CN1304301C

CN1304301C - Process for micro filtering combined fluorine removing by aluminate coagulating

Info

Publication number: CN1304301C
Application number: CNB2005100136568A
Authority: CN
Inventors: 顾平; 张光辉
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2005-06-03
Filing date: 2005-06-03
Publication date: 2007-03-14
Anticipated expiration: 2025-06-03
Also published as: CN1724400A

Abstract

The present invention relates to a fluoride removing technique. The present invention puts forward that an aluminium salt coagulation micro-filtration combination method is adopted to remove fluoride in drinking water. Aluminium salt coagulant and aqueous alkali are adopted to be filled into a coagulation reactor, methods of aeration, or agitation, etc. are used for providing definite turbulent fluctuation, aluminium salt is hydrolyzed and coagulated, and then, the aluminium salt enters a membrane separator to continuously react with fluorides in raw water to form flocculation bodies, and is separated by a hollow fibre membrane to achieve the purpose of fluoride removing. The present invention has the advantages that the aluminium salt and the aqueous alkali with proper amounts are thrown into the raw water containing fluorine, the contents of residual fluorine and residual aluminum in water after treatment can satisfy the requirement of a living drinking water quality standard, and the present invention has significant meaning to reduce the morbidity of skeletal fluorosis of the China. The coagulation reactor of the present invention can be designed into a fixed type or a movable type according to requirements, and a design scale of the coagulation reactor can also be flexibly selected. The present invention is suitable for the temporary water supply of rural areas, remote areas, and field water supply or unexpected events.

Description

Process for micro filtering combined fluorine removing by aluminate coagulating

Technical field

The present invention relates to a kind of technology of Fluoride Removal, exactly is the fluorochemical of removing when making water source production tap water with underground water or surface water wherein.

Background of invention

Natural fluoride pollution has been accelerated in industrial development and mankind's activity.Industrial and mining enterprises are to a large amount of fluoride waste of natural water discharging, and the hydrogen fluoride of volcanic explosion ejection enters water body or soil with rainwater, and water dissolves the fluorine-containing mineral substance in the soil in runoff and infitration process, cause surface water and phreatic fluorine content overproof.Fluorine is a kind of trace element of needed by human, can promote the growth of bone and tooth, but the fluorine-containing tap water that exceeds standard of long-term drinking then can cause skeletal fluorosis, and the content of the drinking water standard regulation fluorine of China is no more than 1.0mg/L.Especially the northern area water of high fluorine content is widely distributed in China a lot of places, and the crowd who influenced by it is nearly 4,500 ten thousand, and skeletal fluorosis has become a kind of main endemy of China.Defluorination method commonly used has bone carbon, activated alumina absorption, aluminate coagulating etc., but bone carbon, activated alumina need frequent regeneration, and complicated operation discharges a large amount of cleaning waste liquids; The a large amount of aluminum ion of remnants causes the worry of people to health behind the conventional aluminate coagulating.Other method, very high as costs such as reverse osmosis, electrodialysis, be unfavorable for promoting.The present invention proposes aluminate coagulating and micro-filtration coupling, and expense is low, and is simple to operation, and the level of automation height can guarantee that again the aluminium content of handling in the water of back is up to standard, is a kind of very practical defluorination method.

Summary of the invention

The purpose of this invention is to provide the micro filtering combined method of a kind of aluminate coagulating and remove fluorochemical in the tap water, make its content satisfy the requirement of Drinking Water matter standard.

The present invention adopts aluminate coagulating and tubular fibre membrane microfiltration assembly to filter, and defluorination is finished by following steps:

(1) in coagulation reactor, adds aluminum salt and alkaline solution simultaneously with intermittent mode;

(2) aluminium salt dosage is determined by fluorine in the former water and pollutant load, and when the aluminium salt that adds all was used for defluorination, the aluminium salt amount that the fluorine of removal unit mass need add at least was (with Al ³⁺Meter) be 7.2gAl/gF; The alkaline solution dosage depends on the pH value and the aluminium salt dosage of former water, and purpose is that the pH value of keeping mixed solution in the membrane separation apparatus in reaction process (is used online acidometer regulation and control) in case of necessity between 6.0～6.7, to reach best defluorination effect;

(3) coagulation reactor provides certain turbulent fluctuation with modes such as aeration or stirring, membrane separation apparatus with aeration mode, make aluminium salt hydrolysis coagulation and with former water in the abundant contact reacts of fluorochemical, the flocs unit that forms is removed by the tubular fibre membrane filtration, thereby reaches the purpose of defluorination.Aluminum salt is Tai-Ace S 150, aluminum chloride and polymeric aluminum etc.Alkaline solution can be sodium hydroxide, calcium hydroxide and yellow soda ash etc.

Beneficial effect of the present invention is: when producing tap water, in fluorine-containing former water, add an amount of aluminium salt and alkaline solution, can make the fluorine of handling remnants in the water of back and the requirement that aluminium content satisfies Drinking Water matter standard, significant to the sickness rate that reduces China's skeletal fluorosis.This method level of automation height, simple to operation, working cost is low, the utilization ratio height of water resources; Can be designed to fixedly or portable as required based on the reactor of this method, design scale also can be chosen flexibly, is highly suitable for rural area and remote districts and open-air water supply or the interim feedwater of accident.

Embodiment

Membrane reactor adopts the hollow fiber microfiltration membrane assembly, and to present embodiment: the nominal pore size of film is 0.22 μ m, and useful area is 0.5m ², the DESIGN OF REACTOR flow is 15L/h, total residence time is 40 minutes.The gas-water ratio of coagulation reactor is 5: 1, and hydraulic detention time is 10 minutes; The gas-water ratio of membrane separation apparatus is that 15: 1, hydraulic detention time are 30 minutes; Intermittently water outlet of reactor, in per 10 minutes circulation, water outlet 8 minutes, sky exposed to the sun 2 minutes.Membrane reactor adopts intermittent operation, turns round every day 8 hours.Specific operation process is: under PLC (programmable logic controller) control, lift pump and volume pump add coagulation reactor with former water, aluminum salt and alkaline solution respectively, aluminium salt is hydrolyzed therein, behind the coagulation, the water in the coagulation reactor enters membrane separation apparatus by gravity or water pump lifting; In membrane separation apparatus, fluorochemical in the water and the reaction of aluminium hydroxide flocs unit generate the fluorine aluminium mixture of indissoluble, water outlet after hollow fiber microfiltration membrane filters.

Test-results shows: when the content of fluorochemical in the former water was 4.2mg/L, aluminium salt dosage was that 23.7mg/L is (with Al ³⁺Meter), the water outlet fluorochemical is lower than 1.0mg/L, and the content of remaining aluminium is lower than 0.05mg/L, can satisfy the requirement of Drinking Water matter standard.(move 8 hours every day) during the reactor intermittent operation, the critical SS in the membrane separation apparatus is the highest can to reach 12g/L, and need discharge the mud in the reactor this moment, otherwise can cause the rapid decline of membrane flux.The membrane reactor operation is after 4 months, and polluted membrane soaks 12 hours in tap water after, flux returns to 78.5% of new film; In 0.04% hydrochloric acid, soaked 12 hours subsequently, flux returns to 93.5% of new film, the shared ratio of irreversible pollution only is 6.5%, illustrate that simple aluminium salt flocs unit can not cause significant pollution to film, so this method has positive effect to reducing water producing cost and applying of this method.

Claims

1. process for micro filtering combined fluorine removing by aluminate coagulating is characterized in that adopting aluminate coagulating and hollow fiber film assembly to filter, and defluorination method is finished by following steps:

(1) the aluminum salt dosage is determined by fluorine in the former water and pollutant load, and when the aluminum salt that adds all was used for defluorination, the fluorine of removing unit mass need add aluminum salt at least with Al ³⁺Count 7.2gAl/gF; The alkaline solution dosage depends on the pH value of former water and the dosage of aluminium salt, and the pH value of keeping mixed solution in the membrane separation apparatus is between 6.0～6.7;

(2) in coagulation reactor, add aluminum salt and alkaline solution simultaneously with intermittent mode;

(3) Jiang Yuanshui, aluminum salt and alkaline solution add coagulation reactor, aluminium salt is hydrolyzed therein, behind the coagulation, water in the coagulation reactor enters membrane separation apparatus by gravity or water pump lifting, water outlet after hollow fiber microfiltration membrane filters, coagulation reactor provides turbulent fluctuation with aeration or alr mode, membrane separation apparatus with aeration mode, make aluminium salt hydrolysis coagulation and with former water in the abundant contact reacts of fluorochemical, the flocs unit of formation is removed by the tubular fibre membrane filtration.

2. according to the described aluminate coagulating micro-filtration of claim 1 defluorination integrated processes, it is characterized in that described alkaline solution is sodium hydroxide, calcium hydroxide and yellow soda ash.

3. according to the described aluminate coagulating micro-filtration of claim 1 defluorination integrated processes, it is characterized in that described aluminum salt is Tai-Ace S 150, aluminum chloride and polymeric aluminum.