Experimental Study On Different Valence State Of Iron Intensified Biochemical Reactions

Eutrophication has been a worldwide concerned environmental problem since the60s，and controlling nitrogen and phosphorus pollution is the fundamental way to solve theproblem。Because the domestic nitrogen and phosphorus pollution increasingly，conventionalnitrogen and phosphorus removal technology has not reached the increasingly effluentstandards of city，so developing new biological nutrient removal technology has become verynecessary。The subject is to study the traditional nutrient removal process by adding spongeiron and cast iron to SBR reactor，because iron ions can participate in microbial biochemicalreactions and energy metabolism processes，so that iron ions involved in electron transferfunction and strengthened the role of the enzymatic reaction activator，and improved theefficiency of biological nutrient removal and refractory organics removal。The efficiency of phosphorus removal by adding sponge iron and iron salts reveals：（1）Sponge iron has a great relationship with the capacity of phosphorus adsorption andadsorption time, temperature, pH and initial concentration of phosphorus。The Effluentconcentration of phosphorus decline rapidly in the beginning and becomes balanced in thelatter part of the adsorption time。When the temperature is30℃，the capacity ofphosphorus adsorption by sponge iron is strongest；when pH value is between2.89-6.87，thelower pH value is，the better phosphorus adsorption；sponge iron absorbed the phosphorus isfitted for Langmuir adsorption isotherm。（2）Compared the effect of phosphorus removalbetween FeCl3and FeSO4，it shows that the efficiency of phosphorus removal is improvedwith increasing pharmaceutical dosage of two iron salts。When iron ion dosage is20mg/L，thetotal phosphorus concentration of two effluent after the treatment of two iron saltsrespectively are lower than1mg/L and have reached the B standards of A level emission ofGB18918-2002《The pollutant discharge standards of urban sewage treatment plant》；whenFeCl3dosage is30mg/L，the TP concentration of effluent water is0.49mg/L，and hasreached the first level emission of standard A。Overall，FeCl3is slightly better than FeSO4atthe aspect of the efficiency of phosphorus removal。Results of experimental study of sponge iron and iron strengthened SBR reactor thatremoves nitrogen and phosphorus show：（1）adding sponge iron、FeCl3、and FeSO4in theSBR system are played on strengthening the role of the reactor，and the removal rate of TP、COD、NH3-N and TN indicators have improved in vary degrees，and strengthening the role ofthe TP and COD are most obvious，and removal effectiveness of TP：Fe (III)> sponge iron> Fe (II)，removal effectiveness of COD：Fe(III)﹦Fe(II)> sponge iron；they also have somerole in strengthening on NH3-N and TN，but they have little effect on these indicators，andremoval effectiveness：sponge iron> Fe (II)> Fe (III)；（2）after adding sponge iron、FeCl3and FeSO4，the sludge MLSS and MLVSS rose and SVI value decline。Pharmaceutical dosagenot only improved the structure of the activated sludge floc but also promoted biologicalflocculation and improved the performance of sludge sedimentation。But each reactor hasdifferent effect on sludge performance，and sludge settling performance in Fe (Ⅱ) reactor isrelatively better，and Fe (III) sludge system has a great impact，and sponge iron system has abetter performance to resist strong impact；（3）The way of phosphorus removal iniron-activated sludge system mainly include：biological phosphorus removal effect、chemicalprecipitation and and adsorption effect、biological chemistry effect，but the chemicalprecipitation play an important role in phosphorus removal。The results of the experiment study of sponge iron and iron salts strengthened SBBRreactor in order to remove biodegradable organics reveal：（1）adding FeCl3、FeSO4andsponge iron in SBBR system strengthen the removal effectiveness of COD and TN in theDMAC wastewater，and COD removal efficiency of three groups are higher than the controlgroup by5.5%、5.6%and6.1%respectively，and the content of TN of three groups are higherthan the control group by11.3%、8.2%and9.5%respectively；the ammonia value of effluentwater is higher than inflow water cause DMAC wastewater organic matter is decomposed bymicroorganisms，meantime the amino-group of organic matter is opened，thus scissionbecome inorganic ammonium ion(NH4+-N) which leads to the improvement of theconcentration of ammonia in water。（2）adding sponge iron、FeCl3and FeSO4plays a rolein strengthening the COD removal in acrylic wastewater，and COD removal rate of threegroups are higher than the control group by7%、5%and4%respectively；sponge iron alsoplays a role in strengthening the ammonia removal and ammonia removal efficiency is higherthan the control group by7%，but adding FeCl3and FeSO4have no strengthen effect on theammonia removal。...