The method of composite anaerobic digestion process domestic waste and sewage plant sludge
Technical field
The present invention relates to a kind of domestic waste and municipal sewage sludge be carried out the technology of Anaerobic Digestion, recyclable biogas and soil conditioner in the innocent treatment procedure that carries out in this way.
Background technology
Domestic waste and municipal sewage sludge all are to be rich in the waste that perishable organic matter is main pollution feature.So utilizing microbial metabolism to make its contained organic stabilization is one of main path of handling.The metabolic characteristics difference of the microbial population that utilizes by treating processes can be divided into two kinds of fundamental method: aerobe is handled and anaerobic biological treatment.Wherein anaerobic biological treatment generally is referred to as anaerobic digestion.Anaerobic digestion is to be finished by the coaction of one group of anaerobic metabolism microorganism, mainly comprises: hydrolysis, acetoxylation and three links of methanation.The metabolic final product of organic anaerobe is with methane (CH
4) and carbonic acid gas (CO
2) digestion formed for the gas-phase product of main constituent (biogas) and organic residue finishes solid.Handle with aerobe and to compare, the main advantage of anaerobic digestion is to produce has the biogas that energy recovery is worth, and the energy consumption that the recovery of biogas not only can the compensation deals process also can have extra section to do clean output.Solid is the same with aerobe processing product does the utilization of agricultural soil amendment and the digestion that the organic residue that digestion produces is formed is finished.The key of domestic waste and municipal sewage sludge anaerobic digestion techniques provides microbial metabolism active control environment condition, but it is discrepant that the organic matter of two kinds of wastes is formed, therefore control condition is also different: the domestic waste digestion initial stage will be controlled the organic acid accumulation, can overcome just that soluble saccharide is more to produce a large amount of organic (fat) acid because of digestible organism contains, make the acidifying environment that occurs low pH value in the digestive organ, cause being fit to metabolic methanation flora generation inhibition under the neutrallty condition, digestion can't be finished.Solution to the problems described above is to enter digestive organ by part digestion product (Digestive system and digestion slag) is back to the digestive organ import after the domestic waste raw material mixes at present, make and contain a large amount of methanation microorganisms in the digestive organ charging, sufficient basicity is provided simultaneously, buffering acidity is not suppressed digestion.But this method will inevitably make digestive organ volumetrical effective rate of utilization reduce, the economy (volume fraction of the material that refluxes usually reaches about 30%) of influence investment.And sewage plant sludge is low because of containing biological easily biodegradable organics ratio, and its topmost technical problem is the conditioning step that hydrolysis becomes digestion rate, and its digestion thoroughness and speed are affected adversely.In addition, containing the security that a certain amount of heavy metal makes its product use in the soil at table as soil conditioner in the sewage plant sludge is on the hazard.J.Mata-Alvarez etc. was published in Bioresource Technology magazine the 74th volume in 2000 for this reason, in " Anaerobicdigestion of organic wastes:An overview of research achievements andperspectives " literary composition of the 1st phase 3-16 page or leaf, sewage plant sludge and domestic waste mixture slaking technology have been proposed, but because after mixing, digestion is carried out in same digestion reactor, mud has in fact just played certain microbial inoculant effect, also brought the water ratio of mixture slaking thing to be limited by the processing ratio of two kinds of wastes simultaneously, the problem that operation control is restricted, and the bigger problem of digestion product dehydrating amount.
Summary of the invention
The Anaerobic Digestion technology that the purpose of this invention is to provide a kind of domestic waste and municipal sewage sludge, with not only recyclable biogas and soil conditioner after this art breading, and can improve waste (organic matter) digestibility, reduce operation energy consumption, simplify operational outfit, reduce the heavy metal content of digestion back solid product effectively, guarantee the security that it is used in table soil as soil conditioner.
To achieve these goals, the present invention is the solvability organic matter that produces by with domestic waste solid phase hydrolytic digestion, be transported in the municipal sewage sludge liquid phase methanator, simultaneously, the liquid of mud liquid phase methanator anaerobic digestion is circulated in the solid phase hydrolytic digestion reactor of rubbish by pump, so, reach purposes such as high digestibility, less energy-consumption with the solid phase hydrolytic digestion of rubbish and compound the carrying out of liquid phase methanation digestion of mud.Concrete technology comprises:
The domestic waste of pre-sorting (selecting macrobead thing and ferrous metal) or categorised collection is filled in the solid phase hydrolytic digestion reactor, and the appropriate tamped density that is densified to rubbish is 400~600kg/m
3, carry out anaerobic hydrolysis digestion, digestion can be done the soil conditioner utilization after finishing solid discharge reactor after sub-electing foreign material such as plastics, non-ferrous metal.Simultaneously with the thickened sludge (solid content>3%) of municipal wastewater treatment plant through heat exchanger I be preheating to 50-54 ℃ become heating mud after, add in the liquid phase methanator and carry out anaerobic digestion, the biogas that digestion produces is delivered to the generating of water-cooled gas internal combustion engine generator, electric energy output utilizes, the afterheat of hot water that reclaims in the engine cylinder chuck is delivered among the heat exchanger I, is used to heat thickened sludge.Digestion is finished can be back to municipal wastewater treatment plant pump well processing discharging after liquid is discharged.
Its characteristics are: the liquid that contains the solvability organic matter that the solid hydrolytic digestion of rubbish produces is transported to heat exchanger II heating (heat exchange) by the supercharging of backflow topping-up pump, adds the liquid phase methanator then and is converted into biogas; And the partially liq of mud anaerobic digestion in the liquid phase methanator also is transported to heat exchanger II after circularly-supercharged pump supercharging, and after heat exchanger II cooling (heat exchange), the waste layer that above stream mode is passed in the solid phase hydrolytic digestion reactor flows out, enter the import of backflow topping-up pump, the liquid that makes rubbish hydrolytic digestion in the solid phase hydrolytic digestion reactor is as overall phegma, conveying is got back to the liquid phase methanator and is formed liquid circulation, and the circulation hydraulic load of rubbish solid hydrolytic digestion is controlled at>30mm.Shunting action by the variable valve I that is provided with between backflow topping-up pump outlet and the solid phase hydrolytic digestion Reactor inlet then, make the liquid that part flows out the solid phase hydrolysis reactor become local circulation liquid, the waste layer of passing in the solid phase hydrolysis reactor is done partial circulating, regulate the opening degree of variable valve I, the ratio of may command local circulation liquid and total phegma, change the liquid that enters solid phase hydrolytic digestion reactor and form, make its pH value 5.5~5.8 that satisfies the digestion of rubbish anaerobic hydrolysis and the condition of fatty acid concentration<10000mg/L.Equally, by regulating the opening degree of the variable valve II that is provided with between circularly-supercharged pump discharge and the import of liquid phase methanator, make liquid that part flows out the liquid phase methanator become local return liquid and in liquid phase methanation Liquid-phase reactor, do partial circulating, control the ratio of local phegma and total phegma, can change the liquid that enters the liquid phase methanator forms, make it satisfy methanation digestion pH value greater than 6.5, the condition of fatty acid concentration<5000mg/L is avoided influencing the Metabolic activity of solid phase hydrolysis or liquid phase methanation flora because of liquid circulation makes two envrionment conditions generation acute variation in the reactor.
Effect of the present invention is:
1. because technology of the present invention is by the liquid phase circulation solid hydrolytic digestion of rubbish and the liquid phase methanation reaction compound string of mud to be joined together, both can make organic hydrolysate methanation effectively, reclaim biogas, also can make the pH value in the hydrolysis reactor, the condition that fatty acid concentration etc. influence hydrolysis rate is optimized, improved overall organic digestion rate, and make the rubbish digestion that in hydrolysis bacterium superiority environment, is hydrolyzed all the time, need not to consider to its control, to be fit to the metabolic problem of methanation flora simultaneously, so digestibility height of the present invention, operation energy consumption is low.
2. the solid particulate matter in the mud flows into and is deposited in the solid phase hydrolytic digestion reactor that anaerobic digestion of refuse uses by circularly-supercharged pump, utilize the interior favourable hydrolysis environment of solid phase hydrolytic digestion reactor of rubbish to digest with the hydrolysising microorganism that gathers, improved the hydrolytic process condition of mud and prolonged hydrolysis time, made the anaerobic sludge digestion effect good especially.
3. because the interior environment of the solid phase hydrolytic digestion reactor of anaerobic digestion of refuse is a slant acidity, therefore the present invention can make in the mud soluble state and the sour molten attitude heavy metal to the environmental influence maximum, be transferred to liquid phase by the acid dissolving, and in liquid phase methanation digestion reactor, combine with stable sulfuration states of matter with the sulfonium ion that wherein exists and accumulate, guaranteed that the soil of most of solid phase anaerobic digestion product utilizes security.
4. digest after digestion product (Digestive system and digestion slag) is back to digestion reactor and garbage raw material mixes with existing, to guarantee methanation content of microorganisms and potential of hydrogen in the digestion raw material, make the uncontrolled method of digestion relatively, anaerobic digestion of refuse of the present invention is reduced 30% with the volume of reactor, can save corresponding initial cost.
Description of drawings
Fig. 1 is a process flow sheet of the present invention.
Embodiment
See also Fig. 1, composite anaerobic digestion method of the present invention comprises the solid phase hydrolytic digestion of rubbish and the liquid phase anaerobic methane digestion of mud.
Wherein the solid phase hydrolytic digestion adopts digestion method in batches, and filling is through the domestic waste of sorting or categorised collection in solid phase hydrolytic digestion reactor.The rubbish loading height reaches 90% o'clock of height for reactor, opens pushing plate, and it is urged to offside, and control pushing plate pushing stroke is so that the tamped density of rubbish is 400~600kg/m
3, be full of by rubbish until the hydrolytic digestion reactor.Backflow topping-up pump, variable valve and heat exchanger with respective lines connection liquid circulation and backflow usefulness begin to digest.The water distribution layer (establishing flow deflector in the water distribution layer) and the layer that catchments that the Punched Steel Plate envelope system that respectively is provided with by above and below in the hydrolytic digestion reactor forms, and the liquid circulation channel that connects to form successively with the opening and the liquid circulation pipeline of reactor side, can in digestive process, carry out the liquid circulation in the reactor, circulation can intermittently or be carried out continuously, but per day cycling time should be greater than 3h, circulation hydraulic load>30mm; The pH value span of control of circulation fluid is 5.5~5.8, and hydrolysis was not suppressed, and also can make it to suppress the activity of methanation flora.The cycle of domestic waste hydrolytic digestion, finished digestion in 10~15 days according to not being all of waste component, finish digestion back control pushing plate and solid output is finished in digestion with the speed that is about 0.1m/min, after trommel screen sub-elects indigested plastics and other foreign material, do the soil improvement agent utilization.And can load rubbish once more and digest.
The continuous flow digestion method is adopted in liquid phase methanation digestion, and the digestion temperature adopts the high temperature territory, is controlled to be 52 ± 2 ℃, and the porous ceramics packing layer is established in vertical stage casing in the liquid phase digestion reactor, height 1.2~2.0m, packing layer voidage 0.5~0.7; Packing layer is divided into the supporting water distribution board, and water distribution board perforate aperture and pitch of holes are 10mm and 30mm; Liquid flow direction is served as reasons down supreme in the reactor, the upper and lower hole of establishing respectively of sidewall of reactor connects circulation fluid import and export pipe, and sidewall of reactor is established the sewage sludge feed hole in addition, and the Digestive system discharger is established in the bottom surface, establish pneumatic outlet at reactor end face highest point in addition, the silk screen foam blocking plate is established in the pneumatic outlet below.The volume of reactor was determined by the sludge digestion hydraulic detention time in 14 days, when single reactor volume can't satisfy the treatment capacity requirement, can establish a plurality of reactors.The pH value of reactor cycles withdrawing fluid is controlled greater than 6.5, fatty acid concentration<5000mg/L.Municipal sewage sludge gravity concentrates the back solid content and answers>3%; Owing to there be circulating in the solid phase hydrolytic digestion reactor, about 70% can deposit therein in the sewage sludge solid in the sludge digestion process, and the liquid phase digestive organ is finished the solid content<1000mg/L of liquid, no longer needs to do solid-liquid separation before the backflow Sewage Plant and handles.Municipal sewage sludge is after gravity concentrates, thickened sludge enters the liquid phase methanator and carries out anaerobic digestion after heat exchanger I preheating, the biogas that digestion produces enters in the water-cooled gas internal combustion engine generator and is converted into electric energy, is used to heat thickened sludge by the hot water that reclaims in the cylinder chuck in heat exchanger I.Liquid and mud concentrated supernatant mixing backflow municipal wastewater treatment plant pump well are finished in the digestion that digestion is discharged.
Partially liq in the liquid phase methanator is through circularly-supercharged pump delivery, and after heat exchanger II heat exchange (cooling), above stream mode is passed waste layer at solid phase hydrolytic digestion reactor and is formed total phegma, and total phegma returns the liquid phase methanator again after supercharging of backflow topping-up pump and heat exchanger heat exchange (heating).Between circularly-supercharged pump discharge and liquid phase methanator pump around circuit pipeline, be provided with connecting branch and variable valve II, can form Liquid-phase reactor local return liquid [do not contact directly and reflux] with waste layer in the solid phase hydrolysis reactor, by changing the open degree of variable valve II, the throughput ratio of may command liquid phase methanator local return liquid and total phegma, and then can effectively control the pH value and the fatty acid concentration of the total phegma that returns the liquid phase methanator, avoid influencing the Metabolic activity of methanation flora because of circulation makes envrionment conditions generation acute variation in this reactor.Equally, be provided with connecting branch and variable valve I between backflow supercharging pump outlet and solid phase hydrolysis reactor circulation fluid inlet pipe, can form solid phase hydrolytic digestion reactor local return liquid, aperture control by variable valve I, can regulate the pH value and the fatty acid concentration that enter solid phase hydrolytic digestion liquid reactor, the hydrolysising condition to solid phase hydrolytic digestion reactor is optimized control thus.