Summary: various sewage treatment commissioning technologies
Date: 2018-01-05
Author: 水世界
What is the commissioning experience of coking wastewater, printing and dyeing wastewater, papermaking wastewater, tannery wastewater, landfill leachate, garment wastewater, SBR process and other sewage treatment? Due to the limited space, the summary of anaerobic - anoxic - aerobic commissioning and SBR process commissioning technology for coking wastewater is introduced in detail. Anaerobic - anoxic - aerobic commissioning of coking wastewater The wastewater treatment project adopts anaerobic - anoxic - aerobic process, and the commissioning of the project is mainly biological. Biological commissioning I, activated sludge indicator mixed liquid suspended solids (MLSS) concentration: refers to the total weight of activated sludge solids contained in the mixed liquid per unit volume, namely, including microorganisms, auto-oxidation residues, non-degradable organics and inorganic substances. Volatile suspended solids (MLVSS) concentration of mixed liquid: refers to the concentration of organic solid substances in the mixed liquid per unit volume, excluding the inorganic salt part, which can accurately represent the amount of active part of activated sludge. Sludge sedimentation ratio (SV%): the percentage of the volume of settling sludge formed after the mixed liquor in the aeration tank is placed in a 100ml measuring cylinder for 30min. It can reflect the sludge volume during the normal operation of the aeration tank, can be used to control the discharge of excess sludge, and can also timely detect sludge bulking or other abnormal conditions. Sludge index (SVI): This index means the sludge volume per gram of dry sludge after the mixed liquid at the outlet of the aeration tank has been settled for 30min. It can reflect the adsorption, coagulation and sedimentation of sludge, and SVI is usually between 80-150. 2、 The commissioning of the biochemical system of activated sludge cultivation and acclimation activated sludge method is first to add EMO efficient bacteria for inoculation. High-efficiency bacteria can greatly shorten the time of sludge cultivation and acclimation. The cultivation and acclimation are carried out in the aerobic tank. Before the activated sludge treatment system is put into operation, the primary work is to cultivate and acclimatize sludge. The cultivation of activated sludge is to provide a suitable growth and reproduction environment for the microorganisms and bacteria that form activated sludge, ensure the required nutrients, oxygen supply (aeration), appropriate temperature and pH, make them multiply in large quantities, form activated sludge, and finally reach the sludge concentration required for sewage treatment. The acclimation of activated sludge is to adapt the cultivated activated sludge to the quality and quantity of sewage to be treated. In the process of sludge acclimation, there are two main changes of microorganisms in sludge. The first is that the number of microorganisms that can use the organic pollutants in the sewage is gradually increasing, and those that cannot be used are gradually dying and eliminated. The second is that the microorganism that can adapt to the water quality, under the induction of the organic matter in the wastewater, produces the inducible enzyme that can decompose and utilize the organic matter. 3、 The cultivation and acclimation of activated sludge 1. The cultivation and acclimation of activated sludge in aerobic tank (1) The cultivation of sludge will dilute and mash the EMO efficient bacteria with sewage, remove the impurities in it, and put it into the aerobic tank. The water level in the aerobic tank will be adjusted to about 1/2 of the normal water level when it is put in. After the addition, the sewage level in the aerobic tank will be increased to the normal water level, and the aeration system will start to operate when the bacteria are added, And carry out closed aeration (that is, continuous aeration without water inflow and drainage). After several hours, stop aeration, discharge half of the sludge for night clearing, and then add sewage. After several hours of closed aeration, stop aeration, discharge half of the sludge for night clearing, and then add sewage. Repeat closed aeration for water change. During this period, pay attention to observe the characteristics of sludge and the control of dissolved oxygen, and keep it between 2-4mg/L. Until fuzzy sludge with flocculating property appears. During the cultivation period, domestic sewage is mainly used. If it is industrial sewage, attention should be paid to the balance proportion of various nutrients in the sewage. When sludge flocs appear in the aerobic tank, sewage will be added to the aeration tank intermittently. The amount of water added to the aeration tank should ensure that the amount of water in the tank can be changed by 1/2 of the tank volume every day. With the progress of culture, the amount of water will be gradually increased so that it can be changed once a day in the later stage of culture. After the effluent from the aeration tank enters the secondary sedimentation tank for about 2 hours, the sludge begins to flow back. (2) The acclimation of sludge will gradually increase the proportion of treated sewage in the influent, or increase the concentration, so that the biological gradually adapt to the new environment. At the beginning, the amount of treated sewage can be 20-30% of the design load of the aeration tank. After reaching a better treatment efficiency, it will continue to increase. After each load increase, it must continue to increase after the biological adaptation is consolidated until the full load. 2. Cultivation and acclimation of sludge in anaerobic tank (1). Dilute and mash EMO efficient bacteria with sewage to remove impurities, raise the sewage in the anaerobic tank to 1/2 of the normal water level, and anaerobic the sewage in the tank for 1-2 days (in cooperation with sludge cultivation in the later aerobic section); (2) Intermittent influent is adopted, and sludge loading rate is controlled at 0.05~0.2kgCOD/(kgVSS. d). (3) When sludge gradually adapts to the nature of wastewater, it gradually has the ability to remove organic matter. When the COD removal rate reaches more than 30%, the volumetric load rate of the influent can be gradually increased, and the range of each increase in volumetric load rate should be about 0.5kgCOD/(m3. d). At this time, the intermittent influent can be transferred to continuous influent, but the influent concentration and influent volume should be controlled to maintain a stable growth. (4) With the increase of the load, the sludge in the reactor gradually changes from loose state to flocs with good sedimentation performance, and the methanogenic activity of the sludge also increases accordingly. (5) During commissioning, the load of the system shall be guaranteed to grow steadily at a growth rate of 20%~30%. Each time the load is adjusted, the removal rate shall be guaranteed to reach 30% and then the load shall be stabilized for 3~4d, and then the load shall be increased. 4、 Chemical dosing (1) Phosphate dosing is added to the regulating tank to regulate the nutrient balance in the sewage; (2) Sodium carbonate is added into the aerobic tank to regulate the pH of the sewage in the tank; (3) The flocculant is added to the air flotation tank to improve the suspended solids and oil in the sewage. The sludge dewatering system is added to help coagulate and regulate sludge properties. 5、 Abnormal conditions and countermeasures of activated sludge sludge bulking: normal activated sludge has good sedimentation performance, and its water content is above 98%. When the sludge deteriorates, the sludge is not easy to precipitate, the SVI value is high, the sludge structure is loose and bulky, and the color also changes, which is sludge bulking. Sludge bulking is mainly caused by the massive propagation of filamentous bacteria. Generally, there are many carbohydrates in sewage, lack of nutrients such as nitrogen, phosphorus and iron, lack of dissolved oxygen, high water temperature or low PH value, which are easy to cause a large number of filamentous bacteria to multiply, leading to sludge bulking. In addition, overload, too long sludge age or too small organic concentration shaving will also cause sludge bulking, and poor sludge discharge will easily cause combined water sludge bulking. In order to prevent sludge bulking, the operation management should be strengthened first, and the sewage quality, dissolved oxygen in the aeration tank, sludge sedimentation ratio, sludge index and microscope observation should be monitored frequently. If abnormal phenomena are found, preventive measures should be taken. Generally, the aeration rate can be adjusted and increased, and sludge can be discharged in time. It is possible to take staged water inflow to reduce the load of the secondary sedimentation tank. The solution to sludge bulking is to take measures against the causes of sludge bulking. When there is no oxygen or high water temperature, the aeration volume can be increased or the water inflow can be reduced to reduce the sludge load, or the sludge concentration can be appropriately reduced to reduce the oxygen demand. If the sludge load is too high, the sludge concentration can be appropriately increased to adjust the load. If necessary, the water inflow should also be stopped for a period of time. In case of lack of nitrogen, phosphorus, iron and other nutrients, nitrifying sludge or nitrogen, phosphorus, iron and other nutrients should be added. If the PH is too low, lime and other additives can be added to adjust the PH. If the sludge loss is large, iron chloride can be added to help coagulate and stimulate the growth of bacterial micelles. Bleaching powder or liquid chlorine can also be added to inhibit the growth of filamentous bacteria, especially to control the expansion of combined aqueous sludge. Inert substances such as asbestos powder, diatomite and clay can also be added to reduce the sludge index.
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