CN111939866B - Method for efficiently treating household garbage leachate and preparing modified aluminum-iron-based adsorbent - Google Patents

Abstract

The invention discloses a method for efficiently treating domestic garbage leachate and preparing a modified aluminum-iron-based adsorbent, which comprises the following steps: weighing aluminum ash and waste scrap iron, mixing and mechanically grinding to obtain activated aluminum-iron mixed powder; respectively weighing hydrochloric acid aqueous solution and activated aluminum iron mixed powder, and mixing and stirring to obtain iron chloride aluminum mixed slurry; respectively measuring domestic garbage leachate and aluminum ferric chloride mixed slurry, mixing and stirring, carrying out low-temperature plasma irradiation, and carrying out solid-liquid separation to respectively obtain a domestic garbage leachate purified solution and polyaluminum ferric chloride slurry; and drying the polyaluminum ferric chloride slurry, grinding to obtain polyaluminum ferric chloride powder, sintering the polyaluminum ferric chloride powder, and cooling to normal temperature to obtain the modified aluminum ferric-based adsorbent. The invention not only purifies the domestic garbage leachate, but also realizes the modification of the ferric aluminum oxide. The method can remove the highest 98 percent of COD, 99 percent of ammonia nitrogen, 99 percent of total phosphorus and 99 percent of lead in the landfill leachate, and the maximum specific surface area of the obtained iron aluminum oxide adsorbent can be 478m ² /g。

Description

A method for efficiently disposing domestic waste leachate and preparing modified aluminum-iron-based adsorbent method

technical field

The invention relates to the field of harmless disposal and resource utilization of hazardous waste, in particular to a method for efficiently disposing of household garbage leachate and preparing a modified aluminum-iron-based adsorbent.

Background technique

Landfill leachate is a highly polluted liquid produced by rainwater scouring and microbial anaerobic action during the domestic waste landfill process. Leachate from landfills accounts for 15%-30% of the total from all sources. If landfill leachate is discharged randomly without reasonable disposal, it will cause serious pollution to the surrounding soil, water (including surface water and groundwater) and the atmospheric environment around the discharge area. The pollutant components in landfill leachate are complex and the concentration is quite high.

Generally speaking, landfill leachate mainly has the following characteristics: complex types of pollutants and high concentration, large changes in water volume and water quality, high content of ammonia nitrogen, presence of heavy metal pollutants, and strong odor. If the landfill leachate is directly discharged into the urban sewage treatment system, it will not only seriously increase the load on the system, but also bring a large amount of non-degradable and toxic pollutants into the activated sludge, resulting in deactivation and poisoning of the activated sludge. The development of appropriate landfill leachate disposal technology has become a hot topic in current environmental governance. At present, domestic and foreign landfill leachate treatment methods mainly include filtration, evaporation, membrane separation, coagulation and precipitation, and advanced oxidation. However, these methods have problems such as long purification process, low leachate purification efficiency, large output of secondary solid-liquid hazardous waste, and difficult disposal of secondary solid-liquid hazardous waste.

Therefore, the key to solving the current landfill leachate disposal problem is to develop a simple process, which can realize efficient purification of landfill leachate, and resource utilization of secondary waste generated in the process of leachate disposal.

Contents of the invention

Purpose of the invention: The technical problem to be solved by the present invention is to provide a method for efficiently disposing of domestic waste leachate and preparing a modified aluminum-iron-based adsorbent. The present invention combines the disposal process of domestic garbage leachate and the preparation process of the modified aluminum-iron adsorbent into one, which not only purifies the domestic garbage leachate but also realizes the modification of alumina iron. The surface area can be up to 478 m ² /g.

The technical problem to be solved by the present invention is to provide a modified aluminum-iron-based adsorbent with high specific surface area.

Technical solution: In order to solve the above technical problems, the present invention provides a method for efficiently disposing of domestic waste leachate and preparing a modified aluminum-iron-based adsorbent, including the following steps:

1) Weighing aluminum ash and scrap iron chips respectively, mixing them, and mechanically grinding them for 2 to 6 hours to obtain activated aluminum-iron mixed powder;

2) Weigh the hydrochloric acid aqueous solution and the activated aluminum-iron mixed powder respectively, mix them, and stir for 6 to 24 hours to obtain the aluminum-iron chloride mixed slurry;

3) Measure the mixed slurry of domestic waste leachate and aluminum ferric chloride, mix, stir and irradiate with low-temperature plasma for 3 to 12 hours, centrifuge, and separate solid and liquid to obtain domestic waste leachate purification liquid and polyaluminum ferric chloride respectively pulp;

4) Dry the polyaluminum chloride iron slurry at 50-150°C, grind it to obtain polyaluminum chloride iron powder, sinter the polyaluminum chloride iron powder for 3-9 hours, cool to room temperature, and obtain modified aluminum Iron-based sorbent.

Wherein, the mass ratio of aluminum ash to scrap iron chips in the step 1) is 2-4:1.

Wherein, the concentration of the hydrochloric acid aqueous solution in the step 2) is 2-6M.

Wherein, the liquid-solid ratio of the hydrochloric acid aqueous solution and the activated aluminum-iron mixed powder in the step 2) is 10-30:1 mL/g.

Wherein, in the step 3), the volume ratio of the domestic garbage leachate and the mixed slurry of aluminum ferric chloride is 1-3:1.

Wherein, the low-temperature plasma action voltage in the step 3) is 10-50 kV, and the low-temperature plasma action atmosphere is oxygen.

Wherein, the sintering temperature in the step 4) is 300-600°C.

The content of the present invention also includes the modified aluminum-iron-based adsorbent prepared by the method.

The reaction mechanism of the present invention: after mixing aluminum ash and scrap iron chips, due to the difference in particle size distribution, the aluminum ash and scrap iron chips collide and squeeze each other during the grinding process, which will generate strong collision force and shear force , resulting in smaller particle size and larger specific surface area. The hydrochloric acid aqueous solution is mixed with the activated aluminum-iron mixed powder. During the stirring process, the aluminum ash and scrap iron chips are gradually dissolved into the liquid with the continuous consumption of hydrogen ions to generate aluminum ions and iron ions. After mixing domestic waste leachate with aluminum ferric chloride, the aluminum ions and iron ions introduced into the mixture can reduce the zeta potential of the colloids in the landfill leachate, and induce the colloids in the leachate to form alum flowers to achieve settlement. During low-temperature plasma irradiation, oxygen in the atmosphere dissociates and ionizes in the discharge channel to generate oxygen free radicals. Oxygen free radicals can convert part of ammonia nitrogen in landfill leachate into nitrogen and nitrate, and can also decompose and mineralize some organic pollutants in landfill leachate through oxidation. Oxygen free radicals can also combine with hydrogen ions to form hydrogen peroxide. Oxygen radicals can also oxidize chloride ions to chlorine gas and hypochlorous acid. Hydrogen peroxide, chlorine and hypochlorous acid can further enhance the decomposition of organic pollutants. At the same time, oxygen free radicals can induce the hydrolysis and polymerization of aluminum and iron in the aluminum chloride-ferric mixed slurry to form a polymerized aluminum-iron coagulant. The polymeric aluminum-iron coagulant can further adsorb the pollutants in the landfill leachate through the adsorption bridging effect and the net capture effect, so as to realize the purification of the landfill leachate. During the sintering process, the polyaluminum iron chloride powder oxidizes and decomposes to produce alumina iron powder. At the same time, the organic matter adsorbed in the polyaluminum chloride iron powder is oxidized and decomposed under high temperature environment to produce carbon dioxide gas. Carbon dioxide gas is quickly released from the alumina iron powder, thereby further increasing the specific surface area of the alumina iron powder. Elements such as phosphorus, nitrogen, and heavy metals adsorbed on the polyaluminum iron chloride powder are rapidly oxidized and fused into the alumina iron powder during the oxidative decomposition process of the polyaluminum iron iron powder, thereby realizing the surface modification of the alumina iron, increasing the Its surface adsorbs active sites.

Beneficial effect: compared with prior art, the remarkable advantage of the present invention is:

(1) The present invention combines the disposal process of domestic waste leachate and the preparation process of modified aluminum-iron adsorbent, which not only purifies the domestic waste leachate but also realizes the modification of alumina iron. The invention can realize the removal of up to 98% COD, 99% ammonia nitrogen, 99% total phosphorus and 99% lead in landfill leachate, and the specific surface area of the obtained alumina-iron adsorbent can be up to 478m ² /g, and the alumina-iron adsorbent is relatively The removal rate of heavy metal pollutants is much higher than commercial alumina and iron oxide.

(2) The disposal and preparation process of the present invention is simple, the disposal and preparation process is easy to realize, and the sources of required raw materials are extensive.

Description of drawings

Fig. 1 is a flow chart of the present invention;

Fig. 2 is a diagram of a low-temperature plasma action device.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

It should be noted that the landfill leachate of the present invention is taken from the Qinglongshan sanitary landfill of domestic waste in Lianyungang City. The mass concentration of COD in the landfill leachate is 1456 mg/L, the concentration of ammonia nitrogen is 945 mg/L, the total phosphorus is 198 mg/L, and the lead ion (Pb ²⁺ ) is 14 mg/L.

Aluminum ash was obtained from Gongyi Beiguanzhuang Hengtong High Temperature Furnace Material Factory, mainly containing 24.43% Al, 60.34% Al ₂ O ₃ , 6.51% SiO ₂ , 3.36% Na ₂ O, 2.32% MgO, 1.68% CaO, 1.36% MnO .

Iron scrap was obtained from Guangzhou Hongda Scrap Metal Recycling Company, mainly including 43.34% Fe, 36.38% Fe ₂ O ₃ , 4.28% SiO ₂ , 3.64% P2O5, 2.36% CaO.

Example 1 Effect of the mass ratio of aluminum ash and scrap iron on the purification of landfill leachate and the specific surface area of modified aluminum-iron adsorbent

According to the mass ratio of aluminum ash to scrap iron chips 1:1, 1.5:1, 1.8:1, 2:1, 3:1, 4:1, 4.5:1, 5:1, 6:1, weigh aluminum ash and Iron scraps were mixed and mechanically ground for 2 hours to obtain nine groups of activated aluminum-iron mixed powders. Mix water and hydrochloric acid and stir evenly to prepare an aqueous hydrochloric acid solution, wherein the concentration of the aqueous hydrochloric acid solution is 2M. Weigh the hydrochloric acid aqueous solution and the activated aluminum-iron mixed powder according to the liquid-solid ratio of hydrochloric acid aqueous solution and activated aluminum-iron mixed powder 10:1mL/g, mix and stir for 6 hours to obtain nine groups of aluminum-iron chloride mixed slurry. According to the volume ratio of domestic waste leachate and aluminum ferric chloride mixed slurry 1:1, measure the domestic waste leachate and aluminum ferric chloride mixed slurry respectively, mix, stir and perform low-temperature plasma irradiation for 3 hours, centrifuge, and separate solid and liquid Nine groups of domestic waste leachate purification liquid and nine groups of polyaluminum chloride ferric slurry were obtained, wherein the low-temperature plasma action voltage was 10kV, and the low-temperature plasma action atmosphere was oxygen. Dry and grind the nine groups of polyaluminum ferric chloride slurry at 50°C to obtain nine groups of polyaluminum ferric chloride powder. Nine groups of polyaluminium-iron chloride powders were sintered for 3 hours and cooled to room temperature to obtain nine groups of modified aluminum-iron adsorbents, wherein the sintering temperature was 300°C.

Detection of COD concentration and calculation of COD removal rate: The concentration of COD in landfill leachate is determined according to the national standard "Dichromate Method for Determination of Chemical Oxygen Demand in Water Quality" (GB 11914-1989); COD removal rate Calculated according to formula (1), where R _COD is the COD removal rate, c _Q and c _t are the COD concentrations (mg/L) of landfill leachate before and after treatment, respectively.

Detection of ammonia nitrogen concentration and calculation of ammonia nitrogen removal rate: the concentration of ammonia nitrogen in landfill leachate is measured according to "Determination of Ammonia Nitrogen in Water Quality by Salicylic Acid Spectrophotometry"(HJ536-2009); the removal rate of ammonia nitrogen is calculated according to formula (2), where R _N is the removal rate of ammonia nitrogen, c _N0 is the initial concentration of ammonia nitrogen in the landfill leachate before treatment (mg/L), and c _Nt is the residual concentration of ammonia nitrogen in the landfill leachate after treatment (mg/L).

Detection of total phosphorus concentration and calculation of total phosphorus removal rate: the concentration of total phosphorus in landfill leachate is determined according to "Determination of total phosphorus in water quality"(GB1893-89); the removal rate of total phosphorus is calculated according to formula (3), where R _p is the removal rate of total phosphorus, c _p0 is the initial concentration of total phosphorus in the landfill leachate before treatment (mg/L), and c _pt is the residual concentration of total phosphorus in the landfill leachate after treatment (mg/L).

Detection of lead ion concentration and calculation of removal rate: The concentration of lead ion in landfill leachate was determined according to "Determination of 32 Elements in Water Quality by Inductively Coupled Plasma Emission Spectrometry" (HJ 776-2015). The lead ion removal rate is calculated according to formula (4), where _Rpb is the lead ion removal rate, c _Pb0 is the initial lead ion concentration (mg/L) in the landfill leachate before treatment, and c _Pbt is the lead ion concentration in the landfill leachate after treatment. Lead ion concentration (mg/L).

Specific surface detection of modified aluminum-iron adsorbent: The specific surface area of modified aluminum-iron adsorbent is detected by specific surface area and pore size measuring instrument (Jingwei Gaobo, model: JW-BK300C), and the calculation model is BET specific surface area (single point).

The results of COD, ammonia nitrogen, total phosphorus and lead ion removal rate and adsorbent specific surface area in landfill leachate are shown in Table 1.

Table 1 Effect of mass ratio of aluminum ash to scrap iron scraps on landfill leachate purification and specific surface area of modified aluminum-iron adsorbent

As can be seen from Table 1, when the mass ratio of aluminum ash and scrap iron scraps is less than 2: 1 (as in Table 1, when the mass ratio of aluminum ash and scrap iron scraps=1.8: 1, 1.5: 1, 1: 1 and Table 1 The lower value not listed in the above), less aluminum ash, the grinding effect becomes worse after the aluminum ash is mixed with scrap iron, the aluminum ions and iron ions dissolved in dilute hydrochloric acid decrease, and the zeta potential reduction effect of the colloid in the leachate becomes less Poor, the production of polyaluminium-iron coagulant is reduced, and the pollutants adsorbed on the coagulant are reduced, resulting in the removal rate of COD, ammonia nitrogen, total phosphorus and lead in landfill leachate and the specific surface area of modified aluminum-iron adsorbent. The mass ratio of aluminum ash to scrap iron was significantly reduced. When the mass ratio of aluminum ash and scrap iron scrap is equal to 2～4:1 (as in Table 1, when the mass ratio of aluminum ash and scrap iron scrap=2:1, 3:1, 4:1), the aluminum ash and scrap iron After the chips are mixed, due to the difference in particle size distribution, aluminum ash and scrap iron chips collide and squeeze each other during the grinding process, which will generate strong collision force and shear force, resulting in smaller particle size and particle specific surface area. big. The hydrochloric acid aqueous solution is mixed with the activated aluminum-iron mixed powder. During the stirring process, the aluminum ash and scrap iron chips are gradually dissolved into the liquid with the continuous consumption of hydrogen ions to generate aluminum ions and iron ions. After mixing domestic waste leachate with aluminum ferric chloride, the aluminum ions and iron ions introduced into the mixture can reduce the zeta potential of the colloids in the landfill leachate, and induce the colloids in the leachate to form alum flowers to achieve settlement. Oxygen free radicals can induce the hydrolysis and polymerization of aluminum and iron in the aluminum chloride-ferric mixed slurry to generate polyaluminum-iron coagulant. The polymeric aluminum-iron coagulant can further adsorb the pollutants in the landfill leachate through adsorption bridging and net capture, so as to realize the purification of landfill leachate. Under high temperature environment, the organic matter adsorbed in the polyaluminium chloride iron powder will be oxidized and decomposed to produce carbon dioxide gas. Carbon dioxide gas is quickly released from the alumina iron powder, thereby further increasing the specific surface area of the alumina iron powder. The COD removal rate in the final landfill leachate is greater than 86%, the ammonia nitrogen removal rate is greater than 88%, the phosphorus removal rate is greater than 90%, the lead removal rate is greater than 85%, and the specific surface area of the modified aluminum-iron adsorbent is greater than 424m ² / g.

When the mass ratio of aluminum ash to scrap iron scrap is greater than 4:1 (as in Table 1, the mass ratio of aluminum ash to scrap iron scrap=4.5:1, 5:1, 6:1 and higher values not listed in Table 1 ), the aluminum ash is too much, the grinding effect becomes worse after the aluminum ash is mixed with scrap iron chips, the aluminum ions and iron ions dissolved in dilute hydrochloric acid decrease, the zeta potential reduction effect of the colloid in the leachate becomes worse, and the coagulation of aluminum and iron The generation of the agent is reduced, and the pollutants adsorbed on the coagulant are reduced, resulting in the removal rate of COD, ammonia nitrogen, total phosphorus, and lead in the landfill leachate and the specific surface area of the modified aluminum-iron adsorbent. Significantly decreased with further increase. Therefore, in general, combining benefits and costs, when the mass ratio of aluminum ash to scrap iron scrap is equal to 2-4:1, it is most conducive to improving the purification effect of landfill leachate and most conducive to improving the specific surface area of the modified aluminum-iron adsorbent. .

Example 2 Effect of the volume ratio of domestic garbage leachate and aluminum-ferric chloride mixed slurry on the purification of landfill leachate and the specific surface of modified aluminum-iron adsorbent

According to the mass ratio of aluminum ash and scrap iron scraps of 4:1, aluminum ash and scrap iron scraps were weighed, mixed, and mechanically ground for 4 hours to obtain activated aluminum-iron mixed powder. Mix water and hydrochloric acid and stir evenly to prepare an aqueous hydrochloric acid solution, wherein the concentration of the aqueous hydrochloric acid solution is 4M. According to the liquid-solid ratio of hydrochloric acid aqueous solution and activated aluminum-iron mixed powder of 20:1mL/g, respectively weigh hydrochloric acid aqueous solution and activated aluminum-iron mixed powder, mix and stir for 15 hours to obtain aluminum-iron chloride mixed slurry. According to the volume ratio of domestic waste leachate and aluminum-ferric chloride mixed slurry 0.5:1, 0.7:1, 0.9:1, 1:1, 2:1, 3:1, 3.2:1, 3.5:1, 4:1 respectively Measure the mixed slurry of domestic waste leachate and aluminum ferric chloride, mix, stir and irradiate with low-temperature plasma for 7.5 hours, centrifuge, and separate solid and liquid to obtain nine groups of domestic waste leachate purification liquid and nine groups of polyaluminum ferric chloride slurry , wherein the low-temperature plasma action voltage is 30kV, and the low-temperature plasma action atmosphere is oxygen. Dry and grind the nine groups of polyaluminum ferric chloride slurry at 100°C to obtain nine groups of polyaluminum ferric chloride powder. Nine groups of polyaluminium-iron chloride powders were sintered for 6 hours and cooled to normal temperature to obtain nine groups of modified aluminum-iron adsorbents, wherein the sintering temperature was 450°C. COD concentration detection and COD removal rate calculation, ammonia nitrogen concentration detection and ammonia nitrogen removal rate calculation, total phosphorus concentration detection and total phosphorus removal rate calculation, lead ion concentration detection and removal rate calculation, modified aluminum-iron adsorbent specific surface detection and implementation example 1.

The results of COD, ammonia nitrogen, total phosphorus and lead ion removal rate and adsorbent specific surface area in landfill leachate are shown in Table 2.

Table 2 The effect of the volume ratio of domestic garbage leachate and aluminum-ferric chloride mixed slurry on the purification of landfill leachate and the specific surface area of modified aluminum-iron adsorbent

As can be seen from Table 2, when the volume ratio of domestic garbage leachate and aluminum-ferric chloride mixed slurry is less than 1:1 (as in Table 2, the volume ratio of domestic garbage leachate and aluminum-ferric chloride mixed slurry=0.9:1, 0.7 : 1, 0.5: 1 and lower values not listed in Table 2), domestic waste leachate is less, and the consumption of hydrogen ions in the aluminum-ferric chloride mixed pulp after the domestic waste leachate is mixed with aluminum-ferric chloride mixed pulp is relatively low less, the efficiency of oxygen free radical-induced hydrolysis and polymerization of aluminum and iron is reduced, the generated polyaluminum chloride is reduced, the amount of pollutant adsorption is reduced, and the removal rate and modification of COD, ammonia nitrogen, total phosphorus and lead in landfill leachate The specific surface area of aluminum-iron adsorbent decreased significantly with the decrease of the volume ratio of domestic waste leachate and aluminum-ferric chloride mixed slurry. When the volume ratio of domestic waste leachate and aluminum-ferric chloride mixed slurry is equal to 1～3:1 (as in Table 2, the volume ratio of domestic garbage leachate and aluminum-ferric chloride mixed slurry=1:1, 2:1, 3: 1 o'clock), after the domestic garbage leachate is mixed with aluminum ferric chloride, the aluminum ions and iron ions introduced in the mixed solution can reduce the zeta potential of the colloids in the landfill leachate, and induce the colloids in the leachate to form alum flowers to achieve settlement . During low-temperature plasma irradiation, oxygen in the atmosphere dissociates and ionizes in the discharge channel to generate oxygen free radicals. Oxygen free radicals can induce the hydrolysis and polymerization of aluminum and iron in the aluminum chloride-ferric mixed slurry to generate polyaluminum-iron coagulant. The polymeric aluminum-iron coagulant can further adsorb the pollutants in the landfill leachate through the adsorption bridging effect and the net capture effect, so as to realize the purification of the landfill leachate. During the sintering process, the polyaluminum iron chloride powder is oxidized and decomposed to produce alumina iron powder. At the same time, the organic matter adsorbed in the polyaluminum chloride iron powder is oxidized and decomposed under high temperature environment to produce carbon dioxide gas. Carbon dioxide gas is quickly released from the alumina iron powder, thereby further increasing the specific surface area of the alumina iron powder. Elements such as phosphorus, nitrogen, and heavy metals adsorbed on the polyaluminum iron chloride powder are rapidly oxidized and fused into the alumina iron powder during the oxidative decomposition process of the polyaluminum iron iron powder, thereby realizing the surface modification of the alumina iron, increasing the Its surface adsorbs active sites. The COD removal rate in the final landfill leachate is greater than 92%, the ammonia nitrogen removal rate is greater than 92%, the phosphorus removal rate is greater than 93%, the lead removal rate is greater than 91%, and the specific surface area of the modified aluminum-iron adsorbent is greater than 436m ² / g. When the volume ratio of domestic waste leachate and aluminum-ferric chloride mixed slurry is greater than 3:1 (as in Table 1, the volume ratio of domestic garbage leachate and aluminum-ferric chloride mixed slurry = 3.2:1, 3.5:1, 4:1 ), too much domestic waste leachate, the effect of reducing the zeta potential of the colloid in the leachate becomes poor, and the removal efficiency of pollutants in the domestic waste leachate becomes poor, resulting in the removal rates of COD, ammonia nitrogen, total phosphorus, and lead in the landfill leachate. With the further increase of the volume ratio of domestic waste leachate and aluminum-ferric chloride mixed slurry, it decreased significantly. Therefore, in general, combining benefits and costs, when the volume ratio of domestic landfill leachate and aluminum ferric chloride mixed slurry is equal to 1 to 3:1, it is most conducive to improving the purification effect of landfill leachate and improving the efficiency of modified aluminum. Iron adsorbent specific surface area.

Example 3 Effect of low-temperature plasma irradiation time on landfill leachate purification and specific surface area of modified aluminum-iron adsorbent

According to the mass ratio of aluminum ash and scrap iron scraps of 4:1, aluminum ash and scrap iron scraps were weighed, mixed, and mechanically ground for 6 hours to obtain activated aluminum-iron mixed powder. Mix water and hydrochloric acid, stir evenly, and prepare hydrochloric acid aqueous solution, wherein the concentration of hydrochloric acid aqueous solution is 6M. Weigh the hydrochloric acid aqueous solution and the activated aluminum-iron mixed powder according to the liquid-solid ratio of hydrochloric acid aqueous solution and activated aluminum-iron mixed powder 30:1mL/g, mix and stir for 24 hours to obtain aluminum-iron chloride mixed slurry. According to the volume ratio of domestic waste leachate and aluminum ferric chloride mixed slurry 3:1, measure domestic waste leachate and aluminum ferric chloride mixed slurry, mix, stir and perform low temperature plasma irradiation 1.5, 2, 2.5, 3, 7.5 , 12, 13, 14, and 15 hours, centrifuge, and separate solid and liquid to obtain nine groups of domestic waste leachate purification liquid and nine groups of polyaluminum chloride ferric slurry, wherein the low-temperature plasma action voltage is 50kV, and the low-temperature plasma action atmosphere is oxygen. Under the condition of 150°C, the nine groups of polyaluminum chloride ferric slurry were dried and ground to obtain nine groups of polyaluminum chloride ferric powder. Nine groups of polyaluminium-iron chloride powders were sintered for 9 hours and cooled to room temperature to obtain nine groups of modified aluminum-iron adsorbents, wherein the sintering temperature was 600°C.

COD concentration detection and COD removal rate calculation, ammonia nitrogen concentration detection and ammonia nitrogen removal rate calculation, total phosphorus concentration detection and total phosphorus removal rate calculation, lead ion concentration detection and removal rate calculation, modified aluminum-iron adsorbent specific surface area detection are implemented at the same time example 1.

The results of COD, ammonia nitrogen, total phosphorus and lead ion removal rate and adsorbent specific surface area in landfill leachate are shown in Table 3.

Table 3 Effect of low-temperature plasma irradiation time on landfill leachate purification and specific surface area of modified Al-Fe adsorbent

As can be seen from Table 3, when the low-temperature plasma irradiation time is less than 3 hours (as in Table 3, when the low-temperature plasma irradiation time=2.5, 2, 1.5 and the lower value not listed in Table 3), the low-temperature plasma irradiation If the time is too short, the oxygen free radicals, hydrogen peroxide, chlorine and hypochlorous acid produced during the low-temperature plasma irradiation process will decrease, the organic pollutants in the landfill leachate will not decompose sufficiently, and the aluminum and iron in the aluminum chloride-iron mixed slurry will be hydrolyzed Insufficient polymerization reaction leads to the removal rate of COD, ammonia nitrogen, total phosphorus and lead in landfill leachate and the specific surface area of the modified aluminum-iron adsorbent decrease significantly with the decrease of low-temperature plasma irradiation time. When the low-temperature plasma irradiation time is equal to 3～12 hours (as in table 3, when the low-temperature plasma irradiation time=3,7.5,12), in the low-temperature plasma irradiation process, the oxygen in the atmosphere dissociates and dissolves in the discharge channel ionized to generate oxygen free radicals. Oxygen free radicals can convert part of ammonia nitrogen in landfill leachate into nitrogen and nitrate, and can also decompose and mineralize some organic pollutants in landfill leachate through oxidation. Oxygen free radicals can also combine with hydrogen ions to form hydrogen peroxide. Oxygen radicals can also oxidize chloride ions to chlorine gas and hypochlorous acid. Hydrogen peroxide, chlorine and hypochlorous acid can further enhance the decomposition of organic pollutants. At the same time, oxygen free radicals can induce the hydrolysis and polymerization of aluminum and iron in the aluminum chloride-ferric mixed slurry to form a polymerized aluminum-iron coagulant. The COD removal rate in the final landfill leachate is greater than 95%, the ammonia nitrogen removal rate is greater than 94%, the phosphorus removal rate is greater than 96%, the lead removal rate is greater than 95%, and the specific surface area of the modified aluminum-iron adsorbent is greater than 448m ² / g. When the low-temperature plasma irradiation time is greater than 12 hours (as in Table 3, when the low-temperature plasma irradiation time=13, 14, 15 and higher values not listed in Table 3), COD, ammonia nitrogen, total phosphorus, The lead removal rate and the specific surface area of the modified Al-Fe adsorbent did not change significantly with the further increase of the low-temperature plasma irradiation time. Therefore, in general, combining benefits and costs, when the low-temperature plasma irradiation time is equal to 3 to 12 hours, it is most beneficial to improve the purification effect of landfill leachate and the specific surface area of the modified aluminum-iron adsorbent.

Comparative example Effects of different comparative processes on the purification of landfill leachate and the specific surface area of modified aluminum-iron adsorbents

The process of the present invention: according to the mass ratio of aluminum ash and scrap iron scraps of 4:1, respectively weigh aluminum ash and scrap iron scraps, mix them, and mechanically grind them for 6 hours to obtain activated aluminum-iron mixed powder. Mix water and hydrochloric acid, stir evenly, and prepare hydrochloric acid aqueous solution, wherein the concentration of hydrochloric acid aqueous solution is 6M. Weigh the hydrochloric acid aqueous solution and the activated aluminum-iron mixed powder according to the liquid-solid ratio of hydrochloric acid aqueous solution and activated aluminum-iron mixed powder 30:1mL/g, mix and stir for 24 hours to obtain aluminum-iron chloride mixed slurry. According to the volume ratio of domestic waste leachate and aluminum ferric chloride mixed slurry 3:1, measure domestic waste leachate and aluminum ferric chloride mixed slurry respectively, mix, stir and perform low-temperature plasma irradiation for 12 hours, centrifuge, and separate solid and liquid Obtain domestic waste leachate purification liquid and polyaluminum chloride ferric slurry, wherein the low-temperature plasma action voltage is 50kV, and the low-temperature plasma action atmosphere is oxygen. Dry the polyaluminum ferric chloride slurry under the condition of 150° C., and grind to obtain polyaluminum ferric chloride powder. The polyaluminium-iron chloride powder was sintered for 9 hours, and then cooled to room temperature to obtain a modified aluminum-iron adsorbent, wherein the sintering temperature was 600°C.

Comparative process 1: According to the mass ratio of aluminum ash and scrap iron scraps of 4:1, aluminum ash and scrap iron scraps were weighed, mixed, and mechanically ground for 6 hours to obtain activated aluminum-iron mixed powder. According to the liquid-solid ratio of water and activated aluminum-iron mixed powder of 30:1mL/g, water and activated aluminum-iron mixed powder were weighed, mixed, and stirred for 24 hours to obtain iron-aluminum mixed slurry. According to the volume ratio of household garbage leachate and aluminum-iron mixed slurry 3:1, measure household garbage leachate and aluminum-iron mixed slurry, mix, stir and perform low-temperature plasma irradiation for 12 hours, centrifuge, and separate solid and liquid to obtain domestic garbage leachate. Filtrate purification liquid and polyaluminium-iron slurry, wherein the low-temperature plasma action voltage is 50kV, and the low-temperature plasma action atmosphere is oxygen. The polymerized aluminum iron slurry is dried and ground at 150° C. to obtain the polymerized aluminum iron powder. The polyaluminum iron powder was sintered for 9 hours and cooled to normal temperature to obtain comparative adsorbent 1, wherein the sintering temperature was 600°C.

Comparative process 2: According to the mass ratio of aluminum ash and scrap iron scraps of 4:1, aluminum ash and scrap iron scraps were weighed, mixed, and mechanically ground for 6 hours to obtain activated aluminum-iron mixed powder. Mix water and hydrochloric acid, stir evenly, and prepare hydrochloric acid aqueous solution, wherein the concentration of hydrochloric acid aqueous solution is 6M. Weigh the hydrochloric acid aqueous solution and the activated aluminum-iron mixed powder according to the liquid-solid ratio of hydrochloric acid aqueous solution and activated aluminum-iron mixed powder of 30:1 mL/g, mix and stir for 24 hours to obtain ferric-aluminum chloride mixed slurry. According to the volume ratio of domestic waste leachate and aluminum ferric chloride mixed slurry 3:1, measure domestic waste leachate and aluminum ferric chloride mixed slurry respectively, mix, stir for 12 hours, centrifuge, and separate solid and liquid to obtain domestic waste leachate purification liquid and aluminum chloride iron slag. The aluminum chloride iron slag is dried and ground at 150°C to obtain aluminum chloride iron slag powder. The aluminum chloride iron slag powder was sintered for 9 hours and cooled to room temperature to obtain comparative adsorbent 2, wherein the sintering temperature was 600°C.

COD concentration detection and COD removal rate calculation, ammonia nitrogen concentration detection and ammonia nitrogen removal rate calculation, total phosphorus concentration detection and total phosphorus removal rate calculation, lead ion concentration detection and removal rate calculation, and adsorbent specific surface area detection are the same as in Example 1.

The results of COD, ammonia nitrogen, total phosphorus and lead ion removal rate and adsorbent specific surface area in landfill leachate are shown in Table 4.

Table 4 Effects of different comparative processes on the purification of landfill leachate and the specific surface area of modified aluminum-iron adsorbents

It can be seen from Table 4 that the purification effect of landfill leachate and the specific surface area of the adsorbent that can be achieved by the process of the present invention are much higher than those of the comparative process 1 and the comparative process 2, and both are higher than the sum of the two.

Claims (8)

1. A method for efficiently disposing of domestic waste leachate and preparing a modified aluminum-iron-based adsorbent, characterized in that, comprising the following steps: 1) Weigh aluminum ash and scrap iron scraps respectively, mix them, and mechanically grind them for 2-6 hours to obtain activated aluminum-iron mixed powder; 2) Weigh hydrochloric acid aqueous solution and activated aluminum-iron mixed powder respectively, mix and stir for 6-24 hours to obtain ferric-aluminum chloride mixed slurry; 3) Measure the mixed slurry of domestic waste leachate and aluminum ferric chloride, mix, stir and irradiate with low-temperature plasma for 3 to 12 hours, centrifuge, and separate solid and liquid to obtain domestic waste leachate purification liquid and polyaluminum ferric chloride respectively pulp; 4) Dry the polyaluminum ferric chloride slurry at 50~150°C, grind it to obtain polyaluminum ferric chloride powder, sinter the polyaluminum ferric chloride powder for 3~9 hours, cool to room temperature, and obtain modified Al-Fe based adsorbent. 2. The method for efficiently disposing of domestic waste leachate according to claim 1 and preparing a modified aluminum-iron-based adsorbent, wherein the mass ratio of aluminum ash and scrap iron scrap in the step 1) is 2 to 4: 1. 3. The method for efficiently disposing of domestic waste leachate and preparing a modified aluminum-iron-based adsorbent according to claim 1, wherein the concentration of the hydrochloric acid aqueous solution in the step 2) is 2-6M. 4. The method for efficiently disposing of domestic waste leachate and preparing a modified aluminum-iron-based adsorbent according to claim 1, wherein the liquid-solid ratio of hydrochloric acid aqueous solution and activated aluminum-iron mixed powder in the step 2) is 10~ 30:1 mL/g. 5. The method for efficiently disposing of domestic waste leachate and preparing a modified aluminum-iron-based adsorbent according to claim 1, wherein the volume ratio of the domestic waste leachate to aluminum-iron chloride mixed slurry in the step 3) is 1~3:1. 6. The method for efficiently disposing of domestic waste leachate and preparing a modified aluminum-iron-based adsorbent according to claim 1, characterized in that the low-temperature plasma action voltage in step 3) is 10-50kV, and the low-temperature plasma The working atmosphere is oxygen. 7. The method for efficiently disposing of domestic waste leachate and preparing a modified aluminum-iron-based adsorbent according to claim 1, wherein the sintering temperature in step 4) is 300-600°C. 8. The modified aluminum-iron-based adsorbent prepared by the method according to any one of claims 1 to 7.

Images