| Metal anion wastewater and flocculated sludge have caused a lot of pollution in the environment,which has attracted wide attention of the society.Reasonable and efficient treatment of pollutants has been the focus of more researches.Enhanced flocculation is a typical technology for treating metal anion pollutants in industry.In the enhanced flocculation technology of polymer flocculant,the molecular structure and basic characteristics of polymerflocculant have a significant impact on flocculation process.There was lack of unified indicators to comprehensively consider the impact of the structure and molecular characteristics of ionic flocculant on enhanced flocculation,which limits the development of this technology.By exploring the relationship between structure and molecular characteristics,the performance of ionic polymer flocculants is improved,which provides a new idea for the technology of polymer flocculants.Flocculated sludge is a kind of solid waste produced in wastewater treatment process.The composition of sludge produced by different processes is different and complex.Traditional sludge treatment technologies have the problem of secondary pollution.Recovery and efficient reuse of flocculated sludge is an urgent problem to be solved.In this paper,the problems of enhanced flocculation technology and reuse of flocculated sludge are studied respectively.The main research contents and results are as follows:(1)A new indicator,specific charge density(SCD),was used to evaluate the performance of cationic polymer flocculants.The effects of molecular weight and charge density of polymer flocculants on enhanced removal of metal anion pollutants were comprehensively considered.The relationship between structure and molecular characteristics of polymer flocculants was analyzed,and the flocculation mechanism of polymer flocculants with different SCD was further discussed.The statistical analysis of pollutant removal and floc characterization showed that the residual of metal anion pollutants was lower by the polymer floccuants of higher SCD value.The results show that the cationic polymer flocculants of higher SCD value could more positive adsorption sites and polymer coils.,which can adsorb pollutants by effective electrial neutralization and bridging.(2)In respect of sludge resources sustainable exploitation,sludge materials were used as coagulant aids through the recycle and carbonization of flocculated sludge,which was synergistically applied to remove metal anion pollutants in the field of enhanced flocculation with polyferric sulfate(PFS).The removal efficiency of Fe(CN)63-pollutants was significantly improved by adding carbonized sludge materials.Specially,the removal rate of Fe(CN)63pollutants was up to 99.50%by carbonized sludge materials at 700℃.Compared with other flocculation technologies,the cost of water treatment of metal anion pollutants was also reduced to a certain extent by adding the flocculated sludge.(3)The flocculated sludge was transformed into porous carbon matrix composites by acidification and high temperature activation of KOH,and used as electrode material to apply in capacitor field.The effects of different treatment processes on the electrochemical properties of sludge materials were compared.The results of electrochemical tests showed that the sludge electrode exhibited excellent energy storage performance after HNO3 acidification and KOH activation with a mass ratio of 1:3.The specific capacitance of the sludge electrode reached 287 F/g at a current density of 1 A/g.In addition,when the current density was 5 A/g,the sludge electrode material showed excellent cycle stability(5000 cycles maintained 93.2%initial capacitance value).It has potential application in supercapacitors. |
PDF Full Text Request