The behavior of ash components in the sludge melting process

The Coke-bed sludge melting process is used for incinerating sewage sludge and producing slag that is recycled as construction materials. The behavior of ash exiting the melting furnace was examined. Heating tests were carried out with different kinds of sludge. Heating from 600°C to 1200°C, weight reduction of around 30% was measured, but reduction rate was due to the kind of sludge. Weight reduction was big when heating up to 815°C, and reduction at a temperature over 815°C was due to the type of sludge. Main materials causing weight reduction were unburnt carbon (C) and some other elements like sulfur (S), chlorine (Cl), some metals like sodium (Na), potassium (K) and oxygen (O) released from some kinds of oxides. Even though very small quantity, zinc (Zn) and lead (Pb) were also vaporized. Some of these vaporized substances precipitate and produce fine particle dust at the low-temperature section of gas treatment facilities. Washing harmless salts out from the dust then recycling the dewatered dust in the melting furnace was found to be effective in maximizing slag recovery and reducing the precipitator load.

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Sludge Melting Process with Hazardous Asbestos Wastes

Water Science & Technology ◽

10.2166/wst.1991.0659 ◽

1991 ◽

Vol 23 (10-12) ◽

pp. 2029-2037 ◽

Cited By ~ 3

Author(s):

S. Sakai ◽

H. Takatsuki ◽

M. Hiraoka ◽

T. Tsunemi

Keyword(s):

Sewage Sludge ◽

Construction Materials ◽

High Strength ◽

Melting Process ◽

Melting Behavior ◽

X Ray Diffraction ◽

Asbestos Cement ◽

Plant Experiment ◽

By Products ◽

Temperature Melting

Sewage sludge melting has been developed and operated in full-scale plants for sludge processing and utilization of the by-products as construction materials. Hazardous asbestos wastes should be disposed of properly so not to lead to environmental pollution. The co-melting process for sewage sludge and asbestos wastes is discussed based on the basic melting behavior of asbestos and the laboratory plant experiment. Microscopic observation and X-ray diffraction analysis showed that asbestos forms could be changed physically and chemically by the high temperature melting. The disappearance of asbestos fibrous forms and chemical changes of its composition in the melted slag are not always concluded to be non-toxic, but considering that the melted slag is a rock-like material with high strength, the melting is acceptable as a method of hazardous asbestos waste disposal. Laboratory scale experiments have been conducted on co-melting disposal of sprayed-on chrysotile asbestos waste and a mixture of lime-added and polymer-added sewage sludge. It was possible to maintain the temperatures around 1600 °C and to discharge slag smoothly. It is also expected that asbestos cement wastes will contribute to the adjustment materials of basicity (CaO/SiO2) in the polymer-added sludge melting.

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Stable Combustion in Sludge Melting Furnace by Fuzzy Logic Control

Water Science & Technology ◽

10.2166/wst.1993.0675 ◽

1993 ◽

Vol 28 (11-12) ◽

pp. 347-354 ◽

Cited By ~ 4

Author(s):

Shunichi Shiono ◽

Takashi Usui ◽

Morio Iriyama ◽

Kazuyuki Suzuki ◽

Yohta. Naka

Keyword(s):

Fuzzy Logic ◽

Control System ◽

Sewage Sludge ◽

Flue Gas ◽

Melting Furnace ◽

Melting Process ◽

Combustion Control ◽

Logic Control ◽

O2 Concentration ◽

Complex Phenomena

This paper discusses combustion control using fuzzy logic for a sewage sludge melting furnace. The sewage sludge melting process is gaining attention as an effective method for reducing sludge volume. The slag from molten sludge is stable, causes no pollution, and can be used as a by-product. However, the operation of a sludge melting plant requires expert operators who have to deal with complex phenomena that take place in a melting furnace. In an effort to facilitate the operation, the authors have employed a control system which features the use of fuzzy logic for automatic combustion control in a cyclone type sewage sludge melting furnace. Confirmation was made that this fuzzy logic combustion control system functioned effectively for controlling the furnace temperature, O2 concentration in the furnace outlet flue gas, and concentration of NOx.

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Sewage Sludge Melting Process: Preliminary System Design and Full-Scale Plant Study

Water Science & Technology ◽

10.2166/wst.1990.0127 ◽

1990 ◽

Vol 22 (12) ◽

pp. 329-338 ◽

Cited By ~ 11

Author(s):

S. Sakai ◽

M. Hiraoka ◽

N. Takeda ◽

T. Tsunemi

Keyword(s):

Sewage Sludge ◽

Treatment Cost ◽

Solid Phase ◽

Construction Materials ◽

Melting Process ◽

Relative Energy ◽

Full Scale ◽

Sludge Treatment ◽

Under Construction ◽

Ash Disposal

A sewage sludge melting process has been developed and some full-scale planls have been installed or are now under construction in Japan. Sludge melting process has its main advantages in that most sorts of hazardous materials, such as heavy metals, are tightly fixed in solid phase and the slag produced by this process can be used as construction materials. This article analyzes sludge treatment and disposal costs of the popular sludge treatment alternatives with emphasis on thermal processes, especially the sludge melting process. From preliminary system designs on a common design basis, relative energy requirements and total treatment & disposal costs were compared. As a result of cost analysis in terms of the annual treatment cost, it was revealed that the lime conditioning systems cost some 50% more than the polymer conditioning, that in a comparison between the incineration and the melting systems the treatment cost differed when the difference in energy cost was significant, and that in the anaerobic digestion systems the superiority in energy balance did not contribute to treatment cost reduction. Even if as one of the cost conditions to introduce the melting system in place of the incineration system, the ash disposal price is set as low as 5,000 yen/t, the coke melting system is still advantageous in the lime conditioning. Further, it turned out that in the polymer conditioning systems it was possible to establish cost conditions to introduce the melting system when the incinerated ash disposal price, the melting process coke ratio and the coke price took certain values.

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Estimation of Energy Saving for Melting Process on Sewage Sludge

Water Science & Technology ◽

10.2166/wst.1991.0657 ◽

1991 ◽

Vol 23 (10-12) ◽

pp. 2011-2018 ◽

Cited By ~ 2

Author(s):

T. Murakami ◽

K. Sasabe ◽

K. Sasaki ◽

T. Kawashima

Keyword(s):

Sewage Sludge ◽

Moisture Content ◽

Energy Saving ◽

Fuel Consumption ◽

Melting Process ◽

System Operation ◽

Operational Conditions ◽

Volatile Solids ◽

Cake Moisture ◽

Very High

The possible volume reduction and stabilization of the sewage sludge associated with the melting process are expected to be greater than with the incineration process. In addition, melted slag can be utilized. However, since the melting process requires a very high temperature to melt inorganics (ash) in the sludge, the technologies to minimize energy consumption, to establish system operation and to prolong durability of facilities should be developed. This paper discusses the auxiliary fuel consumption as follows.(1)Preparation of a model that provides the auxiliary fuel consumption of the melting system on the basis of the mass and heat balances.(2)Evaluation of the auxiliary fuel consumption in the above model using the cake moisture content, the volatile solids of the cake, the dried cake moisture content and the melting temperature as parameters.(3)Examination of the operational conditions for an energy saving melting system based on the results of (1) and (2) above.

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Operational Results of Melting System for Sewage Sludge

Water Science & Technology ◽

10.2166/wst.1991.0632 ◽

1991 ◽

Vol 23 (10-12) ◽

pp. 1773-1781 ◽

Cited By ~ 6

Author(s):

Daisaku Yashiki ◽

Tadahiro Murakami

Keyword(s):

Sewage Sludge ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Melting Furnace ◽

Effective Utilization ◽

History Of ◽

Sludge Properties ◽

Operation Results

Sludge melting furnaces have been applied recently to the treatment of a great deal of sludge generated from the sewage treatment plant. In this report, an explanation is provided of the history of system introduction, outline of treatment flow, sludge properties, operation results and effective utilization of slag generated at the reflector melting furnace, which began operation in July 1988 at the Futakami Sewage Treatment Plant in Toyama Prefecture. The melting furnace almost totally satisfies the needs of its design, and the properties of the generated melted slag exhibit the features that fully enable its effective utilization.

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Survival of Hepatitis A Virus on Two-month Stored Freeze-dried Berries

Journal of Food Protection ◽

10.4315/jfp-21-110 ◽

2021 ◽

Author(s):

Yan Zhang ◽

Xueyan Wang ◽

Y. Carol Shieh

Keyword(s):

Freeze Drying ◽

Hepatitis A ◽

Hepatitis A Virus ◽

Reduction Rate ◽

Radiant Heating ◽

Minimal Processing ◽

Log Reduction ◽

C Storage ◽

Freeze Dried ◽

Heating Up

Imported berries have contributed to U.S. hepatitis A virus (HAV) infections. Minimal processing by freeze-drying is preferred by industry for preserving food quality, but virus inactivation by this process may be limited. This study investigated HAV survival on strawberries during 24-h freeze-drying followed by 22 ° C-storage. The outer surfaces of strawberry slices were prepared and each inoculated with 5 to 6 log 10 PFU HAV, air-dried 20 min, frozen 1 h at -80 °C, and freeze-dried 24 h with radiant heating up to 36 °C. Infectious HAV levels eluted from berry slices were quantified on FRhK-4 cells grown onto 6-well dishes. Freeze-drying trials (n = 17) with radiant heating inactivated ≤1 log 10 PFU per trial, although HAV-inactivation was significantly greater at 36 ºC than 15 ºC heating ( p < 0.01). Average HAV reduction rate on dried berries continuously decreased as storage time increased, 0.2, 0.09, 0.08, 0.04, 0.04 and 0.03 log-reduction/day at day 2, 7, 14, 28, 42, and 56, respectively, with the cumulated log-reduction divided by storage days. Therefore, the best fit regression for the total/cumulative virus reduction (Y) at any given day (X) is Y= 0.2882X 0.4503 (r² = 0.97), with maximum 2.7 log-reduction on berries throughout the drying and subsequent 2-month storage. HAV showed the greatest decline within the first 14-days of storage of dried berries (approximately 70% weekly reduction from its previous week levels), but the HAV reduction rates were still lower than that occurring on fresh produce.

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The Research on Preparation Methods of Sludge-Based Adsorbent and its Application in Water Treatment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.798-799.1166 ◽

2013 ◽

Vol 798-799 ◽

pp. 1166-1169 ◽

Cited By ~ 1

Author(s):

Kun Huang ◽

Bing Xin Du

Keyword(s):

Sustainable Development ◽

Sewage Sludge ◽

Preparation Method ◽

Research Direction ◽

Excess Sludge ◽

Preparation Methods ◽

Gas Treatment ◽

Waste Gas ◽

Waste Gas Treatment ◽

Process Of Urbanization

The accelerated process of urbanization and industrialization leads to the increase of sewage sludge production. The reuse of excess sludge which meets the idea of sustainable development is aimed to develop it into resources. Preparation of sludge-based adsorbents with various functions provides a new way for sludge utilization as a resource in China. The preparation method of sludge-based adsorbents and its application in wastewater and waste gas treatment are introduced. Suggestions about the research direction of sludge-based adsorbents in the future are point out.

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Testing the Performance of a Traditional Furnace Melting Process on Bronze as the Material of Gamelan

Materials Science Forum ◽

10.4028/www.scientific.net/msf.889.99 ◽

2017 ◽

Vol 889 ◽

pp. 99-103

Author(s):

I. Gusti Ngurah Priambadi ◽

I. Ketut Gede Sugita

Keyword(s):

Melting Furnace ◽

Melting Process ◽

Data Retrieval ◽

Musical Instrument ◽

Smelting Process ◽

Melting Time ◽

Time Data ◽

Average Temperature ◽

Furnace Melting ◽

Low Efficiency

Gamelan is traditional musical instrument that evolves especially in Bali, its function is to accompany the religious and cultural ceremonies of Hindus. The making process of gamelan, smelting bronze alloys, is done by using traditional furnaces. The use of charcoal as fuel in smelting process causes melting furnace performance is difficult to determine. That condition impacts the effectiveness of the smelting process especially in determining the needs of fuel and the processing time. Therefore, it influences the productivity of crafters. This research was conducted to test the performance of the furnace in accordance with a design that is commonly used by artisans. The observation was done at the temperature of melting, melting time, data retrieval was conducted repeatedly three times on different days. Based on the analysis and observation in accordance with the experimental design made whereby in the smelting process to achieve the casting temperature indicated as follows. The average temperature of smelting is 730,8 °C, fuel use is 23 kg, melting time is 39.76 minutes as well as the efficiency of the furnace 36.80%. Based on the analysis conducted, low efficiency is due to the surface of the furnace which is designed open, so that during the energy generated in the process of burning a lot of fuel wasted into the environment.

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