SOP for fermentation tank cleaning

1. Purpose: To establish standard operating procedures for cleaning fermentation tanks.
2. Scope: Suitable for biological fermentation tanks with a capacity of 5L or more.
4.1 Pre cleaning of tank body
4.1.1 After each batch of fermentation is completed, release the materials. Carefully remove the pH and DO electrodes and rinse them clean with tap water
4.1.2 Rinse the pH and DO electrode sockets on the tank with a small amount of tap water, then plug them with matching piston plugs and tighten them with screw caps.
4.1.3 For tank cleaning below 50L, loosen the screws and connections on the upper cover, remove the fermentation tank upper cover, remove the inoculation cap, feeding hole plug, defoamer probe, and reserved hole plug, clean and wipe each component with a cloth, and rinse with tap water. Use a soft bristled brush to clean the lid, the interface between the lid and the tank, the inner wall of the tank, and the seal of the mixer. Rinse off any residue and liquid with tap water, and collect the rinsing water in a bucket during rinsing. Check the leather ring and clean it with a cloth (if there is aging, replace it in a timely manner and record it), then assemble the components one by one, cover the fermentation tank, symmetrically tighten the fixing screws, and check the sealing with air to maintain pressure. If there is any air leakage, release the pressure in a timely manner and inspect the leaking area for treatment and resolution. And record the operation content.
4.1.4 For tank cleaning of 50L or more, the feeding cover, inoculation cap, filling hole plug, defoamer probe, and reserved hole plug should be loosened. Use a cloth to clean and wipe each component, and rinse with tap water. Turn on the power sight light and check for large debris such as slag on the inner wall of the tank. If so, use specialized tools to remove the debris. Use a soft bristled brush to clean the inner wall of the lid, the interface between the lid and the tank, the inner wall of the tank, and the seal of the mixer. Rinse off any residue and liquid with tap water, and collect the rinsing water in a bucket during rinsing. Check the leather ring and clean it thoroughly (replace it in a timely manner if it is aging), then assemble the components one by one, pass air and maintain pressure to check the sealing. If there is any air leakage, release the pressure in a timely manner, and inspect the leaking area for treatment and resolution. And record the operation content.
4.2 Alkali washing
4.2.1 After the pre cleaning inspection is completed and the pressure is released, open the feeding port and fill the fermentation tank with clean water. Estimate the volume of water added and record it.
4.2.2 Add 10 grams of NaOH flake alkali or 25 milliliters of NaOH industrial alkali per liter of washing water, and record the actual amount. Close the feeding port, start stirring at a speed of 300rpm, stir evenly, then use a jacket to raise the temperature to 90-95 ℃ and keep it warm for 1 hour. Record the operation details in the cleaning table.
4.2.3 When cooled to below 50 ℃, discharge the alkaline solution from the bottom valve of the tank. Use a covered plastic bucket to store the alkaline solution for formaldehyde recovery.
4.2.4 Rinse the residual alkali in the tank with sufficient tap water until the pH of the effluent is neutral. Record the operation content in the cleaning table.
4.3 Formaldehyde fumigation
4.3.1 After alkaline washing, fumigate once according to the following procedure. This step is applicable for batch alkaline washing of bacterial fermentation tanks, normal fermentation after batch 10 alkaline washing, and when the fermentation tank has been out of use for more than a month before resuming use. If cleaning is required, check the "No" position in the table and make relevant records. Otherwise, check the "Yes" position in the table and skip this step.
4.3.2 Installation of exhaust gas device: Connect the exhaust port, sampling port, and discharge port valves to plastic pipes, which are directly connected to the tail gas cylinder. Fill the cylinder with two-thirds of 1% alkali solution (recycled alkali solution as described in 4.1.5 can be used).
4.3.3 After the alkaline washing is completed, close the bottom valve of the tank, and then add tap water to the tank to cover the steam pipe outlet inside the tank. Add 50mL of 37% industrial formaldehyde to every 10L volume of fermentation tank, record the amount of formaldehyde, close the feeding port, pay attention to connecting the exhaust device (formaldehyde is toxic, avoid inhalation), slowly stir to make the solution uniform, and rotate at a speed of 100rpm.
4.3.4 Direct steam into the fermentation tank to raise the temperature to 90-95 ℃, close the steam valve, seal and keep warm for 30 minutes, and be careful not to overheat or overpressure the fermentation tank. Then slowly open the exhaust valve and let the steam flow to 100 ℃ for 30 minutes. The discharged steam is collected in the tail gas cylinder.
After the insulation is completed, close the steam inlet valve and slowly release the tank pressure from the exhaust port to maintain the exhaust device.
4.3.6 Rinse the inner wall of the fermentation tank with tap water, drain the fermentation tank from the bottom valve, and close all inlet and outlet valves of the fermentation tank.
4.4 Sterilization of empty cans
4.4.1 Slowly introduce steam into the fermentation tank, control the exhaust valve of the fermentation tank, maintain the tank pressure at 0.11mpa, raise the temperature to 121 ℃, and keep it warm for 1 hour.
4.4.2 After the insulation is completed, turn off the steam and release the tank pressure from the exhaust port (maintain the exhaust device). After the pressure is released, keep the exhaust valve open.
4.4.3 Use a jacket to cool the fermentation tank with cold water and remove the exhaust device. Drain the condensate from the discharge valve in the tank.
4.4.4 Fermentation operation can be carried out next.