Sewage Sludge Incineration Research Articles

Development strategy of environmentally friendly sewage sludge incineration technologies in Bureau of Sewerage Tokyo Metropolitan Government

Development strategy of environmentally friendly sewage sludge incineration technologies in Bureau of Sewerage Tokyo Metropolitan Government

下水汚泥焼却灰に含まれる金の選択的分離回収

下水汚泥焼却灰に含まれる金の選択的分離回収

Cesium Speciation in Dust from Municipal Solid Waste and Sewage Sludge Incineration by Synchrotron Radiation Micro-X-ray Analysis.

The chemical behavior of Cs in waste incineration processes is important to consider when disposing of radionuclide-contaminated waste from the Fukushima Daiichi nuclear power plant accident in Japan. To determine the speciation of Cs, we attempted the direct speciation of trace amounts of stable Cs in the dust from municipal solid waste incineration (MSWI) and sewage sludge incineration (SSI) by micro-X-ray fluorescence (μ-XRF) and micro-X-ray absorption fine structure (μ-XAFS) at the SPring-8 facility. The μ-XRF results revealed that locally produced Cs was present in MSWI and SSI dust within the cluster size range of 2-10 μm. The μ-XAFS analysis confirmed that the speciation of Cs in MSWI dust was similar to that of CsCl, while in SSI dusts it was similar to pollucite. The solubility of Cs was considered to be influenced by the exact Cs species present in incineration residue.

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.

Sewage sludge ash — A promising secondary phosphorus source for fertilizer production

Sewage sludge incineration is extensively practiced in some European countries such as the Netherlands, Switzerland, Austria and Germany. A survey of German sewage sludge ash showed that the recovery potential is high, approx. 19,000t of phosphorus per year. However, the survey also discovered that the bioavailability of phosphorus in the sewage sludge ash is poor and that more than half of the ashes cannot be used as fertilizers due to high heavy metal content. A new thermochemical process for sewage sludge ash treatment was developed that transforms the ash into marketable fertilizer products. Sewage sludge ash was thermochemically treated with sodium and potassium additives under reducing conditions, whereby the phosphate-bearing mineral phases were transformed into plant available phosphates. High P-bioavailability was achieved with a molar Na/P ratio >1.75 in the starting materials. Sodium sulfate, carbonate and hydroxide performed comparably as additives for this calcination process. Potassium carbonate and -hydroxide have to be added in a molar K/P ratio >2.5 to achieve comparable P-solubility. The findings of the laboratory scale investigations were confirmed by an industrial demonstration trial for an ash treatment with sodium sulfate. Simultaneously, the volatile transition metal arsenic (61% removal) as well as volatile heavy metals such as cadmium (80%), mercury (68%), lead (39%) and zinc (9%) were removed via the off-gas treatment system. The product of the demonstration trial is characterized by high bioavailability and a toxic trace element mass fraction below the limit values of the German fertilizer ordinance, thus fulfilling the quality parameters for a P-fertilizer.

Mechanisms and kinetics of granulated sewage sludge combustion

This paper investigates sewage sludge disposal methods with particular emphasis on combustion as the priority disposal method. Sewage sludge incineration is an attractive option because it minimizes odour, significantly reduces the volume of the starting material and thermally destroys organic and toxic components of the off pads. Additionally, it is possible that ashes could be used. Currently, as many as 11 plants use sewage sludge as fuel in Poland; thus, this technology must be further developed in Poland while considering the benefits of co-combustion with other fuels.This paper presents the results of experimental studies aimed at determining the mechanisms (defining the fuel combustion region by studying the effects of process parameters, including the size of the fuel sample, temperature in the combustion chamber and air velocity, on combustion) and kinetics (measurement of fuel temperature and mass changes) of fuel combustion in an air stream under different thermal conditions and flow rates. The combustion of the sludge samples during air flow between temperatures of 800 and 900°C is a kinetic–diffusion process. This process determines the sample size, temperature of its environment, and air velocity. The adopted process parameters, the time and ignition temperature of the fuel by volatiles, combustion time of the volatiles, time to reach the maximum temperature of the fuel surface, maximum temperature of the fuel surface, char combustion time, and the total process time, had significant impacts.

하수슬러지 소각재와 무기바인더를 이용한 응용 블록 개발 II

하수슬러지 소각재와 무기바인더를 이용한 응용 블록 개발 II

A substance flow analysis of phosphorus in the food production, processing and consumption system of the Netherlands

Phosphorus (P) is an essential nutrient in agriculture. In recent years 15–18 Mt of P was used as mineral fertilizer in the global food production chain. The major source of this fertilizer is phosphate rock which is unfortunately a finite resource. In the long term this necessitates efficient use of fertilizer and optimized recycling of P rich waste streams (including manure). In order to determine the potential for sustainable use of P we performed a 3-year substance flow analysis (SFA) for the Netherlands, a country characterized by its intensive agriculture and a high livestock density. Such conditions occur in various regions of the world and can easily result either in environmental problems or an unsustainable use of P. Annual quantification of P flows were performed in 2005, 2008 and 2011. These were not restricted to agriculture. Industrial, household/retail and the environmental P-flows were also included. Due to relatively high quantities of feed imports, the national P-surplus amounted to almost 60 Mkg P in 2005, decreasing to 42 Mkg in the year 2011. A large proportion of this reduction was considered to be due to reductions in P fertilizer use. The SFA provided an insight into the fate of the national P surplus and the potential for recycling. In 2011 the major part of the 42 Mkg of P surplus was observed in waste streams from society (23 Mkg, e.g. sewage sludge incineration ashes, household refuse). During this study these waste streams were not reused within the national food production system or elsewhere. The remainder of the surplus accumulated in agricultural soils (around 12 Mkg) or were emitted through surface water (almost 7 Mkg).

Fate of Nitrogen during Fluidized Incineration of Sewage Sludge. Estimation of NO and N2O Content in the Exhaust Gas

This work aims at studying the chemical mechanisms responsible for the formation and destruction of nitrogen oxides during combustion of sewage sludge in a fluidized bed. To do so, a mathematical model has been built in order to represent the relevant phenomena occurring within the reactor and estimate the nitrous emissions as a function of the operating parameters. An important modeling effort has been done in order to predict what becomes of nitrogen initially present in the sludge. The final model allows computing the local concentration of NO, N2O, NO2, HCN, and NH3 at every location of the bed. Numerical estimations of the model are compared to experimental results obtained at industrial scale in a fluidized bed combustor (for which thermal equilibrium is reached using extra gas). This comparison is very good, allowing one to use the model for design and optimization of such reactors.

The investigation of solid slag obtained by neutralization of sewage sludge

The purpose of this research is to investigate the feasibility of utilizing the slag collected after gasification of organic fuel combined with sewage sludge. The residue left after gasification process is likely usable as raw material for production of supercondensers. The sewage sludge neutralization system consists of a dosing system (fuel tank), gasifier, plasma reactor, electrostatic filter, and heat exchangers. For the gasification process, dried solid sewage is supplied in proportion of 70% to biomass 30% by weight. The slag is collected in a specially designed chamber beneath the gasifier. A scanning electron microscope (SEM) was used to evaluate surface morphology of the samples. Elemental analysis of the sewage sludge slag was performed using the energy-dispersive spectroscopy (EDS) method, which showed different solid-state elements contained in the porous structure of the solid phase: carbon 29%, aluminum 26%, potassium 20%, chlorine 1%, and others. The specific surface area of the sewage sludge slag is 6.15 m2/g as the BET analysis shows. In order to use the slag as a secondary raw material, detailed analysis of the structure and properties is necessary for a decision on whether the slag left after gasification of sewage sludge is suitable for any further usages. Initial results indicate that the slag may be used for production of electrodes for supercapacitors.Implications: Every year thousands of tons of sewage sludge are formed in Lithuania. Sewage sludge consists of organic and inorganic compounds. Partial combustion, plasma decomposition, and other methods are used to neutralize the sewage sludge. The incineration of sewage sludge results in generation of solid-phase slag. In this paper the material structure and composition of a solid slag (formed during neutralization of sewage sludge) is considered. Also, the impact the ambient temperature on structure and composition of solid slag is analyzed.

Transformation of apatite phosphorus and non-apatite inorganic phosphorus during incineration of sewage sludge

The recovery of phosphorus from incinerated sewage sludge ash (SSA) is assumed to be economical. Transformation from non-apatite inorganic phosphorus (NAIP) to apatite phosphorus (AP), which has a higher bioavailability and more extensive industrial applications, was studied at 750–950°C by sewage sludge incineration and model compound incineration with a calcium oxide (CaO) additive. Thermogravimetric differential scanning calorimetry analysis and X-ray diffraction measurements were used to analyze the reactions between NAIP with CaO and crystallized phases in SSA. High temperatures stimulated the volatilization of NAIP instead of AP. Sewage sludge incineration with CaO transformed NAIP into AP, and the percentage of AP from the total phosphorus reached 99% at 950°C. Aluminum phosphate reacted with CaO, forming Ca2P2O7 and Ca3(PO4)2 at 750–950°C. Reactions between iron phosphate and CaO occurred at lower temperatures, forming Ca(PO3)2 before reaching 850°C.

An experimental and thermodynamic equilibrium investigation of the Pb, Zn, Cr, Cu, Mn and Ni partitioning during sewage sludge incineration

The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals (Pb, Zn, Cr, Cu, Mn and Ni) during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the FactSage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb>Zn>Cr>Cu>Mn>Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni. With increasing combustion temperature, the presence of organic-Cl (PVC) and inorganic-Cl (NaCl) improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However, the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed PbSiO4 and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl2, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl2, Pb(ClO4)2 and PbCl2O4.

Leachability of heavy metals from lightweight aggregates made with sewage sludge and municipal solid waste incineration fly ash.

Lightweight aggregate (LWA) production with sewage sludge and municipal solid waste incineration (MSWI) fly ash is an effective approach for waste disposal. This study investigated the stability of heavy metals in LWA made from sewage sludge and MSWI fly ash. Leaching tests were conducted to find out the effects of MSWI fly ash/sewage sludge (MSWI FA/SS) ratio, sintering temperature and sintering time. It was found that with the increase of MSWI FA/SS ratio, leaching rates of all heavy metals firstly decreased and then increased, indicating the optimal ratio of MSWI fly ash/sewage sludge was 2:8. With the increase of sintering temperature and sintering time, the heavy metal solidifying efficiencies were strongly enhanced by crystallization and chemical incorporations within the aluminosilicate or silicate frameworks during the sintering process. However, taking cost-savings and lower energy consumption into account, 1100 °C and 8 min were selected as the optimal parameters for LWA sample- containing sludge production. Furthermore, heavy metal leaching concentrations under these optimal LWA production parameters were found to be in the range of China’s regulatory requirements. It is concluded that heavy metals can be properly stabilized in LWA samples containing sludge and cannot be easily released into the environment again to cause secondary pollution.

Simultaneous catalytic reduction of N2O and NOx produced in a fluidized bed incineration of sewage sludge

AbstractFluidized bed incineration of sewage sludge could produce large amounts of N2O due to the relatively high nitrogen content of the sewage sludge and low incineration temperatures. In this study, N2O and NOx emissions released during the fluidized bed incineration of dried sewage sludge powder were investigated. Sewage sludge feeding rate was about 8∼10 kg/h, and bed aspect ratio was fixed to ca. 1.2. Superficial velocity was adjusted to ca. 1.9 m/s. The concentrations of N2O and NOx in the exhaust gas were greatly influenced by bed temperature in a range between 850 °C and 950 °C. In the simultaneous catalytic reduction of N2O and NOx on an Fe/BEA pellet catalyst with NH3, most of the N2O and NOx were removed when heated above the inlet reaction temperature 410 °C. Thus, simultaneous catalytic reduction was shown to be a promising N2O abatement technology for the fluidized bed incineration of sewage sludge. © 2015 Society of Chemical Industry and John Wiley & Sons, Ltd

Emission of Particulate Matter 2.5 (PM2.5) from Sewage Sludge Incinerators in Japan

Because fine particulate matter ≤2.5 µm in diameter (PM2.5) causes health problems, PM2.5 emissions are of concern. However, little research on stationary sources has been conducted. To determine the concentration and filtration behavior of PM2.5, dust was collected from five fluid-bed sewage sludge incinerators (SSIs) sorted by particle size using cascade impactors. The average PM2.5 concentration was 0.00014–4.8 mg/Nm3. The total estimated amount of PM2.5 emissions from the SSIs for all plants in Japan was 0.96–8.9 tons/year. Since the SSIs with dry Electrostatic Precipitators (EP) contributed 75–99% of the total emissions, replacing dry EPs with bag filters would significantly reduce the PM2.5 emissions from SSI.

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

The 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 ratios was found under the oxy-combustion conditions.

Recovery potential of German sewage sludge ash

Incineration of sewage sludge is expected to increase in the future due to growing concerns about the direct use of sludge in agriculture. Sewage sludge is the pollutant sink of wastewater treatment and thus loaded with contaminants that might pose environmental hazards. Incineration degrades organic pollutants efficiently, but since the ash is currently mostly disposed of, all valuable component like phosphorus (P) and technologically relevant metals present in the sewage sludge ash (SSA) are removed from the economic cycle entirely. We conducted a complete survey of SSA from German mono-incineration facilities and determined the theoretical recovery potential of 57 elements. German SSA contains up to 19,000t/a P which equals approximately 13% of phosphorus applied in the German agriculture in form of phosphate rock based mineral fertilizers. Thus, SSA is an important secondary resource of P. However, its P-solubility in ammonium citrate solution, an indicator for the bioavailability, is only about 26%. Treatment of SSA is recommended to enhance P bioavailability and remove heavy metals before it is applied as fertilizer. The recovery potential for technologically relevant metals is generally low, but some of these elements might be recovered efficiently in the course of P recovery exploiting synergies.

A biomass power generation system combined with sewage sludge incineration

A biomass power generation system combined with sewage sludge incineration

Using ash from incineration of municipal sewage sludge to fertilize Virginia Fanpetals

Using ash from incineration of municipal sewage sludge to fertilize Virginia Fanpetals

Energy Saving and Generation on Innovative Sewage Sludge Incineration System

Energy Saving and Generation on Innovative Sewage Sludge Incineration System