Sewage Sludge Incineration Research Articles

Influence of Sludge Incineration Ash on Ryegrass Growth and Soil Phosphorus Status

Phosphorus (P) is a limited resource that could be depleted. Consequently, recycling the P contained in sewage sludge, including sewage sludge incineration ash (SIA), from wastewater treatment plants is a possibility to be explored. A greenhouse experiment using annual ryegrass (Lolium multiflorum L.) was performed with an experimental design of three completely randomized blocks of two soils and 29 treatments: one control without P and two levels of 9 and 26 kg total P ha−1 from 14 different sources: twelve SIAs (not contaminated by trace metals) from the US and Canada, one commercial synthetic fertilizer (triple superphosphate (TSP)), and one commercial rock phosphate (RP). Higher ryegrass biomass levels were achieved at the higher fertilization rate (26 kg total P ha−1) and when using the SIAs with the highest P solubility percentage (PSP) (≥ 54% of total P). The biomass increases following SIA application were as high as 29% and 59% more than the control for the sandy loam and clayey soil, respectively, but 40% less than in TSP for both soils. A similar behavior was observed for P uptake, with a maximum increase of 26% for the clayey soil, and 165% for the sandy loam soil. The ryegrass biomass and P uptake increases due to SIA application were larger than those due to RP application in the clayey soil, but similar to those in the sandy loam soil. The SIAs with a PSP of ≥ 54% significantly increased soil available P stocks and saturation. According to our findings, we conclude that the SIAs from municipal and agrifood industries have a potential for P agricultural recycling, but their efficiencies vary.

Influence of temperature and C/N ratio on nitrifying and denitrifying bacteria of biofilters treating wastewater from de-icing airport runways

One of the key elements in the operational management of airports is effective de-icing of surfaces. The run-off of precipitation water loaded with pollutants from de-icing is a considerable and costly problem. The aim of our research has been to evaluate the applicability of biofilters filled with light expanded clay aggregate (LECA) generated from incineration of sewage sludge and now serving as a matrix for the development of microorganisms. The tested biofilters treated precipitation water polluted with agents used to de-ice airports. The solution was tested on a laboratory scale, in a range of temperatures from 0 to 25°C, and at concentrations of pollutants from airport de-icing expressed as COD and varying from 503.30 to 3827.50 mg O2·L-1. The tested filling allowed nitrifying as well as denitrifying bacteria to grow and develop even at low temperatures. Biofilters provide simultaneous nitrification and denitrification, as well as removal of organic compounds, even at 0°C. Biofilters based on the granulate prepared from fly ash from sewage sludge thermal treatment can be a cost-efficient and low-maintenance technology to treat airport surface runoff.

Transformation of cerium dioxide nanoparticles during sewage sludge incineration

The incineration of sewage sludge leads to the incorporation of Ce from CeO2 nanoparticles into mineral structures.

Deep eutectic solvents as extraction media for metal salts and oxides exemplarily shown for phosphates from incinerated sewage sludge ash

Deep eutectic solvents (DESs) based on natural products can be used as selective extraction media for a wide variety of metal salts and oxides and specifically for phosphates from incinerated sewage sludge ash (ISSA).

Effective adsorption of lead ions using fly ash obtained in the novel circulating fluidized bed combustion technology

Fly ash was examined for the separation efficiency of Pb2+ ions from water in batch experiments. Fly ash is industrial waste produced from the incineration of sewage sludge by the novel circulating fluidized bed combustion (CFBC) technology and was taken into the experiments. Physical and chemical properties of the material were characterized using several methods, such as fraction analysis, particle size distribution, bulk density, composition, morphology, surface and internal structure by elemental analysis, FT-IR, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis, comprehensive thermal analysis, fly ash texture by BET adsorption isotherms, specific surface area, volume of pores, average pore diameter and pore volume distribution by the BJH method. The influence of pH values on zeta potential of the fly ash surface before and after the adsorption process was conducted. The calculated maximum adsorption capacity of Pb2+ by fly ash reached 51.98 mg/g. The kinetic analysis revealed that the adsorption process is better described by the pseudo-second order equation and it is well fitted to the Freundlich model. In conclusion, fly ash obtained in the CFBC technology is a promising low cost adsorbent for the highly effective recovery of Pb2+ from wastewater.

Fixation capability of recycling materials as potential additives for cesium immobilization in contaminated forest soil

The fixation capability of cesium on five recycling materials was compared through two sets of sorption experiments using the materials mixed with and without soil. The estimated Freundlich constant K and the distribution of sorbed cesium on the materials revealed a general order of the fixation capability as carbonized sludge > coconut shell biochar > incinerated sewage sludge ash > rice husk biochar > slag. Parametric strong positive correlations were found existent between the fixation capability of cesium and the property-related indexes of the materials such as cation exchange capacity, organic matter content and the potassium concentration.

Transforming waterworks sludge into controlled low-strength material: Bench-scale optimization and field test validation

In order to reduce landfill disposal of waterworks sludge (alum sludge) and incinerated sewage sludge ash (ISSA), this study proposed an innovative approach for upcycling them into value-added controlled low-strength materials (CLSM). Waterworks sludge interfered with cement hydration reaction and delayed the stiffening time of CLSM (>10 h) due to its high organics content (5%). The addition of triethanolamine (TEA) with a dosage of 0.1 wt% of binder effectively shortened the stiffening time to 4.5 h. The lab-scale results suggested that the optimal CLSM design (6% cement, 14% ISSA, 8% sludge, and 72% recycled fine aggregate at a water/binder ratio of 1.2) complied with the standard requirement of flowability (>200 mm), stiffening time (<5 h), and compressive strength (0.3–2.1 MPa). The pilot-scale field tests further confirmed that the sludge-incorporated CLSM achieved a high flowability (220 mm), short stiffening time (4 h), low compressive strength (1.38 MPa), and easy re-excavatability after 3 months. This study demonstrated that waterworks sludge can be potentially transformed into sustainable construction materials for urban development.

Novel synergy of Si-rich minerals and reactive MgO for stabilisation/solidification of contaminated sediment.

Disposal of significant amounts of dredged contaminated sediment poses an economic and environmental problem worldwide. Transforming contaminated sediment into value-added construction materials using low-carbon MgO cement is a sustainable option; however, the weak mechanical strength and unreliable water-solubility of MgO cement restrict its practical engineering applications. This study elucidates the potential role of industrial Si-rich minerals in the performance enhancement of MgO-based products via the promotion of magnesium silicate hydrate (M-S-H) gel formation. Quantitative X-ray diffraction and 29Si nuclear magnetic resonance analyses indicated that compositions and crystallinities of the Si-rich minerals significantly influence the formation and polymerisation of the M-S-H gel. Pulverised fly ash was found to be a promising Si-rich mineral for generating polymeric M-S-H gel, whereas incinerated sewage sludge ash samples demonstrated a low degree of polymerisation, and the use of glass powder samples gave a low yield of M-S-H. The formation of M-S-H gel enhanced the compressive strength and water resistance (strength retention after water immersion). Further experiments demonstrated that Si-modified MgO cement can transform dredged sediment into fill materials with satisfactory mechanical properties and contaminant immobilisation. Therefore, the synergy between reactive MgO and Si-rich industrial waste is a novel option for sustainable remediation and environmental applications.

Understanding the Behavior of Radioactive Cesium during the Incineration of Contaminated Municipal Solid Waste and Sewage Sludge by Thermodynamic Equilibrium Calculation.

Following the nuclear accident at the Fukushima Daiichi Nuclear Power Plant in 2011, even the municipal solid waste (MSW) and sewage sludge (SS) in northeastern Japan became contaminated by radioactive nuclides such as 137Cs and 134Cs. To understand the state of radioactive cesium (r-Cs) in the incineration residues of the municipal wastes, research groups studied the concentration and the chemical form of r-Cs in the residues, as well as its water-leaching behavior. In the present study, we conducted thermodynamic equilibrium calculations to estimate the possible chemical forms of r-Cs in the incineration residues. Thermodynamic data for cesium oxides and aluminosilicates were collected and compiled into a new database to perform equilibrium calculations for systems that include Cs. The calculation results suggested that Cs (radiocesium and stable cesium) in municipal solid waste was transformed into gaseous CsCl or crystalline aluminosilicate at incineration temperatures and, when a molten aluminosilicate phase (i.e., slag phase) was generated, a proportion of the Cs species was dissolved into the slag phase. In the case of sewage sludge, Cs was calculated to be transformed mostly into crystalline aluminosilicate at incineration temperatures, whereas by analogy with the behaviors of Na and K, Ca,Cs-phosphate double salts were also potential incineration products. These results could account for the high leaching rates of r-Cs from the MSW incineration fly ash and the low leaching rates from the MSW incineration bottom ash and SS incineration fly ash reported in earlier studies. In the case of dewatered SS that included a large amount of slaked lime as a flocculant, it was exceptionally difficult for the calculation to represent the fate of Cs, and we needed to include the contribution of silica sand in a fluidized-bed combustor in the equilibrium calculation to represent the low leaching rates of alkali species from the dewatered SS fly ash. From the results of the thermodynamic equilibrium calculations and also from the calculated standard Gibbs energy of cesium aluminosilicate formation/decomposition reactions, the effects of waste composition and incineration temperature on the fate of Cs were examined: High incineration temperature and large amounts of Ca and Cl in the waste composition increased the fraction of gaseous CsCl in the furnace and thus resulted in the high distribution ratios of Cs in the fly ash of MSW and the high leaching rates of Cs from the fly ash.

Solidification and Stabilization of Sewage Sludge and MSWI Bottom Ash for Beneficial Use as Construction Materials

AbstractThis paper investigates the feasibility of converting municipal sewage sludge and municipal solid waste incineration (MSWI) bottom ash to a construction material for the dikes of a sludge-o...

Residues from Sewage Sludge Incineration for Ceramic Products with Potential for Zinc Stabilization

Serious environmental pollution has been frequently caused by the release of heavy metals from wastes generated from industrial activities. Although some of the heavy metals can be stabilized in ceramic matrix, the replacement of traditional ceramic precursors is needed due to adverse effects caused by clay mining. With abundant contents of aluminum, iron and silicon, the beneficial use of residues from sewage sludge incineration processes has attracted much attention. In this study, ZnO was simulated as zinc-bearing industrial waste, and the stabilization of zinc was achieved in aluminum- and iron-rich ceramic matrix provided by the residues of sewage sludge incineration. Through a 3-h sintering procedure at temperatures ranging from 650 to 1350 °C, zinc was found to be incorporated into a ZnAlxFe2-xO4 spinel solid solution and the incorporation was greatly enhanced by the elevated temperature. The leachability of zinc was found to decline substantially with the continuous formation of the spinel when the samples were extracted in acidic, neutral and basic environments. Besides the effective stabilization of zinc, aluminum and iron can also be well immobilized in the sintered ceramic products. The temperature range of 950-1250 °C was found to be promising to reach the most satisfactory zinc stabilization without extra energy consumption, and to fabricate ceramic products with a variety of microstructures for future application. Therefore, the residues from the sewage sludge incineration can be blended into the existing ceramic sintering processes for making marketable products, which will further alleviate the environmental burden caused by heavy metal release from industrial wastes.

Fertiliser from sewage sludge ash instead of conventional phosphorus fertilisers?

Recycling of phosphorus (P) from municipal waste for the use as a fertiliser can be an alternative to the non-renewable resources of this element as well as a method in the management of civilisation by-products that are a burden to the environment. An innovative phosphorus suspension fertiliser, produced on the basis of ash from incineration of sewage sludge and phosphorus solubilising bacteria Bacillus megaterium was compared in field trials with spring wheat conducted in 2014 and 2015 with superphosphate and phosphorite. The new fertiliser was not inferior to the commercial fertilisers in terms of the effect on wheat yield volumes, the uptake of P by wheat and the sanitary condition of the wheat field, especially when grown protected from weeds, pathogens and pests. It is expected that such a fertiliser can be an alternative to fertilisers produced from non-renewable resources, provided it does not deteriorate the quality of agricultural production and will be safe for the environment.

(Co-)combustion of additives, water hyacinth and sewage sludge: Thermogravimetric, kinetic, gas and thermodynamic modeling analyses

Additives and biomass were co-combusted with sewage sludge (SS) to promote SS incineration treatment and energy generation. (Co-)combustion characteristics of sewage sludge (SS), water hyacinth (WH), and 5% five additives (K2CO3, Na2CO3, Mg2CO3, MgO and Al2O3) were quantified and compared using thermogravimetric-mass spectrometric (TG-MS) and numerical analyses. The combustion performance of SS declined slightly with the additives which was demonstrated by the 0.03-to-0.25-fold decreases in comprehensive combustibility index (CCI). The co-combustion performed well given the 0.31-fold increase in CCI. Kinetic parameters were estimated using the Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose (KAS) methods. Apparent activation energy estimates by OFW and KAS were consistent. The addition of K2CO3 and MgCO3 decreased the weighted average activation energy of SS. Adding K2CO3 to the blend reduced CO2, NO2, SO2, HCN and NH3 emissions. CO2, NO2 and SO2 emissions were higher from WH than SS. Adding WH or K2CO3 to SS increased CO2, NO2 and SO2 but HCN and NH3 emissions. Based on both catalytic effects and evolved gases, K2CO3 was potentially an optimal option for the catalytic combustion among the tested additives.

Improved utilization of phosphorous from sewage sludge (as Fertilizer) after treatment by Low-Temperature combustion

The utilization of phosphorus from sewage sludge is an important method used to solve the shortage of phosphorus resources in the world. However, high levels of toxic compounds and low phosphorus bioavailability in sewage sludge are the main factors limiting its direct agricultural use. This paper proposes a low-temperature combustion method that can enrich the phosphorus in sludge ash. Low temperature-treated sewage sludge ash (LTSA) at different oxygen concentrations (20%, 60%, 100%) were obtained through a specific experimental device. Then, the species and leaching characteristics of phosphorus in LTSAs were analyzed and compared with pyrolysis sewage sludge char (PSSC) and incinerated sewage sludge ash (ISSA). Results show that low-temperature combustion of sludge increased the total phosphorus content in the bottom ash by 45.6%, and the bioavailable phosphorus content increased 2.9 times. Further, by increasing the concentration of oxygen while carrying out low-temperature combustion of sludge, part of the non-apatite inorganic P was converted to apatite P (AP), resulting in a 46.3% increase in AP in the sludge. Low-temperature combustion can also convert heavy metals (Cd, Cr, Cu, Pb, and Zn) in the sludge from an easily leachable form (acid extractable fraction and reducible fraction) to a stable form (reducible fraction) and decrease the leaching of heavy metals. Leaching of Cr and Cu decreased by 97.56% and 98.52%, respectively.

Phosphorus Transformation from Municipal Sewage Sludge Incineration with Biomass: Formation of Apatite Phosphorus with High Bioavailability

Phosphorus (P) is an essential and limited nutrient element for all life. The recovery and reuse of P from municipal sewage sludge (MSS) incineration fly ash are considered to be practical and econ...

Effect of the Addition of Biomass on the Fate and Speciation of Arsenic during Sewage Sludge Combustion

Arsenic (As) emission during sewage sludge incineration is harmful to the ecology and environment. Adding biomass to sewage sludge was proposed to facilitate the conversion of As3+ to As5+ with low toxicity during combustion. In this study, co-firing tests of two sewage sludge samples and four biomass samples were carried out to determine the migration and transformation of arsenic. The results show that the addition of biomass to municipal sewage sludge (MSS) facilitates the fixation of As in bottom ash in the combustion process. During combustion of MSS with biomass, mineral compounds in biomass, such as CaO, Ca2SiO4, or CaSO4, can afford additional reactive sites for the oxidation of arsenic by producing multifarious arsenates, and the availability of mineral active sites in cotton stalk (CTS) and corn stalk (CRS) is higher than that in wood and wheat straw (WS). The inherent mineral compounds in industrial sewage sludge (ISS), such as CaO and Ca2SiO4, provide sufficient reactive sites for the complete...

Fossil Carbon Fraction and Measuring Cycle for Sewage Sludge Waste Incineration

In this study, the fossil carbon contents of the two facilities were analyzed using 10 or more samples for each facility from June 2013 to March 2015. In addition, the optimal measurement period was calculated from the analyzed fossil carbon contents using a statistical method. As a result of the analysis, the fossil carbon contents were found to be less than 35%, indicating that the biomass content of sewage sludge was not 100%. The fossil carbon content could be representative of using yearly period measurements value. When calculating Green house gas (GHG) emissions from waste incineration, South Korea has been calculating only Non-CO2 emissions because it regarded the CO2 emitted in GHGs from sewage sludge (SS) incineration facilities as originating from biomass. However, biomass of the sewage sludge incineration facility is not 100%, so it is necessary to estimate the greenhouse gas emissions considering the fossil carbon content. Therefore, there is a need to increase the reliability of the greenhouse gas inventory by conducting further studies (such as CO2 concentration analysis) related to the calculation of CO2 emissions for the relevant facilities (sewage sludge incinerator).

Determination of hygrothermal properties of cementitious mortar: The effect of partial replacement of cement by incinerated sewage sludge ash

Two sewage sludge ashes were used as substitutes for cement and their effect on the hygrothermal properties of mortar was examined. Different cement to ash ratios and two ash pre-treatment methods (water washing and grinding) were in focus. The impact of cement replacement by sewage sludge ashes on thermal conductivity, sorption isotherms, water vapour permeability and carbonation was described with standard cement-based mortar as the reference material. Measurement results showed that thermal conductivity decreased by 15% when 30% of the cement was replaced by sewage sludge ash. Water vapour permeability increased as the cement to ash ratio was reduced. Sorption was tested by two methods; although differences in the sorption isotherms of mortars were reported when a climatic chamber method was applied, no differences, or only minor differences, were observed with the desiccator method. Measurements revealed that cement-based mortar possessed a higher content of carbonate than cement-ash-based mortar, and it thus appears that the carbonation rate was higher when the cement content was high.

Potential Source Apportionment and Meteorological Conditions Involved in Airborne 131I Detections in January/February 2017 in Europe

Traces of particulate radioactive iodine (131I) were detected in the European atmosphere in January/February 2017. Concentrations of this nuclear fission product were very low, ranging 0.1 to 10 μBq m-3 except at one location in western Russia where they reached up to several mBq m-3. Detections have been reported continuously over an 8-week period by about 30 monitoring stations. We examine possible emission source apportionments and rank them considering their expected contribution in terms of orders of magnitude from typical routine releases: radiopharmaceutical production units > sewage sludge incinerators > nuclear power plants > spontaneous fission of uranium in soil. Inverse modeling simulations indicate that the widespread detections of 131I resulted from the combination of multiple source releases. Among them, those from radiopharmaceutical production units remain the most likely. One of them is located in Western Russia and its estimated source term complies with authorized limits. Other existing sources related to 131I use (medical purposes or sewage sludge incineration) can explain detections on a rather local scale. As an enhancing factor, the prevailing wintertime meteorological situations marked by strong temperature inversions led to poor dispersion conditions that resulted in higher concentrations exceeding usual detection limits in use within the informal Ring of Five (Ro5) monitoring network.

Calculation of the Parameters of Combustion Products of Sewage Sludge

The problems associated with the use of existing thermal installations for the incineration of sewage sludge and the design of new structures are considered. The results obtained by calculating the chemical and phase equilibria are presented. Recommended optimal ratio of primary and secondary air flow rates with its step-by-step approach.