Sewage Sludge Incineration Plants Research Articles

Impact of emissions into the atmospheric air of a sewage sludge incineration plant on public health

Introduction. Urban wastewater sludge (UWS) is an important by-product of traditional urban wastewater treatment. Incineration is considered the most effective and universal method of reducing the volume of a large amount of UWS and their disinfection. However, the situation in the areas where the USW incineration plants are located, as a result of the pyrolytic process products entering the atmospheric air, creates complete uncertainty and unpredictability of the development of events that can lead in certain situations to the formation of an additional risk to public health. The purpose of the study. Hygienic characteristics of wastewater sludge incineration technology based on indicators of atmospheric air pollution and the magnitude of the risk to the health of the population living in the zone of influence of the implemented technology. Materials and methods. At the first stage, the analysis of the information presented in the international databases PubMed, Scopus, and PRINCE was carried out. Based on the results of the analysis, a list of chemical compounds was formed to identify the qualitative composition and determine the amount of pollutants in industrial emissions into the atmospheric air during the implementation of wastewater sludge incineration technology. Sanitary and chemical studies of industrial emissions into the atmospheric air were carried out by the chemical analytical center “Arbitration” of the D.I. Mendeleev Institute for Metrology. Modern high-precision analytical methods have been used to identify and quantify priority atmospheric pollutants. Results. Industrial emissions samples laboratory studies were carried out. Measurement results analysis showed that the indicators of quantitative emissions of harmful (polluting) substances do not exceed the international regulations requirements, most are below the detection limit, and the calculated concentrations do not exceed hygienic standards. The assessment of carcinogenic health risk are determined as acceptable, the probability of developing diseases additional cases from exposure to all the studied carcinogens throughout life in the population permanently residing in the territory in the area of the enterprise location is assessed as insignificant (less than one case). Limitations. In this study, there was a limitation associated with the method for determining concentrations of substances detection limit, which, nevertheless, satisfies the purpose of the study. Since a sample of unknown composition was taken, the entire possible substances spectrum in the emissions was evaluated. Substances with a carcinogenic effect were present in the emissions, but only those substances that had a carcinogenic potential factor were included in the carcinogenic risk assessment.

Investigating phosphorus loads removed by chemical and biological methods in municipal wastewater treatment plants in Poland

The article presents an analysis of the current methods for phosphorus removal applied in municipal wastewater treatment plants in Poland. Within the study, 131 wastewater treatment plants were investigated, constituting 17 630 500 population equivalent, which is about 1/3 of the overall population equivalent (designed) in Poland. The research was based on a detailed technical questionnaire analysis obtained from wastewater treatment plants operators and calculations of pure metal doses in the applied coagulants and their type per a treated wastewater volume, population equivalent and phosphorus load removed. Moreover, a basic statistical analysis based on Pearson's correlation coefficient was applied to validate the relationship between the consumption of coagulants per the removed P load and the treated wastewater volume in 3 categories of wastewater treatment plants in terms of their population equivalent. The analysis results show that a minimum of 1470 Mg of phosphorus removed by 35 wastewater treatment plants based entirely on biological treatment methods could be used for phosphorus recovery to produce struvite, calcium phosphate or other highly bioavailable alternative fertilizer products. Moreover, 1490 Mg of phosphorus removed by other 17 wastewater treatment plants with a minimal coagulant dose (<1 g of metal per m3 of wastewater), increases the base for phosphorus recovery to approx. 2960 Mg per year using sewage sludge or its dewatering liquors. These results suggest that the implementation of the means mentioned above would significantly increase the possibilities for obtaining phosphorus from secondary sources, especially in wastewater treatment plants without sewage sludge incineration plants.

A Two-Stage ORC Integration to an Existing Fluidized Bed Sewage Sludge Incineration Plant for Power Production in the Scope of Waste-to-Energy

This paper presents the design, evaluation, and optimization of an electricity generation system based on the two-stage organic Rankine cycle (TS-ORC), which utilizes the waste heat of an existing fluidized bed sewage sludge incineration (FBSSI) facility. The facility incinerates an average of 300 tons per day of sewage sludge with a dry matter content of 22%. After the drying process, the sewage sludge is burned in a fluidized bed combustor, and exhaust gas at a temperature of about 850-900ºC is released due to the combustion. The system provides the energy required to dry the sludge from this exhaust gas. In this study, a TS-ORC is designed to be coupled to the exhaust gas flowlines discharged to the atmosphere at two different points in the FBSSI plant. The exergy efficiency of the FBSSI facility is found to be 70.5%. Three different working fluids are selected to examine the variations of thermodynamic and thermoeconomic performance parameters of the designed TS-ORC system. The highest power generation in the TS-ORC system (183.40 kW) is achieved using R1234yf as working fluid. R1234yf is also the most expensive fluid for electricity generation among the other working fluids (10.57 $/h). The least electricity generation in the TS-ORC (142.70 kW) occurs at the thermoeconomically most affordable cost with R245fa (9.35 $/h).

Inventory of Wastes Generated in Polish Sewage Sludge Incineration Plants and Their Possible Circular Management Directions

A dynamic development of sewer networks and municipal wastewater treatment plants (WWTPs) leads to the formation a large amounts of municipal sewage sludges (MSSs) which have to be disposed. One of the MSS disposal practices is thermal conversion in mono-incineration plants. Nowadays, there are 11 such installations in Poland, with the total capacity 160,300 Mg d.w. of MSSs per year. This paper presents a comprehensive analysis of wastes generated in Polish MSS mono-incineration plants. As a consequence of MSSs incineration, various types of waste are generated including, for example, bottom and fly ash, dust or solid waste. The most valuable waste is sewage sludge ash (SSA), which can be used in other industries, as fertilizer or construction sectors. In the circular economy (CE) model, SSA should be treated as a secondary source of raw materials, such as phosphates (replacement of nutrients by P-rich ashes in fertilizers) or sand (replacement of sand by ashes in construction materials). Current practices of SSA management include landfilling, recovery at WWTPs or management by external companies (recovery, disposal or collection). To preserve the utility value of SSA, it should be stored selectively, and then directed to raw materials recovery. This creates the possibility of turning waste into a secondary resource, after meeting certain conditions which depend on which product the waste is directed to. Moreover, this waste management practice is recommended in the Polish documents regarding the usage of SSA, and it can strengthen the accomplishment of the European Green Deal, which is the newest roadmap for making the EU’s economy sustainable and circular.

Modification of Phosphorus-Rich Sewage Sludge Combustion Ash Using Pure Source Materials for Analysis of Ash Adhesion Behavior at High Temperature

The deposition of combustion ash on the inner surface of the incinerator wall and the bed materials in a fluidized bed hinder the stable operation of sewage sludge incineration plants and damage th...

Toward Stable Operation of Sewage Sludge Incineration Plants: The Use of Alumina Nanoparticles to Suppress Adhesion of Fly Ash

In sewage sludge incineration plants, fly ash can adhere to the surfaces of both the incinerator and dust filter and then accumulate over time. Since this grown layer can potentially block the gas ...

Effects of combustion temperature on air emissions and support fuel consumption in full scale fluidized bed sludge incineration: with particular focus on nitrogen oxides and total organic carbon.

This article describes a pilot test at a sewage sludge incineration plant and shows its results considering the impacts of reducing the minimum combustion temperature from 850°C to 800°C. The lowering leads to an actual reduction of the average combustion temperature by 25 K and a significant reduction in the fuel oil consumption for support firing. The test shall be used for providing evidence that the changed combustion conditions do not result in higher air pollutant emissions. The analysis focusses on the effects of the combustion temperature on nitrogen oxides (NOx) and total organic carbon emissions. The evaluation of all continuously monitored emissions shows reduced emission levels compared to the previous years, especially for NOx.

The Use of LCA Method to Assess Environmental Impact of Sewage Sludge Incineration Plants

AbstractLife Cycle Assessment (LCA) is one of the new, little more popular in Poland of elements of environmental management. In the world literature one can find many examples of the use of LCA but mainly for comparison purposes. The paper presents results of LCA analysis made on the basis of data from a running incineration of sewage sludge. Performing a thorough analysis of this process enables improved operational system, including through a better use of the resulting products of combustion, as well as determining the impact of the thermal treatment of sludge on the environment and compared the results with data from the literature. To date, in Poland has not been carried out environmental impact assessments and the process of thermal treatment of both sludge and waste, based on the assumptions of LCA.

Ammonia Emission from Sewage Sludge Incineration Process

Abstract In quantitative terms, sludge produced in the process of municipal wastewater treatment represents a small part of the total waste generated in municipal sources - its quantity represents only a few percent of the generated mass of municipal waste. However, the threats it brings, do not allow it to be neglected while designing the wastewater treatment process. At the same time, with increasing requirements regarding the quality of sewage discharged into the environment, there is an increase in the amount of sludge produced in wastewater treatment processes. In recent years, the share of thermal treatment of municipal sewage sludge has risen sharply - about 12 modern sludge incineration plants have been built and construction of new ones is considered. During more than a four-year operation of the sewage sludge incineration plant in the Combined Sewage Treatment Plant in Lodz (GOS) a large ammonia emission from the combustion process was observed. So, a decision was taken to examine this process. The paper presents results of ammonia emission from the combustion of sewage sludge from GOS as a function of temperature.

Life cycle assessment (LCA) of digested sewage sludge incineration for heat and power production

This paper presents a comparative life cycle assessment (LCA) of an existing digested sewage sludge incineration for heat and power production. Operations of an existing sewage sludge incineration plant based on a fluidized bed combustor (FBC) and a hypothetical cement kiln (CK) facility using sludge as a secondary fuel are described in detail as two different scenarios. The comparison of these two scenarios is performed based on 15 impact categories in the characterization stage. The results show that the sewage sludge incineration scenario based on FBC has a better environmental performance in the most of the impact categories including global warming, respiratory organic and inorganic, aquatic and terrestrial ecotoxicity, terrestrial acidification/nutrition, aquatic acidification, land occupation, and mineral extraction. In the human health category, the scores of the CK scenario precedes the scores of FBC scenario because the residual materials of the incineration in the cement kiln are immobilized with the produced clinkers whereas in the FBC system, they are landfilled. This study aims to show the environmental burdens of each option based on different impact categories in order to give a clear perspective to decision makers for drawing an environmentally friendly and sustainable sludge disposal policy.

Utilization of Effluent Water from Wastewater Treatment as a Flue Gas Scrubbing Liquid in a Sewage Sludge Incineration Plant

Compared to common, medium sized wood firing biomass power plants, sewage sludge incineration plants need quite complex systems for flue gas cleaning, as they have to deal with higher amounts of acidic gases like sulfur dioxide (SO2) and hydrochloric acid (HCl). Because of the quite high nitrogen content in the sludge as well nitrogen oxides (NOx), especially nitrogen monoxide (NO), have to be considered. During the current work, a scrubber system was developed, which fulfills the needs of such a plant, using water from the adjacent wastewater treatment plant as a scrubbing liquid. The water is taken from the effluent of the wastewater treatment plant and is returned to the bioreactor of this plant for regeneration after usage. During the extensive testing of the scrubber system, removal efficiencies of up to 99.5 % for HCl and 95 % for SO2 have been achieved. As expected, an increased liquid-to-gas ratio as well as scrubbing liquid recirculation has a positive influence on the removal efficiencies. A major finding was that the nitrite concentration of the fresh scrubbing liquid effects the NO removal efficiency. Nitrite concentrations below or above a certain range resulted in poor NO removal efficiencies, while under ideal conditions removal efficiencies of more than 50 % have been reached. Based on the gained experiences, this system can be developed further and used for flue gas treatment in similar applications. Given that the effluent water is available for free from the wastewater treatment plant, it has very low operational costs, as no additional chemicals are needed.

Conversion of sulfur and nitrogen to gaseous components from sewage sludge combustion under oxy-firing conditions

AbstractThe article presents the results of sulfur and nitrogen conversion to flue gas components during the oxy-combustion of municipal sewage sludge. In Poland, some dynamic changes in the implementation of thermal treatment methods in sewage sludge management have been observed over recent years. A few new installations have been commissioned with a fluidized bed technology under air-firing conditions. Until 30th December 2012, there were in Poland, 11 municipal sewage sludge incineration plants that had jointly a total capacity amounting to 160,000 Mg/y. Since the oxy-combustion technology has been researched widely mainly in coal combustion, the experiments carried out at 0.1 MWth CFB combustor have focused on sewage sludge combustion and sulfur, nitrogen conversion to flue gas components in the conditions of increased oxygen concentration and different process temperatures. The oxygen concentration in a feed gas was increased from 21 to 35% per volume. An increase in sulfur and nitrogen conversion r...

Development of Greenhouse Gas Emission Factors from Sewage Sludge Incinerator

In this study, the researchers have developed the greenhouse gas emission coefficients targeted at sewage sludge incineration plants that treat sewage sludge by incineration. Among the gases emitted from the sewage sludge incineration plants, the greenhouse gases showed concentrations of 6.84% for CO₂, 4.51 ppm for CH₄, and 86.34 ppm for N₂O; calculated into greenhouse gas emission coefficients, these gave 276.06 kg CO₂/ton, 0.0066 kg CH₄/ton, and 0.35 kg N₂O/ton. As the result of calculating the greenhouse gas emission quantity in sewage sludge incineration plants using the greenhouse gas emission coefficients, the gross greenhouse gas emission was 84.63 ton CO₂ eq./day, and the net emission was 23.90 ton CO₂ eq./day; this was 37.52 ton CO₂ eq./day less than the net greenhouse gas emission that was calculated using the standard values of IPCC, which was 61.42 ton CO₂ eq./day. This difference is probably because unlike the standard values of IPCC, the greenhouse gas emission coefficients of this study reflected the special properties of subject facilities. Thus, it is thought that emission coefficient research on the facilities that deviated from the standard values of IPCC should continue to achieve the development of national greenhouse gas coefficient that reflects the special properties of Korea.

Mathematical modelling of sewage sludge incineration in a bubbling fluidised bed with special consideration for thermally-thick fuel particles

Fluidised bed combustor (FBC) is one of the key technologies for sewage sludge incineration. In this paper, a mathematical model is developed for the simulation of a large-scale sewage sludge incineration plant. The model assumes the bed consisting of a fast-gas phase, an emulsion phase and a fuel particle phase with specific consideration for thermally-thick fuel particles. The model further improves over previous works by taking into account throughflow inside the bubbles as well as the floating and random movement of the fuel particles inside the bed. Validation against both previous lab-scale experiments and operational data of a large-scale industrial plant was made. Calculation results indicate that combustion split between the bed and the freeboard can range from 60/40 to 90/10 depending on the fuel particle distribution across the bed height under the specific conditions. The bed performance is heavily affected by the variation in sludge moisture level. The response time to variation in feeding rate is different for different parameters, from 6 min for outlet H2O, 10 min for O2, to 34 min for bed temperature.

Dynamic behaviour of sewage sludge incineration in a large-scale bubbling fluidised bed in relation to feeding-rate variations

In this paper, a mathematical model is developed for the simulation of a large-scale sewage sludge incineration plant. The model assumes the bed to consist of a fast gas phase, an emulsion phase and a fuel particle phase with specific consideration for thermally-thick fuel particles. The developed model is employed to predict the dynamic response of the bed combustion to fluctuations in sludge feeding-rate. Calculation results indicate that the bed combustion is sensitive to fluctuations with response times greater than 30 min, but severe delays exist for both outlet oxygen level and bed temperatures; from 6 to 13 min for O 2 and 22–45 min for temperatures. Depending on the fluctuation frequency, the corresponding phase shifts are 39–96° for outlet O 2, 138–336° for bed temperature and 80–336° for freeboard temperature.

Particle collection efficiency and particle re-entrainment of an electrostatic precipitator in a sewage sludge incineration plant.

In several recent studies it was shown that high atmospheric loads of submicrometer particles in the size range below 500 nm have strong impact on human health. Therefore, extensive research concerning the reduction of fine particle emissions is needed to further improve air quality. Regarding health effects, especially the emission characteristics of fine and ultrafine particles emerging from anthropogenic sources such as combustion processes are of special interest. This study shows that the emission characteristic of an electrostatic precipitator (ESP) due to re-entrainment of fine particles and their subsequent release into the atmosphere can be significantly lowered by application of different operating conditions. For this purpose the particle collection efficiency of an ESP was studied in a municipal sewage sludge incineration plant. Particles were sampled under different operating conditions upstream and downstream from the ESP, and the particle number concentrations were measured simultaneously with aerodynamic particle sizers. In addition, the size distribution of the particles downstream from the ESP was measured with high time resolution by an electrical low-pressure impactor to investigate the particle re-entrainment into the flue gas. To determine the influence of operating conditions, different rapping cycles were investigated regarding their impact on the collection efficiency and the subsequent particle re-entrainment.

Modeling the adsorption of mercury in the flue gas of sewage sludge incineration

Today, mercury is regarded as one of the most harmful substances for the environment. Therefore, legislation is setting increasingly strict flue gas emission limits. Since not in all existing incineration plants special concepts of mercury removal have been foreseen, problems to meet new low emission limit values may rise. Adsorbent injection is one way to reduce the mercury concentration of the flue gas which can in existing plants be installed upstream of the particle removal device. This paper presents a model for the mercury removal in the dust laden flue gas upstream of an electrostatic precipitator. After the investigation of different adsorbents in a laboratory test facility, the adsorption parameters are calculated and the model is used to show the influence of the governing parameters on the adsorption process and to simulate the efficiency of mercury capture in an existing sewage sludge incineration plant. The mercury removal with the fly ash as an adsorbent is simulated and compared with measurements obtained in an industrial plant.

Modeling the adsorption of mercury in the flue gas of sewage sludge incineration

Today, mercury is regarded as one of the most harmful substances for the environment. Therefore, legislation is setting increasingly strict flue gas emission limits. Since not in all existing incineration plants special concepts of mercury removal have been foreseen, problems to meet new low emission limit values may rise. Adsorbent injection is one way to reduce the mercury concentration of the flue gas which can in existing plants be installed upstream of the particle removal device. This paper presents a model for the mercury removal in the dust laden flue gas upstream of an electrostatic precipitator. After the investigation of different adsorbents in a laboratory test facility, the adsorption parameters are calculated and the model is used to show the influence of the governing parameters on the adsorption process and to simulate the efficiency of mercury capture in an existing sewage sludge incineration plant. The mercury removal with the fly ash as an adsorbent is simulated and compared with measurements obtained in an industrial plant.

Reducing the Mercury Emissions from a Sewage Sludge Incineration Plant

AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Abstract Elemental mercury, Hg°;, is not removed in conventional scrubber systems. If the Hg emission limit is to be met, expensive processes must be run. To avoid the high disposal cost of the entrained-bed product a process should be designed which reliably observes the emission limit and, at the same time, confines the problem and clearly reduces waste arisings from offgas purification. Citing Literature Volume21, Issue2February 1998Pages 161-165 RelatedInformation

A design model of sewage sludge incineration plants with energy recovery

A design model of sewage sludge incineration plants has been developed to examine the possibilities for energy recovery. It was evident that, without sludge drying, there was a high fuel (methane) consumptions (149-192 Nm3/t sludge cake at 25% concentrations), but considerable amount of electric energy is obtainable (391-515 kWh/t sludge cake). Sizes of boiler and whole exhaust gases treatment line are in this case quite large. On the contrary, fuel consumption can be lowered down to 20 Nm3/t sludge cake at 44% concentration by introducing sludge drying. In this case fuel is needed only in the afterburning chamber, as the combustion in the fluidized bed furnace is autothermal. Boiler and exhaust gas treatment line are considerably reduced in size when power production is not performed, thus allowing a simpler and smaller plant to be designed.