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The resistance of the filter layer increases for the following reasons: 2 c- l6 q% j, a; k1 A5 r 1) If the turbidity of the water leaving the clarifier does not meet the standards over an extended period, or if there are large amounts of alum flocs in the clear water zone, the solutions are as follows: to address insufficient turbidity levels, one can maintain a sedimentation ratio of 15–30% in the first reaction chamber and increase the amount of chemicals added; to deal with excessive alum flocs in the clear water zone, one can increase the volume of wastewater discharged and reduce the amount of chemicals used. Furthermore, the quality of polyaluminum also has a significant impact on the turbidity of the water exiting the clarifier. 2) A high content of organic matter in river water can undermine the coagulation process. There is a large amount of aluminum hydroxide colloids in the clear water zone of the clarifier, which results in whitening of that zone. When measuring turbidity, the value increases several times if the water sample is left standing for an extended period. Solutions include using chlorine dioxide, increasing the frequency of forced backwashing in the valveless filter, increasing the frequency of wastewater discharge from the clarifier (in smaller amounts), and reducing the dosage of chemicals used. . For filter beds in valveless filters where the resistance is high, the following methods can be used to address this issue: ! h$ p0 H) n8 R: \; w7 L+ p 1) Replace the filter media or take them out for cleaning before reinstalling them; this method is the most effective but requires more time and effort. ( Z' C+ L' U( e1 k2 R+ l9 i& @ 2) Soak the filter media in a 5–10% sodium hydroxide solution for over 10 hours, then clean them using forced backwashing; however, the turbidity of the water output remains high for about a day. & o, x" H 3) Temporary solution: Destroy the device immediately after the forced backwashing starts; this allows it to operate for about 2–4 hours, thereby reducing the amount of water used for backwashing.