Large volumes of water are required for practically every step in the process of manufacturing paper. From pulp making and processing to the bleaching and washing activities carried out during the manufacturing process, each stage is intricately associated with the use of large volumes of water.
According to industry sources, about 85% of this water is used in processing activities, which implies that most of the water ends up as wastewater and residual sludge waste.
Waste water treatment
This presents significant challenges for the paper manufacturer who has to find safe methods of discharging the wastewater and disposing the sludge. One viable solution for achieving this objective is to look for innovative ways to reuse the water. Fortunately, recent advances in the technology of water treatment have led to the effective use of water treatment products for waste water management, discharge water purification and sludge dewatering.
Water Treatment Products
The use of effective water treatment products for purifying wastewater has distinct advantages. They reduce energy consumption and improve the quality of the paper product. They also simplify the production process and minimise production disturbances. They are cost effective and more environmentally friendly.
Electro-chlorination systems now make it possible to safely produce sodium hypochlorite for water treatment on-site without the risks associated with the handling of hazardous chemicals. It is a very effective and economical way of chlorinating water for drinking and for treating water for re-use in the factory. Models with built-in product tanks can be connected to high capacity external tanks for use in large paper manufacturing facilities.
Water treatment dosing pumps are used to transfer chemicals from one tank or drum to another. They are designed to draw a measured quantity of the chemical into a chamber and then inject this volume into the tank or drum being dosed. Dosing pumps are equipped with self-activating, non-return valves which stop the chemical once the required amount has been delivered. This enables them to discharge uniform dosing of the chemicals over a period of time. De-alkalising filters are useful for use with calcium hypochlorite dosing systems where they help in eliminating scaling problems and frequent injector maintenance.
Recycling of wastewater not only allows paper manufacturing facilities to reuse the water, it also helps to recover pulp fibres that slipped through during the production process. Employing membrane technologies for ultra-filtration is useful for treating the wastewater to a level where it can be re-used at the beginning of the manufacturing process.
