Study On Micro-size Materials Applied In Wastewater Treatment

Flocculation, as a high-efficient and simple method, is widely adopted in wastewater treatment field. Whereas the flocculants commonly used at present each has own shortcomings. The unique characteristics of micro-size materials such as surface trait, the little size and quantum effects, make them have a wide application prospect in many aspects. At present, researches on adopting micro-size materials in the flocculants field can rarely be found at home and abroad, say nothing of systematic analysis and study. In the paper, the experiments of treating municipal sewage with the method of mixing the micro-size materials of silicon dioxide and natural zeolite with inorganic compound flocculants were carried out. And the preliminary experiment of further disposing swine wastewater with the method was conducted as well.The results indicated, to the municipal sewage, the compounds of inorganic flocculants had better effects than single flocculant. The characteristics of each flocculant could be effectively exerted. The addition of a small quantity of micro-size SiO₂ and zeolite to flocculants could promote the flocculating effect. The removal rate of COD could enhance 26%. And the slurry volume could reduce 32% for the increase of slurry density. The follow-up treatment difficulty was decreased. The results of sedimentation performance experiments showed, the sedimentation time of the two groups of combining flocculants with micro-size material (SiO₂+PAC+FeCl₃) was reduced by 49.0% and 54.8% respectively than the compound flocculants (PAC+FeCl₃). Moreover, with the increase of micro-size SiO₂, the sedimentation speed became much quicker and the flocculating effects became better. Through experiments, various factors influencing the flocculating effects were analyzed to offer the basic parameters for sufficiently exerting the effects of the compound flocculants.Micro-size compound flocculants also had a desire effect for further treatment of swine wastewater. The addition of micro-size materials could enhance the discolored efficiency, and could obviously improve pH values, which reduced the secondary pollution of outflow to the environment. Compound flocculants can be applied in the further treatment of excrement sewage. However, the concentration of the secondary outflow should not be too high.