Food Processing Wastewater Clarification Belt Filter System

Food Processing Wastewater Clarification Belt Filter System

Category： Belt Filter
Energy Consumption: <15 kW/h
Water Recycling: Closed-Loop System
Noise Level: <65 dB
Certifications: CE
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Belt filter press description

A belt filter press (BFP) provides sludge dewatering by pressing the sludge to force the water through a permeable medium. The process produces a cake (the dewatered product) having a dry solids (DS) content of 30% or more in the case of primary sludge. This is to be distinguished from the lower-energy gravity belt thickener process which achieves a maximum DS content of ~10%.

A BFP combines drainage and mechanical pressure sequentially to remove water. The equipment normally comprises 2−3 recirculating belts, with two belts combining at some point to compress the sludge and squeeze water from it.

Belt filter press principle

The conditioned sludge feed is first conveyed along a gravity drainage section of one of the porous belts, as with a gravity belt thickener. It is then subject to pressure as it is passed between two recirculating belts, forming a wedge zone at the inlet, which travel over a roller. This squeezing action from the two belts in this pressure zone releases more water.

Many belt filter press technologies contain a second pressure zone comprising a series of rollers through which the two belts pass with the sludge solids retained between them. The rollers in this high pressure zone apply tensioning (i.e. stretching) to the belts, exerting both shearing and compressive forces on the sludge which further release more water.

Belt filter technical sheet

Sludge Kinds	Input Concentration %	Capacity m³/h	DS Capacity kg/h	Moisture of Cake %	PAM Consumption %(DP/DS)
Unconcentrated Aerobic Sludge	0.5~1.5	15~30	150~300	~80 (+2)	2~5
Concentrated Aerobic Sludge	2~4	6~12	200~300	~80 (+2)	2~5
Digested Sludge	3~6	7~15	300~400	<80	2~5
Unconcentrated Primary Sludge	0.8~2.0	18~35	300~400	<80	2~5
Concentrated Primary Sludge	3~5	6~12	300~400	<80	2~5
Paper-making Activated Sludge	0.5~2.5	15~35	200~400	<78	3~7
Printing and Dyeing Mixed Sludge	1~3	10~25	180~350	75~78	3~10

Model selection

Model	Belt Width	Sludge Concentration	Outlet Concentration	Capacity	Power
DNT-1000	1000mm	2-4%	15-25%	6-12	1.49kW
DNT-1500	1500mm	2-4%	15-25%	12-15	2.05kW
DNT-2000	2000mm	2-4%	15-25%	15-25	2.6kW
DNT-2500	2500mm	2-4%	15-25%	35-50	4.1kW

Belt Filter Press Advantage

Belt filters are considered simple and reliable, with good availability, low staffing, easy maintenance and a long life. The belt filter is most advantageous when installed such that it is open and viewable at floor level for easier adjustment and monitoring. This is of course subject to what lighting and ventilation will allow.

The belt filter press is often used in wastewater treatment, and thus the odour of the feed sludge, volatile emissions and the chemicals used in treatment, may become a problem. One control method is to use odour-neutralizing chemicals such as potassium permanganate. However this only neutralizes odours and doesn’t affect any gases or chemicals involved. Although all problems can be controlled by enclosing the filter, the enclosure reduces essential visibility and easy access to the machine for maintenance and repairs, leading to the expensive automation of the process.

Belt filter press features

Belt press filters are designed for solids capacity, by weight or volume, rather than wastewater flow. Solids concentration must be determined based on the concentration of primary solids in the feed and further solids that may precipitate during treatment. Solids concentration for a process will vary, thus the design must have the capacity to deal with varying feed solids concentration.

The feed to a belt press filter depends on the type of solids, desired product and filter design. For most sludge types the feed dry solids concentration is typically in the range of 1-10%. The resulting dewatered sludge (or cake) dry solids concentration typically falls in the range of 12-50%. Dilute feed solids concentration results in a cake of higher moisture content whilst a higher feed solids concentration yields an improved solids filtration rate and drier end product.

Belt filter press applications

The belt filter is mainly used for dewatering of sludge and slurry and juice extraction from apples, pears and other fruits, as well as grapes for winemaking, etc. Belt filters are used both municipally and industrially in a range of areas including urban sewage and wastewater treatment, metallurgy and mining, steel plants, coal plants, breweries, dyeing, tanneries, as well as chemical and paper factories.

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