scholarly journals Sewage Sludge Bottom Ash Characteristics and Potential Application in Road Embankment

2019 ◽  
Vol 12 (1) ◽  
pp. 39 ◽  
Author(s):  
Katarzyna Zabielska-Adamska
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Bottom Ash ◽  
Construction Materials ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Natural Soil ◽  
Incineration Plant ◽  
Heavy Metal Concentrations ◽  
Soil Solutions

The paper focuses on sustainability-related applications in civil engineering by using environmentally friendly, alternative construction materials. The paper presents geotechnical properties of thermally converted, municipal sewage sludge in a grate furnace in an incineration plant. Bottom ash and its mixture with sand have been tested to show that they can be considered as a substitute for natural soil built-in road embankments. The product of sewage sludge combustion and its combination with sand meet all code requirements for material suitable for road embankments. As a result of the 30% reduction of resistance to failure values after waste soaking, which causes relatively low California Bearing Ratio (CBR) values of soaked waste, waste should be built into places isolated from groundwater and precipitation. That is also indicated by the possibility of heavy metals leaching from the waste because such content is much higher than in uncontaminated soils, although leaching does not exceed the limits commonly quoted for natural soil solutions. Tested bottom ash as a product of combustion in a grate furnace is a more preferred material for earthworks than fly ash generated during incineration in a furnace with fluidized bed due to the particle size and heavy metal concentrations.

scholarly journals Co-Combustion of Municipal Sewage Sludge and Biomass in a Grate Fired Boiler for Phosphorus Recovery in Bottom Ash

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1708 ◽  
Author(s):  
Andreas Nordin ◽  
Anna Strandberg ◽  
Sana Elbashir ◽  
Lars-Erik Åmand ◽  
Nils Skoglund ◽  
...  
Keyword(s):  
Heavy Metals ◽  
European Union ◽  
Sewage Sludge ◽  
Fixed Bed ◽  
Bottom Ash ◽  
Phosphorus Recovery ◽  
Fixed Bed Reactor ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Critical Element

Phosphorus has been identified as a critical element by the European Union and recycling efforts are increasingly common. An important phosphorus-containing waste stream for recycling is municipal sewage sludge (MSS), which is used directly as fertilizer to farmland. However, it contains pollutants such as heavy metals, pharmaceutical residues, polychlorinated bi-phenyls (PCBs) and nano-plastics. The interest in combustion of MSS is continuously growing, as it both reduces the volume as well as destroys the organic materials and could separate certain heavy metals from the produced ashes. This results in ashes with a potential for either direct use as fertilizer or as a suitable feedstock for upgrading processes. The aim of this study was to investigate co-combustion of MSS and biomass to create a phosphorus-rich bottom ash with a low heavy metal content. A laboratory-scale fixed-bed reactor in addition to an 8 MWth grate-boiler was used for the experimental work. The concentration of phosphorus and selected heavy metals in the bottom ashes were compared to European Union regulation on fertilizers, ash application to Swedish forests and Swedish regulations on sewage sludge application to farmland. Element concentrations were determined by ICP-AES complemented by analysis of spatial distribution with SEM-EDS and XRD analysis to determine crystalline compounds. The results show that most of the phosphorus was retained in the bottom ash, corresponding to 9–16 wt.% P2O5, while the concentration of cadmium, mercury, lead and zinc was below the limits of the regulations. However, copper, chromium and nickel concentrations exceeded these standards.

Decontamination of Heavy Metals From Municipal Sewage Sludge (MSS) by Electrokinetic Remediation

2019 ◽  
Author(s):  
A. Ribeiro ◽  
J. Araújo ◽  
A. Mota ◽  
R. Campos ◽  
C. Vilarinho ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Operation Time ◽  
Electrokinetic Remediation ◽  
Permeable Reactive Barrier ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Reactive Barrier

Abstract A large quantity of sludges resulting from the treatment of MWWTP (Municipal Wastewater Treatment Plant) effluent is generated annually following the increase of population density and acceleration of urbanization. Sludge production in Europe has been predicted by around 12 million tons in 2020. As a solid waste, appropriate disposal of Municipal Sewage Sludge (MSS) has been taken seriously due to its larger volume and toxic substances such as heavy metals. Electrokinetic remediation has more advantages in heavy metals uptake compared to other technologies, due to the ability to treat soils in-situ and to remove heavy metals from soils. In this work, it was studied the remediation of MSS by the electrokinetic remediation coupled with activated carbon (AC) as a permeable reactive barrier (PRB). It was applied an electric current of 3 V cm−1 and it was used an AC/sludge ratio of 30 g kg−1 of contaminated sludge for the preparation of the PRB. In each trial, the evolution of cadmium (Cd), lead (Pb), copper (Cu), chromium (Cr), nickel (Ni) and zinc (Zn) removal from the sludge were evaluated. Results proved that this process is perfectly suited for the removal of chromium, nickel and zinc metals from the sludge. At the end of the operation time, it was achieved a maximum removal rate of 56% for chromium, 73% for nickel and 99% for zinc, with initial concentrations of 2790 mg kg−1, 2840 mg kg−1, and 94200 mg kg−1, respectively. Based on these results, it was proved the technical viability of the proposed technology (electrokinetic with AC as a permeable reactive barrier) to treat municipal sewage sludges.

scholarly journals Heavy metals accumulation from sewage sludge in the Nile tilapia Oreochromis niloticus (Trewavas, 1983) during a sludge-earthworm-fish short-term cycling

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Nahid A.A. Siddig ◽  
Asma A. Ahmed ◽  
Sarra A.M. Saad ◽  
Faisal Hammad Mekky Koua
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Environmental Protection Agency ◽  
Oreochromis Niloticus ◽  
Nile Tilapia ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Short Term ◽  
Treated Soil ◽  
Nile Tilapia Oreochromis Niloticus

Municipal sewage sludge from wastewater treatment is an important nutritional source for sustainable agriculture. Here, we report on the assessment of the accumulation of heavy metals in Nile tilapia Oreochromis niloticus (Trewavas 1983) fed on earthworms Eisenia fetida reared on soil treated with different concentrations of sewage sludge (25% and 100%) during sludge-earthworm-fish short-term cycling. In this short-term cycling the Nile tilapia collected from the White Nile were chosen as final consumers, whereas the earthworms reared on loam soil mixed with different ratios of sludge were used as a feed for the final consumers. Our results indicate that the concentrations of Cd2+, Cr2+, Pb2+ and Zn2+ in the sludge treated soil are proportional to the sludge content in the soil. Importantly, the accumulation of these heavy metals was significantly low in the earthworms and the Nile tilapia in comparison with the treated soil and that these concentrations in the Nile tilapia were below the international limits recommended by the US Environmental Protection Agency (2014). Moreover, the growth and overall flesh quality of the fish were improved as indicated by the growth increase up to 146% when fed on earthworm reared in 100% sludge. Additionally, our physicochemical properties (i.e. pH, soil moisture, electric conductivity and organic matters) evaluation on the soil indicates an improvement of the soil quality when mixed with sewage sludge. These results suggest a sustainable application of sewage sludge in fish culture owing to its high nutritional values, low cost, and low risk of hazardous heavy metals when using primary consumers with heavy metals bioaccumulation capability such as E. fetida.

Effect of pH on metal solubilization from sewage sludge: a neural-net-based approach

1994 ◽  
Vol 21 (5) ◽  
pp. 728-735 ◽  
Author(s):  
Y. G. Du ◽  
T. R. Sreekrishnan ◽  
R. D. Tyagi ◽  
Peter G. C. Campbell
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Neural Net ◽  
Metals Removal ◽  
Complex Biological Process ◽  
System Temperature ◽  
Microbial Leaching ◽  
Metal Solubilization

Microbial leaching for heavy metals removal from municipal sewage sludge is a complex biological process. The ultimate metal solubilization achieved depends on the type of sludge involved (nondigested, aerobically digested or anaerobically digested sludge), the decrease in sludge pH as a result of the leaching operation, and the concentration of metals initially present in the sludge. In addition, the system temperature exerts an indirect but strong influence by its effect on the bacterial growth and acid production process. A neural-net-based model was developed to predict the solubilization of six heavy metals, Cd, Cr, Cu, Ni, Pb, and Zn, from sewage sludge using the bioleaching process. The only input parameters required are the type of sludge, initial metal concentrations in the sludge, and the sludge pH. The model yielded satisfactory predictions of metal solubilization when tested with a number of actual experimental data. Key words: heavy metals, microbial leaching, modelling, neural-net, sewage sludge.

Effects on Speciation of Ni & Cd in Sewage Sludge during Composting only and Co-Composting with Fly Ash Added

2012 ◽  
Vol 209-211 ◽  
pp. 1245-1252
Author(s):  
Zheng Zhong Zeng ◽  
Xiao Li Wang ◽  
Yu Pan ◽  
Zhong Ren Nan
Keyword(s):  
Heavy Metals ◽  
Fly Ash ◽  
Sewage Sludge ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Unstable State ◽  
Land Utilization ◽  
Major Barrier ◽  
Exchangeable Fraction ◽  
State Content

The land use has become the international mainstream and the favorable direction to dispose the municipal sewage sludge in recent years. The heavy metals, however, are the major barrier that limit the land utilization. Batch aerobic composting experiments were conducted to investigate the effect of composting and co-composting with fly ash on the shape of the heavy metals (Ni & Cd) in sludge by using the sawdust to regulate the C/N ratio. Results have shown that co-composting with fly ash can significantly change Ni & Cd species distribution, leading unstable state content of Ni lower than composting only. However, the result is not as good as composting only in terms of Cd. At the same time the fly ash dosage equaling 14% of the dry sludge mass was the optimized quantity to guarantee the lowest exchangeable fraction amount of the two heavy metals.

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