Tire pyrolysis wastewater treatment by a combined process of coagulation detoxification and biodegradation

Recycling waste tires through pyrolysis technology generates refractory wastewater,which is harmful to the environment if not disposed properly.In this study,a combined process of coagulation detoxification and biodegradation was used to treat tire pyrolysis wastewater.Organics removal characteristics at the molecular level were investigated using electrospray ionization(ESI)coupled with Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS).The results showed that nearly 90%of the organic matter from the wastewater was removed through the process.Preference of the two coagulants for different classes of organics in tire pyrolysis wastewater was observed.The covalently bound inorganicorganic hybrid coagulant(CBHyC)used in this work had a complementary relationship with biodegradation for the organics removal:this coagulant reduced toxicity and enhanced the biodegradation by preferentially removing refractory substances such as lignin with a high degree of oxidation(O/C>0.3).This study provides molecular insight into the organics of tire pyrolysis wastewater removed by a combined treatment process,supporting the advancement and application of waste rubber recycling technology.It also contributes to the possible development of an effective treatment process for refractory wastewater.

Degradation of kanamycin from production wastewater with high-concentration organic matrices by hydrothermal treatment

It is known that many kinds of fermentative antibiotics can be removed by temperatureenhanced hydrolysis from production wastewater based on their easy-to-hydrolyze characteristics.However,a few aminoglycosides are hard to hydrolyze below 100℃ because of their stability expressed by high molecular energy gap(E).Herein,removal of hard-to-hydrolyze kanamycin residue from production wastewater by hydrothermal treatment at subcritical temperatures was investigated.The results showed the reaction temperature had a significant impact on kanamycin degradation.The degradation half-life(t1/2)was shortened by 87.17-fold when the hydrothermal treatment temperature was increased from 100℃ to 180℃.The t1/2 of kanamycin in the N2 process was extended by 1.08-1.34-fold compared to that of the corresponding air process at reaction temperatures of 140-180℃,indicating that the reactions during hydrothermal treatment process mainly include oxidation and hydrolysis.However,the contribution of hydrolysis was calculated as 75%-98%,which showed hydrolysis played a major role during the process,providing possibilities for the removal of kanamycin from production wastewaters with high-concentration organic matrices.Five transformation products with lower antibacterial activity than kanamycin were identified using UPLC-QTOF-MS analysis.More importantly,hydrothermal treatment could remove 97.9%of antibacterial activity(kanamycin EQ,1,109 mg/L)from actual production wastewater with CODCr around 100,000 mg/L.Furthermore,the methane production yield in anaerobic inhibition tests could be increased about 2.3 times by adopting the hydrothermal pretreatment.Therefore,it is concluded that hydrothermal treatment as a pretreatment technology is an efficient method for removing high-concentration hard-to-hydrolyze antibiotic residues from wastewater with high-concentration organic matrices.