Ceramic Tile manufacturing industry is one of the most popular industry around the globe. Ceramic tile manufacturing has different process like Calibration, polishing, sizing etc. Maximum water is utilized in polishing and sizing of tiles.
Ceramic industry wastewater not only contains high suspended and total solids but also significant number of dissolved organics resulting in high BOD or’ COD loads. Suspended solids can be removed from the wastewater by chemical precipitation. However dissolved BOD/COD compounds can only be removed by biological or’ chemical oxidation.
Organic compounds present in different kinds of soils and chemicals used in ceramic industry processes cause significant organic and inorganic pollution in wastewater. Because of high mineral content of processed materials wastewater contains high concentrations of suspended and dissolved solids. Organic compounds present in mineral rich soil and in chemicals used for processing cause significant COD levels in the wastewater.
Water management has become an increasingly critical issue in ceramic tile industrial sectors, owing to the large quantities of wastewater they produce, most of the wastewater arises in the polishing and sizing operations of the facilities used for the preparation and application of glazes and other coatings. Thus, chemical coagulants are often added to the industrial effluents to remove the substances producing turbidity before discharge or recycle. Alum, Fecl3, Polyelectrolyte and Lime dosing resulted in significant removal of turbidity and TSS which could lead to water and cost saving. All the coagulants used were capable to reduce the turbidity from 400NTU to far below the allowable concentration, i.e. < 20NTU.
Basic Treatment Process
Preliminary treatment includes screening, grit removal, and flow monitoring. In the Primary treatment the stream from plant collected in the collection chamber. Then the raw effluent pumped to the baffling tank through chemical dosing tank for sedimentation and floatation.
In the baffling tank effluent equalization smooths out flow variation. By providing storage and a constant smooth flow, the sedimentation process will be more effective. It also allows downstream processes to be sized smaller, since the flow from the basin is metered out and does not hydraulically surge the downstream processes.
The gravity flow from baffling tank enters the secondary clarifier. Sedimentation is the process of letting suspended solids settle by gravity. This is accomplished by decreasing the velocity of the slurry/liquid being treated to nearly half the settling rate of suspended solids in a tank. It is necessary to establish detention time, settling rate/overﬂow rate and settling area for the design ﬂow for sizing of the settling tank for various process applications. Commonly known as gravity settlers by process engineers these are tanks where solids are settled naturally or with chemical aid and concentrated slurry is removed as underﬂow and clariﬁed liquid as overﬂow. A mechanism is used in these gravity settlers, to scrape the settled sludge at the boom of the tank towards the central sludge pit continuously. The mechanism is driven by a “Drive System” mounted on the support beams or concrete pier at the top of the tank. The liquid overﬂows through the peripheral weir at deﬁned loading to ensure desired velocity resulting in proper clariﬁcation.
The clarified water collected is passed through pressure sand filter to arrest the turbidity if any and treated water reused in process. The sludge recovered from Clarifier passed through Hydraulic Filter press to form cakes and the water collected again rooted to the collection chamber.