Testing of filter sands for air - raid shelter ventilation - determination of flow resistance 防空洞通风用滤砂试验.气流阻力测定
3.
Manufactures : automatic softener consecutive water supply , inter - current water supply , meter and timer style , automatic filters sand filter , carbon filter , automatic desalination systems and automatic water purification system 水处理设备及系统有：全自动软化水装置连续供水及间断供水流量型及时间型全自动过滤水装置碳滤砂滤全自动除盐水装置全自动纯水装置。
4.
The effort of manganese removal was studied and the kinetics of manganese removal was tried to establish . the factors of dissolved oxygen concentration , fe2 + concentration , ph , p concentration and closing of the filter were studied to evaluate their effort for biological manganese removal , and the correlation of residual manganese and oxidation - reduction potential was also discussed . as the iron content of water was high , experiment results showed that the reaction was zero order , as the iron content of water was low , the reaction was first order . the time needed for the cultivation of biological manganese removal was 60 70 days . the filter operated at the filtration rate of 8 10m / h , silica sand of effective size 0 . 95 1 . 25mm filled the filter to a depth of 1200mm 试验结果表明,成熟后滤砂表面滤膜的x射线衍射图谱与mno _ x ? 5h _ 2o ( x = 1 . 86 )的x射线衍射图谱一样,滤膜成熟后的结构在进水物质不发生变化的情况下不发生变化;合适的碳磷比对生物除锰有明显的促进作用,试验条件下的投磷量不会对出水造成二次污染;生物除锰需要亚铁的参与,亚铁的存在除了能够促进微生物分泌胞外酶并刺激其活性外,还通过铁离子的变价传递电子,催化锰离子的氧化反应,从而促进对二价锰的降解。
