Aerial view of an aeration tank surface at a wastewater treatment plant
After the influent concentration rises, the aeration tank foam thickens and the scum layer covers the tank surface; the secondary clarifier then carries sludge, the online instrument reading of the effluent keeps climbing, and the chemical consumption in the sludge dewatering room rises with it.
Chemi Tech supplies defoamers for the biological systems of municipal wastewater and industrial effluent, drawn from the defoamer KM-1200 series; the dosage is set by the influent quality, the sludge concentration and the aeration method. This grade is non-toxic, harmless and biodegradable, and does not disturb the activity of the activated sludge; Chemi Tech runs measured comparisons of the tank foam-layer thickness and the sludge carry-over from the secondary clarifier, and matches a fitted grade for the customer.
Advantages of Chemi Tech Defoamers
Chemi Tech KM-1200 series defoamer breaks foam quickly, and the scum layer on the tank surface collapses shortly after dosing; at the same time, it does not affect the activity of the activated sludge, and the treatment efficiency and effluent indicators of the biological system are not disturbed; moreover, it is salt-resistant, and its foam suppression stays stable under the high-salt conditions of food-processing and printing-dyeing effluent; and it does not scale or clog membrane modules and aerators, so the membrane flux and the aeration efficiency are maintained; besides, it is biodegradable and introduces no extra burden to the surplus sludge and the effluent.
Industry Pain Points and Solutions
Foam in a biological tank is mostly caused by influent quality fluctuation and sludge ageing, rather than by the aeration being turned up too high; the consequence is scum accumulation on the tank surface and sludge carry-over from the secondary clarifier.
The most common is the accumulation of the scum layer on the tank surface. Foam carries activated sludge to the surface, and after sun and wind drying it hardens into a crust, making the inspection walkway on the tank slippery as well. Chemi Tech fixes the KM-1200 dosage by the influent quality, and the foam collapses before it forms a scum layer.
The next difficulty is sludge carry-over from the secondary clarifier. Foam enters the secondary clarifier with the mixed liquor, the sludge floats up in the settling zone, and the effluent suspended solids rise with it. KM-1200 does not disturb the settling performance of the activated sludge, and the effluent sludge carry-over falls back accordingly.
The aerators and membrane modules are likewise within consideration. KM-1200 is silicone-free, so long-term dosing does not deposit on the aeration discs and membrane surface, and the aeration efficiency and membrane flux are maintained. Chemi Tech checks against the influent quality and the sludge concentration, re-sets the recommended dosing range of KM-1200, and brings both the tank surface and the effluent back into their daily range.
Typical Operating Conditions and Verification
Customer: a wastewater treatment station in a food-processing park in Guangdong, for the daily operation of the aeration tank and the secondary clarifier.
At the production peak, once the influent concentration rose, this station's aeration tank foam spilled over the tank surface and the scum hardened into a crust after sun drying; the secondary clarifier then carried sludge and the online instrument reading approached the limit; the chemical consumption in the dewatering room kept rising. Chemi Tech compared the influent quality and the sludge concentration and then dosed KM-1200, grading the dosage by the return ratio and the aeration method. After dosing, the scum layer on the tank surface collapsed, the sludge carry-over from the secondary clarifier fell, the online instrument reading dropped back to the daily range, and the chemical dosage in the dewatering room no longer increased.
Frequently Asked Questions
Will adding a defoamer to a biological tank affect the activated sludge and the effluent indicators?
Whether a defoamer disturbs the sludge activity is directly related to its composition. KM-1200 has completed dedicated tests of sludge activity and system compatibility in the biological system, and within the recommended dosage range it neither suppresses the sludge activity nor pushes up the effluent indicators. The influent quality, sludge concentration and aeration method together decide the dosage; Chemi Tech provides a recommended use range through parallel comparison of the foam layer thickness and the effluent suspended solids.