Experimental Study On Anaerobic Digestion Of Kitchen Waste

As an important method of organic waste treatmenttechnology,anaerobic digestion could realize the recycling of organic waste resources.It could not only avoid the environmental pollution caused by the accumulation of organic solid waste,but also eliminate the pollution transfer by other treatment methods such as incineration and landfill.Presently,with in-depth understanding in the mechanism of anaerobic digestion,many advanced anaerobic digestion processes with more complex technology as well the higher digestion efficiency,are experimented and applied to engineering practice gradually.Highmoisture content coupled with rich organic matter and grease,food waste is very suitable for anaerobic digestion.In this paper,three experiments were carried out to study the optimum experimental conditions of wet anaerobic digestion,dry anaerobic digestion;meanwhile the restoration of anaerobic digestion system was also studied.Characteristics of gas production and digestive effluent during experiments were analyzed.The main contents of the article are as follows:?1?Wet anaerobic digestion and dry anaerobic digestion were carried out with inoculumfrom anaerobic digestion liquid of pig manure.The feeding loadrateswere gradually increasedandthe biogas production rate increased steadily along with the feeding load.Because of the excessive initialorganic loading in the recovery experiment,the impact of the system was severe,which resulted in unstable operation.The best organic load of wet anaerobic digestion,dry anaerobic digestion and system recovery of kitchen waste were2.7kgVS·?m³·d?^-1?4.6kgVS·?m³·d?^-1and 3.0³.7 kgVS·?m³·d?^-1respectively.Under the condition of the best organic load,the system ran stably and efficiently.If the feed load exceeded the limit load of the system,anaerobic digestion reaction may be suppressed severely and even field.?2?In the steady state,the experimental data of wet anaerobic digestion,dry anaerobic digestion and biogas production recovery system were respectively as follows:pH:7.5⁸.0,8.2⁸.5,8.18⁸.32;VFA:1100⁴000 mg·L^-1,7300¹2000 mg·L^-1,9400¹1200mg·L^-1;total alkalinity:6000⁹000 mg·L^-1,17000¹9000 mg·L^-1,9400¹1200mg·L^-1;ammonia nitrogen:1500²000mg·L^-1,3500⁵500mg·L^-1,4300⁴900mg·L^-1.The data of the digestive index fluctuated in certain range,once beyond this rangethe anaerobic digestion system would likely be in an unstable state?3?After the wet anaerobic digestion experiment was seriously inhibited,pH decreasedcontinually to about 6.3.Manually regulating the pH did not restore the system to a good biogas productionstate,and p H changed repeatedly in the range of 6.25⁷.70,with downward trendoverall.?4?The water content of the digestive fluid increased continuallyand finally reached 96%⁹8%,accompanied by a decline in gas production.The water content of the digestive tract was manual adjusted byreturning the digestive fluid.The specific operation was that the biogas residuefrom the solid-liquid separation of the digestive liquid refluxing to the digestive system together with the feed.When the moisture content of digestive system was adjusted to 85.80%⁸7.73%,the system returned to normal.