A double-layer composite biological filter material for biological aerated filter and its preparation method

Abstract

The invention discloses a double-layer compound biological filter material for an aerated biological filter. The double-layer compound biological filter material is formed by combining an inner layer and an outer layer, wherein the inner layer consists of attapulgite clay and fly ash in a weight ratio of 4:6; and the outer layer consists of attapulgite clay, kieselguhr and coal dust in a weight ratio of 7-10:9-12:1. The preparation method comprises the following steps of: uniformly mixing the attapulgite clay and the fly ash, and forming inner cores of solid spheres in a granulator; uniformly mixing the attapulgite clay, the kieselguhr and the coal dust to obtain mixed powder, continuously and slowly adding the mixed powder into the granulator to coat the surfaces of the inner cores of the solid spheres for granulation to obtain the finished product spheres; and drying the finished spheres naturally for 24 hours and in a constant-temperature fan drying box at the temperature of 120 DEG C for 2 hours, taking the finished spheres out of the drying box, directly putting the finished spheres in a box-typed resistance furnace to sinter the finished spheres at the temperature of between 950 and 1.050 DEG C for 20 minutes, and naturally cooling the finished spheres to obtain the double-layer compound biological filter material. The double-layer compound biological filter material obtained by the preparation method has the advantages of rough surface, high void ratio, good wearing resistance, high strength, easy film formation and high economy and practicability.

Description

technical field [0001] The invention relates to a filter material and a preparation method, in particular to a double-layer composite biological filter material for an aerated biological filter and a preparation method thereof. Background technique [0002] As we all know, in the biofilm process, the biological aerated filter is one of the important equipment. The biological aerated filter (Biological Aerated Filter, BAF) has the advantages of simple process, high treatment efficiency, small footprint, large organic volume load, and retention It has the advantages of short time, integration of biological oxidation and interception of suspended solids, saving of secondary sedimentation tank, low investment, low energy consumption, and high quality of effluent water; during use, the filter material forms a biofilm in the filter tank, and the biofilm is composed of bacteria, Fungi, algae, protozoa, metazoans, etc.; when the sewage flows through the filter bed, some pollutants a...

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Problems solved by technology

[0005] CN1220543C patent "a biologically active filter material for water treatment and its baking process" authorized and announced on September 28, 2005, uses clay as the main raw material, lignin and sulfonate as plasticizers, polyvinyl alcohol As a foaming agent to prepare filter materials, but in the actual use process, the removal rate of COD and ammonia nitrogen is not high, the maximum is about 70%

[0006] CN1291926C patent "A manufacturing method for spherical coal-based microporous biological filter material for wastewater treatment" authorized and announced on December 27, 2006, adopts coal and binder to form at 100-600°C after ball formation; 2008 The CN100423808C patent "Production method of attapulgite ceramsite filter material" authorized and announced on October 8, 2008 uses attapulgite clay, coal gangue, and volcanic ash to be sintered at 350-500°C; Ceramic temperature, high acid and alkali corrosion rates, poor strength and wear resistance, can be used as an adsorbent for water purification, but not suitable for use as a filter material for biological aerated filters, because it is not resistant to backwashing

[0007] CN100355671C patent "a new type of filter material used in the process of biological aeration filter" authorized and announced on December 19, 2007, uses fly ash, cement, sepiolite, etc. to prepare the filter material, because it is aged by cement Prepared by curing, the strength and porosity are not as good as the ceramsite filter material sintered at high temperature

[0008] CN101224359A patent "Preparation method of suspendable composite clay filter material" authorized and announced on July 23, 2008 uses foamed polyethylene to cover attapulgite on the surface, and the prepared sample can be suspended, which is more suitable for fish farming wastewater treatment. Suspension, rolling, collision and friction in water are relatively large, so it is not suitable for film formation in biological aerated filters

[0010] The CN101293768A patent "a biological filter material and its preparation method" authorized and announced on October 29, 2008 is prepared by using clay, fly ash, and pore-forming agents. The pore-forming agents are relatively expensive and have very active chemical properties. Highly dangerous calcium carbide increases the cost of filter material preparation

[0011] CN100453503C patent "biological ceramsite filter material and its preparation method" authorized and announced on January 21, 2009, uses fly ash, sludge, and hydroxymethyl cellulose as binders to prepare filter materials, and is modified by iron coating on the surface. Improve the static adsorption capacity of ammonia nitrogen, but have little effect on biofilm formation