bluuebunny/crossref_metadata_2025 huggingface dataset:
On dimensioning the base of a traditional retaining wall
Authors: Butterfield R.
Published: May 2012

When conventional retaining walls fail, they usually do so either by being transported bodily within a landslide of the material they are retaining or by a local failure of their foundation, particularly if it is a rigid base at shallow depth. The purpose of this letter is to present a rational way of determining the optimum geometry of such a base – for a specific wall height and relevant soil parameters – using a three-dimensional interaction diagram for a rigid base buried at shallow depth. The optimisation procedure required is novel because the loads acting on the base are a function of their dimensions. Furthermore, if the soil strength is scaled down, as in a ‘limit state’ design, the lateral load on the wall is increased whilst the load capacity of the base is decreased. The analysis presented provides a simple means of exploring the consequences of complex interactions of this kind. The methodology developed is independent of the method by which the resultant base loads (V, H, M/B) are decided and the analytical form of the failure locus.
Sea sick? Setting targets to assess ocean health and ecosystem services
Authors: Samhouri Jameal F. , Lester Sarah E. , Selig Elizabeth R. , Halpern Benjamin S. , Fogarty Michael J. , Longo Catherine , McLeod Karen L.
Published: May 2012

The benefits provided by a healthy ocean are receiving increasing attention in policy and management spheres. A fundamental challenge with assessing ocean health and ecosystem services is that we lack a scientific framework for expressing ecosystem conditions quantitatively in relation to management goals. Here we outline and operationalize a conceptual framework for identifying meaningful reference points and quantifying the current ecosystem state relative to them. The framework requires clear articulation of management goals and is built on a review of current scientific understanding and assessment of data availability. It develops a structured approach for choosing among three classes of reference points, including: (1) functional relationships that establish the ocean state that can be produced and sustained under different environmental conditions, (2) time series approaches that compare current to previous capacities to obtain a particular ocean state in a specific location, and (3) spatial reference points that compare current capacities to achieve a desired ocean state across regional (or, if necessary, global) scales. We illustrate this general framework through the lens of ocean health defined in terms of a coupled social‐ecological system, with examples from fisheries, marine livelihoods, and water quality in the USA. Assessment of ocean health and ecosystem services can be significantly influenced by the choice of indicators used to track changes in a management goal, the type of reference point selected, and how one measures the distance of the current state from the reference point. This framework provides flexible, standardized methods for evaluating ocean health and ecosystem services that can advance important components of ecosystem‐based management, including marine spatial planning, ecosystem service valuation, and integrated ecosystem assessments.
Edaphic sorting drives arbuscular mycorrhizal fungal community assembly in a serpentine/non‐serpentine mosaic landscape
Authors: Schechter S. P. , Bruns T. D.
Published: May 2012

Serpentine soil generates distinct plant assemblages, but it is not known how this edaphically extreme environment affects arbuscular mycorrhizal fungal (AMF) assembly or how this may contribute to plant adaptation to serpentine. Our previous studies showed that serpentine and non‐serpentine adapted ecotypes of Collinisa sparsiflora associates with distinct AMF assemblages, but a common garden experiment showed that this pattern was not due to host‐fungal preference. We hypothesized that the observed differences in AMF associated with C. sparsiflora ecotypes was driven by edaphically defined AMF assemblages. To test this idea we employed a broader sampling of the plant community from five serpentine and five non‐serpentine sites in close proximity (50–150 m between sites) and identified AMF and plant species associated with root samples by amplifying rDNA and cpDNA respectively, cloning, and sequencing. We compared AMF and plant assemblages, and measured the relative contribution of distance, plant and soil factors on AMF assembly. Analyses clearly showed that serpentine and non‐serpentine AMF assemblages are distinct—with the complete absence of the non‐serpentine dominant AMF taxon on serpentine. These results show strong edaphic sorting of serpentine tolerant/adapted AMF taxa in serpentine soil and indicate a strong ecological correlation between AMF and plant tolerance to serpentine soil.
Ammonium nitrogen removal from anaerobically digested effluent of swine wastewater using local sand
Authors: Zheng D. , Deng L.W. , Liu N.N. , Yang H. , Liu Y.
Published: May 2012

A type of sand selected in Sichuan, China was identified with high adsorption capacity to ammonium nitrogen. The effects of contact time, initial ammonium concentration and particle size on the sand for removing ammonium from digested effluent of swine wastewater were investigated using a static shaker experiment. Results showed that the optimum contact time for sand to adsorb ammonium was 150 min. As initial ammonium concentration increased, the removal capacity of the sand increased, but the removal efficiency decreased. The adsorbed ammonium increased as the particle size decreased. At ammonium concentrations ranging from 27 0 to 553 mg L-1, the maximum ammonium adsorption capacity of the sand was approximately 0 77 mg g-1 according to the Langmuir equation. Based on these findings, the use of this local sand as an adsorption media for ammonium nitrogen removal from digested effluent of swine wastewater is feasible.
Reality or myth: “Advanced wastewater treatment technologies cannot be cost competitive with conventional treatment processes”
Authors: Ahmadi Motlagh Ali R. , Lacy Stephen , Arora Madan , Ross Jim , Misenhimer Jeff
Published: May 2012

With shortage of water becoming a major concern in many areas, use of recycled water is a necessity for a growing number of municipalities. This paper describes a case study in which two alternatives were considered for upgrading an existing wastewater treatment plant with the goal of producing recycled water. The first alternative consisted of conventional secondary and tertiary unit processes while the second alternative included the advanced treatment technology of membrane bioreactor (MBR). Also, two alternatives were evaluated for disinfection of recycled water; chlorine gas and UV system. The more advanced treatment technologies (MBR + UV), which produce the higher quality recycled water, resulted in higher cost. The paper discusses the design and project execution approaches as how the more expensive advanced treatment processes were made cost competitive with the conventional treatment processes.
Monitoring Ecotoxicity and Nutrients Load in the Reverse Osmosis Concentrate from Bundamba Advanced Water Treatment Plant, Queensland Australia
Authors: Vargas Carlos , Buchanan Alison
Published: May 2012

Bundamba Advanced Water Treatment Plant is one of three plants that contribute purified recycled water in the Western Corridor Recycled Water Scheme. The plant is required to treat reverse osmosis concentrate and to monitor nutrients and metals concentration prior to release into the Brisbane River. In addition, whole effluent toxicity test in the ROC is done annually and the receiving water is monitoring in the discharge outfall for nutrients and metals monthly. Results of these monitoring programs have shown full compliance with toxicity limits imposed by the regulator, and no increase in concentration of metals such as iron, nickel and copper or nutrients such as phosphorus and ammonia in the near field of the discharge outfall in the Brisbane River have been detected. Contrary, data show that the Bundamba Advanced Water Treatment Plant has achieved nutrient reductions of phosphorus and nitrogen that would otherwise be release to the receiving water.
An optimal solution to achieve the energy neutral Waste Water Treatment Plant
Authors: Amiel Christophe , Nawawi-Lansade Delphine , Sorensen Kim
Published: May 2012

Many recent studies have shown processes or models to minimize the energy consumption on a municipal wastewater treatment plant (WWTP) in operation. Today the main drivers are the energy and CO2 reduction.

On existing plants, the potential success of achieving the Energy neutral WWTP depends on the effluent guarantees demanded and the eventual additional carbon sources on the digesters.

Veolia has now developed a tool to estimate the energy consumption and the CO2 impact to select the appropriate treatment lines (water and sludge) up front at the project stage.

The real challenge is to cover the needs of the plant without external carbon sources added to the digester. At the project stage, before the bid of the WWTP, due to time constraints only few comparisons can be performed to predict the energy consumption and CO2 impact and provide the best solution to reach to the energy neutral plant as electricity wise.

One conclusion of the study is that, the raw water characteristics and the effluent guarantee has a great impact on the possibilities to reach the target. Furthermore, working on reducing the power consumption and on increasing the biogas production for example by a continuous Thermal hydrolysis is a good way to go towards self sufficiency.
Towards energy self-sufficiency in wastewater treatment by optimized sludge treatment
Authors: Arnold M. E. , Merta E. S.
Published: May 2012

The role of sludge in renewable energy production and the final disposal of sludge are topical issues. The cost of sludge treatment account for a significant share of the total running costs of a WWTP. By increasing the efficiency of sludge treatment, significant savings can be achieved. Savings can be gained e.g. by more efficient energy utilisation of sludge, combined with optimised wastewater treatment processes. In addition to cost efficiency, environmental sustainability of the applied solutions is crucial. The energy balance and green house gas emissions can be used as tools to evaluate the sustainability of sludge treatment options.

This paper presents a case-based comparison of energy balances, green house gas emissions and costs of municipal wastewater sludge process chains based on anaerobic digestion or incineration. Information from existing plants was used for conducting the study. Several utilisation options were covered for biogas energy as well for energy from sludge incineration.

Based on the results, sludge incineration was the most expensive option of the studied scenarios, but justified if the heat generated can be fully utilised e.g. in district heating. Based on costs and energy balances as well as green house gas emissions it is most preferable in anaerobic digestion chains to feed the generated biogas to a gas engine to produce electricity and heat. Moreover, thermophilic anaerobic digestion can improve the overall economy of a WWTP provided that the biogas yield is sufficiently higher than in a mesophilic process. However increased odour is a risk in thermophilic digestion.

The study showed that the most energy efficient process modifications are always very case bound. However the tools developed in this study are generally applicable to waste water treatment plants for similar analyses.
Experience with the design and operation of sustainable wastewater treatment facilities for pollution control and water reuse in Morocco and Jordan
Authors: Young T. , Brinkley J. , Copithorn R. , Karam J. , Abu-Rayyan O.
Published: May 2012

Operating experience at municipal wastewater treatment plants (WWTPs) in Morocco was used to develop design criteria and operating procedures for the construction of two new WWTPs in Shobak and North Shouneh, Jordan to treat septage from small communities to water reuse standards. The WWTPs use an anaerobic/settling digestion tank, facultative lagoons, intermittent or recirculating sand filters, and reed beds to remove solids, carbon, nitrogen, and pathogens. The facilities are sustainable in that they minimize the use of complex mechanical and electrical equipment, do not require chemicals or high electrical demands, and produce beneficial products for the communities which include irrigation water, reeds, and dried biosolids that can be used as a soil amendment.
Mitigation of emerging pollutants by plants
Authors: Reinhold D. , Aryal N.
Published: May 2012

Low cost, sustainable technologies for addressing pollution of waters with trace concentrations of pharmaceuticals and personal care products (PPCPs) are needed. Plant-based ecosystems for wastewater treatment are low-cost, effective technologies with the potential to address PPCPs. This abstract presents recent research examining the phytoremediation of PPCPs in both aquatic and terrestrial systems and discusses potential implications of phytoremediation of PPCPs. Research indicates that duckweed plants can stimulate microbial degradation of ibuprofen, sorb and uptake fluoxetine, and indirectly affect the fate of triclosan. Additionally, research indicates that food crops phytoaccumulate antimicrobials present in biosolids. The implications of these processes include mitigation of ecotoxicological risk from antimicrobial contamination of surface waters and soils with minimal risk to humans from consumption of phytoaccumulated antimicrobials. Additionally, plants may serve as a long-term reservoir for PPCPs in the environment.
Pricing water for sustainable cost recovery: a study on China's water tariff reform
Authors: Wu H.
Published: May 2012

The emerging water scarcity in China has become a major threat to its sustainable development. In view of the insufficiency of supply-augmentation methods, China adopted water pricing as a demand management approach to restore the balance between water supply and demand. Extensive policies have been developed since the 1990s, aiming to achieve cost recovery, water conservation, and social equity. This paper discusses to what extent cost recovery has been achieved in China's water tariff reform. Following a literature review on water pricing, the concept of sustainable cost recovery is advanced, requiring that both the financial sustainability of water utilities and the sustainability of water resources should be considered. A case study in Chengdu provides an insight into water tariff reform at the local level. The findings indicate that despite much progress in raising the water tariff, the current tariff nevertheless is insufficient to improve further the urban water sector. The paper concludes with recommendations for enhancing cost recovery and improving the effectiveness of the water tariff reforms.
Demonstration of Anaerobic Digestion of Black Water for Methane Capture and Use in an Office Building
Authors: Gallagher Neal , Sharvelle Sybil
Published: May 2012

Waste source separation including separate treatment of graywater and black water (BW) is gaining popularity as a sustainable integrated water management practice. Along that line, feasibility of anaerobic digestion of BW (toilet water only) from a building occupied with laboratory and office space was investigated using a pilot scale (114 L) upflow anaerobic sludge blanket (UASB) operated at an average temperature of 28oC. The goal of the reactor was to achieve removal of organics while also generating methane gas for use as a source of energy. Reactor operational OLR varied between 0.21-0.39 kg COD m−3 d−1 and HRT varied from 2.6-4.0 days. Substantial removal of COD (72%), TSS and VSS (95%), and indicator organisms (1.4 log E. coli & 1.1 log fecal coliforms) was achieved over the study period. Methane biogas (61% CH4) produced during digestion provided potential as a source of renewable energy generated through processing the BW.
Gasification as an optimum alternative for the sludge management
Authors: Peregrina C. , Audic J. M. , Dauthuille P.
Published: May 2012

Assimilate sludge to a fuel is not new. Sludge incineration and Combined Heat and Power (CHP) engines powered with sludge-derived anaerobic digestion gas (ADG) are operations widely used. However, they have a room of improvement to reach simultaneously a positive net power generation and a significant level of waste reduction and stabilization. Gasification has been used in other realms for the conversion of any negative-value carbon-based materials, that would otherwise be disposed as waste, to a gaseous product with a usable heating value for power generation . In fact, the produced gas, the so-called synthetic gas (or syngas), could be suitable for combined heat and power motors. Within this framework gasification could be seen as an optimum alternative for the sludge management that would allow the highest waste reduction yield (similar to incineration) with a high power generation.

Although gasification remains a promising route for sewage sludge valorisation, campaigns of measurements show that is not a simple operation and there are still several technical issues to resolve before that gasification was considered to be fully applied in the sludge management. Fluidised bed was chosen by certain technology developers because it is an easy and well known process for solid combustion, and very suitable for non-conventional fuels. However, our tests showed a poor reliable process for gasification of sludge giving a low quality gas production with a significant amount of tars to be treated. The cleaning system that was proposed shows a very limited removal performance and difficulties to be operated.

Within the sizes of more common WWTP, an alternative solution to the fluidised bed reactor would be the downdraft bed gasifier that was also audited. Most relevant data of this audit suggest that the technology is more adapted to the idea of sludge gasification presented in the beginning of this paper where a maximum waste reduction is achieved with a great electricity generation thanks to the use of a “good” quality syngas in a CHP engine. Audit show also that there is still some work to do in order to push sludge gasification to a more industrial stage.

Regardless what solution would be preferred, the resulting gasification system would involve a more complex scenario compared to Anaerobic Digestion and Incineration, characterised by a thermal dryer and gasifier with a complete gas cleaning system. At the end, economics, reliability and mass and energy yields should be carefully analysed in order to set the place that gasification would play in the forthcoming processing of sewage sludge.
Analysis of Options to Increase Supply for the Virginia Pipeline Irrigation Scheme Utilising Multi-Criteria Decision Analysis
Authors: Hyde K.M. , May R. , Leak M.
Published: May 2012

Many decisions in the water industry, particularly related to large infrastructure projects, involve numerous discrete alternatives and criteria and are often characterised by uncertain consequences, complex interactions, and the participation of multiple stakeholders with conflicting interests. Multi-criteria decision analysis (MCDA) is a methodology that can be used to aid decision making when discrete alternatives are involved, as it facilitates stakeholder participation and collaborative decision making and does not require the assignment of monetary values to environmental or social criteria. This paper demonstrates the application of MCDA to a real case study in the water industry in South Australia. The case study involved undertaking an analysis of options for ensuring sufficient supply of treated wastewater to an expanded horticultural irrigation scheme. Participants from the water utility, United Water, and the water authority, SA Water, were involved in the decision analysis process through two workshops. Eleven options were assessed using fourteen criteria. The ranking of options utilised a reliability approach which took into account the participants preferences (i.e. criteria weights) and the uncertainty in the values assigned to the criteria.
Degradation of dyes by UV/O3/H2O2 and electrooxidation techniques
Authors: Bhaskar Raju G. , Keerthi Ramachandra , Latha S.S. , Prabhakar S.
Published: May 2012

The soil and aquatic environment around the tannery and textile industrial clusters were severely affected over the years. Various technological options are being evaluated to address the treatment of these effluents. The efficacy of cleaner technologies such as advanced oxidation and electro oxidation for the mineralization of four different dyes namely CI Acid black 66, CI Acid brown 16, CI Acid brown 75 and CI Acid brown 85 was studied. The mineralization of dyes is almost complete by advanced oxidation involving UV/O3/H2O2, whereas it is only around 60% by electro oxidation. Conversely, the electrooxidation consumes 10-20 kWh/m3 whereas the photo oxidation requires 2500 kWh/m3. Hence electrooxidation followed by photo oxidation could be economical to treat the effluent solutions containing wide range of organics.
Options for an optimised Utilisation of Digester Gas at Sewage Plants
Authors: Kolisch Gerd , Schirmer Gitta , Salomon Dirk
Published: May 2012

Digester gas produced at sewage plants is usually used in combined heat and power plants (CHPP) or boilers and only a minor portion is wasted in gas torches. In combination with an optimised power consumption of the sewage plant and the implementation of a co-digestion even an energy self-sufficiency of sewage plants is possible (Kolisch et al., 2009). Selling of the digester gas to external consumers or an upgrade to natural gas quality with subsequent injection into the natural gas grid might be alternatives to the conventional use. The mentioned options were investigated in consideration of the current energy consumption of sewage plants. The results show that the internal power production by a CHPP is currently most economic. However, the implementation of a local energy network in order to to deliver an energy surplus to external users can be feasible.
Sewage sludge as bio fuel
Authors: Baten H. H. M. , Peeters R. J. E. J. , Roeleveld P. J. , Zoutberg G. R.
Published: May 2012

Sewage sludge as bio fuel efficiently uses the amount of energy present inside the sludge itself. The sludge is digested, dewatered and dried to a sludge granulate. The sludge is pre treated by thermal hydrolysis to maximize the sludge degradation, the dewaterability and biogas generation. The strong sludge reduction results in a strong reduction (2 to 4 times) of the amount of water to be evaporated and the energy needed in the drying unit. The amount of electricity and heat needed for all the processes can be generated with the amount of biogas produced during sludge digestion. The wastewater treatment plant is hereby changed from energy consuming to an energy producing plant making use of sludge granulates as bio fuel. The concentrated wastewater (nutrients, micro pollutants) generated during dewatering of the digested sludge is less than 1 % of the total wastewater flow treated in the main process. The concentrated wastewater stream can be efficiently treated in compact reactors, with the possibility to recover and reuse resources as phosphate.The technical and economic feasibility of this concept is proven in a desk study for around 4,300 tons dry matter of sludge.
Optimization of WWTP aeration process upgrades for energy efficiency
Authors: Bell K. Y. , Abel S.
Published: May 2012

The volatility of energy prices, desire to improve sustainability, recently proposed legislation, and energy-efficiency project funding have created big opportunities to improve energy and operation efficiency at most water and wastewater facilities. One mechanism of developing these opportunities is through energy management planning. Focusing on wastewater treatment, the majority of electrical energy demand is required for the delivery of air to provide oxygen for biological treatment of waste streams and mixing to suspend solids within process units. Aeration processes can account for 60 percent or more of the overall power consumption at a wastewater treatment plant. Consequently, the recent introduction of direct-drive, high-speed, turbo blowers to the wastewater market has been of great interest with respect to potential energy savings, as well as other ancillary benefits.

Given the significant power consumption required by aeration systems at wastewater treatment facilities, demonstration investigations have been conducted to identify the magnitude of energy savings that wastewater treatment facilities could expect. These studies have shown that energy savings in excess of 35 percent can easily be achieved by replacing existing conventional blower technology with direct-drive turbo blowers. Even greater energy savings are anticipated if other process upgrades, such as automatic dissolved oxygen control, is implemented. This paper provides background information on turbo-blower technology and specific findings from demonstration studies in the United States (U.S.).
Sludge production based on organic matter and nitrogen removal performances
Authors: Serón N. , Puig S. , Meijer S.C.F. , Balaguer M.D. , Colprim J.
Published: May 2012

Excess biomass produced during the biological treatment of wastewater requires costly disposal. As environmental and legislative constraints increase, there is considerable impetus for reducing the sludge production. Nowadays, several strategies for minimizing it production are applied but high costs still limit their application in full-scale wastewater treatment plants (WWTPs). On the other hand, biological nutrient removal (BNR) process may have an impact on the sludge production. This paper deals with the effect on the organic matter and nitrogen performances on the sludge production treating urban wastewater. The results demonstrated that the sewage sludge production was reduced between 50 to 60% (0.38 to 0.16 kg VSS·kg−1 COD) while improving the nitrogen removal efficiency from 33% to 79%. Therefore, an efficient way to minimize the sludge production, it is by operating the WWTP in optimal conditions for nutrient removal.
TOC based control of anaerobic reactor treating wastewater from a fruit juice packaging factory
Authors: Warmenhoven Jan-Willem , Spanjers Henri
Published: May 2012

This paper describes the application of TOC as a control variable for a full-scale expanded granular sludge bed (EGSB) reactor treating wastewater from a fruit juice packaging factory. The carbohydrate-rich wastewater shows high variations in both flow and concentration. Treatment efficiency was too low before the implementation of the TOC based control, while the design loading rate could not be achieved. The poor performance was associated with large fluctuations of the wastewater load in combination with several other factors, including: too small an equalisation tank, insufficient mixing in the equalisation tank and too course a control scheme (based on flow only), which failed to deliver a smooth enough organic loading to the EGSB reactor to secure stable performance. A control strategy based on inline wastewater TOC was developed and implemented in order to cope with the large fluctuations of the wastewater load. This paper describes the TOC based control strategy and the treatment performance obtained after its implementation. Combining TOC based control with better operation of the equalisation tank is shown to have improved the performance of the EGSB reactor. Even with a relatively small equalisation tank in combination with a fluctuating load the control strategy enables stable operation of the reactor. Among other improvements COD removal has increased from 50% to 82% despite a load increase from 1700 to 2100 kgCOD/d, equivalent to an organic loading rate of 11.3 to 14 kg/m3d.
Degradation of dyes by UV/O3/H2O2 and electrooxidation techniques
Authors: Bhaskar Raju G. , Keerthi Ramachandra , Latha S. S. , Prabhakar S.
Published: May 2012

The soil and aquatic environment around the tannery and textile industrial clusters were severely affected over the years. Various technological options are being evaluated to address the treatment of these effluents. The efficacy of cleaner technologies such as advanced oxidation and electro oxidation for the mineralization of four different dyes namely CI Acid black 66, CI Acid brown 16, CI Acid brown 75 and CI Acid brown 85 was studied. The mineralization of dyes is almost complete by advanced oxidation involving UV/O3/H2O2, whereas it is only around 60% by electro oxidation. Conversely, the electrooxidation consumes 10-20 kWh/m3 whereas the photo oxidation requires 2500 kWh/m3. Hence electrooxidation followed by photo oxidation could be economical to treat the effluent solutions containing wide range of organics.
Adapting to socioeconomic, operational and environmental challenges of dairy farm effluent purification in Uruguay through the use of surface flow constructed wetlands
Authors: Avellán C. T. , Rousseau D. P. L. , Lens P. N. L.
Published: May 2012

The 3600 dairy farms in south-western Uruguay, with about 750,000 cows in 2008, play an important economic role. Only about 200 of the farms have a sewage treatment system, since no legal regulations for the disposal of effluents exist, the cost of construction is high and neither direct benefits nor incentives are given. The current systems are mainly lagoons that often lack maintenance, resulting in the eutrophication of rivers. One of our goals was to implement a low cost, robust surface flow constructed wetland using native plants, in order to test the acceptance and willingness to pay of the farmers and to see if the effluent water quality met the national standards even if operating under the lack of maintenance. Within a small catchment, 6 farmers attended a seminar series on water(shed) quality, importance of wetlands and sewage treatment options, explaining the functioning of constructed wetlands and the costs of construction. One of the farmers decided to construct a double lagoon system followed by a surface flow CW using Scirpus americanus. However, construction of the ponds occurred by the farmer himself resulting in inadequate dimensioning. The exceptionally dry summer 2008/2009 also delayed planting but by now plants have established themselves and other emergent macrophytes have followed. So far visual water quality as well as biodiversity has improved. Furthermore, farmers and technicians have become interested in the use of CW and other implementations are envisioned. Also, the legislation on dairy farm effluent is about to change which will boost the necessity for all kinds of sewage systems.
Constructed wetlands are suitable to treat wastewater from Italian cheese productions
Authors: Mantovi P. , Piccinini S. , Marmiroli M. , Marmiroli N.
Published: May 2012

Two horizontal sub-surface flow constructed wetlands (h-SSF CW) were set-up and controlled to determine their efficiency in reducing the polluting load of wastewater from Parmigiano-Reggiano and Grana Padano cheese production. Besides, comparisons were made of biomass production and nutrient uptake of cattail (Typha latifolia) reaped at different stages. The average concentrations of the influent waters were about 250-320 mg/l TSS, 940-1060 mgO2/l COD, 600-700 mgO2/l BOD5, 35 mg/l TKN, 8-13 mg/l total P, 60-170 mg/l animal and vegetable fats and oils. The removal of COD, BOD5 and animal/vegetable fats and oils were above 95%, while resulted 60-65% for nitrogen and very different for phosphorus, varying from 75% in one CW to 20% in the other. Results demonstrated that h-SSF CW could help to solve the problem of the cost-effective disposal of cheese dairy wastewater, being a suitable treatment for reducing pollutants to values in conformance with Italian standards for discharge to a watercourse. Typha latifolia showed considerable biomass yield, though the N and P uptake was quite low if compared with nutrients inputs in CW (about 10%). There is the possibility to maximise biomass yield and nutrient uptake reaping cattail twice a year instead of only one time.
Use of engineered wetlands for onsite treatment of wastewater by the local communities: Experiences from Tanzania
Authors: Njau K. N. , Mwegoha W. J. S. , Kimwaga R. J. , Katima J. H. Y.
Published: May 2012

Since its inception about 10 years ago, Constructed Wetlands (CWs) technology has been well received in Tanzania due to a wide range of functions. CWs are used to treat wastewater from municipal systems, pulp and paper industries, prisons, schools and colleges. Among the recipients of CWs are the Moshi Urban Water and Sewerage Authority (MUWSA) for polishing Waste Stabilization Ponds effluents, Kibo Paper Mills for treating industrial effluents, Shinyanga, Malya and Bariadi Prison and Kleruu Teachers College and Ruaha High School for Treatment of domestic wastewater. All these systems are Horizontal Sub-Surface Flow Constructed Wetlands. This paper reports on results of a survey of the six (6) mentioned operating CW systems, focusing on the existing situation and the observed operation and maintenance challenges and needs. The survey was carried by visiting the CWs and sampling for determination of BOD5, COD, PO42-, NO3-N, and NH3-N. Results from the survey and laboratory analyses in three of these CWs indicated lack of general and site-specific operation and maintenance guidelines, which seriously affect life of these systems, aesthetics and performance of pollutant removal. This is evidenced by failure of these systems to meet local and international permissible discharge limits to the receiving water bodies.
A review of zero discharge wastewater treatment systems using reed willow bed combinations in Ireland
Authors: O'Hogain S. , McCarton L. , Reid A. , Turner J. , Fox S.
Published: May 2012

The concept of a reed willow bed combination has the potential to achieve a zero discharge wastewater treatment system. This paper will present results from a two year study to monitor the performance of a reed willow bed facility at Lynches Lane, Co. Dublin, Ireland. Outline design specifications for the facility will be presented. Monitoring results for a two year period including influent and effluent parameters, rainfall, potential evapotranspiration, and soil classification will be presented and discussed. During the two year monitoring period the system achieved a zero discharge. This paper will discuss the potential widespread application of similar systems in Ireland. This is in the context of a recent EU judgment which declared that Ireland has failed to fulfill its obligations regarding domestic wastewaters disposed of through individual waste water treatment systems. The development of an appropriate zero discharge wastewater facility has the potential to address this source of environmental pollution in Ireland. This paper will discuss the sizing and operation of such systems specific to the climate and soil conditions based on current knowledge and experience. Areas for further studies will be discussed.
Dražovice reed beds and stabilisation pond wastewater treatment system: long-term operation and monitoring results
Authors: Rozkošný M. , Sedláček P. , Sova J. , Funková R.
Published: May 2012

The aim of the paper is to present results of the ten years long monitoring of the treatment processes, efficiency and operation of a wastewater treatment plant combined mechanical pre-treatment, horizontal sub-surface flow reed beds and stabilisation pond as a final purification equipment. The treatment system was built in the Dražovice village (the Czech Republic, South Moravia Region) for 800 population equivalent (P.E.) in 1999. The constructed wetlands with horizontal sub-surface continual flow reed beds, as a main biological step of wastewater treatment, has been built and operated in the Czech Republic since 1990. In case of sources over 500 P.E., there is the legislative requirement for ammonia nitrogen sufficient removal in the Czech Republic. The monitored system represents a category of sources between 500 and 2000 P.E. with the higher treatment efficiency requirements. The plant has been monitored in detail since the start of operation in 1999. A detailed monitoring programme includes: wastewater flow measurement, water temperature and oxygen regime measurement, organic and nutrient pollution removal rate assessment, hydraulic characteristics of the reed bedś filtration medium. Results of the survey include treatment efficiency calculation, hydraulic and mass load assessment. The differences in the achieved efficiency are compared between vegetation and non-vegetation periods.
Potential of hybrid constructed wetland system in treating milking parlor wastewater under cold climatic conditions in northern Hokkaido, Japan
Authors: Sharma P. K. , Inoue T. , Kato K. , Ietsugu H. , Tomita K. , Nagasawa T.
Published: May 2012

A real scale hybrid constructed wetland (CW) system (656 m2), with a configuration of VFA-VFB-HF beds constructed in series is operating since November 2006 in northern Hokkaido, Japan. The system was experimented to assess its capability in purifying 4.5 m3d−1 of high strength milking parlor wastewater under colder climate. Annual mean air temperature at site was recorded as 6.4 oC (extremes vary as -22.8 oC at lowest and 30.6 oC at highest). From the monthly sampling from November 2006 to January 2010, average loading and removal rates of TSS, CODcr, BOD5, TN and TP were 5.4 g m−2 d−1 (98%), 30.3 g m−2 d−1 (88%), 11.5 g m 2 d−1 (89%), 1.2 g m−2 d−1 (76.4%) and 0.2 g m−2 d−1 (76%). System did not stop for a single day, efficiently worked even during snow covered periods and was tolerant to the load fluctuations.
Modelling Chaos? Sanitation Options; Support and Communication Tool
Authors: Castellano D. , de Bruijne G. , Maessen S. , Mels A.
Published: May 2012

The selection of suitable sanitation options is a complex issue. There are many factors that influence the performance of each system. Sanitation suitable for use in low-income housing areas in developing countries is normally based on a combination of options specific to the local context. That makes it really difficult to develop an effective tool for decision-making. To date, decision support tools have failed to make a long-term impact on the choice for sanitation services in rural as well as urban and peri-urban settlements in developing countries. Most relate the choice of a sanitation option to one element (i.e. septic tank or pit latrine) rather than considering the sanitation system as a whole. Some lack transparency or are guided by personal choices and assumptions, which can include as well as exclude relevant aspects for the selection of sanitation systems. Decision-models are generally complex to understand and use and sometimes seem inconsistent. WASTE in collaboration with international experts is developing a practical support instrument to facilitate informed choice of sanitation systems. The tool is a knowledge sharing or awareness mechanism intended to provide a more comprehensive view of a settlement's limitations on the one hand and available sanitation options on the other. It intends to assist a wide range of stakeholders from city officials, planners, CBO's, users, service providers to financial and political authorities. Furthermore WASTE wants to present a practitioner's tool that uses a three-step approach providing a simple interface, flexible framework and transparent outcome. This support tool can be used independently, integrated in strategic sanitation planning as well as provide the base-ground for the selection of sanitation options in a multi-stakeholder participatory process.
Representing wastewater recycling in an integrated urban water modelling tool
Authors: Kinsman D. L. , Mirza F. F. , Maheepala S. , Neumann L. E. , Coultas E. H.
Published: May 2012

Treated wastewater is increasingly being considered as an alternative supply source in urban areas. Assessing its feasibility requires simulating its use using a suitable model. The feedback inherent in any wastewater recycling scenario creates challenges when determining how water from different types of sources like surface water, groundwater and treated wastewater should be allocated to meet demands. This is especially important when an optimisation algorithm determines the water allocation strategy. Releases from surface water sources can be reduced if supply from treated wastewater can be modelled. This allows for more efficient management of the water supply, leading to increased storage levels and fewer demand deficits.

HydroPlanner is an integrated modelling tool developed in part to predict the effects of wastewater treatment and reuse on the supply network. It combines rainfall runoff models, storage models, demand models and wastewater recycling models together in the simulation of urban water systems.

This paper demonstrates that HydroPlanner can model regulated river network systems equivalently to established platforms such as REALM. Additionally it is shown that HydroPlanner can specifically model wastewater treatment and the supply of treated water back to demands, though a further case study is planned to prove its validity for this purpose.
Startup and operation of a large wastewater treatment plant in warm climate and under modified conditions – a case study
Authors: Sarioglu M.
Published: May 2012

This study summarizes the findings and lessons learned from the start up and operation of a large wastewater treatment plant in warm climate under modified conditions. The treatment works comprise of a newly constructed sewage treatment plant located in the city of Dubai, U.A.E with an ultimate capacity of 300 Ml/d. The plant can be reviewed in three major parts; (i) liquid stream, (ii) sludge stream and (iii) odor control stream all having the latest state of the art technology and related equipments. The challenge in starting up the plant was related to the fact that only 20% of the flow was available in the form of hauled sewage to be hauled from septic tanks located in various parts of the city and also from the nearby industry which was uncontrollable. Furthermore, some parts of the plant were not ready to be commissioned on the day of the planned startup not to mention that effluent irrigation main was not complete to receive the treated sewage effluent (TSE) from the plant. A comprehensive commissioning plan was implemented and followed during the startup which was tailored according to the actual conditions. The plant commissioning was conducted in a phased sequence to cater for the expected and unexpected changes related to the inlet conditions. Commissioning and operation of the plant was carried for over 18 months with success considering the challenging and difficult conditions.
Bidding of the ‘Agua Prieta’ Wastewater Treatment Plant for the city of Guadalajara, México
Authors: Pérez H. , Coll C. , Robles R. , Martínez T. , Limón G.
Published: May 2012

During 2008 and 2009 a bidding process was undertaken for the Agua Prieta Wastewater Treatment Plant. The awarded contract included partial financing, design, build, equipment supply, start up and 20 years operation and maintenance. Plant capacity is 8,500 L/s as mean flow and population equivalent of 4.9 millions. The treatment process is composed of pretreatment, primary treatment, activated sludge reactor and secondary clarification. Sludge is anaerobically digested, using the produced biogas for electricity cogeneration. The site in which the plant is located has significant restrictions in relation to size and other features. These had a relevant impact in the offered treatment processes. The purpose of this paper is to share the experiences gained in this complex bidding process, including the guidelines and design criteria incorporated in the bidding documents, as well as the main technical features of the selected proposal. The plant is presently under construction.
Tracer test and hydraulics modeling of a large WWTP
Authors: Fall C. , Flores-Alamo N. , Esparza-Soto M. , Hooijmans C. M.
Published: May 2012

Tracer tests with rhodamine WT were performed at the biggest wastewater treatment plant of Mexico (‘Dulces Nombres’ WWTP, 5 m3/s). The aim was to develop the hydraulics sub-model to represent the aeration tanks, in the context of a project for calibrating the activated sludge model N°1 (ASM1). The planning of the experiment was performed by pre-simulation in AQUASIM, which allowed determining the quantities of dye (8 L per reactor) and sampling schedule that were required. After the tests, the rhodamine concentration profiles of the outlet mixed liquors were fit with different alternative of tank mixing models. Simulating the tracer data allowed to estimate the unknown influent flows, as well as determine the best hydraulics model: 4 completely stirred tank reactors retro-connected through the RAS (return activated sludge).
Secondary clarifiers optimisation in prague's wastewater treatment plant using a mathematical model
Authors: Pollert Jaroslav , Pavlíčková Ing. Dana , Todt Ing. Vladimír
Published: May 2012

The Prague's wastewater treatment plant includes mechanical and secondary biological treatment with an upgrade of the activated sludge process to partial nitrification and gentrification and gas facility. The plant's capacity (population equivalent) is 1.43 million, the hydraulic is 7.0 m3/s (during rains it is 8.2 m3/s). The main aim is to increase efficiency of sludge removal from the secondary clarifiers after necessary reconstruction. A 3D multiphase mathematical model was used to study possible efficiency improvement while 12 different scenarios (+ the present state) were simulated and compared. Simulation of the clarifiers brings new knowledge of their behaviour. The study has resulted in an optimised design of the secondary clarifiers to be used within reconstruction.
Evaluating upgrade possibilities of activated sludge wastewater treatment plants utilizing biofilm-based treatment technologies – an experimental study at the South Pest WWTP
Authors: Szilágyi N. , Kovács R. , Kenyeres I. , Törő B. , Csikor Zs. , Palkó Gy. , Makó M.
Published: May 2012

As more and more wastewater treatment plants (WWTPs) arrive to a point in their lifecycles when their original capacities are not sufficient anymore, the demand for good WWTP retrofitting solutions becomes increasingly critical. One of the typical problems is the suspended solids overload of secondary clarifiers, which is one of the main concerns at the South Pest WWTP as well. Pilot scale studies were carried out at the WWTP with a biofilm based technology applying biofilm carriers imitating plant root structures in order to characterize the potentials of clarifier TSS load reduction while maintaining the existing biodegradation performance of the activated sludge stage. The research demonstrated that the clarifier load can be reduced by more than 90%, while the original biodegradation performance of the system does not decrease. In addition to this, it was demonstrated that the biomass amount in the reactors can be increased substantially opening potentials for further biodegradation capacity.