Odour assessment: determining the optimum temperature and time for Tedlar sampling bag pre-conditioning

2012 ◽  
Vol 66 (8) ◽  
pp. 1806-1811 ◽  
Author(s):  
A. H. Bokowa
Keyword(s):  
Wastewater Treatment ◽  
Flow Rate ◽  
Wastewater Treatment Plants ◽  
Experimental Studies ◽  
Cleaning Process ◽  
Optimum Temperature ◽  
Air Flow Rate ◽  
Volatile Organic ◽  
Temperature Controlled ◽  
The Impact

Odours present in new Tedlar bags can impact the assessment of emissions from sewer collection systems and wastewater treatment plants. Conditioning protocols are needed to minimise the impact of background materials emissions on the sampling and assessment of odourous emissions. Olfactometry analysis has shown that background odour concentrations for new Tedlar bags can be as high as 130 OUE/m3. Experimental studies were undertaken to investigate the impact of different conditioning temperatures in order to determine the optimum temperature for cleaning new Tedlar bags to a level when no detectable odours were present in the sampling bags via dilution olfactometry. For the purpose of this study, new Tedlar bags were cleaned in a temperature-controlled oven that had a constant filtered air flow-rate. From the analysis of odour and volatile organic compounds (VOCs) concentrations found in new Tedlar bags during the cleaning process, it was observed that odour and VOCs concentrations decreased with time. It was also found that the temperature setting plays a significant role in the cleaning of the Tedlar bags as large concentrations of phenols and acetamide, N,N-dimethyl were found in new Tedlar bags and their concentrations decreased following the temperature pre-conditioning.

Oxygen transfer and aeration efficiency - influence of diffuser submergence, diffuser density, and blower type

1998 ◽  
Vol 38 (3) ◽  
pp. 1-6 ◽  
Author(s):  
Martin R. Wagner ◽  
H. Johannes Pöpel
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Flow Rate ◽  
Oxygen Transfer ◽  
Wastewater Treatment Plants ◽  
Air Flow ◽  
Oxygen Absorption ◽  
Air Flow Rate ◽  
Fine Bubble ◽  
Aeration Efficiency

The main factors of fine bubble aeration systems in uniform arrangement in clean water are the air flow rate, the depth of submergence of the diffusers, and the diffuser density. While the influence of the air flow rate on the oxygen transfer parameters is known, knowledge of the influence of the depth of submergence and the diffuser density on the specific oxygen transfer efficiency SOTE [%/m] and on the specific oxygen absorption SOA [g/m3·m at STP] is very limited. Both parameters are of great importance in dimensioning fine bubble aeration systems. Therefore, a literature review was conducted to show the influence of the diffuser submergence and density and the type of blower on oxygen transfer and aeration efficiency. The main review results are, that higher values of specific oxygen absorption can be obtained at higher diffuser density; secondly, the volumetric oxygen transfer rate VOTR [g/m3·h] is higher with increasing depth of submergence at the same air flow rate. Also it can be stated that with greater depth of submergence the specific oxygen absorption [g/m3·m at STP] is reduced. Dependent on the air flow rate and the pressure head, the energy consumption [Wh/m3·m at STP] of the blowers used in wastewater treatment plants is different. For example, the energy consumption varies from 4.3 [Wh/m3·m at STP] (positive displacement blower) to 3.0 [Wh/m3·m at STP] (turbo-compressors) at a pressure of 10 m and an air flow rate of 5,000 m3/h at STP. From the results of the literature review the following conclusions can be drawn: (1) High specific oxygen absorption values (SOA) [g/m3·m at STP] can be achieved applying shallow tanks, high diffuser densities and low specific air flow rates; (2) High aeration efficiencies (AE) [kg/kWh] can be obtained by applying high volumetric oxygen transfer rates and adequate selection of the blowers used at the wastewater treatment plants.

scholarly journals Sewer catchment effects on wastewater and biosolids odour management

2018 ◽  
Vol 77 (9) ◽  
pp. 2348-2354 ◽  
Author(s):  
Ruth Fisher ◽  
Ari Shammay ◽  
Juan Pablo Alvarez–Gaitan ◽  
Richard M. Stuetz
Keyword(s):  
Wastewater Treatment ◽  
Activated Carbon ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Wastewater Treatment Plants ◽  
Local Population ◽  
Community Impact ◽  
Volatile Organic ◽  
Odour Emissions ◽  
The Impact

Abstract The composition of wastewater in sewer catchments is known to affect the performance of wastewater treatment plants (WWTPs). However, there is limited knowledge as to how catchment characteristics, such as types of catchment industries, impact odour emissions from downstream sludge processing and biosolids management. Odorous emissions from biosolids processing at WWTPs can represent a significant community impact when the local population is exposed to odours. The main odorants emitted from biosolids are volatile sulfur compounds (VSCs), however, volatile organic compounds (VOCs) in emissions may also be perceptable after the removal of VSCs in odour abatement systems. Types of compounds present in emissions throughout biosolids processing at five WWTPs of varying sizes and levels of treatment (primary only and primary and secondary) were analysed. The ratio of total VSCs to VOCs in emissions, and the sensorial importance of each class varied between the sites. As a number of the VOCs in emissions were of industrial origin, this variation is likely dependent on industrial flows into the upstream sewer catchment. The impact of different emission compositions on both activated carbon and biologically based odour abatement systems were discussed.

Photocatalytic oxidation of volatile organic compounds present in airborne environment adjacent to sewage treatment plants

2004 ◽  
Vol 49 (1) ◽  
pp. 111-114 ◽  
Author(s):  
C. Raillard ◽  
V. Héquet ◽  
P. Le Cloirec ◽  
J. Legrand
Keyword(s):  
Wastewater Treatment ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Photocatalytic Oxidation ◽  
Wastewater Treatment Plants ◽  
Sewage Treatment ◽  
Hazardous Substances ◽  
Municipal Sewage ◽  
Volatile Organic ◽  
The Impact

Emissions of volatile organic compounds (VOCs) from wastewater in municipal sewage or industrial wastewater treatment plants are often overlooked as sources of exposure to hazardous substances. The impact of such emissions on local airborne environments represents a growing source of scientific, toxicological and public health interest. Actually, VOCs are suspected to be quite dangerous for human health. Some of them belong to the family of odorous compounds and can cause serious annoyance in the neighbourhood of the emission sources. A way to remove VOCs released from sewers and wastewater treatment facilities could be to degrade them by photocatalytic oxidation. TiO2-based photocatalysts are known to be efficient for this kind of application. In the present work TiO2 P25 Degussa was deposited on glass supports. These materials were tested for the degradation of butanone-2 in a photocatalytic reactor. The influence of water vapour (relative humidity) was shown using the Langmuir-Hinshelwood kinetic model.

scholarly journals Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

scholarly journals Ecohydrological modelling of water discharge and nitrate loads in a mesoscale lowland catchment, Germany

2009 ◽  
Vol 21 ◽  
pp. 49-55 ◽  
Author(s):  
Q. D. Lam ◽  
B. Schmalz ◽  
N. Fohrer
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Agricultural Land ◽  
Assessment Tool ◽  
Wastewater Treatment Plants ◽  
Water Discharge ◽  
Swat Model ◽  
Validation Period ◽  
Calibration Period ◽  
The Impact

Abstract. The aims of this study are to identify the capacities of applying an ecohydrological model for simulating flow and to assess the impact of point and non-point source pollution on nitrate loads in a complex lowland catchment, which has special hydrological characteristics in comparison with those of other catchments. The study area Kielstau catchment has a size of approximately 50 km2 and is located in the North German lowlands. The water quality is not only influenced by the predominating agricultural land use in the catchment as cropland and pasture, but also by six municipal wastewater treatment plants. Ecohydrological models like the SWAT model (Soil and Water Assessment Tool) are useful tools for simulating nutrient loads in river catchments. Diffuse entries from the agriculture resulting from fertilizers as well as punctual entries from the wastewater treatment plants are implemented in the model set-up. The results of this study show good agreement between simulated and measured daily discharges with a Nash-Sutcliffe efficiency and a correlation coefficient of 0.76 and 0.88 for the calibration period (November 1998 to October 2004); 0.75 and 0.92 for the validation period (November 2004 to December 2007). The model efficiency for daily nitrate loads is 0.64 and 0.5 for the calibration period (June 2005 to May 2007) and the validation period (June 2007 to December 2007), respectively. The study revealed that SWAT performed satisfactorily in simulating daily flow and nitrate loads at the lowland catchment in Northern Germany.

scholarly journals Life Cycle Assessment of Upgrading Primary Wastewater Treatment Plants to Secondary Treatment Including a Circular Economy Approach

2020 ◽  
Vol 13 ◽  
pp. 117862212093585 ◽  
Author(s):  
Karim M Morsy ◽  
Mohamed K Mostafa ◽  
Khaled Z Abdalla ◽  
Mona M Galal
Keyword(s):  
Wastewater Treatment ◽  
Circular Economy ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Scientific Progress ◽  
Primary Treatment ◽  
Secondary Treatment ◽  
Cumulative Impact ◽  
Process Energy ◽  
The Impact

Although significant progress has been achieved in the field of environmental impact assessment in many engineering disciplines, the impact of wastewater treatment plants has not yet been well integrated. In light of this remarkable scientific progress, the outputs of the plants as treated water and clean sludge have become potential sources of irrigation and energy, not a waste. The aim of this study is to assess the environmental impacts of upgrading the wastewater treatment plants from primary to secondary treatment. The Lifecycle Assessment Framework (ISO 14040 and 14044) was applied using GaBi Software. Abu Rawash wastewater treatment plant (WWTP) has been taken as a case study. Two scenarios were studied, Scenario 1 is the current situation of the WWTP using the primary treatment units and Scenario 2 is upgrading the WWTP by adding secondary treatment units. The study highlighted the influence and cumulative impact of upgrading all the primary WWTPs in Egypt to secondary treatment. With the high amount of energy consumed in the aeration process, energy recovery methods were proposed to boost the circular economy concept in Abu Rawash WWTP in order to achieve optimal results from environmental and economic perspectives.

scholarly journals Global Internal Recirculation Alternative Operation to Reduce Nitrogen and Ammonia Limit Violations and Pumping Energy Costs in Wastewater Treatment Plants

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1606
Author(s):  
Ignacio Santín ◽  
Ramon Vilanova ◽  
Carles Pedret ◽  
Marian Barbu
Keyword(s):  
Wastewater Treatment ◽  
Flow Rate ◽  
Biological Treatment ◽  
Fuzzy Controller ◽  
Wastewater Treatment Plants ◽  
Nitrate Concentration ◽  
Great Influence ◽  
Energy Costs ◽  
Recirculation Flow ◽  
Operational Costs

The internal recirculation plays an important role in different areas of the biological treatment of wastewater treatment plants because it has a great influence on the concentration of pollutants, especially nutrients. A usual manipulation of the internal recirculation flow rate is based on the target of controlling the nitrate concentration in the last anoxic tank. This work proposes an alternative for the manipulation of the internal recirculation flow rate instead of nitrate control, with the objective of avoiding limit violations of nitrogen and ammonia concentrations and reducing operational costs. A fuzzy controller is proposed to achieve it based on the effects of the internal recirculation flow rate in different areas of the biological treatment. The proposed manipulation of the internal recirculation flow rate is compared to the application of the usual nitrate control in an already established and published operation strategy by using the internationally known benchmark simulation model no. 2 as a working scenario. The results show improvements with reductions of 59.40% in ammonia limit violations, 2.35% in total nitrogen limit violations, and 38% in pumping energy costs.

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