Research On VFA Production Performance Of Anaerobic Co-digestion Of Navel Orange Waste Residue And Waste Activated Sludge

In view of the poor degradation performance of navel orange waste residue,low utilization rate,and poor anaerobic digestion stability of the waste activated sludge alone,the characteristics of the waste activated sludge and navel orange waste residue by co-digesting the navel orange waste residue and the waste activated sludge anaerobicly were analyzed.The effect of different pretreatment methods to crack the navel orange waste residue and the toxicity of orange peel essential oil?EO?content on the anaerobic co-digestion system were studied,and the different ratios of navel orange waste residue and waste activated sludge to the anaerobic co-digestion VFA production performance were mainly studied.In order to provide technical support for optimizing the performance of anaerobic co-digestion of navel orange waste residue and waste activated sludge to produce VFA and its resource utilization,reduction and harmlessness.?1?The pretreatment methods of acid-base,low heat,ultrasound,alkali-low heat combination and alkali-ultrasonic combination were used to crack the navel orange waste residue,which improved the cracking performance of navel orange waste residue and determines the best pretreatment method for navel orange waste residue.All pretreatments could promote the reduction of total volatile solids?VS?,improve the cracking rate of navel orange waste residue,and then release more soluble organic matter,which was beneficial to the anaerobic VFA production of navel orange waste residue in the later period.When the strong alkali pH=13,the solid content of navel orange waste residue was significantly reduced,and a large amount of soluble organic matter was dissolved;and,its cracking rate?DD?was the highest,which was 1.78 times that of the alkali-low heat pretreatment?pH=7,T=70??;However,its NaOH dosage was 12 times that of the alkali-low heat pretreatment;Its average particle size was 57.3?m,which was close to the alkali-low heat pretreatment at?pH=7,T=70?average particle size was 58.3?m?.Therefore,the alkali-low heat pretreatment?pH=7,T=70??was more suitable for cracking navel orange waste residue than other pretreatment methods.?2?By controlling the ratio of navel orange waste residue VS and waste activated sludge VS,the best effect of VFA production by mixed substrate anaerobic co-digestion was determined.The optimal ratio of navel orange waste residue to waste activated sludge was navel orange waste residue/waste activated sludge VS=2:1.Compared with the control group?only the waste activated sludge was used as the substrate?,the VFA output of the 2#experimental group?navel orange waste residue VS/waste activated sludge VS=2:1?increased by 45.2 times at the optimal fermentation time of 8d.The community abundance of Methanobacillus archaea and VFA-producing bacteria increased greatly;acetic acid accounted for the largest proportion among the VFA components,and the 2#experimental group was acetic acid type fermentation.?3?By controlling the amount of EO added,the effect of mixed substrate anaerobic co-digestion to inhibit CH₄ production was studied.During the anaerobic toxicity experiment,when the EO content was 550 mg/kg and 750 mg/kg,it didn't inhibit the specific activity of methanogenesis of the anaerobic system;while the EO content was 950¹350 mg/kg,it inhibited the anaerobic system's specific activity of methanogenesis;the half-inhibition concentration IC₅₀=1150 mg/kg.In the process of anaerobic toxicity recovery,when the EO content was550⁹50 mg/kg,the anaerobic system basically recovered its activity;when the EO content was1150 mg/kg and 1350 mg/kg,its anaerobic system could only recover part of the microorganism active.Therefore,high content of EO was highly toxic to anaerobic systems and could better suppress anaerobic CH₄ production;low levels of EO didn't inhibit CH₄ production.