Sewage treatment method and device using modified camphor wood as filler

Abstract

The present application relates to a kind of sewage treatment method and device with modified camphor wood as filler, modified camphor wood is filled as filler in filter tank, and inoculate microorganism in filter tank;Through continuous water inlet and continuous aeration, device debugging is carried out, microorganism is attached to the surface of modified camphor wood and grows and reproduces to form biofilm;Enter running process, continuous water inlet and intermittent aeration, utilize biofilm to treat sewage;Wherein, the modified camphor wood is obtained by soaking camphor wood in 1.5-2.5% sodium hydroxide solution for more than 24h.The present application uses camphor wood as production scrap in biological aerated filter, as the internal filler of upflow reactor, after biological biofilm formation, nitrogen and phosphorus elements in sewage are treated by using the effect of attached microorganism, have good sewage treatment effect, can greatly reduce the filler cost of biological aerated filter, and will not block the device.

Description

Technical Field

[0001] This invention relates to the field of water treatment, specifically to a wastewater treatment method and apparatus using modified camphor wood as filler. Background Technology

[0002] Aerated biological filters, as a relatively mature wastewater treatment technology, have gained widespread acceptance. Compared to the traditional activated sludge process, aerated biological filters offer advantages such as better effluent quality, stable operation, and smaller footprint. As the main component of an aerated biological filter, the packing material, besides filtering suspended media, also influences the growth, reproduction, and renewal of attached microorganisms, thus affecting the biological treatment effect. Therefore, the properties of the packing material have a significant impact on the filter's treatment efficiency, investment cost, operation control, and maintenance.

[0003] Biofilter fillers are mainly divided into organic fillers and inorganic fillers. Currently, artificially produced organic fillers have a very good treatment effect, but the cost is high, which limits their actual use. Common inorganic fillers include ceramsite and activated carbon. Although these fillers have a large specific surface area which is conducive to biofilm adhesion, they are relatively easy to clog, affecting fluid distribution. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a wastewater treatment method and apparatus using modified camphor wood as filler, thereby solving the technical problems of high cost of organic fillers and easy clogging of inorganic fillers in the prior art.

[0005] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows:

[0006] In a first aspect, the present invention provides a wastewater treatment method using modified camphor wood as filler, comprising the following steps: filling a filter bed with modified camphor wood as filler and inoculating the filter bed with microorganisms; adjusting the device by continuous water intake and continuous aeration to allow microorganisms to attach to the surface of the modified camphor wood and grow and reproduce to form a biofilm; entering the operation process, continuously inletting water and intermittently aerating, and using the mature biofilm to treat the wastewater; wherein, the modified camphor wood is obtained by soaking camphor wood in a 1.5-2.5% sodium hydroxide solution for more than 24 hours.

[0007] Preferably, the camphor wood is in the form of long strips with parallel grain, with a thickness of 1-5 mm, a width of 5-20 mm, and a length of 10-50 mm.

[0008] Preferably, the packing material filling rate is 20% to 30% based on the total volume of the filter bed.

[0009] Preferably, during device commissioning, the aeration rate is 50 mL / min to 300 mL / min; the influent flow rate is gradually increased to be equal to the aeration rate.

[0010] Preferably, the concentration of the influent during device commissioning is lower than the concentration of the wastewater treated during operation; during device commissioning, when the effluent ammonia nitrogen removal rate exceeds 60%, the commissioning is completed, the device is successfully started, and enters the operation process.

[0011] Preferably, during operation, the aeration rate is 50 mL / min to 500 mL / min; the aeration-to-stop ratio is 3:1.

[0012] Preferably, during operation, the dissolved oxygen is controlled at 2.5-3 mg / L during aeration and <0.8 mg / L when aeration stops.

[0013] Preferably, during operation, the influent flow rate is 160–300 mL / min, and the hydraulic retention time is 10–14 h.

[0014] Secondly, the present invention provides a wastewater treatment device using modified camphor wood as filler, comprising a wastewater tank, a reactor, and an aeration device. The wastewater tank is connected to the reactor and is used to store wastewater to be treated and supply it to the reactor. The reactor includes a filter tank, with an inlet on the lower wall and an outlet on the upper wall to form an upflow reactor. At least two perforated baffles are provided on the upper side inside the filter tank, with gaps between the baffles for filling with filler material, which is modified camphor wood. The aeration device is used to provide aeration to the filter tank.

[0015] Preferably, an inlet pump and a liquid flow meter are connected between the wastewater tank and the reactor.

[0016] Preferably, the inlet pump is a regular water pump or a peristaltic pump.

[0017] A further preferred embodiment has a pressure gauge installed at the outlet end of the inlet pump.

[0018] Preferably, the aeration device includes an aerator installed outside the filter bed and an aeration head installed at the bottom inside the filter bed. The aerator is connected to the aeration head via a gas flow meter and a hose.

[0019] In a further preferred embodiment, there are two aeration heads; the aeration heads are corundum microporous aerators.

[0020] Compared with the prior art, the beneficial effects of the present invention include:

[0021] This invention utilizes camphor wood, a byproduct of industrial processes, as internal packing material in an aerated biological filter. After biofilm formation, the attached microorganisms treat nitrogen and phosphorus in wastewater. Aerated biological filters using modified camphor wood not only achieve excellent wastewater treatment results but also significantly reduce the cost of the packing material. The camphor wood packing material itself serves as a carbon source for immobilized microorganisms. The increased porosity after modification facilitates wastewater adsorption, and the larger specific surface area promotes oxygen transfer. Its wastewater treatment effect is similar to, or even better than, activated carbon, and its sheet-like shape prevents clogging of the device. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the wastewater treatment device using modified camphor wood as filler according to the present invention;

[0023] Figure 2 This is a schematic diagram of the reactor structure in this invention;

[0024] Figure 3 This is a schematic diagram of the partition structure;

[0025] Figure 4 This is a schematic diagram of the peristaltic pump in this invention;

[0026] Figure 5 This is a top view of the reactor;

[0027] Figure 6 These are actual images of camphor wood before and after modification in Example 1 of this invention;

[0028] Figure 7 This is a graph showing the COD concentration in the effluent from Example 3;

[0029] Figure 8 This is a graph showing the ammonia nitrogen concentration in the effluent from Example 3;

[0030] Figure 9 This is a graph showing the total nitrogen concentration in the effluent from Example 3;

[0031] Figure 10 This is a graph showing the total phosphorus concentration in the effluent from Example 3;

[0032] Figure 11 This refers to the COD concentration and COD removal rate of the influent and effluent under different filling ratios in Example 4.

[0033] Figure 12 This refers to the ammonia nitrogen concentrations in the influent and effluent and the ammonia nitrogen removal rate under different filling ratios in Example 4.

[0034] Figure 13 These are the total nitrogen concentrations and total nitrogen removal rates of the influent and effluent under different filling rates in Example 4;

[0035] Figure 14 This refers to the total phosphorus concentration and total phosphorus removal rate of the influent and effluent under different filling rates in Example 4.

[0036] Figure 15 This refers to the COD concentration and COD removal rate of the influent and effluent under different aeration methods in Example 5.

[0037] Figure 16 Examples 5 show the ammonia nitrogen concentrations and removal rates of influent and effluent under different aeration methods.

[0038] Figure 17 The total nitrogen concentration and total nitrogen removal rate of the influent and effluent under different aeration methods in Example 5;

[0039] Figure 18 This refers to the total phosphorus concentration and total phosphorus removal rate of the influent and effluent under different aeration methods in Example 5.

[0040] Among them, 1-sewage tank; 2-inlet pump; 21-pressure gauge; 22-pump head; 23-pump pipe;

[0041] 3-Liquid flow meter; 4-Gas flow meter;

[0042] 5-Reactor; 51-Filter tank; 52-Baffle plate; 53-Packing material; 54-Inlet; 55-Outlet; 56-Through hole;

[0043] 6-Aerator; 7-Aeration head. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0045] This invention provides a wastewater treatment method and apparatus using modified camphor wood as filler. The method and apparatus can effectively improve the effluent quality and reduce the operation and maintenance costs of aerated biological filters.

[0046] This invention provides a wastewater treatment method using modified camphor wood as filler. The method employs alkali-modified camphor wood chips as filler and uses an upflow process to remove ammonia, nitrogen, and phosphorus. Camphor wood, as a natural organic filler, is a high-strength wood with strong adsorption capacity. After alkali modification, its porosity increases, further enhancing its adsorption capacity. Simultaneously, it can serve as a fixed carbon source for microorganisms attached to the filler surface, resulting in rapid biological renewal and ideal treatment effects. Furthermore, camphor wood chips, as a waste product from production and utilization processes, have the advantages of being readily available and inexpensive. The main steps include:

[0047] S1, Modified camphor wood is used as filler in the filter bed, and microorganisms are inoculated in the filter bed;

[0048] S2, enter the commissioning process, continuous water intake and continuous aeration, so that microorganisms attach to the surface of modified camphor wood, grow and reproduce to form a biofilm;

[0049] S3, entering the operation process, continuously feeds water and intermittently aerates to treat wastewater.

[0050] Preferably, the modified camphor wood is camphor wood that has been soaked in a 1.5-2.5% sodium hydroxide solution for more than 24 hours.

[0051] Further preferred, the modified camphor wood is camphor wood soaked in a 2% sodium hydroxide solution for 24h to 72h.

[0052] Using a 2% sodium hydroxide solution can maximize the surface area and porosity of camphor wood while maintaining high strength. This is beneficial for microbial contact and biofilm formation, maintaining a large microbial population. It also facilitates the mass transfer of oxygen and nutrients required for microbial metabolism, as well as the mass transfer of metabolic waste products. Furthermore, it effectively prevents mechanical damage and improves service life.

[0053] Preferably, the camphor wood used in this invention is in the form of long, strip-shaped pieces, which are irregularly shaped pieces following the grain (along the wood's growth direction). When stacked, gaps exist between individual pieces. The camphor wood has a thickness of 1–5 mm, a width of 5–20 mm, and a length varying from 10–50 mm. Due to the irregular length, width, and thickness of the camphor wood pieces, and their uneven surface, microorganisms can easily adhere and remain. The size of the camphor wood pieces also affects the experimental results. Fillers generally require a large specific surface area; therefore, the wood pieces should not be too large. Smaller pieces can provide more specific surface area. At the same time, if the wood pieces are too small, it can easily cause mechanical damage, disturb the quality of the effluent, and lead to problems such as short circuits in water and air distribution.

[0054] Preferably, the packing material filling rate is 20% to 30% based on the total volume of the filter bed, and most preferably 25%.

[0055] Preferably, during the commissioning process, the aeration rate is 50 mL / min to 300 mL / min; the influent flow rate is gradually increased to be equal to the aeration rate.

[0056] Preferably, the COD concentration of the influent during the commissioning process is lower than the COD concentration of the treated wastewater during operation; the effluent COD and NH3-N removal rates exceed 60% during the commissioning process before entering the operation process.

[0057] Preferably, during operation, the aeration rate is 50 mL / min to 500 mL / min; the aeration-to-stop ratio is 3:1.

[0058] Further preferred, during operation, the DO is controlled at 2.5-3 mg / L during the aeration phase and <0.8 mg / L during the shutdown phase.

[0059] Preferably, during operation, the influent flow rate is 160–300 mL / min, and the hydraulic retention time is 10–14 h.

[0060] This invention also provides a wastewater treatment device using modified camphor wood as filler, see [link to relevant documentation]. Figure 1 It includes a sewage tank 1, an inlet pump 2, a gas flow meter 4, a reactor 5, an aerator 6, and an aeration head 7; the sewage tank 1 is connected to the reactor 5 and is used to store sewage to be treated and supply it to the reactor 5.

[0061] See Figure 2 The reactor 5 includes a filter tank 51, with an inlet 54 on the lower wall and an outlet 55 on the upper wall, forming an upflow reactor.

[0062] As a preferred embodiment, necessary valves may be installed on the inlet 54 and outlet 55 as needed.

[0063] At least two baffles 52 are provided on the upper side of the inside of the filter tank 51. There is a gap between the baffles 52, and the gap is filled with filler 53, which is modified camphor wood.

[0064] See Figure 3 The baffle 52 is made of acrylic with perforations, which serves to block the packing material 53 from passing through the wastewater. The filter tank 51 is bonded with the perforated baffle to prevent the packing material 53 from overflowing. The perforated baffle is located below the outlet 55, preferably 10 cm from the top of the reactor, leaving a 10 cm fluidization space for the packing material carrier.

[0065] Aeration heads 7, preferably two, are placed at the bottom of the filter tank 51 to form a double-head aeration. The aeration heads 7 are connected to the aerator 6, which is located outside the filter tank 51. The inlet 54 is connected to the sewage tank 1 through an inlet pipe, and an inlet pump 2 is installed on the inlet pipe. The outlet 55 is connected to the collection tank through an outlet pipe.

[0066] Preferably, the inlet pump 2 is a regular water pump or a peristaltic pump, and a liquid flow meter 3 is also installed on the inlet pipe; the inlet pump 2 and the liquid flow meter 3 work together to control the inlet flow of the reactor 5.

[0067] As a preferred embodiment, see Figure 4The peristaltic pump includes a driver, a pump head 22, and a pump tube 23. Before using the peristaltic pump, turn the lever of the pump head 22 to open it, smoothly insert the hose into the pump head and straighten it, then turn the lever in the opposite direction to the horizontal position, thus installing the hose and forming the pump tube 23. The pump tube 23 is made of silicone. The inlet end of the peristaltic pump is connected to the sewage tank through the peristaltic hose. A pressure gauge 21 is installed at the outlet end of the peristaltic pump to facilitate monitoring the pump's operation. The outlet peristaltic hose is connected to the inlet of the liquid flow meter 3, and the outlet of the liquid flow meter 3 is connected to the inlet 54 at the bottom of the reactor 5. The driver drives the rotor to rotate, and there is a roller at each end of the rotor, which squeezes the liquid in the pump tube 23 to move forward peristaltively.

[0068] In a preferred embodiment, the aerator 6 is connected to a power source. The output end of the aerator 6 is connected to a gas flow meter 4 via a flexible hose. The gas flow meter 4 is connected to the aeration head 7 via the flexible hose, forming a passage to provide aeration to the reactor 5. The air intake of the device can be controlled by changing the scale of the gas flow meter 4 and the power of the aerator 6. The flexible hose connecting the aerator 6 and the aeration head 7 can either extend from the top of the reactor 5 or have a through hole 56 on the side of the reactor 5 for connecting the aerator 6.

[0069] As a preferred embodiment, see Figure 5 The two aeration heads 7 at the bottom of filter tank 51 are corundum microporous aerators. Corundum aerators are chosen because they have advantages such as simple structure, good sealing, large surface area, and good aeration and agitation. Corundum aerators do not require high air pressure because of their porous structure, which acts as ventilation holes. With sufficient air, large-volume aeration can be achieved. Furthermore, due to the material properties of corundum, they have higher stability and a longer service life under continuous aeration. However, because the pores of corundum aerators are open to the outside, scale easily forms in the pores. The rate of scale formation varies depending on the water quality. Therefore, using dual aerators promotes gas-liquid exchange and extends the service life of the aerators, preventing clogging.

[0070] The specific processing steps of the method and apparatus of the present invention are as follows:

[0071] (1) Put camphor wood chips into a nylon mesh bag, place them in a polyethylene container containing 1.5-2.5% sodium hydroxide solution for more than 24 hours, then take them out and wash them with distilled water for later use.

[0072] (2) The filter is operated in an upflow mode. A baffle is set at the upper third of the filter and filled with modified camphor wood filler. The filler filling rate is 20-30% based on the total volume of the filter.

[0073] (3) After the wastewater enters the device, the modified camphor wood filler can intercept some of the suspended media in the wastewater, and the larger porosity can also adsorb certain pollutants. After inoculation, the microorganisms attach to the surface of the modified camphor wood to grow and reproduce to form a biofilm. During this process, the microorganisms on the biofilm use the nutrients in the wastewater to remove ammonia nitrogen and phosphorus in the water. At the same time, they rely on the modified camphor wood to fix carbon, further promoting the treatment effect of the microorganisms.

[0074] (4) When a dense biofilm is formed, it indicates that the biofilm has matured. The biofilm on the surface of the modified camphor wood can form an anaerobic layer, anoxic layer, and aerobic layer. Nitrification occurs in the aerobic layer, and denitrification occurs in the anaerobic and anoxic layers. The aeration and influent are precisely controlled by a flow meter to achieve the best treatment conditions.

[0075] Currently used packing materials are either expensive and costly or prone to clogging during operation. However, this invention uses modified camphor wood as a biofilm carrier, which has the advantages of low cost and good operating performance. Microorganisms attached to the modified camphor wood use the modified camphor wood as a fixed carbon source, and the large specific surface area and porosity of the modified camphor wood chips also provide effective conditions for the growth of microorganisms.

[0076] The present invention will be further described in detail below through specific embodiments and comparative examples.

[0077] Example 1 (Investigating the effect of different types of raw materials on the packing effect)

[0078] The fillers, including camphor, paulownia, dawn redwood, poplar, pine, green paulownia, Japanese cedar, and London plane tree, were subjected to the same soaking pretreatment under the same conditions, namely soaking in 2% sodium hydroxide solution for 48 hours. Their physicochemical properties were measured, and the specific results are shown in Table 1 below.

[0079] Table 1. Different types of raw materials and fillers and their properties

[0080]

[0081] Among them: 1. Analysis of wood filler components

[0082] (1) Place the filler sample to be tested in an oven and dry it at 80°C until the sample reaches constant weight. Crush the dried sample to 100 mesh.

[0083] (2) Place 1g of sample into a 250mL Erlenmeyer flask, add 100mL of neutral detergent, and put the flask into an autoclave. Sterilize at 100℃ for one hour and then remove the flask. Wash the residue obtained by filtration with water and acetone. After washing, dry the residue in a 60℃ oven until constant weight. Record the mass as W1.

[0084] (3) Place the residue from (2) into a 250 mL Erlenmeyer flask and add 2 mol·L⁻¹ -1 Add 70 mL of hydrochloric acid to an autoclave and sterilize at 100°C for 50 minutes. Remove and filter until neutral. Wash twice with 95% ethanol, anhydrous ethanol, and acetone, respectively. Dry the residue in a 60°C oven to constant weight. Record the mass as W2.

[0085] (4) Place the residue from (3) in a 250 mL beaker, add 10 mL of cold 72% sulfuric acid, degrade at room temperature for 4 h, then add 90 mL of water and let it sit overnight. The next day, wash the residue with distilled water until pH = 6.5, dry it to constant weight, and record the mass as W3.

[0086] (5) Ash the residue in (4) in a muffle furnace at 550℃ for 4 hours, and record the mass as W4.

[0087] The calculation formula is as follows:

[0088]

[0089]

[0090]

[0091] In the formula, W is the sample mass, 1g.

[0092] The change in cellulose content is the rate of change of cellulose content in the modified filler relative to that before modification.

[0093] 2. Porosity

[0094] The wood filler sample to be tested in the experiment was placed in a drying oven and dried at 80℃ until the sample reached constant weight. A certain amount of dried sample was selected, and the dried sample was crushed to 100 mesh. A certain amount of powder was selected and measured.

[0095] The calculation formula is as follows:

[0096]

[0097]

[0098]

[0099] Where ρ is the apparent density of the filler, in g / mL;

[0100] m1 — Mass of the uncrushed sample, g;

[0101] V1 — Volume of undiluted sample, mL;

[0102] ρ' — actual density of the filler, g / mL;

[0103] m2 — Mass of the pulverized sample, in grams;

[0104] V2 — Volume of the pulverized sample, mL;

[0105] P – Porosity of the packing material, %.

[0106] 3. Strength of wooden filler (the ability of wooden filler to resist breakage under water flow impact) test method: The experiment is conducted using a shaking table to simulate water flow impact. The specific measurement steps are as follows:

[0107] Measure 40cm respectively 3 Different types of wooden packing materials were placed in 1L conical flasks, with 0.8L of deionized water added. The flasks were then placed in a constant-temperature shaker at 25℃ and shaken for 192 hours. Afterward, the packing materials were removed, washed with distilled water, and placed in a drying oven at 80℃ for constant-temperature drying and weighing. The calculation formula is shown below:

[0108]

[0109] In the formula: α—strength of the wood filler, degrees;

[0110] m — the remaining mass of the packing material after the water flow impact test, in grams;

[0111] m ’ —The mass of the packing material that has not undergone water flow impact testing, in grams.

[0112] Based on the data in Table 1 above, the preferences for wood fillers were assigned values; the relative comparison method in the relative evaluation method was used to evaluate the selection priority of wood fillers. The same parameter of each wood filler was compared pairwise. After comparison, the relatively preferred filler was recorded as "1", the other as "0", and if both were equal, both were recorded as "0". After comparing all fillers, the total scores were added together. The higher the total score, the higher the selection priority. The results are shown in Table 2 below.

[0113] Table 2. Assignment results of wood fillers

[0114]

[0115] The effect of cellulose on material properties:

[0116] The internal structure of wood-based fillers consists of cellulose, hemicellulose, and lignin linked by hydrogen bonds and various chemical bonds, forming a dense fibrous structure. Cellulose is a large polysaccharide formed by the polymerization of glucose; hemicellulose is a heterogeneous polysaccharide composed of several different types of pentose and hexose sugars, such as xylose, arabinose, and galactose; and lignin is an aromatic polymer composed of oxyphenylpropanol or its derivatives. Therefore, there are more microorganisms capable of decomposing cellulose than those capable of decomposing hemicellulose and lignin. The cellulose content and its changes can, to some extent, reflect the stable carbon release time of the wood-based fillers in water.

[0117] The effects of porosity and strength on material properties:

[0118] Packing materials with higher porosity are more conducive to the contact and attachment of microorganisms, maintaining a larger microbial population, and facilitating the mass transfer of oxygen and nutrients required for microbial metabolism as well as the mass transfer of metabolic waste products.

[0119] Stronger packing materials can effectively prevent mechanical damage, disturbance of effluent water quality, and avoid problems such as short circuits in water and air distribution.

[0120] Under normal circumstances, the density and strength of wood fillers show a negative linear correlation. This is because the higher the porosity of the wood filler, the weaker its ability to resist deformation. The larger the stress area after being impacted by water flow, the greater the impact on the wood filler, and therefore the lower its strength. However, the experimental data above shows that camphor wood, after soaking, achieves a porosity of 69.6% and a strength of 521.54 degrees. Modified camphor wood fillers exhibit better pore structure stability, possessing both high porosity and high strength simultaneously. Therefore, considering all factors, modified camphor wood is the preferred filler. Using other types of wood would result in a poorer filler effect.

[0121] Camphor wood before and after modification Figure 6 As shown, the left side is the modified camphor wood, and the right side is the unmodified camphor wood. The modified camphor wood is lighter in color and has a more uniform color.

[0122] To avoid redundancy, the microorganisms inoculated into the device of the present invention will be described here:

[0123] The biofilm was generated through inoculation. The inoculated sludge consisted of activated sludge from the aeration tank of Jiangxia Wastewater Treatment Plant (MLSS 10.5705 g / L, SV 83.1%, SVI 7.8615 g / L) and psychrophilic Bacillus (produced by Beihai Yeshengwang Biotechnology Co., Ltd.). In the following apparatus of the present invention, a mixture of 2 L of activated sludge and 0.0346 g of psychrophilic Bacillus bacterial solution was added to a 10 L filter tank.

[0124] On the first day, the water and bacterial solution in the device were replaced. On the second day, continuous aeration began at an aeration rate of 225 ml / min. Subsequently, continuous water intake was started, with the influent flow rate increased every two days, successively by 30%, 60%, and finally reaching 100% of the aeration rate. When the removal rates of COD and NH3-N in the effluent exceeded 60% and tended to stabilize, the device was considered to have started up successfully.

[0125] Example 2

[0126] A wastewater treatment method and apparatus using modified camphor wood as filler is disclosed. Modified camphor wood soaked in a 2% sodium hydroxide solution is added as filler, with a filler filling rate controlled at 25%. Laboratory-grade water is used as the influent, with a CODcr of 200-300 mg / L, ammonia nitrogen concentration of approximately 20 mg / L, total nitrogen concentration of approximately 30 mg / L, and total phosphorus concentration of approximately 3.7 mg / L. The reactor aeration-to-shutdown ratio is 3:1, the influent flow rate is 225 mL / min, and the hydraulic retention time is 12 h.

[0127] The reactor is constructed of plexiglass, 650 mm high, 140 mm inner diameter, with a volume of 10 L and an effective volume of 9.2316 L. It features top-flow water intake. A peristaltic pump draws water in from the bottom left side of the unit, filling it to 10 cm from the top, leaving space for the aerobic zone. Intermittent aeration is employed, with 90 min of aeration followed by 30 min of rest. During aeration, dissolved oxygen (DO) is controlled at 2.5–3 mg / L, and during rest, DO < 0.8 mg / L. Two aeration heads are located at the bottom of the reactor. The packing layer is 65 cm high with a 25% filling rate. Perforated baffles are used to bond the reactor together to prevent packing overflow. The bottom perforated baffle is 10 cm from the bottom of the reactor, and the top perforated baffle is 10 cm from the top, providing a 10 cm fluidization space for the packing carrier.

[0128] Comparative Example 1

[0129] The only difference from Example 2 is that untreated camphor wood is added as filler; the other steps and conditions are the same as in Example 2.

[0130] Comparative Example 2

[0131] The only difference from Example 2 is that activated carbon is added as a filler; the other steps and conditions are the same as in Example 2.

[0132] After successful biofilm formation, the effluent from Example 2 and Comparative Examples 1-2 was tested at an aeration rate of 0.05 L / min to 0.25 L / min. The results are shown in Table 3 below.

[0133] Table 3. Effluent test results of Example 2 and Comparative Examples 1-2

[0134]

[0135] Table 3 shows that, under stable operating conditions, the biological filter using modified camphor wood packing exhibits good COD removal and ammonia nitrogen removal effects, and also plays a certain role in phosphorus removal. Comparison reveals that, under the same conditions, the modified camphor wood packing provides the best COD and ammonia nitrogen treatment results, while the phosphorus treatment effect is similar to that of activated carbon. Considering all factors, natural camphor wood is low-cost, less prone to clogging, and offers better treatment results than activated carbon methods. Therefore, using modified camphor wood to treat domestic wastewater is more practical under stable conditions.

[0136] Comparative Example 3

[0137] The only difference from Example 2 is that a downflow reactor is used, i.e., the inlet is at the top and the outlet is at the bottom. The other steps and conditions are the same as in Example 2.

[0138] The results showed that the downflow reactor had insufficient load and the air and water were in countercurrent. The suspended solids were mainly concentrated in the upper part of the packing. Over time, negative head phenomenon would occur in the filter, which would cause channeling, making it easy to clog and resulting in a short operating cycle.

[0139] Therefore, the present invention preferably uses an upflow reactor, in which air and water flow in the same direction, which can promote uniform air and water distribution; at the same time, by using an upflow reactor, suspended solids trapped at the bottom can be carried into the upper part of the filter bed during the rising of air bubbles, thereby increasing the dirt holding capacity of the packing material.

[0140] Example 3 (Investigating the effect of wastewater concentration)

[0141] The only difference from Example 2 is that, after ten days of normal operation of the reactor, the low-concentration wastewater (influent during commissioning) in Example 2 was replaced with normal-concentration domestic wastewater (influent during operation), as shown in Table 4 below; the other steps and conditions are the same as in Example 2, and the effluent results are as follows. Figures 7-10 As shown.

[0142] The following control group was also set up in this embodiment:

[0143] R1 uses camphor wood filler;

[0144] R2 uses modified camphor wood filler;

[0145] R3 uses activated carbon filler.

[0146] Table 4 Different Influent Indicators

[0147]

[0148]

[0149] Depend on Figures 7-10 It can be seen that the COD concentration fluctuated significantly on the tenth day because, starting on the tenth day, the influent to the reactor was changed from low-concentration sewage to normal-concentration domestic sewage (from the commissioning process to the operation process). The number of microorganisms in the reactor was insufficient to completely remove the COD in the influent. After a period of time, the number of microorganisms in the reactor increased, and around the 12th day, the COD concentration in the effluent decreased significantly. Subsequently, it gradually stabilized and eventually returned to the value before the influent was changed. As shown in the figure, the present invention has a good sewage treatment effect, especially in the removal of COD and total nitrogen.

[0150] Example 4 (Investigating the effect of filler filling ratio)

[0151] The only difference from Example 2 is that the filling rate of the packing material was changed to 0% (to investigate the effect of microorganisms on wastewater treatment without packing material, serving as a blank control), 10%, and 30%. All other steps and conditions were the same as in Example 2, and the test results are as follows: Figures 11-14 As shown.

[0152] The results showed that when the filling rate was 0 (i.e., no wood filler was added to the device as a blank control), it reflected the microbial treatment capacity of the microorganisms in the absence of a carrier. As shown in the figure, the microorganisms in the control group had difficulty forming a dense and stable biofilm due to the lack of a carrier for adsorption and growth, resulting in a poor overall treatment effect. This highlights the role of the wood filler carrier in the biological filter of the present invention. In the present invention, modified camphor wood is used as the filler, and the optimal filling rate is between 10% and 30%. According to Example 2, the nitrate nitrogen removal rate of intermittent aeration with a filling ratio of 25% was measured to be 94.27% after 50 days of device startup. As a carbon source for denitrification, its filling ratio is sufficient, so the optimal filling rate is 25%.

[0153] Example 5 (Investigating the impact of operating conditions)

[0154] The only difference from Example 2 is that the influent flow rate and aeration conditions are adjusted; the other steps and conditions are the same as in Example 2.

[0155] The influent flow rate reflects the different initial substrate concentrations of the device. The results showed that, under the same aeration time, the larger the influent flow rate, the worse the effluent quality. This is because a large amount of influent does not come into contact with the microorganisms in the packing material and flows out directly with the effluent, resulting in a poorer treatment effect. However, the influent flow rate is not necessarily better if it is too small. An excessively small influent flow rate will greatly increase the sewage treatment time and reduce the treatment efficiency.

[0156] The difference between no aeration and intermittent aeration is as follows: Figures 15-18As shown, intermittent aeration is significantly more effective than non-aeration in treating wastewater. Without aeration, anaerobic conditions exist, nitrifying bacteria are hypoxic and their activity is inhibited, hindering nitrification. Meanwhile, denitrifying bacteria are active, and organic matter is primarily degraded by them, resulting in effluent ammonia nitrogen concentrations higher than influent concentrations. Considering both treatment effect and treatment time, this method, through comprehensive cross-fertilization experiments with different aeration methods and filling ratios, determined that the optimal operating conditions for the device are an aeration rate of 250 mL / min to 500 mL / min, an influent flow rate of 225 mL / min, an aeration-to-stop ratio of 3:1, and a hydraulic retention time of 12 h. Under these conditions, the device achieves the best treatment effect.

[0157] Example 6 (Investigating the effect of camphor wood soaking time)

[0158] The only difference from Example 2 is that the soaking time of the camphor wood is adjusted; the other steps and conditions are the same as in Example 2.

[0159] The results showed that within 24 hours of soaking, the lignin release from camphor wood chips accounted for 60% of the total experimental release; the release rate reached 90% after 48 hours of soaking; and exceeded 99% after 32 days. Considering both the treatment effect and the treatment time, a soaking time of 48 hours was ultimately selected as the optimal treatment time.

[0160] In summary, the filler used in this invention is modified camphor wood that has been soaked in a 2% sodium hydroxide solution for 48 hours. Compared with the unmodified camphor wood, it has advantages such as high porosity and strong adsorption capacity, further enhancing the advantages of camphor wood as a filler. At the same time, the camphor wood chips are scraps generated in actual production, which are widely available and low in cost. Recycling them as waste helps reduce investment and operating costs and promotes the effective use of resources.

[0161] This invention utilizes camphor wood, a byproduct of industrial processes, as internal packing material in an aerated biological filter. The packing ratio is controlled at 25%, and liquid and gas flow meters are used to precisely control the influent flow and aeration rate to achieve optimal treatment results. After biofilm formation, the modified camphor wood utilizes attached microorganisms to treat nitrogen and phosphorus in wastewater. Aerated biological filters using modified camphor wood as packing material not only exhibit excellent wastewater treatment performance but also significantly reduce the cost of packing material. The camphor wood packing material itself can serve as a carbon source for immobilized microorganisms; the increased porosity after modification facilitates wastewater adsorption, and the larger specific surface area promotes oxygen transfer.

[0162] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for treating sewage using modified camphor wood as filler, characterized by, The method comprises the following steps: The modified camphor wood is filled in the filter tank as filler, and microorganisms are inoculated in the filter tank; The device is debugged by continuous water feeding and continuous aeration, so that the microorganisms adhere to the surface of the modified camphor wood and grow and reproduce to form a biofilm; In the running process, continuous water feeding and intermittent aeration are carried out, and the biofilm is used to treat sewage; The modified camphor wood is obtained by immersing camphor wood in a 1.5-2.5% sodium hydroxide solution for more than 24 hours; The camphor wood is in the shape of a long strip with a smooth grain, with a thickness of 1-5 mm, a width of 5-20 mm, and a length of 10-50 mm; The filling rate of the filler is 20-30% based on the total volume of the filter tank; In the device debugging, the aeration rate is 50-300 mL / min; the water feeding flow rate is gradually increased to be equal to the aeration rate; In the device debugging, the concentration of the water feeding is lower than the concentration of the sewage treated in the running process; when the ammonia nitrogen removal rate of the effluent exceeds 60% in the device debugging, the debugging is ended, and the running process is entered.

2. The method of sewage treatment with modified camphor wood as filler according to claim 1, characterized in that, In the running process, the aeration rate is 50-500 mL / min; and the aeration-off ratio is 3:

1.

3. The method of treating sewage with modified camphor wood as claimed in claim 2, wherein, In the running process, the dissolved oxygen is controlled to be 2.5-3 mg / L during aeration, and the dissolved oxygen is less than 0.8 mg / L during the aeration-off period.

4. The method of treating sewage with modified camphor wood as claimed in claim 1, wherein, In the running process, the water feeding flow rate is 160-300 mL / min; and the hydraulic retention time is 10-14 h.

Images