Abstract

 

This regulation aims to strengthen the management of wastewater treatment equipment, processes, and water quality to ensure the safe and normal operation of wastewater treatment, achieving the purpose of water purification, sludge treatment and disposal, and environmental protection. The regulation includes general requirements and operating procedures for various systems. General requirements involve operation management, safe operation, and maintenance, requiring operation management personnel and operators to be familiar with the treatment process, equipment operation requirements, and technical indicators. They should conduct inspections as required, keep operation records, promptly handle or report abnormal situations, maintain equipment cleanliness, and take safety precautions. The operating procedures for each system detail the operation management of the pH adjustment pool, reaction pool, flocculation pool, pressurized dissolved air flotation process, aeration bioreactor, sedimentation tank, secondary reaction pool, filter backwashing process, sludge thickening tank, sludge dewatering, blower, and cooling tower, as well as chemical preparation procedures. The regulation also provides detailed explanations of abnormal problems and solutions related to sedimentation tanks and activated sludge.

 

 

Source: Environmental Honeybee

 

General Principles

 

1. This regulation is formulated to strengthen the management of wastewater treatment equipment, processes, and water quality, ensuring the safe and normal operation of wastewater treatment to achieve the purpose of water purification, sludge treatment and disposal, and environmental protection.

 

2. The operation, maintenance, and safety of wastewater treatment shall comply with this regulation and the provisions of relevant national standards.

 

 

General Requirements

 

 

1.1 Operational Management Requirements

1. Operation management personnel must be familiar with the plant's treatment processes and the operational requirements and technical indicators of facilities and equipment.

2. Operators must understand the plant's treatment processes and be familiar with the operational requirements and technical indicators of the facilities and equipment at their posts.

3. Each post should have a process system network diagram, safe operation procedures, etc., and these should be displayed in a conspicuous location.

4. Operation management personnel and operators should inspect the structures, equipment, electrical appliances, and instruments according to requirements.

5. Operators at each post should keep operation records on time. Data should be accurate and error-free.

6. Operators should promptly handle or report to the competent authority when abnormal operation is detected.

7. Various mechanical equipment should be kept clean and free of water or gas leaks.

8. The weirs and pool walls of water treatment structures should be kept clean and intact.

9. According to the requirements of different electromechanical equipment, regular checks should be carried out, and lubricating oil or grease should be added or replaced.

1.2 Safe Operation Requirements

1. Operators and maintenance personnel at each post must undergo technical training and practical production experience and pass an examination before taking up their posts.

2. Equipment should be started only after the necessary preparations have been made.

3. Motors should not be started if the power voltage is more than or less than the rated voltage by 5%.

4. Operators should follow electrical operation procedures when switching electrical switches.

5. Power must be cut off during equipment maintenance, and a maintenance sign must be hung on the switch before operation.

6. In rainy or snowy weather, operators should pay attention to anti-slip when patrolling or operating on structures.

7. Clean the electromechanical equipment and the surrounding environment. Strictly prohibit wiping the running parts of the equipment. Washing water must not splash onto cable heads, energized parts of motors, or lubrication parts.

8. Operators at each post should wear complete labor protection supplies and take safety precautions.

9. Protective and life-saving facilities and supplies should be equipped in conspicuous locations on the structures.

10. Non-personnel are strictly prohibited from starting or stopping the electromechanical equipment at their posts.

1.3 Maintenance Requirements

1. Operation management personnel and maintenance personnel should be familiar with the maintenance regulations for electromechanical equipment.

2. Regular inspections, maintenance, and anti-corrosion treatment should be carried out on the structure of the structures and various valves, railings, ladders, pipelines, etc., and damaged lighting equipment should be replaced in time.

3. Various equipment connecting parts should be checked and tightened frequently, and easily damaged parts of the couplings should be replaced regularly.

4. Various pipeline valves should be regularly tested for opening and closing.

5. Electrical control cabinets should be regularly inspected and cleaned, and their various technical performances should be tested.

6. The limit switches and manual and electric interlocking devices of electric valves should be checked regularly.

7. After each pump stop, the sealing condition of the packing or oil seal should be checked and necessary processing should be carried out. Packing, lubricating oil, and grease should be added or replaced as needed.

8. For devices with steel wire ropes, the rope must be replaced if the wear and tear is more than 10% of the original diameter, or if one strand has broken.

9. In addition to daily maintenance, various mechanical equipment should also undergo major, medium, and minor repairs according to design requirements or manufacturer's requirements.

10. When overhauling various mechanical equipment, the coaxiality, static balance, and other technical requirements must be ensured according to the equipment's requirements.

11. Lubricating oil, grease, laboratory wastewater, and other miscellaneous items replaced from maintenance equipment must not be discarded into the wastewater treatment facilities.

12. Temporary power lines must not be arbitrarily connected when repairing mechanical equipment.

13. The testing, maintenance, and cycle of lightning protection and explosion-proof devices for buildings and structures should comply with the regulations of the electricity and fire departments.

14. Fire-fighting facilities and other protective supplies should be regularly inspected and replaced.

 

Operating Procedures for Each System

 

 

Operating Procedures for pH Adjustment Pool, Reaction Pool, and Flocculation Pool

1. Open the raw water pump to pump wastewater into the pH adjustment pool, and simultaneously open the air intake valve to keep the water agitated. The air intake valve should remain open.

2. Start the ferrous sulfate pump and the PAM pump, and adjust the dosage of ferrous sulfate and PAM by opening the reflux valve.

3. Regularly check the wastewater in the pool, observe the flocculation formed in the pool, and adjust the dosage of chemicals. If the flocs are small, add more PAM.

Operation Procedure for Pressurized Dissolved Air Flotation

The pressurized dissolved air flotation system combines the flocs formed in the reaction tank with tiny air bubbles, allowing them to float up due to buoyancy, thereby removing CODcr, BOD5, SS (suspended solids in water), etc.

1. Start the return water pump, pump the return water into the container tank. The water level in the tank must be more than half of the tank volume. Then add compressed air. The air and water are mixed in the aeration tank for about 10 minutes. When the dissolved air water turns milky white, it is qualified. The pressure gauge should be controlled at around 0.3-0.4 MPa.

2. When the floating scum reaches 50-100mm, press the button to start the scum scraper and scrape the scum into the scum collection tank.

3. When the amount of scum in the scum collection tank reaches a certain level, raise the overflow gate of the flotation tank to raise the water level and flush the scum collection tank. After flushing, lower the valve to the normal operating water level.

Operation Procedure for Aerated Bioreactor

The aeration bioreactor system mainly uses aerobic conditions to allow the organic matter in wastewater to be adsorbed, oxidized, and reduced by microorganisms in activated sludge, oxidizing and decomposing complex macromolecular organic matter into simple inorganic matter, thereby purifying the wastewater.

1. Adjust the aeration volume according to the specific situation and adjust the air intake by controlling the valves.

2. The aeration tank should be controlled by adjusting the sludge load, sludge age, or sludge concentration.

3. The dissolved oxygen at the outlet of the aeration tank should be 2mg/l.

4. Regularly observe the activated sludge community, supernatant transparency, sludge color, state, smell, etc., and regularly test and calculate the relevant items reflecting the sludge characteristics.

5. Abnormal phenomena such as sludge expansion and sludge floating in the sedimentation tank caused by changes in water temperature, water quality, or aeration tank operation mode should be analyzed for their causes, and the system operating conditions should be adjusted and appropriate measures taken to restore normal operation according to the specific situation.

6. When the water temperature in the aeration tank is low, appropriate measures should be taken to extend the aeration time, increase the sludge concentration, increase the sludge age, or use other methods to ensure the wastewater treatment effect.

7. When foam and scum occur in the aeration tank, the cause should be analyzed based on the foam color, and corresponding measures should be taken to restore normal operation. Turn on the defoaming pump and sprinkle defoaming agent as needed.

8. Add nutrients to the bioreactor according to the sludge conditions. Generally, nutrients are added at a ratio of BOD5:N:P=100:5:1. The N source is urea, and the P source is sodium phosphate or disodium hydrogen phosphate.

Sedimentation Tank Operation Procedure

1. Regularly inspect the sedimentation effect of the sedimentation tank, such as effluent turbidity, sludge level, state of settled suspended solids, surface sludge or scum, etc. Check whether various pipelines and accessories, sludge scraping devices are normal, whether the flow from each weir is uniform, whether the weir is severely blocked, and clean the effluent weir and effluent channel of retained debris and floating objects.

2. Discharge sludge in a timely manner according to sludge production and sludge storage time, generally 2-4 hours. Use valves to control the amount of return sludge, and send the remaining sludge to the sludge thickening tank, controlling the ratio of return sludge to net discharged sludge. The sludge discharge amount of the sedimentation tank can be determined according to the sludge settling ratio, mixed liquor sludge concentration, and secondary sedimentation tank sludge level.

3. Observe the effluent quality of the sedimentation tank and do not allow sludge to float in the sedimentation tank.

4. The thickness of the supernatant in the sedimentation tank is generally around 0.5-0.7 meters.

Secondary Reaction Tank Operation Procedure

When the water level in the effluent channel is the same as the water level in the secondary reaction tank, start the pump to pump water into the secondary flotation tank for solid-liquid separation. When the water level in the effluent channel drops to 10cm from the bottom of the tank, stop the pump. Keep the air pipe valve in the tank open to keep the water in the tank agitated.

Filtration and Backwashing Operation Procedure

Filtration mainly treats the remaining CODcr, BOD5, and tiny SS components and synthetic detergents in the water after physical and chemical and biological treatment. The filter uses cobblestone as the bottom support filler, quartz sand as the middle part, and activated carbon as the upper filler. Because the filter layer adsorbs and saturates after running for a period of time, the adsorption effect will deteriorate, resulting in poor effluent quality. Therefore, backwashing is required to restore the activity of the filter material.

1. Close the inlet valve at the top of the filter tank and the outlet valve at the bottom, and open the backwash inlet valve.

2. Start the backwash pump and backwash for 12 minutes.

3. Turn off the backwash pump, open the inlet valve at the top of the filter tank and the outlet valve at the bottom, and close the backwash outlet valve. Backwashing is complete.

Sludge Thickening Tank Operation Procedure

The sludge thickening tank thickens the remaining sludge in the sedimentation tank. The thickening condition will affect the treatment effect of the dewatering machine.

1. Observe whether the outflow from each weir of the effluent weir is uniform, and keep the effluent weir and effluent channel unobstructed and clean.

2. Turn on the sludge dewatering pump and filter press according to the actual situation to dewater the sludge.

3. The moisture content of the sludge discharged from the thickening tank should be controlled at 95-97%.

Sludge Dewatering Operation and Management

1. When using mechanical equipment for sludge dewatering, appropriate chemical conditioners such as PAC or PAM should be added.

2. The dosage of chemical conditioners should be determined through experiments based on factors such as the properties and solid concentration of the sludge.

3. After sludge dewatering is complete, the equipment and filter cloth should be immediately rinsed clean; otherwise, rinsing will be very difficult after the sludge dries.

Blower Operation and Management

1. The blower air volume should be adjusted according to the oxygen demand of the aeration tank.

2. In case of abnormal phenomena such as sudden power failure in the blower and water/oil cooling system, measures should be taken immediately to ensure that the blower does not malfunction.

3. The blower ventilation passage should be kept clean, and no items are allowed inside.

4. During blower operation, operators should observe the blower and motor's wind pressure, oil temperature, oil pressure, air volume, current, and voltage, and record them in a timely manner. If an abnormal situation cannot be resolved, the machine should be stopped immediately.

5. The cooling and lubrication systems should be checked regularly to ensure that they are unobstructed and that the temperature, pressure, and flow rate meet the requirements.

Cooling Tower Operation and Management

The purpose of the cooling tower is to reduce the water temperature to a level suitable for microbial growth, thereby enhancing the ability of microorganisms to degrade organic matter in wastewater.

1. Operate the cooling tower according to the water temperature of the neutralization tank. Start the cooling pump when the water temperature in the neutralization tank is above 30℃; otherwise, do not start it.

2. When the blower and pump are running simultaneously, the valves should be opened gradually, and the water volume should be adjusted to an appropriate level to prevent excessive water flow and overflow. Use the appropriate water level markings in the cooling tower's water receiving bucket to confirm the appropriate water level.

Reagent Preparation

1.FeSO₄ PAC: Close the connecting valve between the two barrels, pour the reagent into the reagent tank, add water while stirring. After the reagent is completely dissolved, open the connecting valve and use natural pressure to press the reagent into the other barrel. Close the connecting valve when starting the pump. The reagent tank needs to be cleaned periodically to prevent clogging.

2.H₂  SO ₄ NaOH: Open the tap water valve and add water to half the volume. Then, turn on the pump and add H ₂  SO ₄ or NaOH until the barrel is full. Note that water must be added first, then the reagent.

Abnormal Issues and Solutions for Sedimentation Tanks

(1) Effluent contains fine suspended particles

This indicates that the sedimentation effect is poor in some parts of the sedimentation tank. The reasons include: water volume load shock or long-term overload; reduced residence time due to short-circuiting, causing flocs to flow out of the effluent weir before settling; excessive aeration of activated sludge in the aeration tank, causing the sludge to self-oxidize and disintegrate.

Solutions include: adjusting the uneven water distribution facilities for inflow and outflow to reduce the impact of shock load, which helps to overcome short-circuiting; adjusting the operating parameters of the aeration tank to improve sludge flocculation performance, such as supplementing nutrients when deficient, shortening the sludge age when sludge ages excessively, and adjusting the aeration amount when aeration is excessive; evenly distributing the load impact of the supernatant liquid from the concentration tank and the load impact of the excess sludge entering the primary sedimentation tank.

(2) Effluent weir is dirty and effluent is uneven

Due to sludge adhesion, algae growth on the weir, or objects such as floating scum stuck in the weir opening, the effluent weir becomes dirty, and some weir openings may even be blocked, resulting in uneven effluent.

Solutions include: regularly cleaning the effluent weir opening of stuck debris; adding chlorine for disinfection to prevent sludge and algae from growing and accumulating on the weir opening.

(3) Sludge floating

Reasons for sludge floating include: excessive sludge retention time, incomplete degradation of organic matter; denitrification of sludge in the sedimentation tank, reduction to N ₂ causing sludge to float.

Solutions include: ensuring normal storage and sludge discharge time; checking for sludge discharge equipment failures; cleaning sludge from the sedimentation tank walls, components, or dead corners; reducing the nitrification level of sludge in the aerobic treatment system; increasing sludge return flow and adjusting sludge age; preventing the entry of deteriorated sludge from other structures.

(4) Sludge scraper failure

The sludge scraper stops running due to excessive load.

Solutions include: reducing sludge storage time and sludge volume; checking if the scraper is stuck by bricks, tools, or loose parts; replacing damaged wire ropes and scraper plates in a timely manner; preventing ice formation on the surface of the sedimentation tank; reducing the speed of the sludge scraper.

Abnormal Issues and Solutions for Activated Sludge

(1) Sludge does not grow or decreases

The sludge does not increase for a long time or increases and then decreases rapidly. The main reasons are: insufficient or severely unbalanced nutrients required by the sludge; poor sludge flocculation, resulting in loss with effluent; excessive aeration, causing self-oxidation of sludge.

Solutions include: improving sedimentation efficiency to prevent sludge loss, such as allowing sludge to settle directly in the aeration tank or adding a small amount of flocculant; inputting sufficient nutrients, increasing influent volume, adding external nutrients (supplementing C, N, or P), or using high-concentration, easily metabolized wastewater; reasonably controlling the aeration amount, adjusting it according to the sludge volume and dissolved oxygen concentration in the aeration tank.

(2) Dissolved oxygen is too high or too low

Excessive DO in the aeration tank may be due to sludge poisoning or low sludge concentration and sludge load during the initial cultivation phase. Low DO in the aeration tank may be due to low sludge discharge, high sludge concentration in the aeration tank, or high sludge load and high oxygen demand. In these cases, adjustments should be made based on the actual situation, such as adjusting the influent water quality, sludge discharge amount, and aeration amount.

(3) Sludge disintegration

Turbid water quality, floc dissolution, and reduced treatment efficiency are all manifestations of sludge disintegration. Operational causes include: sludge poisoning, damage or loss of microbial metabolic function, and loss of sludge purification and flocculation activity. In most cases, this is caused by accidental wastewater discharge, which should be overcome during production or pre-treated locally; during normal operation, if the treatment water volume or wastewater concentration is consistently low while aeration remains normal, excessive aeration occurs, causing excessive self-oxidation of sludge, decreased bacterial floc flocculation performance, sludge disintegration, and further partial or complete loss of sludge activity. In this case, the aeration rate should be adjusted, or only part of the aeration tank should be operated.