Division BAT 33 In order to prevent and reduce emissions of pollutants into receiving waters from the whole mill, BAT is to use a suitable combination of the techniques specified in BAT 13, BAT 14, BAT 15 and BAT 16 and of the techniques given below.
United Kingdom
| Technique | Description | Applicability | |
|---|---|---|---|
| a | Extended modified cooking before bleaching. | See Section 1.7.2.1 | Applicability may be limited due to pulp quality requirements (when high strength is required). |
| b | Oxygen delignification before bleaching. | ||
| c | Closed brown stock screening and efficient brown stock washing. | Generally applicable. | |
| d | Evaporation of effluents from the hot alkaline extraction stage and incineration of concentrates in a soda boiler. | Limited applicability for dissolving pulp mills, when multistage biological treatment of the effluents provides a more favourable overall environmental situation. | |
| e | TCF bleaching. | Limited applicability for market paper pulp mills producing high brightness pulp and for mills manufacturing speciality pulp for chemical applications. | |
| f | Closed-loop bleaching. | Only applicable to plants that use the same base for cooking and pH adjustment in bleaching. | |
| g | MgO-based pre-bleaching and recirculation of washing liquids from pre-bleaching to brown stock washing. | Applicability may be limited by factors such as product quality (e.g. purity, cleanliness and brightness), kappa number after cooking, hydraulic capacity of the installation and capacity of tanks, evaporators and recovery boilers, and a possibility to clean the washing equipment. | |
| h | pH adjustment of weak liquor before/inside the evaporation plant. | Generally applicable to magnesium-based plants. Spare capacity in the recovery boiler and ash circuit is needed. | |
| i | Anaerobic treatment of the condensates from the evaporators. | Generally applicable. | |
| j | Stripping and recovery of SO2 from the condensates of evaporators. | Applicable if it is necessary to protect anaerobic effluent treatment. | |
| k | Effective spill monitoring and containment, also with chemical and energy recovery system. | Generally applicable. |