Research On Advanced Treatment Of Papermaking Middle-stage Wastewater With Chemical Coagulation

Waste water pollution of paper-making industry has been the focus of attention in the field of prevention and treatment of waste-water discharge.Consumption Paper industry need consume a big amount of water,and meanwhile the number of sewage disposal is very large.Environmental pollution is quite serious.With the increase of environmental protection efforts and the shortage of water resources,sewage discharge standard will be more strict.The enterprises will be faced to an important subject that advanced treatment of the papermaking middle-stage wastewater and up to reused standard.The area of Shandong province is lack of water.The paper industry's environmental protection in Shandong Province,particularly the treatment of waste water,has been at the forefront of the industry.Government and corporate pay much attention to environmental pollution,and the facility is operating well.This title is set up by the Shandong Environmental Protection Agency in this context,which is a part of the subject of paper-making waste water treatment.This article studys advanced treatment of the papermaking middle-stage wastewater with coagulation technology and lay the foundation for wastewater reuse.In this paper,chemical coagulation technology was used to treat papermaking middle-stage wastewater with different coagulant and studied the amount of reagent, pH,reaction time,the precipitation time on the degradation effect,It made a comparative study on wastewater's chemical oxygen demand CODcr and the color removal before and after coagulation and summed up the best process conditions.This paper was focused on advanced treatment of the papermaking middle-stage wastewater with coagulation PAC,PFS,as well as Fenton reagents,analysing effect factor containing coagulation dosage,pH,reaction time,deposition time and the removing rates of COD_cr and colour after coagulation,summed up the best conditions. Experimental results showed that under the conditions of value of pH 7.0～8.0, PAC/PFS ratio 2,coagulation dosage 400 mg/L,PAM addition of 1mg/L,mixing speed 70n/min,stirring time 10 mins,deposition time 30 mins,for the best conditions,and COD_cr down to 90mg/L below,the removal efficiencies of COD_cr were more than 70%, and the color down to 90 times,the color removal rate above 82%.The result was most efective.The four factors of CODcr and color removal in orthogonal is the same of the impact of the order of priorities,and followed by descending coagulant type→dosage→reaction time→the flocculant.For Fenton reagents,when pH adjusted to 3,Fe²⁺dosage 1 mmol/L and H₂O₂ 4mmol/L,the reaction time 40min,deposition time 30min,was the optimal level for the portfolio and has the best removal efficiency.The COD_cr reduced to 45mg/L and the removal rate was 85%,the color down to 50 times and the removal rate was 90%. The four factors of CODcr and color removal in orthogonal is not the same of the impact of the order of priorities,The results orthogonal analysis affected COD_cr of primary and secondary followed by descending order of Fe²⁺dosage→H₂O₂ dosage→pH→reaction time,but for color removal is H₂O₂ dosage→pH→Fe²⁺ dosage→reaction time.