Study On Indicators For Granular Activated Carbon Screening And Adsorption Cycle Determining

Activated carbon is a kind of functional carbon materials, which is developed porosity, large surface area, strong adsorption ability, as an excellent adsorbent, activated carbon has been widely used in water treatment technology,With the activated carbon is more and more widely applied, four kinds of granular activated carbon (GAC) were treated by water taken from South to North Water Diversion Project for screening and adsorption saturation of activated carbon, by analyzing the correlation of each index, the best indicator of screening and adsorption cycle determining is selected.The study is based on water taken from South to North Water Diversion Project, the relationship between adsorption performance and the specific surface area, pore volume, pore size of activated carbon were investigated; According to the adsorption rate and adsorption isotherm experiments, the study analysised the adsorption properties of GAC to organic matter in raw water, the correlation between the indicators and the removal rate of organic matter in raw water was fitted by Freundlich equation, the results showed that the removal rates of CODMn and DOC were well correlated with iodine value, the coefficient correlations, R2 were 0.8745 and 0.8474 respectively, the removal rates of UV254 was well correlated with methylene blue value (R2=0.9454), indicating the capability as indicator for GAC selection, the coefficient correlations between humic acid, tannic acid, caramel and the removal rates of CODMn,UV254 and DOC were lower than 0.8.Study on indicators for adsorption cycle determining, a kind of GAC which was prepared four different adsorption saturation was be choosed. For investigating the residue rate of adsorption ability, the correlation between the remaining rate of adsorption performance indicator and the removal of organic matte was analyzed. Studies show that:When the removal rate of GAC to organic matter in the raw water less 30%, iodine value, methylene blue value, humic acid, tannic acid, caramel fell to 53%,66%,25%,8%,47% respectively, when the activated carbon adsorption ability of organic matter in raw water quality gradually weakened and nearly saturated state, the removal rate of iodine value, methylene blue value, caramel remained at nearly 50%.Of all five adsorption performance indicators, it was found that the iodine value, methylene blue value, and tannic acid were negatively related to the residual rate of the GAC absorption ability. The R2 (iodine value) about CODMn,UV254,DOC were 0.9409,0.9680,0.9346 respectively; the R2 (methylene blue value) about CODmn, UV254, DOC were 0.9921,0.9977,0.8404 respectively; the R2 (tannic acid) about CODMn, UV254, DOC were 0.9550,0.9667,0.8941 respectively; the coefficient correlations between humic acid, caramel and the removal rates of CODMn, UV254, DOC were lower than 0.9.In order to evaluate the adsorption capacity of GAC in the pool, the experiment analyzed the CODMn, UV254 of activated carbon pool, and iodine value, methylene blue value change in Quehua plant during 2012.01-2014.03. To 2014.03, the average removal rate of UV254 value from 35.11% to 21.84%; the average removal rate for CODMn value from 27.27% to 14.04%, indicating that activated carbon for organic still has some adsorbing effect, but the adsorption capacity gradually weakened. At the same time, to 2014.01, the average values of iodine value and methylene blue were 650.9mg/g,64.06mg/g in 3# to 12# grid of ctivated carbon pool, compared with the original carbon decreased by 33.1% and 38.99%, which obviously reflected the decline degree of adsorption capacity of activated carbon pool. According to the effluent quality inactual operation of actived carbon pool water, CODMn<0.3mg/L,UV254<0.1cm-1,explain the biological degradation greatly maked up the impact about the adsorptive capacity of activated carbon weaken. As well as taking into account the greater fluctuation of water quality, it is difficult to ensure the stability of the carbon pool of water, wecan consider to add some new carbon or on the part of regeneration of actived carbon pool.