Urban sewage and industrial wastewater treatment method commonly used activated sludge, biological sludge is often highly hydrophilic colloids, organic content, is extremely difficult to dehydration. Treated with cationic polyacrylamide, with less dehydration, high efficiency, easy to separate. Alcohol plant wastewater, brewery wastewater, monosodium glutamate factory wastewater, wastewater sugar mills, meat plant wastewater, wastewater beverage plants, textile printing and dyeing wastewater. Cationic polyacrylamide than using anionic polyacrylamide, nonionic polyacrylamide or inorganic effect several times or several times higher. Because this type of waste water generally has a negative charge. Polyacrylamide selection is mainly based on the charge of sewage water quality of different types to be, according to the water quality characteristics to choose cationic polyacrylamide, anionic polyacrylamide, or zwitterionic polyacrylamide, the process is generally from experiments Room small scale, large manufacturers try to finalize the product selection, to analyze specific issues. Whatever the quality of what the industry, selecting the right model is the most critical, when mutated incidents have occurred, once changed, we must calmly, do not just look at the problem itself, to find solutions, itself polyacrylamide Selection is a highly experimental procedure.