Influence of Backwashing on Biomass in BAC Layer and Water Quality Parameters under 4 Modes of Used Carbon Substitution
Taking the outflow of sand filter of the water treatment plant(WTP)as the backwashing water of the biological activated carbon column,the effects of backwashing on biomass in carbon layer and outflow parameters under four modes of carbon substitution were studied.The results showed that the loading ratio of worn carbon had an influence on biomass and outflow indices to different extents.Generally,the biomass on the new carbon was slightly higher than that of worn carbon(granular charcoal that had been in use for three years),while the biomass loss rate of carbon column with high proportion of worn carbon after backwashing was lower.The loss rate of total biomass after air-water backwashing was greater than that after water backwash alone,but the loss of attached biomass was basically unchanged,indicated that the use of water backwashing alone could be attempted in the biological activated carbon pool.While the change of CODMn in the outflow was not obvious,the removal rates of UV254,DOC,BDOC,NBDOC and THMFP all increased to different extents after backwashing.Therefore,backwashing had both advantages and disadvantages.It could not only flush out some biofilms attached to the activated carbon,but also had a strong scouring force on microorg anism.At the same time,it could restore the adsorption capacity of activated carbon and enhanced the removal effect of organic matter.Backwashing had the strongest recovery ability on the adsorption capacity of the carbon layer of the 4#carbon column filled with refined new carbon,but its biomass loss rate was the highest,indicated that compared to the 3#carbon column filled with crude new carbon,the biological system on the 4#carbon column had relatively weak resistance to hydraulic erosion.Therefore,the selection of refined or crude activated carbon should be based on whether the activated carbon tank mainly utilizes its adsorption capacity or biodegradation ability.
万方数据
维普
