Renovation of Disinfection Contact Tank for Hospital Sewage

Hospital sewage carries pathogenic bacteria, viruses and other microorganisms, and the disinfection contact tank is the core structure to guarantee sufficient reaction time between sewage and disinfectant. Many old medical wastewater stations face problems such as short flow, insufficient hydraulic retention time, corrosion and poor mixing effect, which lead to unstable disinfection and failure to meet emission standards. Zhengzhou Puhua Technology, a professional environmental protection equipment manufacturer, provides integrated hospital sewage treatment solutions, including contact tank structural renovation, dosing system upgrading, online monitoring and supporting sewage treatment equipment customization.

Common Problems of Old Hospital Sewage Contact Tanks

The first typical defect is short-circuit flow and dead zones. Many early contact tanks lack diversion baffles or have unreasonable baffle layout. Part of the sewage flows out quickly without reaching the required contact time, while stagnant sludge accumulates in dead corners and decomposes anaerobically. Second, insufficient effective volume. The tank cannot meet the required hydraulic retention time: general hospital sewage needs at least 1 hour of contact time, and infectious disease hospital sewage requires more than 1.5 hours. Third, serious anti-corrosion failure. Long-term erosion by chlorine-based disinfectants and sewage causes concrete peeling, water leakage and structural aging. Fourth, unreasonable dosing position and poor mixing. Disinfectant cannot mix evenly with sewage, resulting in uneven residual chlorine. Fifth, missing sampling ports, sludge discharge outlets and online monitoring interfaces, making daily inspection and compliance testing difficult.

Core Renovation Content for Disinfection Contact Tank

First, optimize internal flow baffle structure. Install or rebuild diversion baffles inside the tank to form a folded flow channel, control the length-width ratio above 20:1, and eliminate short flow and dead zones. The tank is usually divided into two independent compartments for alternate operation, convenient for maintenance without shutting down the whole sewage station.

Second, adjust effective volume to meet retention time. Recalculate the water inflow peak value of the hospital. Expand the tank body or partition it reasonably if the volume is insufficient. Reserve sludge deposition space at the bottom, and set sludge discharge pipes to regularly remove accumulated sediment.

Third, carry out anti-corrosion reinforcement. Repair cracked and spalled concrete, and apply special anti-corrosion coating resistant to chlorine agent. For severe corrosion cases, FRP lining or stainless steel inner lining can be adopted to extend service life.

Fourth, upgrade the disinfectant dosing and mixing system. Optimize the dosing point before entering the contact tank, install static mixers to realize rapid mixing. Match automatic dosing equipment linked with online residual chlorine detector, adjust dosing amount automatically according to water quality and water volume fluctuation. Zhengzhou Puhua Technology can supply supporting sodium hypochlorite dosing devices, online residual chlorine monitors and dechlorination units.

Fifth, add functional interfaces. Set standard sampling ports at the outlet section of the contact tank, reserve installation positions for liquid level sensors and online monitoring probes, and transform overflow and emptying pipelines to facilitate emergency maintenance and sampling inspection.

Common Supporting Process Matching After Renovation

Most hospital sewage adopts the route of pre-treatment → biochemical treatment → secondary sedimentation → disinfection contact tank. If the raw water has high SS and organic matter, it is necessary to strengthen the pre-treatment effect before the contact tank, otherwise suspended solids will consume a large amount of disinfectant and reduce disinfection efficiency. For projects with strict residual chlorine emission limits, a dechlorination tank can be added after the contact tank to avoid excessive residual chlorine entering the municipal pipe network. Zhengzhou Puhua Technology can complete the whole process design, including grille, regulating tank, biochemical tank, sedimentation tank and disinfection system.

Key Points for Construction and Acceptance

Arrange construction in non-peak period of hospital water consumption, build temporary emergency drainage and temporary disinfection facilities to ensure the hospital sewage can still be treated normally during renovation. After construction, carry out hydraulic test and disinfection effect verification, continuously monitor residual chlorine and pathogen indicators, and check whether the actual hydraulic retention time meets the design requirements. All renovation works must comply with hospital wastewater discharge specifications.

Summary

The renovation of hospital sewage disinfection contact tank focuses on solving short flow, insufficient retention time, corrosion and unstable dosing. Structural optimization, anti-corrosion repair and automatic monitoring upgrading are the main transformation directions. Zhengzhou Puhua Technology has rich experience in medical sewage compliance renovation. It can conduct site survey, customize contact tank renovation scheme and provide complete sets of hospital sewage treatment equipment to help hospitals stably reach the standard and pass environmental inspection.