A novel method of sewage sludge pre-treatment - HTC

Abstract

Abstract. The aim of the paper is to present a relatively new technology -hydrothermal carbonization (HTC) of municipal sewage sludge. The HTC process was conducted in a stainless steel, Zipperclave Stirred Reactor, with a volume of 1000 ml, equipped with a MagneDrive Agitator. The control panel provides a programme which regulates the heater temperature and mixer speed. The main parameters of the process were temperature (~200C), pressure (~1.5 MPa) and residence time (4, 7, 10, and 12 h). In order to understand the process, the physical, chemical, thermal, and structural characteristics of the solid product, hydrochar, was investigated. Therefore, the ultimate and proximate analyses, and HHV for raw material and obtained hydrochar are presented. The majority of carbon, of the initial present carbon, remained within hydrochar. TA analysis was used to detect the initial and final temperature for the combustion of raw material and hydrochar. This technique is very useful for predicting the combustion characteristics of carbonaceous material. When considering the use of hydrochar as a solid fuel, more energy can be derived from hydrochar than from e.g. incineration of waste, and its carbon emission should be less significant. Therefore, HTC can be an environmentally beneficial technique for the combustion process.

Upgrading Hydrothermal Carbonization (HTC) Hydrochar from Sewage Sludge

“…This was due to the release of CO 2 and H 2 O chemical species by dehydration and decarboxylation, which are the major reaction mechanisms of HTC [27]. Furthermore, the nitrogen and sulfur contents of the raw material decreased from 7.8 to 4.73% and from 0.99 to 0.6% due to the solubilization via the HTC, which are in good agreement with previously reported literature [28,29]. The change of properties could lead to the reduction of the potential risk of generating harmful pollutants such as NO x and SO x in the thermochemical process.…”

Process Waters from Hydrothermal Carbonization of Sludge: Characteristics and Possible Valorization Pathways

“…A wide range of biomass feedstocks, including cellulose [ 13 ], bamboo [ 14 ], loblolly pine [ 15 ], fruit waste [ 16 ], olive waste [ 17 ], tomato peel [ 18 ], agro-industrial waste [ 19 ], walnut shell and sunflower stem [ 20 ], microalgae [ 21 , 22 ], municipal solid food waste [ 23 , 24 ], distiller’s grains [ 25 ], animal manure [ 26 , 27 ], have been applied in HTC to gain fuels or materials. Interestingly, HTC has also been applied to municipal sewage sludge [ 28 , 29 , 30 , 31 ], anaerobically digested sewage sludge (ADSS) [ 32 ] and anaerobically digested biomasses [ 10 ].…”

Hydrothermal Carbonization of Biosolids from Waste Water Treatment Plant

“…For example, in one HTC at 200 • C, 2.1 MPa for 1-6 h, the hydrochar yield was 74-81% and depended on the carbonization time [10]. Another HTC on sewage sludge was carried out at 200 • C, 1.5 MPa and residence time of 4, 7, 10, and 12 h [11]. The higher heating value of the product was 14.73 MJ/kg for residence time of 10 h [10].…”