Sludge Incineration Process Research Articles

Investigation of Sludge Waste Incineration in a Novel Rotating Fluidized Bed Incinerator

New regulations in the United Kingdom have forbidden sea dumping since December 1998, and in the near future new incinerators will be required to dispose of about five million wet tonnes of sewage sludge per year. A research programme is being carried out at the Sheffield University Waste Incineration Centre (SUWIC) to design and operate a novel high-efficiency rotating fluidized bed (RFB) incinerator suitable for burning large quantities of sewage sludge. Incineration experiments carried out in a 200 mm ID rotating fluidized bed have demonstrated that the novel RFB technology is well suited to the incineration of sludge waste. Pre-dried chicken waste pellets, with similar characteristics to sewage sludge, were used as a sewage sludge surrogate. Water was added to the dry sludge pellets to generate the required moisture content. Results from this study showed that the sludge thoughput for the RFB incinerator was significantly higher than the conventional fluidized bed incinerator. It was found that the bed hydrodynamics were critical for the sludge incineration process in the RFB and design of the distributor plate had a strong effect on the quality of bed mixing, and hence on the sludge incinceration process.

Emission Characteristics of Greenhouse Gas N2O from Sewage Sludge Incineration Process.

N2O is one of the important greenhouse gas, and it has been pointed out that its contribution to global warming will increase in the future. In the past, higher level concentration of N2O emission was reported for some sewage sludge incinerators than at other fixed emission sources including a solid waste incinerator. Therefore, we investigated the practical factors of N2O emission from the sewage sludge incineration originated from the difference of incinerator type and coagulant type used for dehydration. As a result, it was cleared that emitted amount of N2O is strongly depended on the incineration temperature and the coagulant type used for dehydration process. Amounts of N2O emitted from sewage sludge incineration in FY 1995 in Japan was estimated at 4030t on a nitrogen basis and thought to more increase to the future.

Sludge Incineration Process of Kyoto City – The Employment and Heat Balance of the Step Grate Stoker Furnace

Kyoto City, an ancient city of international tourism, has been actively constructing its public sewerage system as one of the most important policies of the city. As of April, 1989, 79.6% of the urbanization promotion area of the city has been sewered. The fully completed sewerage system will be established in 1994, the 1200th anniversary of the founding of the city as the ancient Heian capital of Japan. However, the increase of the sewered ratio effects a steady increase in the influent volume of wastewater. Due to the inland location of the city, sludge produced in the wastewater treatment plants has been landfilled after incineration, but recently the securing of appropriate sites for landfill is difficult, and hence sludge treatment and disposal is an important issue for Kyoto City. In order to minimize the ultimate disposal volume, incineration of the entire volume of sludge has been undertaken in early days of sewerage operations. This report introduces the sludge incineration system and assesses the newly adopted step grate stoker furnace. At present, Kyoto City has 4 treatment plants in operation. The Toba Treatment Plant, which has the largest treatment capacity receives sludge cake trucked from the Fushimi Treatment Plant and excess sludge pumped through pipes from the Kisshoin Treatment Plant, and incinerates the whole amount of sludge cake generated in the plant. The sludge cake produced at the Ishida Treatment Plant is incinerated at an adjacent refuse sanitation plant together with the municipal refuse from the city. The characteristics of sludge treatment systems are given in this report. The step grate stoker furnace system was introduced to reduce the final disposal volume and to save energy. Through comparison with the multiple-hearth furnace system the actual results of operation were verified. The volume of generated ash was decreased by more than 50%, and energy consumption was reduced by 77%, resulting in an 18% reduction of operating expenses.