Solid-phase Heterotrophic And Sulfur Autotrophic Denitrification Combined Process In HABR System

NO3--N is a main contaminant of groundwater due to excessive use of nitrogenous fertilizer in agricultural industry, inappropriate disposal of untreated sanitary and sewage infiltration. Excess NO3--N can cause methemoglobinemia when ingested by infants, and could cause carcinoma, malformation and mutation when transformed into nitrosoamines. Conventional biological heterotrophic denitrification exists the disadvantages of secondary pollution and high operating costs, while sulfur autotrophic denitrification exists the disadvantages of low denitrification efficiency and an increase of hardness and SO42- in the effluent. The combined heterotrophic and autotrophic for dringking water dentrification becomes a research focus owing to its hige removal loading and perfect pH buffering performance.The subject is based on the latest research achievements of solid-phase heterotrophic nitrification and sulfur autotrophic denitrification, propose solid-phase heterotrophic denitrification and sulfur autotrophic denitrification combined system in Hybrid Anaerobic Baffled Reactor(HABR). The experiment explore optimum process parameters of the integrated system through the research of three aspects:starting process of integrated system, regulatory operating process, the realization mechanism and microbial characteristics.The experiment was started at low volume loading under the environment temperature (25± 1)?, the NO3--N removal efficiency of the integrated systm improving steadily while the NO3--N volume loading of influent varied as:72 g/(m3·d)?80 g/(m3·d)?96 g/(m3·d). The removal efficiencies of NO3--N was 99% without the accumulation of NH4+-N and NO2--N. The NO3--N removal percentage of each system was 50% while the NO3--N volume loading was 96 g/(m3·d). The system was starts successfully within 72 days.The resulus of influencing factors stages showed that:C/N ratio had a great effect on the denitrifying situation of the first system, its NO3--N removal percentage increased with the increase of C/N ratio; The temperature had great effect on the denitrification efficiencies of the system, the average denitrification efficiencies of 25? was 2.03 times compared to 10?; the maximum NO3--N treatment loading was 108 g/(m3·d), NO3--N removal rate increased with the increase of HRT and it reached the best denitrifying situation at 24 h.The HABR integrated system showed pefect synergy at NO3--N removal percentage, alkalinity effect, sulfate production without adding traditional carbon source; lignocellulose contents and Scanning Electron Microscope (SEM) results demonstrated that part of the cellulose was degradated, and the increase of SO4- had the promoting effect of sawdust degradation.PCR-DGGE microbial characteristics analysis results of the integrated system showed that it found 18 obvious bands at 4 swimming lane totally. And they belong to(Proteobacteria? Anaerolineaceae?Bacteria Clostridiaceae?Gemmatimonadetes?Thiobacillus?Comamonadaceae? Rhodanobacter)8 species. Denitrifying bacteria was the dominant bacteria in the 4 cancelluses, and the sulfur denitrifying bacteria was also the dominant bacteria of the second system. And the population diversity analysis results showed that the third cancellus had the most abundanted.