Study On The Effect Of Sponge Iron Dosage On SBR Reactor

In recent years, with the process of urbanization and industrialization, there is a large amount of wastewater which not achieve discharge standard dumped into water-body. Led the the water quality to worsen. Eutrophication is a severe problem especially for the lake and reservoir with the main pollutant is COD, TN and TP. In a large number of water treatment process, SBR reactor is one of the most popular biological treatment process bacause of the operation control flexibility and strong shock resistance. Traditional SBR reactor also has disadvantages such as low sludge concentration and instability treatment effect of phosphorus and nitrogen. Spongy iron has large specific surface and high iron content. This subject combined spongy iron with SBR reactor and fromed Biological Sponge Iron System which let SBR reactor and spongy iron play their merits.This paper use the common SBR reactor as control, studied the effect of adding sponge iron on SBR reactor from the following several aspects respectively:(1)The dosage of sponge iron was 40g/L, 90g/L and 150g/L on the effect of removal chemical oxygen demand, ammonia, total nitrogen and total phosphorus in SBR reactor;(2)The dosage of sponge iron was 40g/L, 90g/L and 150g/L on the effect of the iron content in the sludge, floc structure of activated sludge, properties(MLSS, MLVSS, MLVSS/MLSS and SVI) of activated sludge, TTC-DHA activity of sludge, INT-ETS activity of sludge and the number of iron bacteria;(3)The dosage of sponge iron was 40g/L on the effect of the process of denitrification and denitrification in SBR reactor;(4)The adding of sponge iron on the effect of removal phosphorus by biological way in SBR reactor. In order to study the effect of adding sponge on the removal of phosphorus in biological way, we studied the K+ and Mg2+ characterization of biological phosphorus removal effect in three different systems, and used K+ concentration changes to characterized biological phosphorus removal ability in sponge iron-SBR reactor. The above research results show that:(1)Compared with common SBR reactor, the removal effect of COD, TN and TP was best when the sponge iron dosage was 40 g/L. the reactor which added sponge iron whose removal effect of TN and TP was better than the common SBRreactor. But when the dosage of sponge iron was 90 g/L and 150 g/L the promoting effect is unapparent than when the dosage was 40g/L, especially to the COD removal efficiency. The removal effect of COD was worse when the dosage was 90 g/L and 150 g/L.(2)After adding sponge iron, the reactor,s Fe(Ⅱ), Fe(Ⅲ) and TFe concentration were increased, and the sludge flocs become dense, forming inside the dark brown clumps. And the sludge flocs become darken, smaller and the filamentous material become less while the dosage added. The MLVSS and MLSS of the sponge iron-SBR reactor was greater than common SBR reactor. The MLVSS/MLSS and SVI of the sponge iron-SBR reactor was greater than common SBR reactor. Adding sponge iron enhances the TTC- DHA and INT- ETS activity and stimulate the growth of iron bacteria. The iron bacteria amount in the reactor which sponge iron added amount was 40 g/L, 90 g/L and 150 g/L reactor are 75, 275, and 275 times for common SBR.(3)There are three stages of nitrification in SBR reactor. The maximum nitrification rate of SBR and sponge iron- SBR were 0.947 mg/(g MLVSS·h) and 0.652 mg/(g MLVSS·h) and NO3--N generation rate were 0.619 mg/(g MLVSS·h) and 0.027 mg/(g MLVSS· h). The nitrification rate of SBR is higher. The nitration reaction time is shorter. The NO3--N generation rate of sponge iron-SBR reactor is lower than nitrification rate. Simultaneous nitrification and denitrification exist in the sponge iron-SBR reactor. The denitrification process of sponge iron-SBR reactors divided to three stages, the maximum denitrification rate is 0.366mg(g MLVSS·h).(4)The K+ and Mg2+ concentration changes in three different system are identify with PO43-concentration changes. Indicate that K+ and Mg2+ participate in the biological phosphorus removal process. △K/△P values and △Mg/△P values are relatively stable, can be used as a parameters of the biological phosphorus removal capacity. A high concentration of iron ion in the Biological Sponge Iron System completely compete phosphorus with phosphorus-accumulating bacteria. K+ concentration not decreases in the process of phosphorus removal. The phosphorus removal is not by phosphorus-accumulating bacteria. The phosphorus removal in the sponge iron system relies mainly on the iron ion precipitation.