Effect of sewage sludge content on gas quality and solid residues produced by cogasification in an updraft gasifier

Journal Article · Mon Oct 15 00:00:00 EDT 2012 · Waste Management

DOI:https://doi.org/10.1016/J.WASMAN.2012.04.018· OSTI ID:22089889

Seggiani, Maurizia ^[1]; Puccini, Monica ^[1]; Raggio, Giovanni ^[2]; Vitolo, Sandra ^[1]

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1. Department of Chemical Engineering, Industrial Chemistry and Material Science, University of Pisa, Largo Lucio Lazzarino 1, 56126 Pisa (Italy)
2. Italprogetti Engineering SPA, Lungarno Pacinotti, 59/A, 56020 San Romano (Pisa) (Italy)

Highlights: Black-Right-Pointing-Pointer Cogasification of sewage sludge with wood pellets in updraft gasifier was analysed. Black-Right-Pointing-Pointer The effects of sewage sludge content on the gasification process were examined. Black-Right-Pointing-Pointer Sewage sludge addition up to 30 wt.% reduces moderately the process performance. Black-Right-Pointing-Pointer At high sewage sludge content slagging and clinker formation occurred. Black-Right-Pointing-Pointer Solid residues produced resulted acceptable at landfills for non-hazardous waste. - Abstract: In the present work, the gasification with air of dehydrated sewage sludge (SS) with 20 wt.% moisture mixed with conventional woody biomass was investigated using a pilot fixed-bed updraft gasifier. Attention was focused on the effect of the SS content on the gasification performance and on the environmental impact of the process. The results showed that it is possible to co-gasify SS with wood pellets (WPs) in updraft fixed-bed gasification installations. However, at high content of sewage sludge the gasification process can become instable because of the very high ash content and low ash fusion temperatures of SS. At an equivalent ratio of 0.25, compared with wood pellets gasification, the addition of sewage sludge led to a reduction of gas yield in favor of an increase of condensate production with consequent cold gas efficiency decrease. Low concentrations of dioxins/furans and PAHs were measured in the gas produced by SS gasification, well below the limiting values for the exhaust gaseous emissions. NH{sub 3}, HCl and HF contents were very low because most of these compounds were retained in the wet scrubber systems. On the other hand, high H{sub 2}S levels were measured due to high sulfur content of SS. Heavy metals supplied with the feedstocks were mostly retained in gasification solid residues. The leachability tests performed according to European regulations showed that metals leachability was within the limits for landfilling inert residues. On the other hand, sulfate and chloride releases were found to comply with the limits for non-hazardous residues.

• OSTI ID: 22089889
• Journal Information: Waste Management, Vol. 32, Issue 10; Other Information: Copyright (c) 2012 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
AMMONIA
ASH CONTENT
BIOMASS
CHLORIDES
DIOXIN
ENVIRONMENTAL IMPACTS
EXHAUST GASES
GASIFICATION
HEAVY METALS
HYDROCHLORIC ACID
HYDROFLUORIC ACID
MOISTURE
PACKED BEDS
POLYCYCLIC AROMATIC HYDROCARBONS
SANITARY LANDFILLS
SEWAGE SLUDGE
SOLID WASTES
SULFATES
SULFUR CONTENT
WOOD FUELS