Studies Of Humic Acid With Fenton Oxidation And Flocculation Treatment In The Landfill Leachate

In this study, we conducted a series of experiments regarding Fenton oxidation and flocculation treatment of humic acid in landfill leachate,the main study is divided into three parts.The first part, the investigation of Landfill leachate materialized and coagulation sedimentation characteristics of humic acid, the results showed that the humic acid is a kind of complex organic matter, mainly composed of elements of C and O, and contain a variety of functional groups, such as carboxylic and phenolic groups, aromatic ring. Humic acid of Landfill leachate in 2009 year is abbreviative of 09 HA, it contains acid group, carboxyl group, phenolic hydroxyl are more than humic acid of Landfill leachate in 2006 year is abbreviative of 06 HA, and their structures, element content, molecular weight and particle size are different.Visibility, under different landfill time humic acid is complexity in the Landfill leachate. And then using ferric chloride and ferrous flocculant to deal with two kinds of humic acid, they had poor effect on high concentrations of humic acid flocculation and sedimentation. Taking into account the actual circumstances of leachate, we added several main components to test. The result is that ammonia has a certain promoting effect on the removal of flocculation of humic acid; Alkalinity, EDTA, sodium citrate would inhibit the removal of humic acid and has a poor effect on flocculation.The second part, through Fenton oxidation and flocculation to examine high concentration of humic acid processing effect:(1) Preliminary experiments of Fenton oxidation and flocculation treatment of humic acid, both low-dose ferrous and high-dose ferrous, role in the effect of two kinds of humic acid is different, COD removal rate and hydrogen peroxide’s dosage is related. COD oxidation(CODoxid) increased with adding the hydrogen peroxide, while COD coagulation(CODcoag) first increased then declined. The best COD removal rate reached 80%, and TOC removal rate reached 60% of 09HA; 06HA’s COD and TOC removal rate both up to 83%. In Fenton process, 09 HA has based on oxidation; 06 HA has a hard time in oxidative degradation, and remove COD, TOC by Fenton flocculation mainly.(2) Researched that the effects various with different initial p H, ferrous, hydrogen peroxide. The results show that: in the initial conditions p H = 5, when 06 HA ferrous was 3 mmol/L, and hydrogen peroxide was 93.75 mmol/L, COD and TOC removal rate reached 83%; when the 09 HA ferrous was 5 mmol/L, hydrogen peroxide was 93.75 mmol/L, COD removal efficiency rate was 80%, and TOC removal efficiency rate was 65%.(3) The effect of glucose and phenol dosage on Fenton process was investigated by analysis of p H, ORP, dissolved iron ion and H2O2 levels during Fenton oxidation with [Fe2+] 0 = 10~200 mmol/L. The identification of secondary iron mineral was carried by XRD, SEM and BET. The results showed that the instantaneous p H and ORP values at the end of 1 min increased gradually and then decreased rapidly with the increase in H2O2/Fe2+ molar ratio as a result of Fenton process with [Fe2+]0 ≧ 50 mmol/L. It was found that at the initial conditions of [Fe2+]0 = 200 mmol/L, [H2O2]0 = 200 mmol/L and at p H = 3.3, the addition of 4.17 mmol/L glucose, 4.17 mmol/L phenol and 8.33 mmol/L glucose resulted in the exhaustion of H2O2 after 15 min, 10 min and 2 min, respectively, while the dosage of 8.33 mmol/L phenol, 16.66 mmol/L glucose and 16.66 mmol/L phenol lead to Fe2+ concentration of 7.40 mmol/L, 27.40 mmol/L and 58.83 mmol/L, respectively, after 60 min of reaction time. The second iron minerals formed from Fenton reaction at the initial p H of 3.3 were identified as schwertmannite by XRD, among which the particles formed with addition of glucose or phenol were composed of spheroids with surface spikes by SEM.The third part, we have examined infrared spectrum of humic acid with Fenton oxidation and flocculation and floc fractal dimension changes, and test results showed that through the analysis of the infrared spectrum of Fenton oxidation and flocculation reaction, known Fenton oxidation has certain influence on humic acid functional groups and humic acid’s flocculation. At low levels of iron, the area and dimension of 09 HA were larger than 06HA; When high doses of ferrous, without blending p H of 7, flocculation of 09 HA was larger than 06 HA. After blending p H of 7, flocs and dimension were increasing. There were different effect regarding different humic acid Fenton oxidation and flocculation.