bluuebunny/crossref_metadata_2025_split huggingface dataset:
Septage dewatering in vertical-flow constructed wetlands located in the tropics
Authors: Koottatep T. , Polprasert C. , Oanh N. T.K. , Heinss U. , Montangero A. , Strauss M. 
Published: May 2018

Constructed wetlands (CWs) have been proven to be an effective low-cost treatment system, which utilizes the interactions of emergent plants and microorganisms in the removal of pollutants. CWs for wastewater treatment are normally designed and operated in horizontal-flow patterns, namely, free-water surface or subsurface flow, while a vertical-flow operation is normally used to treat sludge or septage having high solid contents. In this study, three pilot-scale CW beds, each with a surface area of 25 m2, having 65 cm sand-gravel substrata, supported by ventilated-drainage system and planting with narrow-leave cattails (Typha augustifolia), were fed with septage collected from Bangkok city, Thailand. To operate in a vertical-flow mode, the septage was uniformly distributed on the surface of the CW units. During the first year of operation, the CWs were operated at the solid loading rates (SLR) and application frequencies of, respectively, 80-500 kg total solid (TS)/m2.yr and 1-2 times weekly. It was found that the SLR of 250 kg TS/m2.yr resulted in the highest TS, total chemical oxygen demand (TCOD) and total Kjeldahl nitrogen (TKN) removal of 80, 96 and 92%, respectively. The TS contents of the dewatered septage on the CW beds were increased from 1-2% to 30-60% within an operation cycle. Because of the vertical-flow mode of operation and with the effectiveness of the ventilation pipes, there were high degrees of nitrification occurring in the CW beds. The nitrate (NO3) contents in the CW percolate were 180-250 mg/L, while the raw septage had NO3 contents less than 10 mg/L.
Due to rapid flow-through of the percolates, there was little liquid retained in the CW beds, causing the cattail plants to wilt, especially during the dry season. To reduce the wilting effects, the operating strategies in the second year were modified by ponding the percolate in the CW beds for periods of 2 and 6 days prior to discharge. This operating strategy was found beneficial not only for mitigating plant wilting, but also for increasing N removal through enhanced denitrification activities in the CW beds. During these 2 year operations, the dewatered septage was not removed from the CW beds and no adverse effects on the septage dewatering efficiency were observed.
Aerobic biological treatment of grease from urban wastewater treatment plants
Authors: Canler J. P. , Royer C. , Duchène Ph. 
Published: May 2018

Biological grease treatment is rapidly expanding in France, with about sixty plants recorded in 1998. They are designed at a volumetric loading of 2.5 kg COD/m3 of reactor per day. Several sites have been selected for their representativity and studied.
Prior to detailed monitoring over a long period, preliminary investigations provided some information on the operation of these reactors. They showed that most of them are not optimized (low removal efficiency), but have limited operational constraints given their low load. This study enabled us to assess the quantity actually skimmed from the surface of the aerated grease separator in relation to the lipids in raw sewage, and to define the precautions to be taken for sampling and analysis of grease, before any data interpretation.
A detailed measurement series was then implemented. It shows the considerable value of this process for the reduction of lipids and highlights the main operational parameters in order to obtain high performance while keeping low operating constraints.
The impact of biomass harvesting on phosphorus uptake by wetland plants
Authors: Kim S-Y. , Geary P.M. 
Published: May 2018

Two species of macrophytes, Baumea articulata and Schoenoplectus mucronatus, were examined for their capacity to remove phosphorus under nutrient-rich conditions. Forty large bucket systems with the two different species growing in two types of substrate received artificial wastewaters for nine months, simulating a constructed wetland (CW) under high loading conditions. Half of the plants growing in the topsoil and gravel substrates were periodically harvested whereas the other half remained intact. Plant tissue and substrate samples were regularly analysed to determine their phosphorus concentrations.
With respect to phosphorus uptake and removal, the Schoenoplectus in the topsoil medium performed better than the Baumea. Biomass harvesting enhanced P uptake in the Schoenoplectus, however the effect was not significant enough to make an improvement on the overall P removal, due to the slow recovery of plants and regrowth of biomass after harvesting. From P partitioning, it was found that the topsoil medium was the major P pool, storing most of total P present in the system. Plant parts contributed only minor storage with approximately half of that P stored below ground in the plant roots. The overall net effect of harvesting plant biomass was to only remove less than 5% of total phosphorus present in the system.
Surmounting the engineering challenges of Everglades restoration
Authors: Goforth G.F. 
Published: May 2018

The South Florida Water Management District, in partnership with other agencies and stakeholders, is undertaking one of the world's largest ecosystem restoration programs. The foundation of the nutrient control program for the Everglades is a set of six large constructed wetlands, referred to as Stormwater Treatment Areas (STAs). The initial treatment goal is to reduce phosphorus entering the Everglades to 50 parts per billion. The STAs comprise almost 17,000 hectares, with a capital cost of approximately $700 million. Approximately 4,720 hectares are currently operational, another 2,600 hectares are in the start-up phase, and construction is just getting under way on the remaining areas.
Throughout the design process, engineers and scientists collaborated to capture the best available information on wetland treatment systems, and to develop the most appropriate design criteria. Some of the more challenging issues included characterizing stormwater inflows and phosphorus loads, determining appropriate nutrient removal performance characteristics, and estimating hydraulic design parameters relating to densely vegetated systems.
The design process combined in-house staff with engineering consultants, construction contractors, external review groups and independent peer-review. This paper summarizes major design aspects and key assumptions, and sets the stage for addressing future challenges associated with achieving long-term water quality goals of Everglades restoration.
Experimental results on constructed wetland pilot system
Authors: González J.M. , Ansola G. , Luis E. 
Published: May 2018

Research into a constructed wetland for wastewater treatment using M.H.E.A. (Hierarchical Mosaic of Artificial Ecosystems) pilot system was carried out over a vegetative period in 8 different flow and vegetable composition series. The system consisted of a free water pond as a first step working as primary treatment followed by a zone with Typha sp. and surface flow and finally a woody zone with a subsurface flow and planted with ligneous species (Salix sp., Populus sp., Fraxinus sp. and Alnus sp.).
Removal efficiency in the study reflects an optimal result: 80-99% total suspended matter removal, 82-98% organic matter removal, 70-98% nutrients removal and up to 99.9% faecal bacterial disinfecting. Effluent characteristics were in accordance with European Union legislation criteria for wastewater treatment systems.
Virus removal by soil passage at field scale and ground-water protection of sandy aquifers
Authors: Schijven J.F. , Hassanizadeh S.M. 
Published: May 2018

Virus removal from groundwater by soil passage often appears to be much higher during the first few metres due to the presence of more favorable sites for attachment than thereafter. A model is presented which interprets virus removal as a function of collision efficiencies αbeta; and αλl, inactivation rate coefficient μll and rate parameter γ. Initial high removal is determined by αβ, which decreases exponentially at a rate γ to a constant base removal rate that is determined by αλ and μl.
A hypothetical worst case was simulated to calculate the travel distance and time required for 9 log10 protection against virus contamination of groundwater wells in anoxic sandy aquifers. Unfavorable conditions for attachment were assumed. Virus was constantly leaking from a sewage pipe lying at the groundwater table. Mixing reduced virus concentration by 3.1 to 4.0 log10. For an additional 5.0 to 5.9 log10 protection against virus contamination by attachment and inactivation, residence times of about three to seven times longer than the current guideline of 60 days are needed, depending on abstraction rates, aquifer thickness and grain size of the sand.
PID and PLC units for the real-time control of sewer systems
Authors: Campisano A. , Modica C. 
Published: May 2018

Moveable gates for the real-time control (RTC) of sewer systems storage capacities are usually operated by controllers which, on the basis of local water level or flow velocity measurements, calculate the regulation errors of the monitored variables, determining the necessary regulator movements to lead the flow conditions to the desired set point.
In this paper the results of an investigation on the influence of proportional-integral-derivative (PID) controllers and programmable logic controllers (PLC) for the RTC of moveable sluice gates positioned into sewer systems are presented. The analysis of response time, damping and regulation errors provided information on the PID parameter calibration values and on the PLC control function performances.
A comparison between the two kind of controllers has also been carried out.
Sensitivity analysis and auto-calibration of an integral dynamic model for river water quality
Authors: van Griensven A. , Francos A. , Bauwens W. 
Published: May 2018

ESWAT – Extended Soil and Water Assessment Tool – was developed to allow for an integral modelling of the water quantity and quality processes in river basins. ESWAT is a physically based, semi-distributed model, with a moderate-to-large number of parameters and input and output variables (depending on the desegregation scheme). An auto-calibration procedure was implemented for the optimisation of the process parameters. The procedure is based on a new approach for multi-objective calibration and incorporates the algorithms of the Shuffled Complex Evolution Method. The optimisation uses a global optimisation criterion, whereby several output variables can be taken into account simultaneously. A statistical method enables the aggregation of the objective functions for individual variables, hereby avoiding the weighting problem. To select the important parameters for the optimisation, a sensitivity analysis precedes the calibration. The latter analysis is based on the One-factor-At-a-Time (OAT) design approach.
The sensitivity analysis and the calibration procedure are applied to the river Dender in Belgium. The river is characterised by high pollution loads and long residence times in summer periods.
Neighbourhood catchments: a new approach for achieving ownership and change in catchment and stream management
Authors: Carroll C. , Rohde K. , Millar G. , Dougall C. , Stevens S. , Ritchie R. , Lewis S. 
Published: May 2018

The Neighbourhood Catchment approach integrates land and stream management practices at a property and through to a local catchment scale, links production and environmental goals, and is a building block to achieve ownership and change at a sub-catchment scale and larger.
Research conducted in two 'focus' Neighbourhood Catchments has shown that land management practices that retain &gt;30% soil cover reduce sediment movement to streams. The Neighbourhood Catchment approach engages both early and cautious adopters, and enables continuous improvement of resource management to take place, and be recorded at an individual property and local catchment scale.
Pollution control of industrial wastewater from soap and oil industries: a case study
Authors: Abdel-Gawad S. , Abdel-Shafy M. 
Published: May 2018

Industrial wastewater from soap and oil industries represents a heavy pollution source on their receiving water body. This paper studies a case of pollution control at Tanta Soap and Oil Company, Banha Factory, Egypt. The factory production includes soap, edible oil, and animal fodder. About 4,347 m3/day of industrial wastewater effluent was discharged via gravity sewers to the public sewerage system. Most of the effluent was cooling water because the cooling process in the factory was open circle. In spite of the huge quantity of cooling water being disposed of, disposal of wastewater was violating pertinent legislation.
Three procedures were used for controlling the pollution at the Banha Factory. Firstly, all open circuit cooling systems were converted to closed circuit thus reducing the quantity of the discharged wastewater down to 767 m3/day. Secondly, the heavily polluted oil and grease (O&G) wastewater from the refinery unit is treated via two gravity oil separator (GOS) units, dissolved air floatation (DAF), and biological units in order to reduce the high levels of O&G, BOD, COD, and SS to the allowable limits. Thirdly, the heavily polluted waste effluent from the ‘red water’ saponification unit is treated separately by acidification to convert the emulsified fatty acid to free form in order to be separated through an oil separation unit.
The effluent is then passed to liming stage to neutralize excess acidity and precipitate some of the dissolved matters. The mixture is finally clarified and the pH is adjusted to the allowable limits. The effluent wastewater from the three processes is collected and mixed in a final equalization tank for discharging effluent to the public sewerage system. The characteristics of the effluent water are very good with respect to the allowable Egyptian limits for discharging effluent to the public sewerage system.
Minimisation of costs by using disintegration at a full-scale anaerobic digestion plant
Authors: Winter A. 
Published: May 2018

Various half-scale and lab-scale investigations have already shown that the disintegration of excess sludge is a possible pre-treatment to optimise anaerobic digestion. To control these results different methods of disintegration were investigated at a full-scale plant. Two stirred ball mills and a plant for oxidation with ozone were applied.
A positive influence of disintegration on the anaerobic biodegradability can be established with application of a stirred ball mill. Biogas production as well as the degree of degradation were increased by about 20%. Laboratory investigations also validate that disintegration increases the polymer demand and leads to a lower solid content after dewatering. A higher pollution level of process water after dewatering even with ammonia and COD corroborates the results of the anaerobic degradation.
Capital costs for the stirred ball mill, costs for energy, manpower and maintenance can be covered if the specific costs for disposal are high. If the development of costs in future and the current discussion about sludge disposal are taken into account sewage sludge disintegration can be a suitable technique to minimise costs at waste water treatment plants.
Comparison of conventional rule based flow control with control processes based on fuzzy logic in a combined sewer system
Authors: Klepiszewski K. , Schmitt T.G. 
Published: May 2018

While conventional rule based, real time flow control of sewer systems is in common use, control systems based on fuzzy logic have been used only rarely, but successfully. The intention of this study is to compare a conventional rule based control of a combined sewer system with a fuzzy logic control by using hydrodynamic simulation. The objective of both control strategies is to reduce the combined sewer overflow volume by an optimization of the utilized storage capacities of four combined sewer overflow tanks. The control systems affect the outflow of four combined sewer overflow tanks depending on the water levels inside the structures. Both systems use an identical rule base.
The developed control systems are tested and optimized for a single storm event which affects heterogeneously hydraulic load conditions and local discharge. Finally the efficiencies of the two different control systems are compared for two more storm events. The results indicate that the conventional rule based control and the fuzzy control similarly reach the objective of the control strategy. In spite of the higher expense to design the fuzzy control system its use provides no advantages in this case.
Waste stabilisation pond developments in New Zealand
Authors: Archer H.E. , Mara D.D. 
Published: May 2018

Waste stabilisation ponds have been a popular form of wastewater treatment in New Zealand both for large cities and small communities. Over 100 systems have been constructed ranging in size from over 500 ha to less than 0.1 ha. The largest pond system in New Zealand was at Manukau, Auckland and consisted of four ponds with a total of 530 ha. However, ongoing odour and midge releases and an algae parasite problem plus a requirement to reduce ammonia and total nitrogen in summer, led to the decision to decommission the ponds and allow the area to revert to tidal mudflats. The second largest pond system is at Christchurch and totals 226 ha. In contrast to Manukau, the Christchurch ponds have not caused significant odours and final effluent quality has been good. Christchurch has two parallel trains each with three ponds in series. It is proposed to retain and develop the ponds into a seven cells in series arrangement to reduce short-circuiting.
Odour emissions from the Manukau and Christchurch ponds have been measured by the use of olfactometry. Dispersion of odours has been modelled and the extent of “odour travel” determined on a statistical probability basis using actual meteorological data. It can be demonstrated that residential areas can co-exist with ponds, which are not overloaded, with separation distances of 200 metres.
Dynamic mathematical model of high rate algal ponds (HRAP)
Authors: Jupsin H. , Praet E. , Vasel J.-L. 
Published: May 2018

This article presents a mathematical model to describe High-Rate Algal Ponds (HRAPs). The hydrodynamic behavior of the reactor is described as completely mixed tanks in series with recirculation. The hydrodynamic pattern is combined with a subset of River Water Quality Model 1 (RWQM1), including the main processes in liquid phase. Our aim is to develop models for WSPs and aerated lagoons, too, but we focused on HRAPs first for several reasons:• Sediments are usually less abundant in HRAP and can be neglected• Stratification is not observed and state variables are constant in a reactor cross section• Due to the system's geometry, the reactor is quite similar to a plugflow type reactor with recirculation, with a simple advection term.
The model is based on mass balances and includes the following processes:Phytoplankton growth with NO3-, NO2- and death• Aerobic growth of heterotrophs with NO3-, NH4+ and respiration• Anoxic growth of heterotrophs with NO3-, NO2- and anoxic respiration• Growth of nitrifiers (two stages) and respiration.
The differences with regard to RWQM1 are that we included a limiting term associated with inorganic carbon on the growth rate of algae and nitrifiers, gas transfers are taken into account by the familiar Adeney equation, and a subroutine calculates light intensity at the water surface. This article presents our first simulations.
Seasonal influence of waste stabilisation pond effluent on DAF/F (dissolved air flotation/filtration) process operation
Authors: Buisine F. , Oemcke D. 
Published: May 2018

The Bolivar wastewater treatment plant (WWTP), North of Adelaide, South Australia encompasses the largest waste stabilisation pond (WSP) system in the Southern hemisphere. The wastewater effluent will ultimately be fully reused for agriculture irrigation. A dissolved air flotation/filtration (DAF/F) plant was installed for tertiary treatment downstream of the stabilisation lagoons for supply to the irrigation scheme. Chemical treatment in the form of coagulation and flocculation is required to assist the separation process.
The DAF/F plant operation is highly dependent on the raw water algal population. Seasonal variations seem to be the main abiotic factors affecting the algal population growth. Significant doses of chemical can be required to respond to rapid changes of water quality. United Water International is currently assessing the appropriate chemical treatment for short term response, and is also working with Flinders University of South Australia on determining ways to manage the lagoons and to control the water quality feeding the DAF/F plant in the long term. This paper outlines the effect of seasonal variations of WSP effluent quality on the DAF/F process operation, the findings for an adapted chemical treatment, and the eventual possibilities for lagoon management.
Flow velocities and shear stresses during flushing operations in sewer collectors
Authors: Campisano A. , Modica C. 
Published: May 2018

Many relevant problems of drainage systems such as first flush pollution, flow capacity reduction and consequent risks of surcharges are worsened by sediment accumulation in sewer collectors. For the solution of these problems several sediment cleansing methods and techniques, e.g. mechanical methods, traps and flushing devices, have been developed and applied in the last decades. In particular, simulation studies and experimental campaigns have shown the effectiveness of flushing methods as preventive cleansing strategy in sewer collectors.
In this paper the results of a numerical investigation for determining flushing waves characteristics both in terms of duration and flow rate are presented. The collector section lengths where flow velocities and average shear stresses determined by flushing waves exceed minimum threshold values are evaluated using a dimensionless approach. The results, related to the operative ranges of the practical applications, are exposed by means of graphs and regressive equations.
The design, operation and performance of a municipal hybrid reed bed treatment system
Authors: O'Hogain S. 
Published: May 2018

The first Irish municipal application of a hybrid reed bed treatment system (RBTS) was designed and constructed at Colecott, County Dublin. The hybrid design for Colecott RBTS was based on modifications to the Max Planck Institute Process (MPIP). The constituent parts of the design were a septic tank, a pump sump, two stage vertical flow beds, a secondary settlement tank, a horizontal reed bed, an outlet chamber and outfall pipe. The population at the time of design was 48, but with future development in mind 60 was used as the population equivalent (pe). Construction and operational characteristics are outlined. Results of a two year monitoring study are presented, showing good performance and producing a final effluent with 88% BOD removal, 89% COD removal and 99% SS removal.
Percentile compliance with EU discharge standards were BOD 60%, COD 100%, SS 100% with 50% for nitrogen and 0% for PO4. Surface water input increased flows to twice the average, resulting in increased maintenance visits without affecting results. The ability to deal with the excess inflow is demonstrated by the system. The method of distribution to the primary vertical beds was satisfactory while that on the secondary vertical beds was not.