Toxicity Evaluation On Papermaking Wastewater And Analysis On The Degradation And Migration Of Typical Pollutant

Closely related to the national economy, has a broad development prospects, thepapermaking industry, who played an increasingly attracted role in the modern economy ofthe world, is internationally recognized as the "limitless" industry.Due to the huge wastewateremissions containing large amounts of persistent organic pollutants (POPs) and weakbiodegradability,it’s meaningful to arouse great attention of the papermaking wastewatertoxicity evaluation, research the migration and transformation mechanism of typicalcontaminant. This paper is intended to do the toxicity evaluation and figure out the migrationand degradation mechanism of persistent toxic substances produced in the pulp and paperbleaching process, which will provide theoretical basis and technical support to persistenttoxic pollutants control and transformation in China’s pulp and paper industry wastewatertreatment.In pulp bleaching process, bleach experiences interactions with lignin, produced a largenumber of organic toxic pollutants. Although the discharge standards of domesticpapermaking industry wastewater is becoming increasingly strict, the treatment process iseventurally improved, but it is not allowed to ignore that the wastewater after treatment willdo great harm to the natural environment. In order to make people understand this kind ofharm more intuitively, toxicity test have to do with the routine index of water qualitydetection at the same time, to explore the toxicity change to aquatic organisms in wastewatertreatment process of the pollutant through the use of organisms. Zebrafishes were used in thisstudy as subject creatures to evaluat the acute toxicity, wastewater toxicity evaluation wascarried out through the96h acute toxicity test in degradation process. The results show that,as the treatment process propulsion of papermaking wastewater: the96h LC50values of eachworking procedure section were gradually decreases.the raw water, the96h LC50values ofthe primary effluent, the secondary effluent, the tertiary effluent were4.12,4.59,9.08,55.1respectively, according to the industrial wastewater acute toxicity division standard,wastewater toxicity were high,high,high and low toxic level, safety concentration were1.311,1.485,2.678,16.014, respectively.The cause of the toxicity and the reasons for such changes was discussed in microscopicview after the harm to human health of papermaking wastewater in macroscopic view, thisresearch analysised what produced COD and TOC and toxic substance, figured out them inwhat sort of material form exists in each working procedure section of papermaking wastewater. GC-MS was used to track and identify pollutants in type and the relative contentin the primary settling-aerobic-coagulating air floating each component of sewage treatmentprocess, ion chromatographic was used to determine kinds of small molecule organic acidchange. The raw papermaking wastewater was detected88kinds of organic pollutants,including15kinds of phenols,18kinds of long chain fatty hydrocarbon,9ketone,9aldehydes,5kinds of ester compounds,12monocyclic aromatic compounds,5kinds ofalcohols, small molecule organic acids,containing acetic acid and propionic acid; The primarysettling water detected43species organic matter, including18kinds of aliphatichydrocarbons,4kinds of ketone material,7kinds of monocyclic aromatic compounds,4esters,4phenolic substances; The secondary effluent water containing32kinds of organicmatter, including13kinds of fat hydrocarbon,2kinds of phenols,2kinds of ester material,6kinds of monocyclic aromatic compound; After coagulation air-flotation treatment, pollutantkinds oftertiary effluent reduced to26, including monocyclic aromatic substance contentabout33.44%,3kinds of phenolic,9fat hydrocarbon,3ester, small amount of alcohol andketone, accounting for the total organic content of0.75%and1.56%.As one of the most important pollutants in papermaking wastewater, PAHs willaccumulate and continuous enrich and amplify in fish and shrimp through the food chain,which will be a serious threat to human health. This study make polycyclic aromatichydrocarbon as a typical pollutants, optimize the GC-MS pretreatment conditions,to find outthe influence of each conditions on the determination results.GC-MS was used to track PAHsdegradation after the sewage treatment plant with the optimal conditions, quantitativelyanalysis PAHs in the papermaking wastewater treatment process, discusses the contribution oforganic pollutants and its harm size of the PAHs produced in papermaking wastewater. Theresults showed that using DB-5as GC-MS detection chromatographic column, methylenechloride as extraction agent,30min as the best extraction time,1.0gNaCl as salting-out agent,mechanical oscillation time20min, this method is simple, rapid, maneuverable andrepeatable. Using the optimization method in determination, it’s found that6kinds of PAHspollutants: naphthalene,1-chloride naphthalene,1-methyl naphthalene,1-aminotetrahydronaphthalene,1,4-dichloro naphthalene,1-amino pyrene in primary settling water.Compared with the raw water and tertiary effluent water sample, kinds of PAHs in thewastewater change from6for2, only naphthalene and1-chloride naphthalene remaining;naphthalene degradation rate reached68.05%,1-chloride naphthalene degradation ratereached54.56%in the treatment process.