When synthetic fabrics had almost replaced bronze wires, there was a need of proper cleaning, as earlier, all cleaning systems were being imported. Most of the complaints in fabrics were related to improper cleaning or quality of water. So the need of a specialist in this field was felt and Kingsley came into being, with the experience of their close associates Wires & Fabriks (S.A) Ltd who were leaders in paper machine clothing in India. Team Paper Mart had a discussion with Mr. Devesh Khaitan on why water management is needed, its benefits, available solutions etc.
Why Water Management?
• Paper quality parameters such as printability, runability, cross section variance depends on water resource management.
• Increasing water scarcity and water costs.
• Increasing energy costs for moving water in a paper mill with required flow, at specified pressure and temperature by means of pumps.
• Stricter environmental regulations and effective waste water (effluent) treatment to observe most stringent norms.
• Water is the primary vehicle for almost all corrosion, deposition, fouling, and failure problems in a paper mill.
• Water systems audit carefully identifying for practices that fall in “vital few” which could shut the mill down e.g.
i) Un-insulated caustic feed line that can freeze.
ii) High pressure boiler that can lead to tube rupture.
iii) Automatic condensate dumps will perform as desired.
Water Management in Indian Paper Industry
It is found that most events impacting asset protection and reliability in a paper mill are related to water contamination.
Water consumption per MT in Paper Mills Globally
- Wood based paper mills: 50-75 M / Ton
- Waste paper based mills: 10-25 M /Ton
Water consumption per MT in Indian Paper Mills
- Wood based: 160-200 M / Ton
- Waste Paper based: 70-100 M /Ton
Total water consumption by Paper Mills in India
- Annual Consumption: 1000 Million cubic meters
- Waste water generated: 700 Million cubic meters.
Areas where water consumption can be reduced & the subsequent benefits
Paper mill uses a huge amount of water for the production of paper. Due to the process the water gets contaminated, mainly by fibres. The new technologies that are designed and manufactured can help in the purification of the water that is drained out from the paper machine. The following benefits can be derived by reducing the consumption of water:
• Recovery of the fibres from the process water that can be reused by the paper mill as raw material thus reducing the amount of fibres to be produced starting at the pulper. The amount could be less but helps in decreasing cost.
• Recovery of the treated water (by help of high pressure filters and continuous self cleaning sand filters) in order to be reused in the process.
Right water & fibre recovery equipments helps in reduction of fresh water consumption and water pollution because lower amount of treated water is discharged to the rivers or municipal channels leading to better realisation for the mills.
Water Management Solutions
Whether a small or a big unit, the environment has to be looked upon and cannot be ignored. In order to reach the goals a basic water treatment plant based on recovery of the fibres that are contained in process waters (water drained from the paper machine) is required.
The high efficiency Dissolved Air Flotation unit is a suitable unit for the clarification of the water and fibre recovery. The unit is able to reach removal of suspended solids up to 99% and consistency of the floated sludge up to 5% letting to reuse the fibres directly in the machine chest. The clarified water from the floatation unit then should be passed through continuous self cleaning sand filter. It is maintenance free and remove solids lower than 5 ppm. This system is 100% full proof as they are running all over the world. A low cost alternative solution is also available i.e. using 2 stage High Pressure Filters. Filtrate water can be used for showers instead of using fresh water thus additionally reducing the fresh water consumption.
In our opinion a system made by flotation unit and sand filter is the suitable system for every paper mill for recovery of raw material, reduction of fresh water consumption, reduction of water consumption / tons of paper produced. Typically pay back time for the described plants is 6 -8 months.
Further there is one more step in water management i.e. an effluent treatment plant. There are different solutions depending on the grade of treatment that is required to be reached. A physical treatment process can be applied (and a flotation unit is the suitable solution) or a biological treatment plant can be adopted.
The biological treatment plants contribute to the purification of the water by reducing some parameters likeBOD(Biochemical Oxygen Demand) and COD (Chemical Oxygen Demand). A biological treatment plant not only allows the paper mills to return in the process a very good quality water but also helps a lot from an environmental point of view, a very sensible idea nowadays specially for the water that is to be drained out of the mill into the river.
Water management gaining pace & Kingsley offerings
Water Management has gathered pace in all the Industries mainly due to environmental issues. Nowadays zero discharge concept is coming into picture i.e. 100% back water being recycled and again used in the process. Mills have also gone to the extent that the excess water or not useable water for process is used for plantation and other purposes. The above is only possible when people running the industry realise it (which they have). Government has also to an extent become conscious about the environment and has issued guidelines for each and every industry which they have to follow.
One of hurdles that the industries would need to overcome is the cost involved in setting up the equipments required to have a good water management. Selection of technology plays a very vital role, which is lacking a bit in our industry. Most of the equipments at present are being imported by big mills which is expensive.
We therefore, now can offer the same technology at competitive price compared to imported technology. We offer equipments through which paper mills can recover up to 99% of their fibre from the back water, can also recover fillers which they would like to reuse in the process. We can offer equipments which would give them excellent water quality (less than 10 PPM), equipment which can give them pulp with a consistency of around 12-13% and also a complete biological treatment plant.