Study On Anaerobic Digestion Of Cephalosporin Bacterial Residue

At present, China has become the world’s largest country of antibiotic APImanufacturer and exporter. But in the meanwhile an enormous amount of antibioticsbacteria residue (ABR) have been produced. In2008, ABR was classified as hazardouswaste in China. And since then reasonable disposal methods of ABR with low energyconsumption, low pollution and high efficiency have not yet been found. Therefore, theproblem of antibiotic residues treatment and disposal has become a bottleneck thatrestricts the development of drug industry in China. The anaerobic digestion treatment ofcephalosporin bacterial residue (CBR), with alkaline-thermal pretreatment to increase thecontent of dissolved organic matter in CBR been investigated in this research. Thebiodegradability of CBR was evaluated by biochemical methane potential (BMP) test toconfirm the optimal pretreatment conditions. The CBRs before and after pretreatmentedwere taken into anaerobic digestion to identify the optimal control parameters. To providetechnical reference for effectively treatment and disposal of CBR, an anaerobic digestionstudy which mixed kitchen waste was carried out at the same time. The research resultswere summarized as follows.Based on analyzing the basic physical and chemical properties of CBR, thealkaline-thermal pretreatment is conducted to investigate the effect of CBR lysing, andthen the biodegradability of bacterial residue is evaluated with BMP tests. The optimalpretreatment temperature, alkali amount and pretreatment time are determined as75°C,6%and30min respectively by orthogonal experiments analysis. The accumulative biogasyield and gas production rate on the above optimal condition are495mL and0.27L/gVSaddedrespectively, which is3.54times that of untreated ones.Comparing the five different organic loading operation condition, the results ofanaerobic digestion tests indicate that the optimal volume loading is4gVS/(L d). Undersuch conditions, the VS removal rate is51.8%, the daily average biogas yield is5.03L/d,and the daily average methane yield rate is0.252L/(gVSadded d) respectively. Theanaerobic digestion reactor runs well in the whole process of the experiment. However,since the carbon-nitrogen ratio of bacterial residue is relatively low, the content ofammonia in the anaerobic digestion reactor has shown a rising trend, and the production ofbiogas was inhibited when the concentration of ammonia exceeded the threshold of 3000mg/L.To solve the problem of low carbon-nitrogen ratio and ammonia inhibition, kitchenwaste which has a relatively high carbon-nitrogen ratio mixed to anaerobic digestion. Theresearch compared CBR with five different carbon-nitrogen ratios with anaerobicdigestion that mixed kitchen waste. Results show that kitchen waste can effectivelybalance the carbon-nitrogen ratio and improve the biogas yield, removal rate of VS andsolve the problem of ammonia inhibition. In addition, results indicate that the reactor showa better efficiency with4gVS/(L d) volume loading when the carbon-nitrogen ratio were20/1and25/1. For carbon-nitrogen ratio of20/1, the final methane yield and methaneproduction rate were6.38L and0.32L/(gVSadded d). While for carbon-nitrogen ratio of25/1, they were6.68L and0.334L/(gVSadded d), respectively. The optimumcarbon-nitrogen ratio of20/1was thus determined as the experiment mainly aims toprocessing CBR.