The Treatment Of Perchlorate From Water By Moving Bed Biofilm Reactor

As a type of persistent pollutant, perchlorate is easy to migrate, difficult to degrade andhas strong stability. After entering the body, perchlorate can cause a reduction of thyroidhormone secretion, affect the normal growth and metabolism of human body adversely.Therefore, looking for a quick, effective, economical removal method of perchlorate isimminently needed. As a new biofilm reactor, moving bed biofilm reactor has bothadvantages of traditional biofilm process and activated sludge process, which has resistanceto shock loading, not easy to jam, compact structure, not need to reflow and treatment effectis good. Perchlorate degradation bacteria was investigated as the research object of thisexperiment, draw the growth curve and investigate the effect of different pH, temperatureand degradation time on perchlorate degradation rate and then determine the optimumconditions for the degradation of perchlorate. Using artificial inoculation method to biofilmculturing and then biofilm domesticated. In order to determine the optimum conditions ofthe moving bed biofilm reactor, investigate the effect of perchlorate initial concentration,temperature, pH, dissolved oxygen, hydraulic retention time on perchlorate removal rate.The main research results were as follows:Perchlorate degradation bacteria was cultured under the conditions of anaerobic,25℃and pH=7, the maximum growth could reach after12d, the OD600value was0.336measured by spectrophotometer. The study had found perchlorate degradation bacteria couldreach the maximum degradation rate at25℃and the degradation rate was73.51%; at pH=7and the degradation rate was73.36%; after13d and the degradation rate was78.56%.During the course of biofilm culturing, biofilm growth rate could reach a maximumvalue after12d and biomass tend to be stable after21d, gradually formed biofilm, removalrate presented an increase volatility and remained stable at about90%finally. After abouttwo months of biofilm domesticated, perchlorate removal rate remained stable basically.During the treatment of perchlorate by moving bed biofilm reactor, with the increase ofperchlorate initial concentration, the average removal rate had gradually increased and whenthe initial concentration was20mg/L, the average removal rate reached a maximum value.When pH was7, the temperature was25℃, perchlorate was completely removed after24h.When the biofilm reactor was sealed, it had been undetectable presence of perchloratesubstantially after24h, however, when the biofilm reactor was open, perchlorate was not removed substantially. When HRT was12h, perchlorate could be removed completely.Moving bed biofilm reactor could remove perchlorate effectively, after a period ofbiofilm and domesticated, biomass increase in the reactor. Moving bed biofilm reactor couldremove low concentration of contaminated water, for higher concentration of contaminatedwater could achieve good removal efficiency. From the measurement results, the treatmentof perchlorate by the reactor is very appropriate, removal efficiency is very stable and theeffluent concentration of perchlorate is below the detection limit basically.