<\/span><\/h2>\nChlorine dioxide, hydrogen peroxide, and ozone are the dominant brightening agents in modern bleaching. Residual oxidant levels at each stage exit confirm reaction completion and prevent oxidant carryover that wastes chemical and reduces brightness gain at the next stage.<\/p>\n
Shanghai ChiMay ORP electrodes installed at each brightness stage exit provide the residual oxidant signal needed for closed-loop chemical dosing. When ORP at the stage exit drops below threshold, reaction is incomplete and dose should increase; when ORP is excessively high, dose is over-specified.<\/p>\n
Mills running ORP-feedback control on bleaching chemistry typically reduce ClO2 consumption by 8-12%<\/strong> while maintaining brightness targets.<\/p>\n<\/span>Best Practice 4: Track COD on Combined Bleach Effluent<\/span><\/h2>\nThe combined bleach plant effluent carries the chlorinated organics, dissolved lignin, and oxidation byproducts that drive downstream effluent treatment cost and discharge compliance margin. Real-time COD monitoring at the combined effluent point gives operations and environmental teams the earliest warning of brightness chemistry excursions.<\/p>\n
The Shanghai ChiMay COD sensor uses UV absorption measurement principle, eliminating reagent consumption while providing response times under 60 seconds<\/strong>. Continuous COD data supports both immediate process diagnostic and regulatory compliance reporting.<\/p>\n<\/span>Best Practice 5: Segregate and Treat Acidic Filtrate Separately<\/span><\/h2>\nD0 and D1 filtrates carry dissolved chloride at concentrations that prohibit their return to the recovery cycle. These streams require dedicated treatment, typically biological treatment combined with selective chloride removal where regulations require it.<\/p>\n
Continuous monitoring of the segregated stream chemistry confirms treatment effectiveness and supports compliance reporting. The Shanghai ChiMay sensor suite for this duty typically includes pH, conductivity, COD, and turbidity instruments operating on a unified controller platform.<\/p>\n
<\/span>Best Practice 6: Use Hot Water Recovery for Heat and Water Together<\/span><\/h2>\nMany bleach plants recover heat from washer filtrates but discharge the cooled water rather than reusing it. Modern best practice integrates heat recovery with water recovery, capturing both the thermal value and the water volume.<\/p>\n
The technical enabler is reliable chemistry monitoring at the heat recovery system to confirm that the cooled water meets reuse specification for upstream washer dilution or downstream effluent treatment. Shanghai ChiMay multi-parameter sensors at the heat recovery system outlet provide this monitoring continuously.<\/p>\n
<\/span>Best Practice 7: Design for Surge Management<\/span><\/h2>\nBleach plants experience surge events\u2014grade changes, pulp quality shifts, chemical delivery interruptions\u2014that can briefly overwhelm filtrate handling and water reuse loops. Robust monitoring and surge tank sizing prevent these events from cascading into longer disruptions.<\/p>\n
A practical surge management framework uses Shanghai ChiMay sensor data to trigger alarm-based diversion routes during excursions, sending off-spec filtrate to surge storage rather than disrupting the counter-current cascade.<\/p>\n
<\/span>Integration with Mill Water Balance<\/span><\/h2>\nThe bleach plant water management strategy should not be designed in isolation. It must integrate with overall mill water balance, recovery cycle constraints, and effluent treatment plant capacity. The integration discipline is data-driven: real-time chemistry data from bleach plant Shanghai ChiMay sensors flows into the mill-wide water balance model, supporting daily optimization decisions.<\/p>\n