WO2011154760A1

WO2011154760A1 - A dehydrogenation and drying method and installation for sludge conditioning at room temperature

Info

Publication number: WO2011154760A1
Application number: PCT/IB2010/001428
Authority: WO
Original assignee: Zhu, Qing, Hai
Priority date: 2010-06-11
Filing date: 2010-06-11
Publication date: 2011-12-15
Also published as: CA2715773A1

Abstract

This invention is a technology in the sludge treatment field specializing in sludge dewatering equipment and installations. Sludge is produced as a waste product during wastewater treatment processes. The resulting sludge is high in organic content, and highly decomposable emitting foul odour. The sludge has low density and high moisture content. It is also a hydrophilic matter with a colloidal structure that poses challenges for dewatering. As sludge contains high nitrogen and phosphorous, if released into water body, it promotes eutrophication, resulting in low dissolved oxygen and deterioration of water quality. Sludge contains pathogen, parasites and other harmful substances which are transferrable to human within the biosphere causing health problems. This new technology provides effective treatment of sludge waste at relatively low energy consumption.

Description

A DEHYROGENATION AND DRYING METHOD AND INSTALLATION FOR SLUDGE CONDITIONING AT ROOM TEMPERATURE DESCRIPTION

This invention is a technology in the sludge treatment field specializing in sludge dewatering equipment and installations. Sludge is produced as a waste product during wastewater treatment processes. The resulting sludge is high in organic content, and highly decomposable emitting foul odour. The sludge has low density and high moisture content. It is also a hydrophilic matter with a colloidal structure that poses challenges for dewatering. As sludge contains high nitrogen and phosphorous , if released into water body, it promotes eutrophication, resulting in low dissolved oxygen and deterioration of water quality. Sludge contains pathogen, parasites and other harmful substances which are transferrable to human within the biosphere causing health problems. This new technology provides effective treatment of sludge waste at relatively low energy consumption. TECHNICAL BACKGROUND

Wastewater treatment, an important part of environmental protection, produces increasingly large quantity of sludge that is difficult to be dewatered. The traditional centrifugal hydro-extractor, belt filter press, and frame filter press are only able to decrease water content of sludge to 75-85%, and hence are considered ineffective. Heating and drying are employed in most cases to further dewater the sludge, but potential problems of high energy consumption, offensive odour, and air pollution are also created.

Combining processes of sludge conditioning, mechanical dewatering, and cold air stripping, the invention provides a new means and equipment for dewatering of sludge at ambient temperature, reducing water content of sludge from 95-98% to 20-30% without additional source of heat such as burning of coal, oil, or gas. This is in compliance with the globally promoted concept of energy saving and carbon reduction, offering a solution to the problem of environmental pollution caused by sludge dewatering. INTRODUCTION TO THE INVENTION

In order to solve the problem of lack of sludge dewatering equipment and the environmental impact caused by heating and drying of sludge to reduce its water content during dewatering process, the invention provides a means and an equipment for conditioning, dewatering, and drying of sludge at ambient temperature.

1. The conditioning device comprises an additive weighing unit, a feeding unit, a discharging unit, and a stirring unit.

2. The additive weighing unit includes a crew conveyor and a weighing pad.

3. A display unit showing quantity of feed and discharge, a feeding unit, a discharging unit, and a stirring unit are also available in the conditioning device. . The dewatering device is a plate press dewatering device. The plates are equipped with certain number of springs and a feeding inlet at the center of each plate . The plates are mobile, and each filtering unit is of a composite structure. Hydraulic unit is integrated with dewatering unit and controlling unit in the hydraulic cylinder. A cooling unit is installed in the cylinder. Cavities are available in the plates with sealing units at the sides of the plates. Water is discharged through an inverted-V-shape water container followed by troughs at two sides of the container. Flipping the water container by 180 degrees transforms it into a holder of filter cake.

5. The drying device is a mixing roller equipped with

automatic tilting system inside. Cold air stripping unit is available below the roller, and dust collecting unit above.

THE SPECIFIC IMPLEMENTATION METHOD

• First, condition the slurry of 95-98% water content in slurry settling tank [2] by stirring.

• Weigh certain quantity of conditioner to combine with

water in a predetermined ratio, and pump it into [2] to mix with the slurry. After conditioning for a preset time period (mixing time and speed depend on composition of slurry), pump it into plate press dewatering device [3].

• Each filtering plate of the plate press dewatering device is of a mobile and composite structure, made from

high-pressure-resisting material, and is equipped with certain number of springs [4] which provide preloading and sealing [5] to avoid leaking of feed.

^• Feeding is done at the center [6] of the filtering plates.

Cavities [7] with net lining are available at two sides of each of the filtering plates, increasing water output of filter chamber.

• When starting hydraulic cylinder to raise pressure, the

filtering plates are pushed forward by piston-rods, and volume of the filter chamber is hence reduced. Filter cake is then dewatered under an evenly distributed pressure.

• A cooling unit [8] in the cylinder ensures undisturbed

provision of pressure.

• Water is discharged through an inverted-V-shape water container followed by troughs at two sides of the

container.

• Flipping the water container by 180 degrees automatic

tilting system [9] transforms it into a holder of filter cake, which transports the cake into a drying unit below when the cake drops.

After stirring and stripping, the process of conditioning, dewatering, and drying of sludge is then completed, reducing water content from 95-98% to 20-30%. ADVANTAGES OF THE INVENTION

First condition the sludge according to its composition, add conditioner of accurate quantity, then pump the additive to conditioning device to mix with slurry, and stir. The advantage of the conditioning device is that it works with all kinds of sludge by adding conditioner according to the composition of the sludge, and completely mixing the sludge with the conditioner, creating favorable condition for the subsequent dewatering process. The conditioned sludge is pumped to dewatering device, producing filter cake with low water content, which can be further lowered through cold air stripping. The entire system is a continuous integrated production process. Because the process is completed at ambient temperature, cost is minimized, and the

requirements of environmental protection, energy saving, and carbon reduction are also met.

Claims

CLAIMS OF RIGHT

^• Annex 1 - Process flow of installation and sludge dewatering process.

• Annex 2 - Installation of automatic weighing/conditioning unit of additives.

• Annex 3 - plate press dewatering device.

• Annex 4 - Position of pressure spring of filtering plate.

• Annex 5 - Position of enclosed part in filtering plate.

• Annex 6 - Feeding inlet is positioned at centre of each filtering plate.

• Annex 7 - 2 concave sides of filtering plate.

• Annex 8 - Cooling unit in hydraulic cylinder.

• Annex 9 - Automatic tilting system for collection of waste water and filter cake.

• Annex 10 - Drying and dust collecting units.