DAF Sludge Storage, balance & buffer holding wastewater tanks can be used for a variety of purposes with the most common application is the blending and homogenization of highly concentrated primary, secondary or digested sludge.
Various solutions are used to mix the sludge itself based on the volume and type of sludge with the dosed thickening chemicals. These tanks are in throughout the wastewater/sludge treatment process.
Let's take a look at some:
DAF Sludge Storage Tanks - Used on Dissolved Air Flotation [DAF] water treatment systems for high volumes of wastewater containing a low percentage of solids. – More details here
Sludge Balance Tanks - Balance tanks are used where the flow rate of wastewater varies greatly or where its composition, strength or temperature varies sufficiently. – More details here
Sludge Buffer Holding Tanks - Buffer tanks used to hold sludge from the thickener before delivery to the filter press. – More details here
Let us look at more on the sludge treatment, thickening and dewatering stages
Sludge Treatment & Thickening
During sludge treatment, it is necessary to reduce and ameliorate the sludges produced within the biological wastewater treatment. 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.
Sludge Dewatering Stages
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.
1: Adding flocculent
Chemical coagulants are added to the water in the 3-stage flash mixer to destabilise the smaller individual particles and cause them to begin aggregating.
2: Flash Mixing
After the flocculent is introduced, the flash mixer mixes the water vigorously so that the chemicals are evenly dispersed in the water. And coagulation begins during this process as the coagulants neutralise the electrical charge of the fine particles.
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. Floc consists of larger masses of particulates bonded together in clusters of about 0.1 to 3 mm in size and it critical that the floc is not too small or may not settle well or too big and it will likely break apart.
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.
Following this process transfer pumps are generally used to complete the sludge dewatering process.
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 or dewatering ports allow draining of the water off the sludge while leaving the sediment in the bottom of the cone tank.
Sludge Tank Mixers
Industrial sludge tank mixers are required for blending and homogenization of primary sludge and these are specified to each product and size of the vessel. With mixers, side access to the vessel is recommended for maintenance of the mixer and tank.