Treatment Of High Organic Substance Content Wastewater By Cationic Tannin-polychloride Complex Coagulant

Condensed tannin-larch valonia, a kind of nature organic polymolecule and formaldehyde solution and dimethylamine water solution were used as raw materials to complete the Mannich reaction for tannin modification and the production (cationic tannin named CAT) was obtained. Material ratio, reaction temperature and reaction time were changed to obtain the optimal operating conditions under the standard of cationic degree of CAT. The optimal operating conditions were obtained, tannin(frame units):HCHO: (CH3)2NH(mol ratio)=l:4:4.8, reaction temperature 60 and reaction time 2.5 h. IR spectra experiments were used to prove the modification reaction was succeeded.Aluminum polychloride (PAC) easily available from market and CAT reacted at certain temperature for certain time and a complex coagulant was then attained. The optimal operating conditions under the standard of the removal of CODcr using the complex coagulant, were obtained, CATrPAC 1:4, reaction temperature 30 . and reaction time 1 h.The complex coagulant was used in high organic substance content wastewater treatment at room temperature and the amount of coagulant was 100 mgL-1. The removals of filterable CODcr, chroma and chaotic were 67.1 %, 70 % above and 80 % above, respectively.It was proved that the removal of CODCr used by the complex coagulant was better than used by CAT or PAC through the compare experiments. It was proved that the removal of CODCr used by the complex coagulant was better than used by the mixture solution of CAT and PAC. The complex coagulant was used to treat other wastewater and the results showed that the complex coagulant had good effect to acid wastewater.