CN100438969C - Preparation method and application of composite iron-aluminum phosphorus removal adsorbent - Google Patents

Abstract

The preparation method and application of composite iron-aluminum phosphorus removal adsorbent belong to the field of environmental protection. FeCl ₃ , and AlCl ₃ solutions are fully mixed and then added NaOH solution, the molar ratio of the three is 3:2:14; after mixing and reacting and standing still, filter out the product, wash with water repeatedly until the effluent is neutral; at 100-110 ℃ and made into granular adsorbent with uniform size. For the application of this adsorbent, an adsorption and phosphorus removal process is added to the conventional water treatment process. The adsorption and phosphorus removal process consists of 2-4 phosphorus removal adsorption pools running in series. The phosphorus removal adsorption pool has the same structure as the filter tank. The phosphorus removal adsorbent is used as the filter material, the particle size range is 0.5mm-0.8mm, the thickness of the adsorption layer is 1.0-1.5m, the hydraulic load of the adsorption tank is 5m/h-8m/h, and the empty bed contact time is 30-40min. The adsorbent has a wide range of applications for phosphorus removal, excellent pollution removal efficiency, simple regeneration, low raw material price, easy availability and safety.

Description

Preparation method and application of composite iron-aluminum phosphorus removal adsorbent

technical field

The invention belongs to the field of environmental protection, and in particular relates to an adsorption phosphorus removal technology for drinking water source water and urban sewage treatment plant discharge water.

Background technique

In recent years, due to the key role of phosphorus on the reproduction and growth of microorganisms, countries all over the world have paid special attention to the control of phosphorus content in water bodies. Studies have shown that phosphorus is one of the elements that have a significant limiting effect on microbial regrowth in pipe network systems. For most water quality, when the total phosphorus concentration is lower than 1 μg/l, phosphorus will become a limiting factor for microbial growth in water, so It is of great significance to reduce the phosphorus content in the effluent water as much as possible in the water supply treatment to ensure the sanitation and safety of drinking water. In addition, the eutrophication of water caused by excessive nitrogen, phosphorus and other nutrients discharged into the water body has become an environmental problem of global concern. Studies have shown that the controlling factor of most eutrophic water bodies is phosphorus, and the output of sewage treatment plants should be reduced as much as possible. The phosphorus content in water can effectively prevent the occurrence of eutrophication in the receiving water body, so phosphorus removal from wastewater is very important to protect the water environment. And in 1996, the country's newly revised "Sewage Comprehensive Discharge Standard (GB8978-1996)" has clearly stipulated the phosphate content in the discharged sewage.

At present, there are many methods for phosphorus removal in water treatment, and biological methods and chemical methods are usually used. Among them, the biological method of phosphorus removal is based on the principle of phosphorus uptake and release by phosphobacteria, and dephosphorization is achieved through aerobic-anaerobic alternate operation. This method has the advantages of low operating costs and can remove organic pollutants in water. The disadvantage is that the process has poor stability. , the operation is strict, and affected by the temperature and pH of the wastewater, it has a strong dependence on the concentration of organic matter in the water. When the concentration of organic matter in the water is low and the content of phosphorus is high, it is difficult to meet the phosphorus discharge standard, and the content of phosphorus in the source water for water treatment is low. Usually below 100μg/l, it is also difficult to carry out traditional biological phosphorus removal. Chemical phosphorus removal mainly refers to the method of using metal ions produced by iron salts, aluminum salts and lime and phosphate to form insoluble phosphate precipitates to remove phosphorus in water. This method is reliable in operation and can achieve a high phosphorus removal rate. However, this process is a precipitation-dissolution equilibrium reaction process. In order to achieve a high phosphorus removal rate, especially the extremely low phosphorus content in the feed water source, in order to achieve the conditions for phosphate precipitation, it is necessary to add a higher metal ion precipitant, thus This leads to a substantial increase in the cost of chemicals, and at the same time, the content of residual metal ions in the effluent increases, and the chroma increases. In addition, the sludge produced has a large water content, which is difficult to handle and easily causes secondary pollution. In addition, the common disadvantage of biological and chemical phosphorus removal is that neither can recover phosphorus.

Phosphorus removal by adsorption method is to use the large specific surface area provided by the adsorbent to separate phosphorus from water through the process of adsorption, ion exchange or surface precipitation of phosphorus on the surface of the adsorbent. The adsorption-desorption method can realize the elimination of phosphorus pollution in wastewater At the same time, the purpose of reclaiming phosphorus resources and turning waste into treasure, so adsorption phosphorus removal has been developed in the field of wastewater treatment, and various types of adsorbents have emerged, among which activated alumina is a traditional adsorbent, which is widely used at present, but the adsorption capacity Not high enough, and the operating cycle is short. In addition, as an efficient and low-consumption method for removing specific solutes from low-concentration solutions, adsorption phosphorus removal is more suitable for the removal of trace phosphorus in drinking water. However, the role of phosphorus in drinking water has not been fully understood and valued for a long time. , has not been able to be associated with the quality of drinking water, especially the biological stability of drinking water, so there has been no report on the method of removing trace phosphorus in water by adsorption. In addition, the requirements for phosphorus removal in drinking water are very different from those in sewage. In particular, there are great differences in the limit content, and the phosphorus removal adsorbents that may be used are also greatly constrained by the water treatment process and water quality requirements. Environmental protection and improving water supply security are of great significance.

Invention content:

From the perspective of protecting the water environment and improving the safety of water supply, the present invention has successfully developed a composite iron-aluminum phosphorus-removing adsorbent suitable for both drinking water treatment and urban sewage treatment. Water treatment can obtain deep phosphorus removal, and the relevant indicators meet the national drinking water standard (GB5749-1985) and the Ministry of Health "Drinking Water Hygienic Standards" (Weifa Jianfa [2001] No. 161); For the discharge water treatment of urban sewage treatment plants, the relevant indicators of effluent can meet the requirements of "Comprehensive Wastewater Discharge Standard (GB8978-1996)".

For realizing the above object, the technical scheme adopted in the present invention is as follows:

1, the preparation method of a kind of composite iron-aluminum dephosphorization adsorbent provided by the invention is characterized in that:

Weigh the raw materials as FeCl ₃ , AlCl ₃ and NaOH, and the molar ratio of the three is 3:2:14; make an aqueous solution, mix the FeCl ₃ , and AlCl ₃ solutions thoroughly, then add NaOH solution, mix the reaction fully and let stand before filtering The product is produced, and the product is washed repeatedly with water until the effluent is neutral; it is dried at 100-110°C and made into a granular adsorbent with uniform size.

2. The application of a composite iron-aluminum dephosphorization adsorbent provided by the present invention is characterized in that:

The adsorption and phosphorus removal process is added to the conventional water treatment process. The adsorption and phosphorus removal process is composed of 2-4 phosphorus removal adsorption pools running in series. Each phosphorus removal adsorption pool has the same structure as the filter tank. The aluminum phosphorus removal adsorbent is used as the filter material, the particle size range of the adsorbent is 0.5mm-0.8mm, the thickness of the adsorption layer is 1.0-1.5m, and the lower part of the adsorption layer is equipped with a pebble layer and a drainage system with the filter tank for regular backwashing and adsorption of pool water Force load 5m/h-8m/h, empty bed contact time 30-40min.

3. Regeneration method of composite iron-aluminum phosphorus removal adsorbent:

When the adsorbent is saturated with phosphorus, it can be regenerated with aluminum sulfate solution to restore its adsorption and phosphorus removal performance.

Advantages of the present invention:

1. Composite iron-aluminum phosphorus removal adsorbent has a wide range of phosphorus removal applications, not only for the removal of trace phosphorus in water treatment, but also for the removal and recovery of constant phosphorus in wastewater treatment;

2. Excellent decontamination efficiency, which can further strengthen the removal of turbidity and organic pollutants by the water treatment process while completing the dephosphorization effect;

3. The regeneration method of composite iron-aluminum phosphorus removal adsorbent is simple and easy to operate;

4. The raw materials for the production of composite iron-aluminum dephosphorization adsorbents and the regenerant aluminum sulfate are conventional water treatment chemicals, the raw materials are low in price, easy to obtain, safe to use, and have no toxic or side effects;

Detailed ways:

Weigh the raw materials as FeCl ₃ , AlCl ₃ and NaOH, and the molar ratio of the three is 3:2:14; mix FeCl ₃ , and AlCl ₃ solution well, then add NaOH solution, fully mix the reaction and let it stand, then filter out to form The product is washed repeatedly with water until the effluent is neutral; the above product is dried at 100-110°C and made into a granular adsorbent with uniform size.

The present invention is carried out in the laboratory, and the present invention is described in detail below by examples. The particle size range of the adsorbent is 0.5mm-0.8mm,

Example 1: A water supply plant uses polluted river water as its water source. The total phosphorus in the raw water is 125ug/L, the dissolved phosphorus is 86ug/L, the turbidity is 10.5NTU, and the COD _Mn is 5.6mg/L. In the experiment, 13mg/L of conventional coagulant aluminum sulfate was added under rapid stirring. After mixing, reaction, precipitation and filtration, the turbidity of the effluent was 1.0NTU, the COD _Mn was 2.4mg/L, and other indicators also reached the standards of GB5749-1985. standard, but the total phosphorus is 7.5ug/L, and the dissolved phosphorus is 5.2ug/L, which cannot meet the biological stability requirements of effluent water quality. The filtered effluent is subjected to adsorption and phosphorus removal treatment. The adsorption and phosphorus removal process consists of three phosphorus removal adsorption ponds operated in series. The thickness of the adsorption layer is 1.0m, the hydraulic load of the adsorption pond is 6m/h, and the empty bed contact time is 30min. After testing, the turbidity, total phosphorus and dissolved phosphorus in the effluent of the adsorption tank were not detected, and the COD _Mn was 0.6mg/L, and the effluent was biologically stable drinking water.

Example 2: A water supply plant uses polluted reservoir water as its water source. The total phosphorus in the raw water is 87ug/L, the soluble phosphorus is 54ug/L, the turbidity is 8.5NTU, and the COD _Mn is 3.4mg/L. In the experiment, 10mg/L coagulant polyaluminum was added under rapid stirring. After mixing, reaction, precipitation and filtration, the turbidity of the effluent was 0.2NTU, COD _Mn 0.8mg/L, and other indicators also reached the standard of GB5749-1985 , but the total phosphorus is 4.5ug/L, and the dissolved phosphorus is 4.2ug/L, which cannot meet the biological stability requirements of effluent water quality. The filtered effluent is subjected to adsorption and phosphorus removal treatment. The adsorption and phosphorus removal process consists of two phosphorus removal adsorption ponds operated in series. The thickness of the adsorption layer is 1.5m, the hydraulic load of the adsorption pond is 6m/h, and the empty bed contact time is 35min. After testing, the turbidity, total phosphorus and dissolved phosphorus in the effluent of the adsorption pool were not detected, and the COD _Mn was 0.5mg/L, and the effluent was biologically stable drinking water.

Example 3: A water supply plant uses surface river water polluted by domestic sewage and industrial wastewater as its water source. The total phosphorus in the raw water is 186ug/L, the soluble phosphorus is 150ug/L, the turbidity is 8.5NTU, and the COD _Mn is 6.4mg/L. In the experiment, 14mg/L coagulant polyaluminium was added under rapid stirring. After mixing, reaction, precipitation and filtration, the turbidity of the effluent was 1.0NTU, COD _Mn 2.8mg/L, and other indicators reached the standards of GB5749-1985. However, the total phosphorus is 22.5ug/L, and the soluble phosphorus is 14.2ug/L, which cannot meet the biological stability requirements of effluent water quality. The filtered effluent is fed into the adsorption dephosphorization process. The adsorption dephosphorization process consists of 4 dephosphorization adsorption ponds operated in series. The thickness of the adsorption layer is 1.3m, the hydraulic load of the adsorption pond is 8m/h, and the empty bed contact time is 40min. After testing, the turbidity of the effluent from the adsorption tank was 0.2NTU, total phosphorus and dissolved phosphorus were not detected, and the COD _Mn was 0.8mg/L. The effluent was biologically stable drinking water.

Embodiment 4: A sewage treatment plant intends to discharge treated effluent into GB3838-88 (surface water environmental quality standard) IV waters, and needs to meet the secondary standard of "Comprehensive Wastewater Discharge Standard (GB8978-1996)", the second The total phosphorus content in the effluent treated at the second stage is 1470ug/L, which does not meet the discharge requirements. The secondary effluent of the sewage treatment plant is treated by the adsorption dephosphorization process consisting of 4 dephosphorization adsorption ponds running in series. The thickness of the adsorption layer is 1.0m, the hydraulic load of the adsorption pond is 8m/h, the contact time of the empty bed is 30min, and the effluent of the adsorption pond The total phosphorus has dropped to 680ug/L, and other indicators have also reached the secondary standard of "Integrated Wastewater Discharge Standard (GB8978-1996)".

Embodiment 5: A certain sewage treatment plant intends to discharge the treated effluent into GB3838-88 (surface water environmental quality standard) III waters, and needs to meet the first-level standard of "Comprehensive Wastewater Discharge Standard (GB8978-1996)", the second The total phosphorus content in the effluent treated at the first stage is 1800ug/L, which does not meet the discharge requirements. The secondary effluent of the sewage treatment plant is treated by the adsorption dephosphorization process consisting of 4 dephosphorization adsorption ponds running in series. The thickness of the adsorption layer is 1.3m, the hydraulic load of the adsorption pond is 8m/h, the contact time of the empty bed is 40min, and the effluent of the adsorption pond The total phosphorus has dropped to 380ug/L, and other indicators have also reached the first-level standard of "Integrated Wastewater Discharge Standard (GB8978-1996)".

Claims (2)

1, a kind of preparation method of Fe-Al compound dephosphorizing absorbent is characterized in that, may further comprise the steps:

1) takes by weighing raw material FeCl ₃, AlCl ₃And NaOH, three's mol ratio is 3: 2: 14;

2) three kinds of raw materials are made into the aqueous solution, FeCl respectively ₃And AlCl ₃Solution fully mixes the back and adds NaOH solution, fully hybrid reaction and leave standstill after leach product, water cyclic washing product to water outlet be a neutrality;

3) above-mentioned product is dried and makes the uniform granulated sorbent of size under 100-110 ℃.

2, the application of the Fe-Al compound dephosphorizing absorbent prepared of method according to claim 1 is characterized in that:

In conventional water treatment process, set up adsorption and dephosphorization technology, adsorption and dephosphorization technology is made up of the dephosphorization adsorption tank of 2-4 series operation, each dephosphorization adsorption tank is constructed same filter tank, adopt granular Fe-Al compound dephosphorizing absorbent to make filtrate, the adsorbent particle size range adopts 0.5mm-0.8mm, adsorbent layer thickness is 1.0-1.5m, adsorption tank hydraulic load 5m/h-8m/h, and empty bench grafting touches time 30-40min.