1. When the treated sewage concentration is high (CODcr value is greater than 5000mg/L), the operation mode of effluent reflux can be adopted. The reflux ratio is determined according to the specific conditions, generally between 50% and 200%. Effective recirculation not only reduces the influent concentration, but also increases the influent volume, ensuring uniform distribution of water flow within the treatment facility and avoiding short-flow phenomena. The reflux can also prevent the influent concentration and the violent fluctuation of the pH value in the anaerobic reactor, so that the anaerobic reaction can be smoothly carried out, that is, the demand for alkalinity of the anaerobic reaction can be reduced, and the running cost can be reduced. The anaerobic reaction is a capacity process, and the effluent temperature is higher than the influent water. Therefore, when the winter temperature is low, the reflux is also beneficial to ensure that the temperature in the reactor is constant, and the anaerobic microorganisms are allowed to move at the optimum temperature as much as possible.
2. The temperature of general industrial wastewater is difficult to reach 35 ° C and requires heating (especially in winter). Therefore, in order to save the energy required for heating, on the one hand, it is necessary to pay attention to heat preservation, to prevent the heat loss of the reactor as much as possible. On the other hand, it is necessary to give full play to the characteristics of large sludge concentration in the reactor, and to increase the sludge concentration in the reactor as much as possible. , weaken the effect of temperature on anaerobic reactions.
3. Biogas should be removed in a timely and effective manner. The anaerobic digestion process of pyridine is accompanied by the generation of biogas, which can agitate the sludge and promote the mixed contact of sewage and sludge, which is an advantageous side. At the same time, the presence of biogas will also play a similar role in flotation. When the biogas overflows, part of the sludge will be brought to the liquid surface, resulting in the generation of scum and the increase of suspended solids content and water quality. Therefore, a gas baffle and a gas collecting hood are to be provided, and the biogas is taken out from the anaerobic digestion device, and a sufficient sedimentation zone is left in the vicinity of the effluent water to ensure the effluent water quality.
4. The sludge load should be appropriate. In order to maintain the balance of the three stages of the anaerobic digestion process, the formation and consumption of intermediate products such as volatile fatty acids are balanced, and the pH is prevented from falling due to acid accumulation. The organic load of the influent water should not be too high, generally not exceeding 0.5 kg CODcr/(kgMLSS. d). A higher volumetric load can be achieved by increasing the sludge concentration in the reactor while maintaining a relatively low sludge load. In general, the volumetric load of an anaerobic digestion unit is above 5 kg CODcr/(m3.d), even up to 50 kg CODcr/(m3.d), which is much higher than an aerobic treatment unit.
5. To fully premature anaerobic environment. Oxygen-free is a prerequisite for the normal activities of anaerobic microorganisms, and methane bacteria must be effective in an absolute anaerobic environment. In the process of lifting the sewage into the anaerobic digestion unit and returning the water, it is necessary to avoid contact with the air as much as possible to minimize the chance of contact with the air. If there is no water drop or agitation in the process of water flow, the adjustment tank, reflux tank, etc. should be covered and closed, and the gas lift pump should not be used for sewage lifting. The anaerobic reaction structure is preferably subjected to a gas tight test to ensure that it is tight and leak free.