Study On The Coupled Three-dimensional Biofilm-electrode And Sulfur Autotrophic Denitrification System For The Deep Denitrification In Synch With The Removal Of Paes

Nowadays nitrogen and phosphorus are usually regarded as the most needed removing contaminants in urban waste water treatment plants(WWTPs), while environmental endocrine disruptors such as Phthalate Esters(PAEs) are optional control objects in the effluent effluent standards, thus have not been paid adequate attention. Besides, the concentration of PAEs is rather low in waste water, which makes it difficult to be further removed, so relevant disposal technology still requires improvements. In the process of upgrading and regeneration of WWTPs in Beijing, it was required that after advanced treatment the secondary effluent should reach the class IVquality of the surface water, with the exception of TN, but no specific control of PAEs was mentioned. For those reclaimed water plant whose source water is secondary effluent, regular treatment technology shows agreeable removing effects towards sensory indexes such as chromaticity and turbidity, but often need extra carbon source or chemical reagent to remove nitrogen and phosphorus. As for PAEs micropollutants, the removal efficiency is quite limited. As the constant expansion of usage of reclaimed water, the security and healthfulness of reclaimed water is getting increasing concern.In this study, three-dimensional biofilm-electrode reactor coupled with sulfur autotrophic deep denitrification technology(3DBER-S) was used in WWTPs in order to realize deep denitrification and simultaneous removing two kinds of PAEs(DBP and DEHP), so that the reclaimed water can met the regulated limitation. Meanwhile, the removal mechanism was investigated via molecular biological technology.The results showed that several mechanisms of denitrification and removing were combined in 3DBER-S system. Structurally speaking, autohydrogentrophic denitrification, sulfur autotrophic denitrification and electrochemical hydrogen denitrification worked synergistically in time and space. The system conducted PAEs via the synergistc effect of adsorption, biodegradation and electrochemistry. Firstly, active carbon took up quite a large proportion of the filler, which had remarkable strong adsorption capacity of PAEs. Secondly, biodegradation was performed by denitrificationmicrobial population in the reactor. Furthermore, hydroxyl radical generated by electric current could degradebiorefractory PAEs into readily biodegradable matters, which were finally decomposed into H2 Oand CO2.3DBER-S system showed significant removal ability of nitrogen and PAEs. Under the condition of I=300mA, HRT=12h, T = 20- 25 oC, and pH = 7.0- 7.5, the removal rate of DBP and DEHP reached above 95%, their concentration in effluent met the regulated limitation of The Reuse of Urban Recycling Water Quality Standard for Groundwater Recharge(DBP3μg·L-1、DEHP8μg·L-1); meanwhile, 3DBER-S system kept high denitrification efficiency, where the removal rate of TN reached above 94% and the effluent concentration was about 1- 2mg·L-1.The study provides theoretical guidance for practical application of 3DBER-S technology. It has important significancefor improving the condition of over high TN and substandard endocrine disruptors such as PAEs in effluent, essentially enhancing the quality of reclaimed water.