Pretreatment device and method for kitchen waste leachate

Abstract

The invention provides a pretreatment device for kitchen waste leachate. The pretreatment device comprises an impurity removal unit, an oil extraction unit, a solid-residue separation unit, an air floatation unit and a temperature adjustment and heat recovery unit. According to the pretreatment device for kitchen waste leachate, the mode of combining mechanical dehydration and flocculation air floatation is adopted, ammonia nitrogen cannot be increased while COD and SS are removed, the process selection range of a subsequent biochemical system is wider, and odor is easier to control. The invention further provides a pretreatment method of the pretreatment device for kitchen waste leachate. The pretreatment method comprises the following steps: (a) removing impurities; (b) extracting oil; (c) carrying out solid-slag separation; (d) carrying out air floatation separation; and (e) carrying out temperature adjustment and heat recovery. According to the pretreatment method, most SS and animal and vegetable oil are removed through a three-phase centrifugal machine and a two-phase centrifugal machine. The pretreatment device has the advantages of being high in SS and animal and vegetableoil removal efficiency, small in agent consumption, small in occupied area and the like.

Description

technical field [0001] The invention belongs to the technical field of kitchen waste treatment, and in particular relates to a pretreatment device and method for kitchen waste leachate. Background technique [0002] Kitchen waste leachate is the most common waste generated in urban daily life and belongs to municipal solid waste. Food waste leachate is mainly manifested in the following water quality characteristics and treatment difficulties: (1) The concentration of various pollutants is quite high, and the concentration of pollutants in food waste leachate is quite high, COD: 150000~250000mg / L, BOD: 100000~ 200000mg / L; SS: 80000~100000mg / L; animal and vegetable oils: 20000~40000mg / L. Such a high concentration of pollutants cannot be directly received by any biochemical treatment system. (2) The oil content is quite high. The animal and vegetable oil content of kitchen waste leachate is about 20,000-40,000mg / L. If such a high oil content is directly entered into the sewa...

AI Technical Summary

Problems solved by technology

Such a high concentration of pollutants cannot be directly received by any biochemical treatment system

(2) The oil content is quite high. The animal and vegetable oil content of kitchen waste leachate is about 20,000-40,000 mg / L. If such a high oil content is directly entered into the sewage treatment system for treatment, the treatment system will collapse.

(3) The content of impurities is high. The leachate of food waste may contain hard particles such as shell debris, glass debris, bone slag, and gravel, as well as larger particles such as chopsticks and plastics. If these impurities enter the back-end wastewater treatment in large quantities system, it will not only cause equipment failure and pipeline blockage, but also affect the operation of the membrane if the biofilm treatment process is used

(6) High salinity, the kitchen waste leachate itself has a high salinity, the conductivity reaches 20-30ms / cm, and the salinity is 15PSU. Due to the high solid content of the kitchen waste leachate, the pH value is low , the pretreatment needs to add sodium hydroxide to adjust the pH value, flocculant, coagulant agent, etc., and the salinity will be further increased

A big problem with this treatment process is that the waste water stays in the CSTR anaerobic digestion system for a relatively long time. While the carbon-containing organic pollutants are removed to the greatest extent, the nitrogen-containing organic matter will be converted into ammonia nitrogen and discharged, so it is anaerobic. The wastewater after oxygen digestion contains extremely high ammonia nitrogen concentration, usually 2000mg / l-3000mg / l, while COD is only 10000-15000mg / l. This kind of wastewater with a seriously unbalanced carbon-nitrogen ratio is easy to be treated in the subsequent biochemical treatment process. Ammonia nitrogen exceeds the standard, nitrite poisoning and other phenomena appear, which is extremely difficult to deal with, and the process options are also narrow, and additional carbon sources need to be added

Images