The Effects Of Ammonia Concentration On The Performance Of Simultaneous Sulfide And Nitrate

The technology of simultaneous anaerobic denitrification and desulphuration inwastewater is become the research focus due to its advantages of low cost, lesssecondary pollution, no additional carbon sources, etc. However, the influentammonium will affect the characteristics of desulphurization and denitrification in thereactor. In this study the characteristics of desulphurization and denitrification wereinvestigated in the reactor under different influent ammonia concentration conditions.The effect of ammonia concentration on the transformation of the ammonia nitrogen,nitrate nitrogen and sulfur compound were investigated. In this thesis, the effects ofdifferent influent ammonia concentration on the performance of desulfurization anddenitrification were mainly studied under the conditions of high nitrate to sulfide ratio,low nitrate to sulfide ratio, high sulphide load and inoculation amount. The mainresults and conclusions are as follows:(1) In the systems with the low nitrate to sulfide ratio (0.4), the sulfide100mg/L,the results show that when the influent concentration of ammonia is above90mg/L,the removal efficiencies of sulfide are up to about90%, the desulfurization is same to agroup without ammonia. The removal efficiencies of ammonia nitrogen in the systemsare32.65%,10.77%,8.94%,15.71%,18.63%. The reactor influent ammoniaconcentration of120mg/L nitrate removal is optimum.24-hour removal efficiency is81%.(2) In the systems with the high nitrate to sulfide ratio (0.6), the sulfide100mg/L,influent ammonia nitrogen of0mg/L,30mg/L,60mg/L,90mg/L,120mg/L five groupssulfide removal followed by73.65%,80.67%,87.27%,88.84%,91.38%after28hours. The results show that removal efficiency of sulfide increased as ammoniaconcentration increased. The corresponding removal efficiency of ammonia are12.67%,11.90%,15.85%,17.62%,18.32%, the results show that the ammoniaoxidation may be directly involved in the desulfurization process. Intermittent changewater results show that the influent ammonia concentration had more influence ondenitrification than desulfurization in the system.(3) When the concentration of sulfide increased from100mg/L to200mg/L,intermittent change water results show that after12days the nitrate removal efficiencyof the five systems are95.39%,86.03%,39.40%,27.63%,19.34%. The removalefficiency of nitrate decreased as ammonia concentration increased. However, influentammonia concentration has little effect on the desulfurization process, removalefficiency of sulfide are all above90%in five systems. The average removal efficiencyof ammonia in turn65.3%,57.8%,39.1%,57.8%and23.7%, showed that improvesulfide load will increase the rate of the oxidation of ammonia.(4) Under the influent sulphide concentration is200mg/L,80mg/L of nitrate, theeffect of different inoculation amount on the performance of simultaneous anaerobicnitrate and sulfide removal process was investigated. The study found that after2daysremoval efficiency of sulfide are all above90%. The results indicated that the amountof thiobacillus denitrificans vaccination has little effect on desulfurization in thesystem. When volume of inoculated bacterium fluid is up to100mL, the removalefficiency of nitrate is optimum in the system, the removal efficiency of nitrate reachedmore than94%on the second day. Correspondingly, denitrification of the system haveno inoculant is slow, and the removal efficiency of nitrate only reached90%after fourdays.