Entering a wastewater treatment plant is like stepping into a massive "city intestinal hospital." Every corner and every piece of equipment here is silently working to purify wastewater. The inspectors are the "general practitioners" of this hospital, shuttling between the pipeline jungle and the machine matrix every day, using their keen eyes, sensitive sense of smell, and professional tools to conduct a meticulous "physical examination" of the entire system. Today, let's follow the footsteps of the inspectors and see what wastewater treatment plants inspect every day!

I. Inlet: The "first checkpoint" for wastewater entering the plant

As soon as you enter the plant area, you can hear the sound of water flowing from the inlet from afar. This is the "gate" for wastewater entering the plant. The inspector's eyes first focus on the screen machine—it's like a giant "iron comb," specifically intercepting large debris such as plastic bags, branches, and tissues in the wastewater. If the "comb teeth" get stuck and debris piles up into a small mountain, the subsequent equipment will "go on strike" in minutes! The inspector must not only check whether the screen machine chain is loose and whether the teeth are deformed, but also lie down by the guardrail, use a flashlight to illuminate the water surface, and carefully check for any that have slipped through the net.

The nearby sedimentation tank is like a steady "sand and mud catcher." The inspector squats down, gently stirs the water surface with a bamboo pole, and observes the rate at which the sand particles sink. If strange whirlpools suddenly appear on the water surface, or if the mud and sand that should be settling "run" to the surface, then be vigilant: Is there a malfunction in the sand suction machine? Or is the water flow speed abnormal? At this time, the inspector must immediately take out their phone, take photos of the abnormal situation, and contact the maintenance personnel.

II. Biological Treatment Area: The "Super Gym" for Microorganisms

Passing through the buzzing blower room, we arrive at the core area of wastewater treatment—the biological treatment area. The aeration tanks here are like a giant "microorganism canteen," where billions of microorganisms "feast," decomposing pollutants in the wastewater.

The inspector holds a dissolved oxygen meter and carefully inserts the probe into the pool. "2.8 mg/L, normal!" he nods in satisfaction. Dissolved oxygen is the "oxygen ration" for microorganisms. If the value is too low, the microorganisms will "go hungry," and the treatment effect will be greatly reduced; if it is too high, it will waste energy. In addition to measuring data, the inspector will stare at the water surface like observing a work of art: fine and uniform small bubbles are normal, but if large bubbles suddenly appear, or a thick layer of white foam floats on the surface, it's like the microorganisms are "sounding the alarm"—the water quality may be impacted, or there may be a problem with the sludge!

The adjacent secondary sedimentation tank is the "big stage" for mud and water separation. The inspector stands by the pool, his eyes fixed on the outlet: clear and transparent water flow is the "top student." If the water contains specks of sludge, it's like unexpected debris suddenly appearing on the stage. The speed of sludge reflux needs to be adjusted immediately, or the scraper needs to be checked to see if it's being lazy.

III. Chemical Dosing Room: The "Magic Laboratory" for Wastewater Purification

Pushing open the door of the chemical dosing room, the smell of various chemicals hits you. This is like a mysterious "magic laboratory," where chemicals such as PAC (polyaluminum chloride) and PAM (polyacrylamide) are the "magic powder" that makes the wastewater clear.

The inspector tiptoes to check the liquid level gauge of the chemical storage tank: "PAC is only one-third left, it's time to restock!" he mutters, quickly recording it in his notebook. Then, he squats down and checks the operation of the chemical dosing pump. These little guys are like precise "chemical couriers." If the measurement is inaccurate, adding too much or too little chemical will affect the wastewater treatment effect. The inspector reaches out to touch the pump body to feel if the temperature is normal; he listens carefully to see if there is any unusual noise. If he finds chemical leakage at the pipe joints, he will immediately transform into a "maintenance expert," put on gloves, tighten the valve, and clean up the leaked chemicals.

IV. Sludge Treatment Area: The "Metamorphosis" Factory for Sludge

The sludge produced by wastewater treatment is like "waste" in the "city's intestines," but in the sludge treatment area, they will undergo a magical "metamorphosis".

In the sludge thickening tank, the inspector pokes the surface sludge layer with a bamboo pole: "The thickness is a bit high, the de-sludging speed needs to be increased!" If the sludge accumulates here for too long, it will not only emit unpleasant odors, but may also affect subsequent processing. Further ahead, the sludge dewatering machine is "rumbling," squeezing the sludge into mud cakes. The inspector approaches and carefully observes the moisture content of the mud cakes: if the mud cakes are soft and dripping with water, it means the dewatering effect is not good; if they are too dry and hard, it may be due to excessive equipment pressure. He occasionally touches the filter cloth to check for damage, like giving the machine a "skin check".

The most nerve-wracking part is the biogas system! The inspector holds a gas detector, holds his breath, and slowly moves around the biogas pool and biogas pipes. If the instrument suddenly emits a sharp alarm, it means there is a biogas leak! Biogas is flammable and explosive, and if it encounters an open flame, the consequences are unimaginable. At this time, the inspector must remain calm, quickly close the relevant valves, evacuate personnel, and contact professional personnel for handling.

V. Electrical Equipment Room: The "Power Heart" of the Plant

Entering the electrical equipment room is like entering a "steel forest," with switchboards, transformers, and motors neatly arranged. This is the "power heart" of the entire plant. If there is a problem, the entire plant will "shut down".

The inspector puts on insulated gloves and carefully opens the switchboard. The dense wires and switches inside are like jumping "notes" in his eyes. He uses an infrared thermometer to scan each terminal: "65℃, normal!" If the temperature of a certain part is too high, it's like a harsh discordant sound in the score, possibly due to poor contact, and over time it may even cause a fire. He will also carefully check whether the wire sheathing is damaged or has scorch marks, like giving the wires a "full body checkup".

The standby generator in the corner is the plant's "lifeline." The inspector manually starts it once a month to listen to whether the engine roar is normal and check whether the fuel tank is full. In case of a power outage, this generator will immediately "take over" to ensure that the wastewater treatment system continues to operate.

VI. Environment and Safety: The "Invisible Guardians" of the Plant

Don't think that inspections only focus on equipment; the plant's environment and safety are equally important! Inspectors walk along, looking up to check for rust or leaks in overhead pipes; they look down to check for puddles or oil spills on the ground—these seemingly insignificant details can become safety hazards.

In the hazardous waste temporary storage area, inspectors carefully verify the type and quantity of hazardous waste and check whether the storage containers are properly sealed. If they find damaged packaging bags or missing labels, they will immediately replace them to prevent the leakage of toxic and harmful substances from polluting the environment.

Even the plant's green areas are not overlooked by the inspectors! Before summer rainstorms, they check whether the drainage channels are clear; when winter cold snaps arrive, they put "warm clothes" on outdoor pipes to prevent freezing.

The inspection work at the wastewater treatment plant is like a never-ending relay race, repeated every day but allowing no room for carelessness. From the inlet to the outlet, from the equipment to the environment, every corner, every parameter, affects whether the city's wastewater can be discharged up to standard, and whether our ecological environment can remain clean and beautiful. Next time you pass a wastewater treatment plant, take a closer look—hidden within is the persistence and wisdom of countless inspectors guarding the blue skies and clear waters!