Analysis of spectra of effluent from DC reactor for treating traditional Chinese medicine wastewater

The characteristics of effluent of a novel double circle (DC) reactor for treating the wastewater from traditional Chinese medicine were investigated at different operation conditions. The analytical techniques including 3D excitation-emission matrix (EEM) fluorescence spectra and fourier transform infrared (FTIR) spectra were adopted, which could provide new thoughts for effective monitoring of anaerobic reactor performance. The results showed that when HRT was 24 h, the DC anaerobic reactor could achieve the COD removal efficiency of 94%, and the methane production rate of 0.37 m³ CH₄/kg'COD. At the same time, the absorption peak of coenzyme F₄₂₀ (Ex/Em = 420/470 nm) appeared obviously in the EEM spectra of the effluent. When HRT reduced to 12h, although the COD removal rate was 90%, the absorption peak coenzyme F₄₂₀ decreased, whereas the absorption peak of fulvic acid-like appeared, indicating that HRT should not be reduced further. When the temperature was reduced from to 30℃ to 20 ℃, the characteristics of anaerobic sludge were influenced by the variation of temperature. The absorption peak at 3400cm changed from blunt peak to sharp peak in the FTIR spectra of the effluent. Particularly, the addition of rhein in the influent caused the accumulation of organic acids in the reactor. Hence, the methanogens activity was severely inhibited. Meanwhile, the absorption peaks of humic acid and fulvic acid-like were significantly enhanced in the EEM spectra of the effluent.