The commonly used water purification flocculant for sewage desliming is polyacrylamide, and sludge dewatering is also a key step in the sewage treatment process. After polyacrylamide is added to the sludge for conditioning, the moisture content of the filter cake continues to decrease. This is because polypropylene Amide has the effect of adsorption and bridging, which can make sludge particles form flocs quickly, and it also has a dehydration effect, which can transform hydrophilic colloids into hydrophobic colloids, making them insoluble in water and finally dewatering . When the dosage of polyacrylamide is small, the concentration is dilute, and the effect of flocculation and dehydration is poor. However, excessive polyacrylamide will cause the long chain to be unable to expand due to the excessive concentration, and the dehydration effect will be weakened.
The characteristics of the sludge: the sludge floc structure can be divided into outer layer and inner layer; the outer layer of the floc includes a suspended surface layer, a viscous layer, and a free bound EPS layer; the inner layer of the floc includes a tightly bound EPS layer and pellets, and Protein is the main component in each layer of sludge; when the outer layer of flocs decreases, it can promote the improvement of the dewatering performance of the sludge. As the dosage increases, the protein content continues to increase. It shows that after the addition, the floc structure of the sludge has changed, and the settling performance of the sludge has also been continuously increased. The sludge particles gradually become larger, and the sludge layer and the supernatant layer have a clear dividing line. This is generally the situation after the polyacrylamide is put into the municipal sewage. When the polyacrylamide dosage exceeds a certain amount, the sludge The sedimentation effect is initially reduced. Too much or too little flocculant will affect the specific resistance of sludge. It is not that the larger the increase of polyacrylamide, the better. We must determine the increase of polyacrylamide based on the actual situation. Practice has shown that the sludge sedimentation speed is different when the outside temperature is different. At the same moment, the higher the temperature, the faster the sludge sedimentation. However, the practical engineering production needs to combine economic benefits, the temperature is too high, the energy consumption is too large, and the benefits cannot be maximized.
In the range from 100r/min to 200r/min, as the speed increases, the sedimentation volume of sludge after all becomes smaller; after 200r/min, the sedimentation volume of sludge initially increases. When the mixing speed is 150r/min, the water content of the sludge is the lowest, and the dehydration effect is obvious.
After many times of practice, it has been proved that the sedimentation rate of sludge will be different under different conditions of PH value. When the sewage pH is 5, the sludge sedimentation speed is the fastest. The sedimentation speed of sludge will also be affected by the pH value. Regardless of whether the pH value is too small or too large, the pH value of the sewage should be adjusted according to our own practice. The dewatering function of the treated sludge under acidic conditions is better than that under alkaline conditions.
Post time: May-31-2021
