[0036] Below in conjunction with accompanying drawing 1, the present invention is further described in detail through specific embodiments, the following embodiments are only descriptive, not restrictive, and cannot limit the protection scope of the present invention.
[0037] The treatment methods of container washing wastewater include pretreatment, physicochemical treatment, biochemical treatment, advanced treatment and sludge treatment in turn. The treatment processes are as follows:
[0038] 1. Pretreatment: Pretreatment includes grease trap and conditioning pool.
[0039] The main purpose of the pretreatment of the present invention is to remove large suspended solids and floating oil substances, and to adjust the water quality and quantity, which is beneficial to the subsequent stable treatment.
[0040] The grease trap is used to remove suspended solids and oil slicks in the wastewater. Since the density of oil is smaller than that of water, when the oily wastewater flows through the grease trap, the oil floats up, and the water flows into the subsequent treatment system from the lower part. In the invention, the oil separation tank is divided into three partitions, which are separated by a diversion wall, and the container washing wastewater is pumped into the first oil separation pool by a pump. Over time, the upper part of the grease trap is enriched with a certain amount of suspended solids and oil slicks, and it is cleaned manually.
[0041]The water collecting and regulating tank is used to homogenize the water quality and quantity to ensure the sufficient and effective mixing of the tank washing wastewater. The tank washing wastewater after oil separation flows into the water collection and adjustment tank, and stays in the water collection and adjustment tank for 24 hours. The effective volume of the water collection and adjustment tank of the present invention is 10m 3 , There are two submersible sewage pumps in the water collecting adjustment tank, and the water outlet of the submersible sewage pump is equipped with a bypass and a water outlet regulating valve to control the amount of water entering the subsequent system; there is a pipeline connected with the blower in the water collecting adjustment tank. The tank washing wastewater in the tank plays a stirring role to prevent sludge from depositing in the tank; on the other hand, it plays a role of pre-aeration to effectively curb the generation of odor.
[0042] 2. Physical and chemical treatment
[0043] In the physicochemical treatment of the present invention, a combined DAF air flotation device integrated with pressurized dissolved air flotation is selected, and the flocculation flotation agent is put into the DAF air flotation device, and the pretreated tank washing wastewater is physicochemically treated. The air flotation device removes more than 90% of petroleum substances, and the COD removal rate reaches 40%, which not only meets the requirements of the subsequent biochemical treatment of influent water, but also meets the requirements of the oil content of the discharged water, so as to reduce the adverse effects on the subsequent microbial system. The processing capacity of the DAF air flotation device of the present invention is 5m 3 /h.
[0044] DAF air flotation device has the following advantages:
[0045] (1) The residence time of wastewater in the DAF air flotation device is short, generally 3 to 5 minutes; while the current residence time of wastewater in the air flotation device is 15 to 30 minutes;
[0046] (2) The DAF air flotation device adopts a proprietary dissolved air release device, which has a large service area, and the diameter of the generated bubble particles is small and uniform, and the release device is never blocked;
[0047] (3) The reflux dissolved air system of the DAF air flotation device adopts a unique control method to ensure uniform mixing of soda and water and stable operation;
[0048] (4) The DAF air flotation device adopts the inclined plate separation system, and the separation efficiency can be doubled;
[0049] (5) The DAF air flotation device is an integrated device, and the structure design is very delicate;
[0050] (6) The DAF air flotation device is a closed device, which will not produce secondary pollution during this process.
[0051] 3. Biochemical treatment
[0052] The tank washing wastewater after physical and chemical treatment is subjected to biochemical treatment. Currently, the biochemical treatment can be anaerobic, aerobic, or the two processes are used in series. Since the tank washing wastewater to be treated in the present invention contains refractory organic pollutants, the present invention adopts an anaerobic and aerobic series treatment process. Improve the biodegradability of wastewater; on the other hand, the anaerobic treatment unit removes part of the COD and reduces the organic load of the subsequent aerobic treatment.
[0053] The anaerobic treatment technology of the present invention adopts AF anaerobic filter. The AF anaerobic filter is an anaerobic bioreactor filled with microbial carriers. A part of the anaerobic microorganisms attached to the filler to form an anaerobic biofilm, and the other part was suspended in the space of the filler. The AF anaerobic filter is filled with various types of solid fillers, such as slag, porcelain rings, and plastic to treat tank washing wastewater. The tank washing wastewater is kept in contact with the filler with anaerobic microorganisms during the flow process. Anaerobic microorganisms grow on the filler and have a good bond breaking effect on long-chain hydrocarbons, naphthenes and simple aromatic organics.
[0054] Advantages of AF anaerobic filter: high organic load; short hydraulic retention time, strong shock load resistance; no need for sludge return, convenient operation and management. For the present invention, on the one hand, since the pre-treatment process is air flotation treatment, the input air flotation agent has a certain inhibitory effect on microorganisms, and the anaerobic tank can act as a buffer tank for the microorganism system, reducing the impact on subsequent aerobic treatment units. On the other hand, the subsequent aerobic unit is operated intermittently, which determines that the anaerobic system cannot operate continuously, so that the anaerobic tank is left standing for a long time to produce gas, which leads to the partial loss of water when the anaerobic tank enters water. The anaerobic sludge floats, and the filler in the AF anaerobic filter can effectively overcome the shortcomings in this aspect. While improving the anaerobic treatment efficiency, it can retain part of the floating anaerobic sludge and reduce the loss of anaerobic sludge. The effective volume of the AF anaerobic tank of the present invention is 5m 3 , the residence time of the tank washing wastewater in the pool is 1 day.
[0055] Since the amount of water treated in the present invention is small, from the perspective of treatment effect and operation management, intermittent treatment has advantages. The commonly used aerobic processes mainly include: 1. Traditional activated sludge method; 2. Biological contact oxidation method; 3. Gas stripping three-phase fluidized bed; 4. PAC biological activated carbon activated sludge method; 5. SBR process. Among these processes, the SBR process is very mature, and has strong adaptability and treatment effect for the treatment of refractory wastewater, and can also meet the requirements of intermittent operation. Therefore, the SBR reaction tank is selected for aerobic treatment.
[0056] Compared with the continuous activated sludge process, the SBR reaction tank has the following advantages:
[0057] (1) The secondary sedimentation tank and sludge return equipment are not set up separately, and there are few structures to be treated, and the process flow is simplified;
[0058] (2) Strong adaptability to changes in water quality, the SBR reaction tank is a completely mixed type, and the resident wastewater in the reaction tank after drainage can fully dilute the wastewater entering the tank, which is suitable for high-concentration wastewater treatment;
[0059] (3) The SBR reaction tank is generally designed according to the complete mixing model in space, and the standard plug-flow mode in terms of time, with a large substrate concentration gradient and a fast average reaction rate. it is good;
[0060] (4) The setting of anoxic mixing in the water inlet stage plays the role of sludge selection, which can inhibit the excessive reproduction of filamentous bacteria that induce filamentous bacteria sludge bulking, and reduce the probability of sludge bulking;
[0061] (5) The treatment effect is stable. When the influent concentration increases, measures such as prolonging the aeration time or increasing the intensity can improve the treatment efficiency and ensure that the effluent quality is stable and up to standard;
[0062] (6) The aerobic, anaerobic, and anoxic appear alternately, and the functions of denitrification and phosphorus removal can be realized simultaneously in one reactor.
[0063] In order to domesticate high-efficiency biological colonies and shorten the domestication period, high-efficiency microbial strains XY1 are added in the early stage of operation.
[0064] The process of tank washing wastewater in the aerobic stage is as follows:
[0065] The tank washing wastewater is evenly overflowed from the anaerobic tank to the SBR reaction tank, without aeration during the water inflow period, to maintain the anoxic state in the tank and improve the denitrification effect of the system. After the water inflow is completed, the blower is turned on, and the wastewater is oxygenated and aerated. During the aeration period, the dissolved oxygen in the pool is kept above 2mg/L. Microorganisms perform sufficient oxidative degradation in the high dissolved oxygen state, which can well remove COD and BOD in wastewater.
[0066] The tank washing wastewater is treated once a day in the SBR reaction tank. The aeration time in the SBR reaction tank is 8 hours. The tank capacity includes the drainage volume and the tank storage volume for one day. Therefore, the effective tank capacity is 20m 3. The SBR reaction tank has a built-in high-efficiency microporous aeration head, which is connected to the blower to improve the dissolution rate and utilization rate of oxygen.
[0067] The SBR reaction tank selected in the present invention uses a single-machine PLC control system because it runs for one cycle a day; in addition, due to the subsequent advanced treatment system, the decanter is omitted, and the submersible pump is directly replaced to reduce investment. The tank washing wastewater is directly pumped into the subsequent advanced treatment system by the submersible pump and enters the advanced treatment.
[0068] 4. In-depth processing
[0069] The tank washing wastewater after the biochemical treatment is subjected to advanced treatment, and the advanced treatment of the present invention adopts the MBBR reaction tank and the ozone catalytic oxidation tank.
[0070] (1) MBBR Moving-Bed Biofilm Reactor (MBBR) is an innovative biofilm reactor that has received much attention from researchers in recent years. Compared with the activated sludge method, the operation stability of the system is improved, the organic load capacity and efficiency are improved, the head loss is small, and generally no return flow is required. It has the characteristics of high processing capacity, small footprint, compact structure and no sludge bulking. The core part of MBBR is a suspended filler with a specific gravity close to that of water, which is directly added to the aeration tank as an active carrier of microorganisms, relying on the aeration in the aeration tank and the lifting effect of the water flow, so that the carrier is in a fluidized state. It is a process that combines the activated sludge method of suspended growth and the biofilm method of attached growth.
[0071] The basic design idea of the moving bed biofilm reactor is to be able to run continuously, without clogging, without backwashing, and with less head loss. And the biological carrier has a large radiation area, which can be achieved by growing the biofilm on a smaller carrier unit, and the carrier moves freely with the water flow in the reactor. In an aerobic reactor, the carrier is moved by aeration; in anoxic and anaerobic reactors, the carrier is moved by mechanical stirring.
[0072] The present invention selects a special filler to be placed in the MBBR, the filler is a porous granular filter material, and its main components include silicon, aluminum, calcium, sodium, magnesium, titanium, manganese, iron, nickel, cobalt and molybdenum minerals and trace elements. Irregular porous light particles, thereby increasing the specific surface area of the carrier, enabling more enhanced microorganisms to be loaded on the filler, and further degrading the organic matter contained in the water, that is, to achieve the purpose of reducing COD. The effective volume of the MBBR reactor used in this method is 10m 3 , The MBBR reactor is connected with the blower, and the MBBR reactor conducts reasonable aeration through the valve according to the COD concentration of the final effluent, so as to ensure the discharge of wastewater up to the standard and reduce the operating cost.
[0073] (2) The ozone catalytic oxidation pool has two passages, one leads to the blower and the other leads to the ozone generator. The ozone catalytic oxidation tank generates strong oxidant ozone from the ozone generator, which further oxidizes the soluble organic matter that is not decomposed or extremely difficult to biochemically degrade in the MBBR reactor, and turns macromolecules into small molecules, which are easily biochemically degraded. If there is no catalyst, the consumption of ozone will be large (generally 1 gram of ozone is needed to decompose 0.8 grams of COD, which is 20 times that of the general one), the power consumption is large, the operating cost is high, and the oxidation efficiency is low. Since ozone works with general chemical fibers, metals, etc., the current domestic nano-scale TiO 2 The catalyst "thin layer" and fibers cannot be used, so that 1 gram of ozone can degrade 20 grams of COD, which opens up prospects for ozone in wastewater treatment.
[0074] Therefore, the present invention adopts nano-scale titanium dioxide to catalyze the ozone oxidation reaction. The photocatalysis of nano-scale titanium dioxide and its application are the current research hotspots at home and abroad. The use of nano-sized titanium dioxide to catalyze the ozone oxidation process has decolorized (destroyed its chromophore) and oxidative decomposition of most colored substances, which greatly improves the oxidative decomposition efficiency of ozone. Covalently bonded organics have a good oxidation effect.
[0075] The present invention mainly utilizes "anaerobic hydrolysis acidification" and nanoscale TiO to remove toxic and harmful organic substances or extremely difficult biochemically degradable organic substances in container washing wastewater. 2 Catalyze the ozone oxidation reaction, so that toxic and harmful substances are decomposed in two stages or converted from macromolecular organic matter to small molecular organic matter, and then biochemically degraded into CO 2 and H 2 O, that is, harmless treatment.
[0076] The ozone generator used in the present invention produces 50g/h of ozone, and the effective volume of the ozone catalytic oxidation tank is 10m 3. On the one hand, the ozone catalytic oxidation tank is equipped with a perforated aeration pipe to fully mix the wastewater with ozone to effectively disinfect the wastewater so that it can meet the standard of reclaimed water reuse; on the other hand, the ozone catalytic oxidation tank plays the role of a clean water storage tank , the owner can reuse the sterilized effluent water for the preliminary cleaning of the container, and the rest of the water is discharged up to the standard.
[0077] 5 Sludge treatment
[0078] The tank washing wastewater will produce a certain amount of sludge and scum during the treatment process, which requires further sludge treatment. The invention periodically collects the scum from the air flotation device and the sludge discharged from the anaerobic tank and the SBR reaction tank to the sludge thickening tank through a pump. The effective capacity of sludge thickening tank is 5m 3 , external sludge screw pump, transported to the plate and frame filter press for sludge dewatering, the supernatant is returned to the adjustment tank for secondary treatment, and the dewatered sludge is collected and disposed of in a centralized manner according to relevant regulations.
[0079] The indicators of the water quality after the treatment in the present invention meet the national "Comprehensive Discharge Standard of Wastewater" GB8978-1996 secondary discharge standard, "Tianjin Comprehensive Wastewater Discharge Standard" DB12/356-2008 secondary discharge standard, and combined with the "Urban Wastewater Recycling and Utilization" GB /T-18920-2002 Urban Miscellaneous Water Quality Standard, on the premise of ensuring that the conventional wastewater monitoring indicators meet the standard, ensure that the treated clean water can be used as the initial washing water for cleaning containers, saving water resources, which is consistent with the patent number of 200710056415.0 ratio, reducing the content of suspended solids and oils.
[0080] Comparison of the water quality index before treatment and the water quality index after treatment in the present invention
[0081] project
