Sustained Shockwave Plasma (SSP) Destruction of Sewage Sludge – A Rapid Oxidation Process

Sewage sludge is destroyed and neutralized in an environmentally safe way by rapid, plasma-assisted oxidation. The material is rendered inert where it is being produced, leaving behind a benign and useful solid oxidation byproduct and producing a clean off-gas. The solid product can be used as a cement or aggregate. The process is based on oxidation enhancement by employment of sustained Shockwave plasma and controlled oxidation to provide an off-gas which can effectively be handled by gas cleaning systems to provide a degree of purity required by the most stringent air quality standards. The process is very compact, owing to very rapid throughput and near-stoichiometric air requirements. It is entirely enclosed. The Neutrail SSP process comprises three main steps; drying, oxidation and gas cleaning. The oxidation step consists of three distinct sections. It is designed to completely destroy all organic structures, limit acid gas formation and to retain a maximum amount of all volatile heavy metals in the solid residue in a non-leachable form, thereby making it possible to devise a gas cleaning system which can deliver a clean off-gas economically.

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Gasification as an optimum alternative for the sludge management

Water Practice & Technology ◽

10.2166/wpt.2011.0080 ◽

2011 ◽

Vol 6 (4) ◽

Cited By ~ 2

Author(s):

C. Peregrina ◽

J. M. Audic ◽

P. Dauthuille

Keyword(s):

Power Generation ◽

Anaerobic Digestion ◽

Sewage Sludge ◽

Combined Heat And Power ◽

Gas Production ◽

Waste Reduction ◽

Fluidised Bed ◽

Sludge Management ◽

Gas Cleaning ◽

Cleaning System

Assimilate sludge to a fuel is not new. Sludge incineration and Combined Heat and Power (CHP) engines powered with sludge-derived anaerobic digestion gas (ADG) are operations widely used. However, they have a room of improvement to reach simultaneously a positive net power generation and a significant level of waste reduction and stabilization. Gasification has been used in other realms for the conversion of any negative-value carbon-based materials, that would otherwise be disposed as waste, to a gaseous product with a usable heating value for power generation . In fact, the produced gas, the so-called synthetic gas (or syngas), could be suitable for combined heat and power motors. Within this framework gasification could be seen as an optimum alternative for the sludge management that would allow the highest waste reduction yield (similar to incineration) with a high power generation. Although gasification remains a promising route for sewage sludge valorisation, campaigns of measurements show that is not a simple operation and there are still several technical issues to resolve before that gasification was considered to be fully applied in the sludge management. Fluidised bed was chosen by certain technology developers because it is an easy and well known process for solid combustion, and very suitable for non-conventional fuels. However, our tests showed a poor reliable process for gasification of sludge giving a low quality gas production with a significant amount of tars to be treated. The cleaning system that was proposed shows a very limited removal performance and difficulties to be operated. Within the sizes of more common WWTP, an alternative solution to the fluidised bed reactor would be the downdraft bed gasifier that was also audited. Most relevant data of this audit suggest that the technology is more adapted to the idea of sludge gasification presented in the beginning of this paper where a maximum waste reduction is achieved with a great electricity generation thanks to the use of a “good” quality syngas in a CHP engine. Audit show also that there is still some work to do in order to push sludge gasification to a more industrial stage. Regardless what solution would be preferred, the resulting gasification system would involve a more complex scenario compared to Anaerobic Digestion and Incineration, characterised by a thermal dryer and gasifier with a complete gas cleaning system. At the end, economics, reliability and mass and energy yields should be carefully analysed in order to set the place that gasification would play in the forthcoming processing of sewage sludge.

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Two-stage gasification of dried sewage sludge: Effects of gasifying agent, bed material, gas cleaning system, and Ni-coated distributor on product gas quality

Renewable Energy ◽

10.1016/j.renene.2021.12.069 ◽

2021 ◽

Author(s):

Yong-Seong Jeong ◽

Tae-Young Mun ◽

Joo-Sik Kim

Keyword(s):

Sewage Sludge ◽

Two Stage ◽

Gas Cleaning ◽

Cleaning System ◽

Product Gas ◽

Bed Material

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Design and Commissioning of the Largest and the Smallest Fluidized Bed Incinerator Ever Built by Lurgi

17th International Conference on Fluidized Bed Combustion ◽

10.1115/fbc2003-007 ◽

2003 ◽

Author(s):

H. Huenchen ◽

L. Pachmayer ◽

O. Malerius

Keyword(s):

Sewage Sludge ◽

Fluidized Bed ◽

Flue Gas ◽

Circulating Fluidized Bed ◽

Waste Material ◽

Design Parameters ◽

Cross Sectional ◽

Gas Cleaning ◽

Bubbling Bed ◽

Cleaning System

Since communities and companies are deciding to dispose sludges of different origin in a safe and nonpolluting way, more and more sludge is burnt either in mono-combustion or co-combustion units. Lurgi Energie und Entsorgung GmbH, one of the most experienced fluidized bed designer, is commissioning two bubbling bed incinerators of totally different incinerator size in 2002. In France the smallest fluidized bed incinerator ever built by Lurgi with a cross-sectional bed area of 4 m2 is designed to burn 750 kg (d.m.)/h sewage sludge. In spite of the small size it consists of all equipment necessary for sewage sludge incineration, including a disc dryer, a thermal oil boiler for heat recovery and a complete state of the art flue gas cleaning system. Air pollutants are removed in a circulating fluidized bed adsorber (CFB) designed in accordance with the new Lurgi CIRCOCLEAN® process. In United Kingdom the largest bubbling bed incinerator ever built by Lurgi with a cross-sectional bed area of 32 m2 is going to start its operation in 2002. The plant burns a mixture of thickened and mechanically dewatered primary and secondary sludge and different plastic residues from waste paper recycling plants. In order to provide sufficient disposal capacity of the waste material generated at the Kemsley Paper Mill site some parts of the installation consist of parallel streams or units (e. g. waste material handling and storage). The overall design throughput rate of mixed waste material is 22.8 t(a.r.)/h, corresponding to a thermal load of 29.1 MW. Due to the specific properties of the paper sludge, the formed ash can be used as an adsorbent/reactive compound for the capture of acidic pollutants. The flue gas cleaning system consists of a zeolite dosing unit to remove dioxins/furanes upstream of a baghouse filter. The paper presents the main design parameters of both disposal facilities and peculiarities of the burnt materials in comparison to other sludges. Since the plants are still in the commissioning phase only problems that might occur during the operation of the plant and tendencies in the operation behavior are described.

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