A method for preparing a biofilm packing using waste sludge

Abstract

The present invention discloses a method for preparing a biofilm filler using waste sludge, belonging to the field of water treatment. The raw materials for preparing the filler, by weight percentage, are specifically: 60% - 70% of a polymer matrix, 10% - 35% of excess sludge, and 5% - 10% of Fenton iron sludge. The preparation method is as follows: collect the excess sludge and Fenton iron sludge after dehydration in the sewage treatment process, dry and crush them, and then sieve them for standby. Mix the polymer matrix and the sieved dry sludge in a certain proportion and add them into a twin-screw extruder, and extrude and form through a filler mold. The biofilm filler has a rough surface and good biocompatibility, which is beneficial to the growth of microbial biofilm attachment; the filler preparation method is simple and low-cost, effectively realizing the resource utilization of waste, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the field of water treatment, and particularly relates to a method for preparing a biofilm filler using waste sludge. Background Art

[0002] In recent years, with the increase in the treatment volume of urban sewage and industrial wastewater, the amount of waste sludge generated during the treatment process has also been increasing year by year, and the problem of waste sludge disposal has become increasingly prominent. Waste sludge not only includes the excess sludge generated during the biochemical treatment process, but also includes the Fenton iron sludge generated during the advanced oxidation treatment process. Waste sludge has a complex composition, containing rich organic matter and nitrogen, phosphorus nutrient elements, as well as trace elements such as iron, calcium, magnesium, sulfur, copper, manganese, boron, and platinum. In addition, there are also toxic and harmful substances such as heavy metals, pathogenic bacteria, and pathogenic microorganisms. Therefore, if waste sludge is not effectively disposed of and rationally utilized, it will not only pose a serious threat to the ecological environment, but also cause waste of the available resources in the waste sludge.

[0003] Traditional sludge disposal methods include sanitary landfill, incineration, land use, etc., but the above methods still pose a risk of re-polluting the surrounding soil, air, and groundwater. Currently, new processes for waste sludge disposal and resource utilization include making building materials (such as bio-bricks, cement, ceramsite), generating energy (such as producing biogas, hydrogen, oil), preparing catalysts, etc., but the above new processes often have problems such as high costs and imperfect technologies.

[0004] As the core part of the biological membrane method for sewage treatment, the filler directly affects the sewage treatment effect, investment cost, and operating cost. Currently, fillers made of high molecular polymers are commonly used in the biological membrane method. The main advantages of such fillers are stable chemical properties, long-term repeatable use, a filler density close to that of water, and relatively low kinetic energy required for fluidization. However, they also have the disadvantages of relatively high costs, a smooth filler surface, and a slow microbial film formation rate.

[0005] Chinese Patent with Application No. 201910629318.9 discloses a water treatment filler and its preparation method, including an embedding carrier and embedding content. The embedding carrier includes: 20 - 30 parts of montmorillonite, 90 - 110 parts of waste incineration fly ash, 15 - 25 parts of carbon fiber bundles, 3 - 5 parts of gelatin, 5 - 8 parts of modified chitosan, 20 - 30 parts of agricultural and forestry waste. The embedding content includes: 58 parts of vitamin E, 7 - 9 parts of lysine, 3 - 5 parts of 6-benzyladenine, 15 - 18 parts of iron, 15 - 17 parts of zinc, 5 - 8 parts of manganese, 6 - 7 parts of cobalt, 20 - 30 parts of glucose. Anaerobic fermentation is carried out on the agricultural and forestry waste to obtain a fermentation product. The raw materials of the embedding carrier are added to the fermentation product for roasting to obtain the embedding carrier, and the embedding carrier and the embedding content are coated to obtain the water treatment filler. During the implementation of this invention, the COD removal rate is 50% - 99%, NH4 +The removal rate of -N is 70%-99%, and the removal rate of TP is 61%-69%. Although the addition of embedded contents (such as vitamin E, lysine, 6-benzyladenine, iron, zinc, glucose, etc.) in the filler preparation method proposed by this invention can play a certain promoting role in the removal of water pollutants, it will greatly increase the filler production cost and is not suitable for large-scale production.

[0006] Chinese Patent No. 201110257488.2 discloses a filler for sewage treatment, and the weight parts of its components are: 100 parts of polyether polyol, 44.7 parts of toluene diisocyanate, 0.1-0.6 parts of triethylenediamine, 0.8 parts of silicone surfactant, 3.3 parts of distilled water, 0.06-0.14 parts of stannous octoate, and 20-40 parts of carbon source loading materials. During the implementation of this invention, the nitrate nitrogen removal rate is 21%-47%, and the static carbon source release amount of the filler is 6.8%-43.8% of the total carbon source amount. The purpose of this invention is to solve the problem of insufficient carbon source in sewage treatment plants by adding carbon source to polyurethane foam. However, the toluene diisocyanate added during the preparation process of this filler has certain toxicity and may have an adverse impact on the growth of activated sludge film formation. From the current status of water treatment, combining filler production with the resource utilization of waste sludge, improving the film formation speed of the filler by adding waste sludge, reducing the filler production cost, and at the same time making reasonable resource utilization of the waste sludge have broad market prospects. Summary of the Invention

[0007] In view of the above background technology, the purpose of this invention is to provide a method for preparing a biofilm filler using waste sludge.

[0008] To achieve the above purpose, the technical solution proposed by this invention is: a method for preparing a biofilm filler using waste sludge, which is characterized in that during the production of a filler with a polymer matrix, different ratios of excess sludge and Fenton iron sludge are added to increase the surface roughness of the filler, improve the compatibility between the filler and microorganisms, promote the growth of microbial film formation, and at the same time reduce the filler production cost. The specific steps are as follows:

[0009] (1) Collect the dehydrated waste sludge in the sewage treatment process. The water content of the waste sludge is 75%-85%. Bake the waste sludge at 120°C - 210°C for 2 - 4 hours to make it into dry sludge.

[0010] (2) Crush the dry sludge with a crusher, and sieve it through a 50 - 100 mesh sieve for standby.

[0011] (3) Uniformly mix 60%-70% of the polymer matrix by weight, 10%-35% of the sieved excess sludge, and 5%-10% of the sieved Fenton iron sludge to obtain a mixture.

[0012] (4) Add the above mixture into a twin-screw extruder and extrude it through a stuffing die.

[0013] Preferably, the waste sludge is excess sludge and Fenton iron sludge.

[0014] Preferably, the polymer matrix is any one or a mixture of polyethylene, polypropylene, polyvinyl chloride, chlorinated polyvinyl chloride, and polyvinylidene fluoride.

[0015] In the above method, the temperatures of each zone of the twin-screw extruder are 170 - 180 °C, 180 - 190 °C, 190 - 210 °C, 170 - 185 °C, the screw speed is 200 - 600 rpm, and the extrusion cooling temperature is 35 - 50 °C.

[0016] Advantages of the present invention:

[0017] (1) The excess sludge and Fenton iron sludge used are inevitable products in the sewage treatment process and are easily obtained in large quantities. By adding the dried and ground waste sludge during the stuffing production process, not only the stuffing preparation cost is reduced, but also the "treatment of waste with waste" effectively realizes the resource utilization of waste.

[0018] (2) The method and materials for preparing the biofilm stuffing in the present invention are simple, and there is no need to add excessive substances to the stuffing production process. The carbon, nitrogen, and phosphorus of the waste sludge itself are utilized, especially the Fenton iron sludge can provide trace elements such as iron and small amounts of aluminum, manganese, silicon, and cobalt necessary for the growth of microorganisms, thereby promoting the growth of microbial biofilms on the surface of the stuffing.

[0019] (3) Adding the dried and ground waste sludge during the stuffing preparation process makes the surface of the stuffing rough, which is beneficial for the attachment of microorganisms. At the same time, since the stuffing composition contains biomass itself, the biocompatibility between the stuffing and the activated sludge is enhanced. Detailed implementation mode

[0020] The present invention will be further described below in conjunction with specific embodiments.

[0021] Example 1

[0022] (1) Collect the excess sludge and Fenton iron sludge after dehydration in a coking wastewater treatment process. The moisture contents of the excess sludge and Fenton iron sludge are 83% and 85% respectively, and dry the excess sludge and Fenton iron sludge at 150 °C for 3 h to form dry sludge.

[0023] (2) Crush the dry sludge with a crusher and pass it through a 60-mesh sieve.

[0024] (3) Uniformly mix 35% polyethylene, 30% polyvinyl chloride, 25% of the sieved excess sludge, and 10% of the sieved Fenton iron sludge by weight to obtain a mixture.

[0025] (4) The mixture is added into a twin-screw extruder and extruded through a filling die to form the mixture.

[0026] In order to verify the above filler biofilm formation and sewage treatment effects, the following experiments were conducted:

[0027] The experiment was conducted in a cylindrical reactor with an effective volume of 5L and a filler filling rate of 40%. The inoculated sludge was taken from the secondary sedimentation tank of the municipal sewage treatment plant. The inoculated sludge and filler were added to the reactor, and simulated wastewater was added for aeration. After 24 hours, aeration was stopped, and the reactor was allowed to settle. The supernatant was discharged and fresh simulated wastewater was injected for aeration. When the COD and ammonia nitrogen removal rates were greater than 50%, the reactor was considered to be successfully started and switched to continuous water inlet. The simulated wastewater COD concentration was 230mg / L, NH4 + -N concentration is 20mg / L, TP concentration is 2mg / L. Observe the biofilm formation time of the reactor and monitor the effluent COD and NH4 + -N and TP concentrations. The specific results are shown in Table 1.

[0028] Table 1 Sewage treatment effect of the filler prepared in Example 1

[0029]

[0030] Example 2

[0031] (1) The residual sludge and Fenton iron mud after dehydration in a printing and dyeing wastewater treatment process were collected. The moisture contents of the residual sludge and Fenton iron mud were 85% and 75%, respectively. The residual sludge and Fenton iron mud were dried at 200° C. for 2 h to form dry sludge.

[0032] (2) Crush the dry sludge with a crusher and pass it through a 100-mesh sieve.

[0033] (3) 10% by weight of polypropylene, 30% by weight of polyethylene, 30% by weight of polyvinylidene fluoride, 25% by weight of sieved residual sludge, and 5% by weight of sieved Fenton iron mud are uniformly mixed to obtain a mixture.

[0034] (4) The mixture is added into a twin-screw extruder and extruded through a filling die to form the mixture.

[0035] In order to verify the above filler biofilm formation and sewage treatment effects, the following experiments were conducted:

[0036] The experiment was carried out in a cylindrical reactor with an effective volume of 7 L. The packing filling rate was 60%. The inoculated sludge was taken from the denitrification tank of a municipal sewage treatment plant. The inoculated sludge and the packing were added to the reactor, and at the same time, simulated wastewater was added for stirring. After 12 h, the stirring was stopped, and the mixture was allowed to settle statically. The supernatant was removed, and then fresh simulated wastewater was injected for stirring. When the denitrification rate reached stability, it was considered that the reactor was successfully started, and the influent was changed to continuous flow. The COD concentration of the simulated wastewater was 150 mg / L, and the NO3 - -N concentration was 30 mg / L. The film formation time of the reactor was observed, and the effluent COD and NO3 - -N concentrations were monitored. The specific results are shown in Table 2.

[0037] Table 2 Sewage treatment effect of the packing prepared in Example 2

[0038]

[0039] Comparative Example 1 (without adding Fenton iron sludge)

[0040] (1) The dewatered excess sludge in a certain coking wastewater treatment process was collected. The water content of the excess sludge was 83%. The excess sludge was dried at 150 °C for 3 h to form dry sludge.

[0041] (2) The dry sludge was crushed by a crusher and then passed through a 60-mesh sieve.

[0042] (3) 35% polyethylene, 30% polyvinyl chloride, and 35% of the sieved excess sludge were uniformly mixed by weight to obtain a mixture.

[0043] (4) The above mixture was added to a twin-screw extruder and extruded through a packing die to form a shape.

[0044] In order to verify the film formation and sewage treatment effect of the above packing, an experiment was carried out. The experimental setup was the same as that in Example 1. The film formation time of the reactor was observed, and the effluent COD, NH4 + -N, and TP concentrations were monitored. The specific results are shown in Table 3.

[0045] Table 3 Sewage treatment effect of the packing prepared in Comparative Example 1

[0046]

[0047] In summary, the method for preparing a biofilm filler using waste sludge provided by the present invention has the advantages of simple production process and low production cost. Through "treating waste with waste", the resource utilization of waste is effectively realized. From the specific implementation results, the biofilm filler prepared by the present invention can effectively remove COD, nitrogen, and phosphorus in water, and the reactor startup time is short, less than 5 days. From the perspective of the filler production cost and application effect, the method for preparing a biofilm filler using waste sludge provided by the present invention has high engineering practical value.

[0048] The present invention is not limited to the above embodiments. Based on the technical solutions disclosed by the present invention, those skilled in the art can make some substitutions and deformations to some technical features without creative labor according to the disclosed technical content, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A preparation method of a biofilm filler, which is implemented based on a biofilm filler prepared using waste sludge, is characterized in that, The biofilm filler prepared from the waste sludge comprises the following raw materials by weight percentage: 60%-70% of a high molecular polymer matrix, 10%-35% of residual sludge, and 5%-10% of Fenton iron sludge; the residual sludge is the dehydrated residual sludge in the sewage treatment process; the high molecular polymer matrix is one or a mixture of more of polyethylene, polypropylene, polyvinyl chloride, chlorinated polyvinyl chloride, and polyvinylidene fluoride; It includes the following steps: Step 1: Collect the dehydrated residual sludge and Fenton iron sludge in the sewage treatment process. The water contents of the residual sludge and Fenton iron sludge are both 75%-85%. Bake the residual sludge and Fenton iron sludge at 120°C-210°C for 2-4 hours to make them into dry sludge; Step 2: Crush the above dry sludge with a crusher, and sieve it through a 50-100 mesh sieve for standby; Step 3: Uniformly mix 60%-70% of the high molecular polymer matrix, 10%-35% of the sieved residual sludge, and 5%-10% of the sieved Fenton iron sludge to obtain a mixture; Step 4: Add the above mixture into a twin-screw extruder and extrude it through a filler die to form a shape.

2. The preparation method of the biofilm packing according to claim 1, characterized in that, The temperatures of each area of the twin-screw extruder are 170-180°C, 180-190°C, 190-210°C, 170-185°C, the screw speed is 200-600 rpm, and the extrusion cooling temperature is 35-50°C.

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