Heat treatment-dehydration-fertilizer making method for town sewage and sludge

A technology for urban sewage and dewatered sludge, which is used in sewage/sludge fertilizer, dewatering/drying/concentrating sludge treatment, sludge treatment through temperature control, etc. Large energy consumption and other problems, to achieve the effect of shortening waste liquid treatment time, reducing costs, and reducing heat treatment temperature

Inactive Publication Date: 2008-05-28
TSINGHUA UNIV
View PDF0 Cites 13 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

On the one hand, whether it is high-temperature heat treatment or low-temperature heat treatment, it is necessary to heat a large amount of water in the remaining sludge (water content above 95%) to the corresponding temperature under high pressure, which consumes a lot of energy and costs a lot.
On the other hand, sludge heat treatment will also produce a high concentration of extractant. Since mos

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Heat treatment-dehydration-fertilizer making method for town sewage and sludge

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The moisture content of the dehydrated cake produced by an urban sewage treatment plant is 81%, and the organic matter content in the dry solid is 74%.

[0032] Add 0.16wt% sodium hydroxide to the dewatered cake, then use the screw pump to transport it to the horizontal screw heat processor, feed it with high-pressure steam (250 ° C, 4 MPa) to heat it to 140 ° C, and the residence time is 40min; after the sludge reacts, it enters the water cooler, and after cooling, it is mechanically dehydrated. As a result of the reaction, compared with before treatment, the dry solid mass decreased by 40%, and the moisture content of the dewatered cake was 47%; the chemical oxygen demand (COD) in the waste liquid was 103.0g / L, and the humic acid content was 31.0g / L. After full filtration and purification, the content of humic acid is 3.1wt%, the content of heavy metals is Cd≤0.01wt%, As≤0.002wt%, Pb≤0.002wt%, which is in line with the "Guidelines for the Use of Fertilizers" of the Mi...

Embodiment 2

[0034] The moisture content of the dehydrated cake produced by an urban sewage treatment plant is 80%, and the organic matter content in the dry solid is 61%.

[0035] Add 0.08wt% sodium hydroxide to the dewatered cake, then use the screw pump to transport it to the horizontal screw heat processor, feed it into high-pressure steam (250 ° C, 4 MPa) to heat it to 120 ° C, and the residence time is 100min; after the sludge reacts, it enters the water cooler, and after cooling, it is mechanically dehydrated. As a result of the reaction, compared with before treatment, the dry solid mass decreased by 35%, and the moisture content of the dewatered cake was 56%; the COD in the waste liquid was 99.7g / L, and the humic acid content was 22.2g / L, which was purified and concentrated by 2 times through full filtration Humic acid content is 4.4wt%, heavy metal content Cd≤0.01wt%, As≤0.002wt%, Pb≤0.002wt%, in line with the Ministry of Agriculture's "Fertilizer Use Guidelines"; ultrafiltration...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

No PUM Login to view more

Abstract

A heat treatment-dehydration-making fertilizer method of urban sewage and sludge is provided, which pertains to the treatment filed of solid waste. Sodium hydroxide is added into dewatered sludge and stirred, hypoxic steam with temperature and pressure more than 250 DEG C and 4MPa is input, the temperature is raised to 120-140 DEG C for 40-100 min; the temperature is reduced to less than 100 DEG C, dehydrated liquid and dehydrated sludge cake with amount decreased are obtained after dehydration; the dehydrated liquid is treated by sand filtration and microfiltration, then whole filtration is carried out and the concentrated solution with humic acid more than 3wt percent is obtained; the humic acid liquid fertilizer is obtained after the concentrated solution is added with additive. The invention can greatly reduce the expenses of sludge heat treatment; water content of the obtained dehydrated sludge cake is less than 60 percent and the total solid reduces by 35 percent; the heavy mental content of the obtained humic acid liquid fertilizer is low, the pH value keeps in the range of weak alkaline and the pathogen is inactivated; the method is safe and efficient, complies with Fertilizer Application Guideline of National Ministry of Agriculture and can be widely applied to harmless, quantitative reduction and resource utilization treatment of urban sewage and sludge.

Description

technical field [0001] The invention relates to a method for dehydrating and making fertilizer after urban sewage sludge is heat-treated, and belongs to the field of solid waste treatment. Background technique [0002] Most of the urban domestic sewage in my country is treated by the activated sludge method, and a large amount of excess sludge is produced every year. According to the discharge of domestic sewage in 2006, 30 billion tons, the treatment rate is 40%, and the sludge (water content 99%) is produced as sewage According to 1% of the treatment capacity, about 120 million tons of excess sludge will be produced, which is converted into about 6 million tons of dewatered cake (80% moisture content). With the increase of domestic sewage discharge and the improvement of treatment rate in my country, the sludge production will continue to grow. The dehydrated cake not only produces a large amount, but also has a high moisture content and organic matter content, which is di...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Application Information

Patent Timeline
no application Login to view more
IPC IPC(8): C02F11/12C02F11/18C05F7/00
CPCY02A40/20Y02W30/40
Inventor 金宜英李欢聂永丰
Owner TSINGHUA UNIV
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap