Sludge Dewatering Tanks

Sludge Dewatering Tanks are used for various mainly in the water treatment industry.  In the main sludge, tanks are used for the following applications.

• Sludge Thickening
• Sludge Treatment
• Sludge Dewatering

What is Sludge?

Sludge is generally a thick, soft, wet mud or a similar viscous mixture of liquid and solid components which is a product produced during the refining process of wastewater treatment. Sludge covers a multitude of materials, many very different from each other with the common denominator, despite appearances, is that they generally have a very high water content. Increasing costs involved in its disposal, sludge treatment is becoming one of the greatest costs in running an effective wastewater treatment plant.

Sludge is generally classed as.

• Primary Sludge
• Biological Sludge
• Mixed Sludge
• Digested Sludge
• Mineral Sludge

What is Sludge Treatment?

Sludge treatment is necessary to reduce and to ameliorate the sludges produced within the biological wastewater treatment. Sludge from a treatment process there will generally have fewer solids in it than it looks like, as a typical DAF plant sludge will be approximately 5% solid or 95% water equating to 19 tonnes of water and 1 tonne of solids from a 20-tonne load of sludge. By increasing the solids content of the water gives a lot of costs savings on the plant.

What is Sludge Thickening

Sludge thickening is the treatment the sludge undergoes and is possible to reach a volume reduction of up to 80 % by thickening before further treatment is required.  This is where wastewater treatment plants drive the sludge off regularly and usually takes place directly in the sludge storage tank.

What is Dewatering?

Dewatering is the reduction of the sludge liquid amount after the thickening process as the liquid still must be dewatered to a dry and porous form generally by machine processes such as a filter press and centrifuge. Sludge Dewatering Tanks are fitted with outlets up the side of the tank to draw water off.

How Is Sludge Dewatered?

Sludge is generally conditioned before thickening and dewatering through either mineral or organic conditioning.  Flocculation Tanks will be used to carry out the process of creating the flocs. These work in the following steps

Step 1 – Adding flocculent

Chemical coagulants, also known as flocculants, are added to the water in the 3-stage flash mixer to destabilise the smaller individual particles and cause them to begin aggregating.

Step 2 – Flash Mixing

After the flocculent is introduced, the water is mixed vigorously by the flash mixer so that the chemicals are evenly dispersed throughout the water.  Coagulation begins during the flash mixing process as the coagulants neutralise the electrical charge of the fine particles.

Step 3 – Flocculation

After the initial more aggressive mixing, flocculation begins after slowing down the mixing so that the smaller particles produced during the coagulation start adhering together.  After the flocculation process, most of the particles should have bonded together, which is called the Floc.  Floc consists of larger masses of particulates bonded together in clusters of about 0.1 to 3 mm in size. It is critical that the floc is not too small otherwise, it does not settle well enough or too big otherwise, it will likely break apart in the flocculation tank.

Step 4. Clarification

Clarification is the last of the steps in the flocculation process are in conical tanks which hold the water long enough to allow the floc and other particulates to move to the bottom of the tank. This process can remove particles, sediments, oil, natural organic matter, and colour.

Mineral & Organic Conditioning

• Mineral chemicals such as iron salts and lime are used frequently found in filter press applications. Ferric Chloride and Iron Sulphate are mainly used in conjunction with lime to condition the sludge before a filter press allowing better filtration by the coagulating the colloids and by micro-flocculation of the precipitates.  Lime is often used as a conditioning agent with iron salts bringing a mineral nature to the sludge
• Organic chemicals such as coagulants and flocculants, generally cationic in nature, allow the formation of flocs creating a release of the water. This water will thus be easily eliminated during the dewatering step.

Enduramaxx Sludge Dewatering & Decant Tanks

In addition to providing bespoke sludge holding tanks and wastewater storage solutions for a diverse cross-section of clients, equipment mounting, and customisation of these sludge tank include welded fittings, sockets, and flanges. Racking ports allow draining of the water off the sludge while leaving the sediment in the bottom of the cone tank. Other options include industrial mixers liquid level sensor assemblies, fill pipes are available. PN16 and ANSI welded flanges, welded sockets and as well as airtight lids and vents are available to suit your project.

Sludge Dewatering Tanks

Our sludge tanks can be customised to project requirements with fittings, flanges, sludge decanting valves and pipework.  Side access to the tank for maintenance of the tank is an option available to the save the tank having to be accessed from the top hatch of the tank.

View our Sludge Tank Range

Dished Base Conical Sludge Tanks

Sludge tanks are vital in wastewater treatment plant for storage of raw effluent, treated effluent, final effluent, raw sewage and sewage sludge.  Conical tanks aid decanting/cleaning to a system of multiple tanks as it allows the sludge in the tank to settle out sludge further so more water can be recovered and further digest the sludge before disposing of.  Decant valves are fitted to these to draw off the water of the water as it settles.  A bottom drawing out the cone allows the thickened sludge to be taken away for treatment or disposal.

View our Conical Sludge Tank Range

As well as Sludge Dewatering Tanks, Enduramaxx can offer a range of bulk chemical tanks, dosing tanks, polymer mixers, coagulation and flocculation equipment – for more details please get in touch.