Study On Mechanism And Application Of Photosynthetic Bacteria In Eliminating Formaldehyde

Indoor air for mal dehyde pollution ha s become an i mpor tant envir onmental i ssu e du e t o it s wi de source,heavy polluti on,and di ffi cult treat ment.Phot osynt heti c bact eria ha ve a fl exible and variabl e metaboli c model and are ther efor e wi dely u sed i n t he tr eatment of sewage.T he r esult s show t hat photosyntheti c bact eria have a good purificati on effect on inorga nic and organi c pollutant s i n sewa ge,and the u se of i mmobili zed photosyntheti c ba cter ia ha s hi gh r emoval effi ci ency.For t he suspensi on of photosyntheti c bact eria,no r esearch ha s yet been conduct ed to i nvesti gat e the appli cation pot ential of u sing phot osynthesi s bact eria to build a react or to r emove for maldehyde polluti o n.In thi s study,t he kineti cs of formal dehyde absorption by immobili zed phot osyntheti c bact eria and t he mechani sm of formal dehyde metaboli sm wer e invest igat ed fir st.T hen,immobili zed phot osyntheti c ba ct eria wer e used t o constru ct suspended bior eactor s.S ci ndapsu s i s an indoor orna mental pla nt t hat can be ea sil y cultivat ed,and the r oot syst em of the r eact or ha s a good puri fying effect on indoor air pollutant s.T her efore,i n t hi s study,a fi lter-t ype bi orea ctor wa s also constructed usi ng gr een root syst em and immobili zed photosynt hetic bact eria.B y anal yzing t he effecti veness of the t wo rea ct ors in the removal of i ndoor air pollution from for maldehyde and T VOC,the appli cation pot ential of phot osynt het ic bact eria i n the r emoval of air for mal dehyde a nd T VOC polluti on was i nvesti gated.N ew technol ogi es for the puri fi cation of indoor for mal dehyde a nd organic pollutant s wer e devel oped.T he research results obtained are as foll ows:1,Rhodopseudomonas palustri s?R P?wa s u sed a s experi mental mater ial t o investigat e the t oxi cit y of 15,30 and 60 mg·L for maldehyde solution on su spended RP cel l s.T he result s showed that t hese for maldehyde solutions ha d no effect on t he gr owt h of RP.15-60 mg·L for maldehyde solution di d not produce toxi cit y to RP cell s.T he effects of t hree light?wavel engt h 700 nm?i ntensiti es?4,8 a nd 12 klux?on t he gr owth and formal dehyde a bsor pti on of su spended RP wer e anal yzed.T he r esults showed t hat t he i ncr ea se in li ght i nt ensit y ca n i ncr ea se t he gr owth of R P and t he effici ency of for maldehyde a bsor pti on.Usi ng sodium al gi nate and sodiu m car boxymet hyl cellul ose to embed RP cell s i n t he i nter stit ial space of t he sponge,t he r esults showed t hat t he i mmobi lized R P was more effective at absorbi ng formal dehyde tha n suspended RP cell s.T he kineti cs of absor pti on of for maldehyde by sponges wit h RP cell s wa s exa mi ned.T he results showed that t he RB-absorbi ng sponges a bsor b for maldehyde in a manner si milar t o t hat of por ous mat erial s.For mal dehyde i s fir st adsorbed by the embeddi ng mat erial and moi sture i n t he i nt erstices of t he sponge and then absorbed i nt o RP cel ls..T he RP-embedded sponge wa s tr eated with 15and 30 mg·L^-1 H^{1 3}CHO.^{1 3}C-NMR anal ysi s showed that H13CHO wa s absorbed i nto t he embedded RP cell s and then oxi di zed to for mi c a cid.For mi c aci d wa s subsequentl y assi mi lated i nto carbohydrates?Gluc and Fruc?.T he organi c aci ds include 3PG A,PA,Icit,Ala,Ile,Glu,Gln,Asp,and some metabolit es i ncludi ng for mi c aci d,G luc and Fruc,a nd I cit and Ile are secreted into t he treat ment liqui d.T he R P-embedded sponge bl ock s als o have t he abi lit y t o a bsor b and metaboli ze gaseous for maldehyde,but the removal effici ency of gaseou s for maldehyde i s not a s good a s t hat of l iqui d formal dehyde.2.T he u se of embedding RP sponges and water-ba sed suspensi on bior eactor s whi ch a ssembly per for ma nce has r eached t he practi cal appli cation level shows t hat t he volu me of the sponge bl ock s fil l ed in the react or water ta nk and t he a mount of air ent eri ng t he rea ctor ar e affecting the r emoval of formal dehyde from the r eactor.T he i mporta nt factor o f effi ci ency i s to opti mi ze the r eact or conditi ons a nd use 6L embedded R P sponge a nd 6L water to assemble t he rea ct or.When t he air inta ke i s t he largest(7.8m³·mi n^-1),t he for maldehyde purificati on effi ci ency of i ndoor air polluti on i s 1mg·m^-3.⁸0%.T he air containi ng for maldehyde during the operation of the rea ct or i s fir st bl own i nto t he r eact or wat er tank and then di ssol ved i n the aqu eou s soluti on i n the wat er tank.T he sponge soaked i n the wat er i s adsor bed int o t he voi ds,and fi nall y the R P photosynt hetic bact eria embedded in t he sponge are absor bed.And conver sion,t he secr eti on of some meta boli tes l ed to an i ncrea se in t he COD of the aqueous tank solution,but no odor ous substances wer e produced.T he r eactor was placed i n a r eagent st orag e r oom wher e t he concentrati on of for maldehyde wa s 0.5-1.5 mg·m^-3 and T VOC was 6.5 mg·m^-3 for 31 days.T he result s showed that the r emoval rat e of for maldehyde and T VOC gradually incr ea sed during t he operation,a nd the concentrati on of for maldehyde and T VOC in indoor air wa s i ncr ea sed.Gra dually decr eased,t he for maldehyde concentrati on i n t he i ndoor air was r edu ced t o 0.04 mg·m^-3(below the national standard value of 0.08 mg·m^-3)a ft er 31 da ys,and the T VOC concentrati on was r edu ced to 0.5 mg·m^-3?accordi n g t o the requirement s of the nati onal standard?,and t he C ADR value of for mal dehyde pol lution was reached.At 481.4 m³·h^-1,the viabil ity of photosyntheti c ba ct eria cell s wa s-95%,a nd the per for mance of the r eact or wa s stable under the set conditions.3.T he absorpt ion abi lit y of for mal dehyde i n green radi x r oot wa s investi gated.T he result s showed t hat the ra dix root ca n absorb low concentrati ons of formal dehyde wel l a nd transfer to st ems and l eaves for metaboli sm.T he tr eat ment of 60 mg·L^-1 formal dehyde soluti on for gr een radish only caused a small a mount of cell s in t he root ti p.D ea th?8%?.^{1 3}C-N MR anal ysi s of t he metaboli c profil e of H^{1 3}CHO i n t he r adix r oot showed t hat t he main product s of for mal dehyde metaboli sm in t he gr een radish r oot wer e for mi c a cid,etha nol and a ceti c a cid.A smal l a mou nt of formic a ci d was oxidi zed to produce CO ₂,a nd the a ssimil ation of formal dehyde i n root cell s al so produced a small amount of Sugars?Gluc and Fruc?a nd organi c a ci ds such as Mal?mali c a ci d?,Ci t?citri c a cid?,Glu?glutami c aci d?.T he filt er-type bior ea ctor wa s constructed usi ng r oot green stalks and RP-embedded sponge str ips.Anal ysi s of the rea ct or per forma nce showed that the height of the r eactor loaded sponge wa s a k ey fact or affecting the r emoval of for ma l dehyde and T VOC,and t he r eaction wa s opti mi zed a ft er conditi ons wer e opti mized.T he hei ght of t he sponge i s fi xed at 20cm.Under the conditi on t hat the air volu me i s(1.2m³·min^-1)and the for mal dehyde concentrati on of t he i nlet i s 7.0mg·m^-3,t he r emoval rat e of for maldehyde i n the r eact or rea ches 95%,and t he capa city of the sponge to r emove for maldehyde i s 500mg·m^-3·h^-1.