Air flotation tank function
The overall agglomeration effect of floating slag in the floating zone is good. The floating slag is scraped off in a timely manner, and the air flotation effluent must be relatively clear to reduce the burden of subsequent biochemical tank treatment.
Operation steps
(1) Water level control: The air flotation tank must maintain a certain water level before starting up (generally higher than the inlet flow meter of the dissolved air pump);
By adjusting the opening of the pump outlet valve or the return pipe valve in the regulating tank, the water volume in the reaction zone of the inlet floating tank can be reduced to less than the processing capacity of the air flotation tank (with an upper limit fluctuation range not exceeding 10%);
(2) Requirements for the coagulation reaction effect of reaction zone reagents: first start the dosing system before starting the water inlet, and when shutting down, the water pump should be closed first before stopping the dosing; Add PAC to the first compartment of the reaction zone (if the pH is below 6.0, alkaline agent needs to be added to this compartment to increase the pH value to 7-8, and this pH value should be tested frequently) to complete the coagulation reaction (neutralization); Enter the second compartment and add PA (viscous organic agent) to complete the flocculation reaction, even if small particles of alum floc aggregate into large particles of alum floc, in order to improve the effect of capturing alum flocs in the floating slag layer of the air flotation zone. The reaction is based on the observation of obvious flocs and clear stratification between water and flocs; The dosage of PAC and PAM should be adjusted in a timely manner according to the on-site water quality and reaction conditions;
Operation steps and requirements for solvent pump
(1) Before starting up: Confirm that the motor direction matches the indicated direction of the water pump. It is strictly prohibited to reverse and damage the water pump. Before starting up, open the water volume regulating valve on the inlet pipe and the valve on the outlet and inlet floating pool pipeline of the dissolved gas tank;
(2) Power on: Turn on the start button of the solvent pump, wait for the motor to reach the rated speed, slowly open the outlet valve of the solvent tank (inlet float tank pipeline), and adjust the outlet pressure of the solvent pump to 0.5MPa; Slowly close the inlet control valve to create a vacuum on the inlet side of the dissolution pump. When the vacuum pressure gauge at the inlet of the dissolution pump reaches 0.01-0.02mPa (negative pressure), open the air inlet control valve to allow the air intake to reach 10% -15% of the inflow flow rate of the dissolution pump. At this point, the inflow volume (reflux volume) of the dissolution pump is 20-30% of the treatment capacity of the air flotation tank. The outlet pressure of the dissolution pump drops to the normal range of 0.4-0.5Pa (bubble diameter of 30 μ m, good air solubility).
(3) Shutdown: Due to the presence of a check valve at the outlet of the solvent pump, there is no need to close the outlet valve of the solvent tank; Press the stop button of the dissolution pump, and then close the inlet valve. If the dissolution pump is shut down for a long time, the water in the pump body should be drained to prevent the pump from freezing and scaling after shutdown.
Operation steps of scraper
(1) Check if the scraper is in good electrical condition; Check whether the wheel rail contact and engagement are good, and whether the travel switch is sensitive. Enter the next operation after it is normal;
(2) When the thickness of the floating slag is 3-5cm (forming a slag layer), turn on the scraper button to scrape the slag, and adjust the liquid level in the air flotation zone to discharge the air flotation sludge in a timely manner to ensure the water discharge effect; At the same time, prevent clean water from the air flotation zone from entering the sludge hopper of the air flotation tank to reduce sludge production; The scraping time (cycle) is generally 2-3 minutes, but it also needs to be adjusted according to the specific amount of slag
(3) Shutdown: After completing one scraping operation, the machine needs to be stopped and enter the next scraping cycle after the formation of the floating slag layer again;
Attention
(1) Pay attention to the operation points and sequence of the three units of air flotation tank reaction, gas dissolution, and slag scraping. If it is not the first time to start up, add chemicals first, adjust the water inlet of the regulating tank lifting pump, adjust the dosage and effect, start the air flotation system, and start the slag scraping machine after the formation of floating slag;
(2) When starting the solvent pump, the air intake valve must be closed, and the solvent pump is strictly prohibited from idling without water! During normal operation, the pressure range of the vacuum gauge at the inlet of the solvent pump should be controlled between 0.01-0.02Pa (negative pressure), and the outlet pressure of the solvent pump should be controlled between 0.4-0.5IPa;
(3) The air flotation tank needs to be shut down for a long time (more than 3 days) due to maintenance and other situations. In order to timely discharge the sediment that may exist in the air flotation tank into the sludge tank and prevent the accumulation of flocs for a long time, which may cause scaling and block the flow channel; Normally, sediment is discharged every half month during normal operation.
Operating Procedures for Dosing System
1. Functions of the dosing system:
Mainly providing the required coagulants for air flotation reaction and sludge conditioning to enhance reaction efficiency and improve treatment efficiency.
2. Operation steps:
(1) Preparation and dosing of PAC (polyaluminum chloride) agent
① First, put tap water into 2/3 of the PAC chemical tank, turn on the PAC mixer, and add all the required PAC into the tank while stirring. Continue adding water until it reaches 4/5 of the tank, then stop adding water and continue stirring for 30 minutes before adding; The quality ratio of PAC dissolution can be controlled at around 3-5% to ensure stable and continuous reaction effects.
② Open the PAC dosing pump outlet reflux valve to prevent damage to the pump caused by accidental closure of the remote dosing point valve; At the same time, open the dosing valve at the outlet of the dosing pump, and then turn on the PAC dosing pump for dosing. The dosing is adjusted and controlled based on the on-site reaction effect;
③ Stop dosing: When the entire PAC dosing point (mainly the air flotation reaction zone) needs to be shut down, press the PAC dosing pump stop button.
(2) Preparation and Dosage of PAM (Polyacrylamide) Agent
① First, put tap water into 2/3 of the PAI dosing box, turn on the PAI mixer, and slowly and evenly sprinkle the required PAI into the dosing box. While stirring, continue adding water until it reaches 4/5 of the dosing box, then stop adding water and continue stirring until the PAI is completely dissolved; PAI cannot be used immediately and requires several hours of hydration for better results; The quality ratio of PAI dissolution can be controlled at around 0.1-0.2% to ensure consistent drug concentration, stable and continuous reaction effect.
② Open the outlet reflux valve of the PAI dosing pump to prevent damage to the pump caused by accidental closure of the remote dosing point valve; At the same time, open the dosing valve at the outlet of the dosing pump, and then turn on the PAI dosing pump for dosing. The dosing is adjusted and controlled based on the on-site reaction effect;
③ Stop dosing: When all PAI dosing points (mainly the air flotation reaction zone) do not require dosing, press the PAM dosing pump stop button.
Notes:
(1) It is forbidden to add the reagents while preparing them (the concentration cannot be guaranteed);
(2) When preparing PAM, it is strictly forbidden to pour the required reagents directly into the dissolving box to prevent the reagents from agglomerating and affecting the use effect of the reagents, while wasting the reagents and increasing the treatment cost; in winter, PAM should be prepared in hot water in advance to dissolve it, and then diluted in the dissolving box to prepare it to the required concentration;
(3) Control the relative ratio of the reagents and water to keep the reagent concentration relatively stable and reduce the impact on the treatment system;
(4) Prepare the reagents in time to ensure the normal operation of the reaction pool;
(5) Strengthen the daily maintenance and management of the dosing equipment to avoid running, bubbling, dripping and leaking. If the equipment fails, the company's mechanics should be asked to solve it in time. Equipment maintenance depends on careful operation and maintenance at ordinary times.
(6) The dosing system should be cleaned regularly to remove debris.