diffuse sources, a wetland was constructed in 1996. Annual wetland retention of total-N varied in the range of 2,500-8,100 kg (6-36% of influent) during 1998-2001, according to mass balances calculated from monthly sampling. During airport de-icing, January-March 2001, 660 kg urea-N out of 2,600 kg applied urea-N reached the wetland according to daily sampling. This indicated that 75% of the urea was transformed before entering the wetland. Urea was found to be only a minor part (8%) of total-N in the wetland influent. Calculations of cumulative urea-N loads at the wetland inlet and outlet respectively, showed a significant urea transformation during February 2001 with approximately 40% of the incoming urea-N being transformed in the wetland system. These results show that significant amounts of urea can be transformed in a wetland system at air temperatures around 0°C.
Behaviour of metals associated with sediments in a wetland based system for road runoff control
Authors: Pontier H. , Williams J.B. , May E.
Published: May 2018

Innovative road runoff control systems, which combined flow-balancing basins with constructed wetlands, on the recently constructed Newbury Bypass were monitored over 18 months. The results have shown that despite variability in the pollutant loadings, the system generally promoted removal and accumulation of sediments and associated metals. The correlation structure of the data set indicated possible removal processes, and enabled interpretation of the behaviour of these pollutants. Correlation of metal content in settling solids between successive upstream and downstream parts of the wetland gave indications of potential regression models for metal behaviour, despite variability in flows, pollutant loadings, and other conditions. Other findings suggested that the combined flow balancing and pollutant removal functions could be improved by avoiding transport of sediments, fluctuations in conditions and by the promotion of processes favouring metal retention by bed deposits.
Removal and speciation of heavy metals along the treatment path of wastewater in subsurface-flow constructed wetlands
Authors: Lim P.E. , Mak K.Y. , Mohamed N. , Noor A. Md.
Published: May 2018

This study was conducted to: (1) evaluate the performance of constructed wetlands in removing Zn, Pb and Cd, respectively, and Zn, Pb, Cd and Cu in combination and (2) investigate the speciation patterns of the dissolved metals differentiated according to their detectability by anodic stripping voltammetry (ASV) and their lability towards Chelex resin along the treatment path of metal-containing wastewater in horizontal subsurface-flow constructed wetlands. Four laboratory scale wetland units planted with cattails (Typha latifolia) were operated outdoors for six months. Three of the units were, respectively, fed with primary-treated domestic wastewater spiked with Zn(II), Pb(II) and Cd(II) whilst the fourth was spiked with a combination of Zn(II), Pb(II), Cd(II) and Cu(II). The results demonstrate that a metal removal efficiency of over 99% was achievable for wetland units treating the metals singly or in combination provided the sorption capacity of the media was not exceeded. When treating the metals in combination, an antagonistic effect, more significantly for Pb and Cd, on the sorptive metal uptake by media was observed. Based on the metal speciation patterns, the wetland system seemed to be capable of maintaining the ASV-labile metal species at relatively low level (<10%) before media exhaustion.
Ecological economics for water policy and management: a need for major shifts in thinking
Authors: Söderbaum P.
Published: May 2018

Economics cannot be separated from values and ideology. Attempts to influence the political agenda by raising the fundamental issues of paradigm, ideology and institutions in various arenas are crucial. It is recognized that problems related to water quality and availability are linked with all kinds of activities and sectors in society.
Microbial community evaluation of anaerobic granular sludge from a hybrid reactor treating pentachlorophenol by using fluorescence in situ hybridization
Authors: Montenegro M.A.P. , Araujo J.C. , Vazoller R.F.
Published: May 2018

We used in situ hybridization with fluorescently labeled rRNA-targeted oligonucleotide probes concurrently with microscopic examinations and methane measurements to characterize the microbial community of an anaerobic hybrid reactor treating pentachlorophenol (PCP) with a mixture of fatty acids (propionic, butyric, acetic and lactic) and methanol. Archaeal cells detected with probe ARC915 prevailed in anaerobic granular sludge without and with the addition of PCP in a range of 2.0 to 21.0 mg/L to the reactor. This group accounted for 81 and 90% of the DAPI-stained cells before and after the addition of 21 mg/L of PCP, respectively. In these conditions, cells detected with the Methanosarcinales specific probe (MSMX860) were the only methanogenic Archaea found and accounted for 59 to 87.6% of the DAPI-stained cells. No cells were detected by the Methanomicrobiales (MG1200), Methanobacteriaceae (MB1174) and Methanococcaceae (MC1109) specific probes. Bacterial cells detected with probe EUB338 were found in very low numbers, which ranged from 5.7 to 1.0% of the DAPI-stained cells. This finding agrees with the scanning electron microscope examinations, in which cells morphologically resembling Methanosaeta and Methanosarcina were predominantly observed in the granular sludge. Results contributed to the investigation of the importance of the methanogens during PCP degradation.
Virtual waterless manufacturing: zero intake, zero emission
Authors: Sharma A.
Published: May 2018

Innovative application of a systematic approach to reduce freshwater intake and achieve zero emissions could help in reducing the adverse impact of industrial activity on world water resources. Cleantech is a strategic enviro-management technique to reduce the generation of pollutants in a process at source, through minor process modification, material substitution, improved manufacturing practices or low cost treatment.
Modeling of the Acid Orange 7 anaerobic biodegradation
Authors: Méndez-Paz D. , Omil F. , Lema J.M.
Published: May 2018

It was found that 1-amino-2-naphthol, an intermediate generated during the anaerobic degradation of Acid Orange 7, is a redox mediator which plays a significant role in the transport of electrons to the dye, thus giving to the whole process an autocatalytic nature. Evidences of the autocatalytic behaviour were observed in experimental data previously obtained under batch and fed-batch conditions. In this paper, a kinetic model considering all these factors is proposed and validated. In batch assays, this model agrees satisfactorily with the experimental data. In the case of fed-batch assays, the autocatalytic model only can be applied satisfactorily after the first feeding, since the degradation of Acid Orange 7 after the second and third feedings followed a first-order kinetic. This fact can be explained due to the presence of the redox mediator previously generated during the reactions that took place after the first feeding.
Water participation for poverty alleviation - the case of Meseta Purépecha, Mexico
Authors: Escamilla M. , Kurtycz A. , van der Helm R.
Published: May 2018

The construction of small water reservoirs has been used in an effort to alleviate poverty in the Meseta Purépecha region in Mexico. The programme's rationale can be characterised as incentive-based participation, using both local employment and shared risks concepts. The programme so far has been a relative success. However, in the light of poverty alleviation questions have to be raised about the isolated nature of the programme as well as the role of the incentives used.