Greenhouse gas production in wastewater treatment: process selection is the major factor

2003 ◽  
Vol 47 (12) ◽  
pp. 43-48 ◽  
Author(s):  
J. Keller ◽  
K. Hartley
Keyword(s):  
Power Generation ◽  
Wastewater Treatment ◽  
Greenhouse Gas ◽  
Fossil Fuels ◽  
Treatment Process ◽  
Sludge Treatment ◽  
Anaerobic Processes ◽  
Aerobic Processes ◽  
Wastewater Pollutants ◽  
Aerobic Sludge

Many practical design and operating decisions on wastewater treatment plants can have significant impacts on the overall environmental performance, in particular the greenhouse gas (GHG) emissions. The main factor in this regard is the use of aerobic or anaerobic treatment technology. This paper compares the GHG production of a number of case studies with aerobic or anaerobic main and sludge treatment of domestic wastewater and also looks at the energy balances and economics. This comparison demonstrates that major advantages can be gained by using primarily anaerobic processes as it is possible to largely eliminate any net energy input to the process, and therefore the production of GHG from fossil fuels. This is achieved by converting the energy of the incoming wastewater pollutants to methane which is then used to generate electricity. This is sufficient to power the aerobic processes as well as the mixing etc. of the anaerobic stages. In terms of GHG production, the total output (in CO2 equivalents) can be reduced from 2.4 kg CO2/kg CODremoved for fully aerobic treatment to 1.0 kg CO2/kg CODremoved for primarily anaerobic processes. All of the CO2 produced in the anaerobic processes comes from the wastewater pollutants and is therefore greenhouse gas neutral, whereas up to 1.4 kg CO2/kg CODremoved originates from power generation for the fully aerobic process. This means that considerably more CO2 is produced in power generation than in the actual treatment process, and all of this is typically from fossil fuels, whereas the energy from the wastewater pollutants comes primarily from renewable energy sources, namely agricultural products. Even a change from anaerobic to aerobic sludge treatment processes (for the same aerobic main process) has a massive impact on the CO2 production from fossil fuels. An additional 0.8 kg CO2/kg CODremoved is produced by changing to aerobic sludge digestion, which equates for a typical 100,000 EP plant to an additional production of over 10 t CO2 per day. Preliminary cost estimates confirm that the largely anaerobic process option is a fully competitive alternative to the mainly aerobic processes used, while achieving the same effluent quality.

Identifying energy and carbon footprint optimization potentials of a sludge treatment line with Life Cycle Assessment

2013 ◽  
Vol 67 (1) ◽  
pp. 63-73 ◽  
Author(s):  
C. Remy ◽  
B. Lesjean ◽  
J. Waschnewski
Keyword(s):  
Wastewater Treatment ◽  
Life Cycle Assessment ◽  
Life Cycle ◽  
Greenhouse Gas ◽  
Carbon Footprint ◽  
Energy Demand ◽  
Fossil Fuels ◽  
Sludge Treatment ◽  
Treatment Line ◽  
The Impact

This study exemplifies the use of Life Cycle Assessment (LCA) as a tool to quantify the environmental impacts of processes for wastewater treatment. In a case study, the sludge treatment line of a large wastewater treatment plant (WWTP) is analysed in terms of cumulative energy demand and the emission of greenhouse gases (carbon footprint). Sludge treatment consists of anaerobic digestion, dewatering, drying, and disposal of stabilized sludge in mono- or co-incineration in power plants or cement kilns. All relevant forms of energy demand (electricity, heat, chemicals, fossil fuels, transport) and greenhouse gas emissions (fossil CO2, CH4, N2O) are accounted in the assessment, including the treatment of return liquor from dewatering in the WWTP. Results show that the existing process is positive in energy balance (–162 MJ/PECOD * a) and carbon footprint (–11.6 kg CO2-eq/PECOD * a) by supplying secondary products such as electricity from biogas production or mono-incineration and substituting fossil fuels in co-incineration. However, disposal routes for stabilized sludge differ considerably in their energy and greenhouse gas profiles. In total, LCA proves to be a suitable tool to support future investment decisions with information of environmental relevance on the impact of wastewater treatment, but also urban water systems in general.

Fate of nonylphenol polyethoxylates and nonylphenoxy acetic acids in an anaerobic digestion process for sewage sludge treatment

2006 ◽  
Vol 53 (11) ◽  
pp. 221-226 ◽  
Author(s):  
M. Minamiyama ◽  
S. Ochi ◽  
Y. Suzuki
Keyword(s):  
Wastewater Treatment ◽  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Treatment Process ◽  
Sludge Treatment ◽  
Testing Apparatus ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Sewage Sludge Treatment ◽  
Acetic Acids

Many environmental problems caused by endocrine disruptors (EDs) have been reported. It is reported that EDs flow into sewage treatment plants, and it has been pointed out that these may be shifted from the wastewater treatment process to the sludge treatment process. Little is known about the fate of EDs accumulated in sewage sludge, so we carried out a study to clarify the fate of EDs in sewage sludge treatment processes, especially in an anaerobic digestion process. In this study, nonylphenol (NP) was selected as a target ED. Nonylphenol ethoxylates (NPnEO) or nonylphenoxy acetic acids (NPnEC), which were the precursor of NP, were added to an anaerobic digestion process, and mass balance was investigated. The following results were obtained from the anaerobic digestion experiments. (1) NP1EO was injected to an anaerobic digestion testing apparatus that was operated at a retention time of approximately 28 d and a temperature of 35 °C with thickened sludge sampled from an actual wastewater treatment plant. Approximately 40% of the injected NP1EO was converted to NP. (2) NP1EC was injected to an anaerobic digestion testing apparatus with thickened sludge. As a result, almost all injected NP1EC was converted to NP. When NP2EC was injected, NP2EC was not converted to NP until the 20th day.

scholarly journals The applied mechanical equipments for wastewater treatment in the észak-Alföld region

2017 ◽  
pp. 171-178
Author(s):  
István Szőllősi ◽  
Tamás Antal ◽  
Zsuzsanna Uri ◽  
László Simon ◽  
Attila Szilágyi
Keyword(s):  
Wastewater Treatment ◽  
Sewage Treatment ◽  
Specific Energy Consumption ◽  
Capacity Utilization ◽  
Mechanical Equipment ◽  
Sludge Treatment ◽  
Sludge Stabilization ◽  
Almost All ◽  
Small Capacity ◽  
Aerobic Sludge

In this study we presented the results of a survey research, which was performed during 2015 at 34 sewage treatment works, operating in Észak-alföld region (Hungary). The survey focused on applied mechanical equipment and works of art of the sewage treatment establishments. The results of the survey showed that the majority of the examined sites (approx 65%) are working with capacity utilization of 50–100%,merely the 12% of plants was overload. It was found analyzing of specific energy consumption of the sites that the largest value (1.1 kWh per m3) was at the plants with smaller capacity (0–1000 m3 per day). It was clear during the questionnaire processing of the survey that almost all of the works applied activated sludge for sewage treatment The sludge treatment of the sewage plants is conducted by two methods; aerobic- and mixed (anaerobic and aerobic) sludge stabilization. We suggest for the plants with small capacity to use deep aerators, since anachronistic method used the at 3% of the settlements.

scholarly journals A Practical Approach to Reduce Greenhouse Gas Emissions from Open Dumps through Infrastructure Restructuring: A Case Study in Nanjing City, China

2018 ◽  
Vol 10 (8) ◽  
pp. 2804 ◽  
Author(s):  
Jing Ma ◽  
Zhanbin Luo ◽  
Fu Chen ◽  
Qianlin Zhu ◽  
Shaoliang Zhang ◽  
...  
Keyword(s):  
Power Generation ◽  
Greenhouse Gas ◽  
Co2 Emissions ◽  
Fossil Fuels ◽  
Greenhouse Gas Emission ◽  
Technical Process ◽  
Nanjing City ◽  
Landfill Management

A new environmental ban has forced the restructure of open dumps in China since 1 July 2011. A technical process was established in this study that is feasible for the upgrade of open dumps through restructuring. The feasibility of restructuring and the benefit of greenhouse gas emission reductions were assessed according to field surveys of five landfills and four dumps in Nanjing. The results showed that the daily processing capacities of the existing landfills have been unable to meet the growth of municipal solid waste (MSW), making restructuring of the landfills imperative. According to an assessment of the technical process, only four sites in Nanjing were suitable for upgrading. Restructuring the Jiaozishan landfill effectively reduced the leachate generation rate by 5.84% under its scale when expanded by 60.7% in 2015. CO2 emissions were reduced by approximately 55,000–86,000 tons per year, in which biogas power generation replaced fossil fuels Fossil fuels accounted for the largest proportion, up to 45,000–60,000 tons. Photovoltaic power generation on the overlying land has not only reduced CO2 emissions to 26,000–30,000 tons per year but has also brought in continuing income from the sale of electricity. The funds are essential for developing countries such as China, which lack long-term financial support for landfill management after closure.

scholarly journals Wastewater Treatment Process: A Modified Mathematical Model for Oxidation Ponds

2021 ◽  
Vol 86 (1) ◽  
pp. 76-86
Author(s):  
Syafiqah Hanis Mohd Fauzi ◽  
Norazaliza Mohd Jamil
Keyword(s):  
Mathematical Model ◽  
Wastewater Treatment ◽  
Treatment Process ◽  
Oxygen Demand ◽  
Wastewater Treatment Process ◽  
Modified Model ◽  
Monod Equation ◽  
Runge Kutta Method ◽  
Oxidation Ponds ◽  
Wastewater Pollutants

Wastewater treatment aims to eliminate as many suspended solids as possible from the remaining water, known as effluent, before it is released into the environment. Pond oxidation methods have been practically proven successful for the wastewater treatment process because of their low construction and maintenance costs. This study aimed to investigate the degradation of wastewater pollutants through an oxidation pond treatment system. The purpose was to observe the relationship between the concentration of bacteria which are phototrophic and coliform, chemical oxygen demand (COD), and dissolved oxygen (DO). In this paper, a modified model consist of a set of an ordinary differential equation (ODE) has been developed by incorporating the Monod Equation. The model was solved numerically using the 4th order Runge Kutta method embedded in the MATLAB software. The sum of squared estimate of errors (SSE) for the modified model was compared with the SSE of the existing model. The results revealed that the modified model demonstrated a lower SSE compared to the existing model. Thus, the modified mathematical model gives better result than the existing model. The model provides an excellent approximation for concentration needed for an oxidized pond to produce good water quality.

Methane Emissions in Wastewater Treatment Process and Emissions Calculation in Henan Province

2015 ◽  
Vol 768 ◽  
pp. 553-560
Author(s):  
Bing Tao Liu ◽  
Wei Sheng Chen ◽  
Peng Ju Ding
Keyword(s):  
Wastewater Treatment ◽  
Greenhouse Gas ◽  
Treatment Process ◽  
Sewage Treatment ◽  
Methane Emissions ◽  
Scientific Basis ◽  
Calculation Model ◽  
Henan Province ◽  
Wastewater Treatment Process ◽  
Greenhouse Gas Inventories

The process of wastewater treatment is one of the sources of greenhouse gas emissions from urban human activities and methane is a source of greenhouse gases can not be ignored. According to the method recommended by IPCC Guidelines for National Greenhouse Gas Inventories 2006,a calculation model was established to assess methane emissions of wastewater treatment in Henan.Then methane emissions from wastewater treatment in Henan province in the year of 2010 were estimated. The results showed that net methane emissions from the sewage treatment process was 21,764.1 tons, and methane from the industrial wastewater generated process was 98,609.33 tons. The results will provide a scientific basis for policy maker to mitigate the methane emission from the sewage treatment process of Henan province.

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