A kind of iron salt coagulant in-situ hydrolysis that utilizes generates the method that hydrous iron oxide is used for removing reuse water phosphorus
Technical field
The invention belongs to the reused water processing technical field, particularly a kind of iron salt coagulant in-situ hydrolysis that utilizes generates the method that hydrous iron oxide is used for removing reuse water phosphorus.
Background technology
The body eutrophication that the discharging of source of students such as nitrogen, phosphorus key element causes pollutes and becomes the current important water environment pollution problem of China, and phosphorus is the limiting factor of many body eutrophications.There is the phosphorus problem that exceeds standard in many municipal effluent plant effluents, and take economically viable reinforced phosphor-removing measure to guarantee the Sewage Plant qualified discharge, and this is significant for the control body eutrophication.
The coagulant sedimentation phosphor-removing effect is remarkable, stable, also can effectively remove colourity in the water, turbidity, SS, COD
Cr, BOD
5Deng pollutent.In addition, adopt the Coagulation Method dephosphorization not need additionally significantly purification facility, and have that technology is simple, floor space is little, advantage such as investment and running cost are low.Contrast, ferric flocculants such as iron trichloride, ferrous sulfate, ferric sulfate have better phosphor-removing effect than aluminium salt.But, in the municipal effluent plant effluent phosphorus often with coexistences such as organism, suspended particulate, above-mentioned pollutent also can consume coagulating agent and significantly improve molysite throwing amount.The sewage effluents lower for basicity, that surge capability is more weak, tend to occur iron salt hydrolysis not thoroughly, problems such as iron level rising in little, the water outlet of flco particle diameter, colourity increase, sedimentation and filtration weak effect.Adopt adsorbents adsorb dephosphorization such as hydrous iron oxide, calcium phosphate powder, tripolite loading iron carbonyl, compound hydroxyl ferro-aluminum can avoid the disadvantageous effect of coagulation, but have problems such as cost height, performance of the adsorbent are low, regenerative operation complexity.How improving generation and the phosphor-removing effect of sorbent materials such as hydrous iron oxide, is to expand the important way that coagulation technology is used in the reuse water dephosphorization is handled.
The present invention is directed to the problems referred to above, with trivalent iron salt (Fe
3+) with the OH of certain mol proportion
-Mix, its appropriate hydrolysis is formed hydrous iron oxide, take full advantage of the active height of its dephosphorization, the abundant advantage of adsorption site, to improve the removal effect of reuse water ferric salt coagulation for phosphorus removal.The present invention can be applicable to municipal wastewater treatment plant secondary effluent deep purifying, and also can be applicable to municipal effluent plant effluent or rainwater is the reused water processing engineering at water source.
Summary of the invention
The objective of the invention is, be the not good enough regeneration water factory of water source and coagulation for phosphorus removal effect at the municipal wastewater treatment plant secondary effluent that exceeds standard with phosphorus, provide a kind of economy, effectively, the method that is easy in engineering, use, with effective phosphor-removing effect that improves, thereby improve the problem of body eutrophication.
Know-why of the present invention is, adds molysite and alkali salt solution and phosphorus in the municipal wastewater treatment plant secondary effluent and reacts, and molysite and alkali salt solution reaction original position generate hydrous iron oxide (In situ FeO
xH
y) can condense absorption phosphorus and improve its settling property.Molysite can directly improve the phosphorus surface potential by the charge neutrality effect, and generated in-situ In situ FeO
xH
yAlso adsorbable phosphorus improves its surface potential and settling property; Further, adopt the solid-liquid separation reactor to remove particulate form phosphorus.Through above-mentioned processing, the phosphorus removal effect will significantly improve.
In order to realize improving the purpose of phosphorus removal effect in the reuse water, the present invention takes following technical scheme:
1, the dissolving under fully stirring with alkali salt and molysite respectively forms alkali salt solution and iron salt solutions.Wherein the mol ratio of ferro element is 0.02: 1~3: 1 in the hydroxide radical in the alkali salt and the molysite.
The mixing salt of one or more in the optional sodium hydroxide of described alkali salt, calcium hydroxide, the potassium hydroxide etc.; Described molysite can be selected from one or more the mixing salt in iron(ic) chloride, ferric sulfate, iron nitrate, poly-ferric chloride, bodied ferric sulfate, the polymerization iron nitrate etc.
The mol ratio of ferro element is determined according to following principle in hydroxide radical in the alkali salt and the molysite:
When former water pH less than 6.5 and water in total alkalinity during less than 250mg/L, the mol ratio of ferro element is 2: 1 (not containing 2: 1)~3: 1 (containing 3: 1) in the hydroxide radical in the alkali salt and the molysite; When former water pH greater than 6.5 and less than 7.5 and water in total alkalinity during less than 250mg/L, the mol ratio of ferro element is 1: 1 (not containing 1: 1)~2: 1 (containing 2: 1) in the hydroxide radical in the alkali salt and the molysite; When former water pH greater than 6.5 and less than 7.5 and water in total alkalinity during greater than 250mg/L, the mol ratio of ferro element is 0.2: 1 (not containing 0.2: 1)~1: 1 (containing 1: 1) in the hydroxide radical in the alkali salt and the molysite; When former water pH greater than 7.5 and water in total alkalinity during less than 250mg/L, the mol ratio of ferro element is 0.05: 1 (not containing 0.05: 1)~0.2: 1 (containing 0.2: 1) in the hydroxide radical in the alkali salt and the molysite; When former water pH greater than 7.5 and water in total alkalinity during greater than 250mg/L, the mol ratio of ferro element is 0.02: 1 (not containing 1: 1)~0.05: 1 (containing 0.05: 1) in the hydroxide radical in the alkali salt and the molysite.
2, certain density alkali salt and molysite are added to pending water, add that to select can be the position of any one the added liquid preparation before the regeneration water factory mixed cell.Alkali salt and molysite dosage are for the original position that adds to the pending water generates hydrous iron oxide In sim FeO
xH
yIn the concentration of iron between 20~100mg/L.
3, after alkali salt and iron salt solutions add to the water, the In situ FeO that reaction generates
xH
yCan give full play to the active height of its dephosphorization, the abundant advantage of adsorption site, more phosphorus are adsorbed on its surface in the water.The In situ FeO that has adsorbed phosphorus
xH
yFurther take off steady cohesion in the coagulation unit, and finally removed by solid-liquid separation unit.
In situ FeO
xH
yCan adopt the dystopy preparation method or adopt in-situ preparation method to be prepared, it is characterized in that: with iron salt solutions as solution A, with alkali salt solution as solution B; In above-mentioned solution, the molar ratio range between hydroxide radical and the iron is 0.02: 1~3: 1.
Adopt the dystopy preparation method to be prepared In situ FeO
xH
yThe time, solution A added in the solution B fully mix, or solution B added in the solution A fully mix, or solution A and solution B added in the container simultaneously mix; The mixing time scope is 10s~3min;
Adopt in-situ preparation method to be prepared In situ FeO
xH
yThe time, solution A and solution B are added respectively in the phosphorous water, the two adds time order and function is one of following mode in proper order: add solution A earlier, add solution B after fully mixing; Add solution B earlier, add solution A after fully mixing; Solution A adds the back simultaneously with solution B and fully mixes; When solution A and solution B are not when adding simultaneously, solution A and solution B add that successively the timed interval is 5s~60s.
Described pending water refers to that phosphorus concentration refers in particular to municipal wastewater treatment plant secondary effluent or rainwater as the regeneration water source greater than the water of 0.5mg/L in the regeneration water source.
Described mixed cell is one or more the combination in waterpower mixing reactor, aeration mixing reactor, the mechanically mixing reactor.
Described solid-liquid separation unit is selected from one or more the combination in horizontal sedimentation tank, inclined tube/inclined-plate clarifying basin, media filtration, the ultrafiltration/micro-filtrate membrane filtration.
The technique effect that the present invention realizes is as follows:
1. need not to carry out the large-scale engineering transformation and get final product the treatment effect that efficient hardening improves phosphorus in the municipal wastewater treatment plant secondary effluent, method is simple, and the construction investment cost is low, is easy to realize in engineering;
2. use operating process easy, need not to increase complicated operation bidirectional on water factory daily operation management basis;
3. adopt medicament to be water purification medicament or water-purifying material commonly used in the water treatment, with low cost;
4. can obviously improve the removal effect of phosphorus in the water, and reduce settled water turbidity and particle concentration, reduce the filter tank operating load, prolong filtration cycle.
Embodiment
Embodiment 1
Certain regeneration water factory is the water source with the municipal wastewater treatment plant secondary effluent, and the treatment process of employing is waterpower hybrid reaction-advection sedimentation-quartz sand filtration.Phosphorus content is 3mg/L in the former water, and turbidity is 20NTU, and the flocculation agent of employing is iron trichloride, flocculation agent throwing amount is 50mg/L, but treatment effect is undesirable, shows as heavy back water, filter back water turbidity is higher, heavy back water tp removal rate only is 50%, and the filter cycle is 20 hours.
Adopt method reinforced phosphor-removing of the present invention: the 1) dissolving under fully stirring with sodium hydroxide and iron trichloride obtains sodium hydroxide solution and liquor ferri trichloridi respectively.2) sodium hydroxide solution and the liquor ferri trichloridi mol ratio according to 2: 1 is added simultaneously to the medicament filler place of water factory's mixed cell tubular static mixer front end, and added amount of chemical is for to count 50mg/L with the throwing amount of iron trichloride.3) after sodium hydroxide solution and liquor ferri trichloridi add to the water, the In situ FeO that reaction generates
xH
yAdsorbable more phosphorus has adsorbed the In situ FeO of phosphorus
xH
yFurther take off steady cohesion in the coagulation unit, and final remove by precipitation, filtering unit, heavy back water tp removal rate significantly improves to 70%, filter cycle stretch-out to 24 hour.
Embodiment 2
Certain regeneration water factory is the water source with the municipal wastewater treatment plant secondary effluent, and the treatment process of employing is mechanically mixing reaction-sloping plate deposition-multi-medium filtering.Phosphorus content is 4mg/L in the former water, and turbidity is 25NTU, and the flocculation agent of employing is poly-ferric chloride, flocculation agent throwing amount is 40mg/L, but treatment effect is undesirable, shows as heavy back water, filter back water turbidity is higher, heavy back water tp removal rate only is 50%, and the filter cycle is 22 hours.
Adopt method reinforced phosphor-removing of the present invention: the 1) dissolving under fully stirring with potassium hydroxide and poly-ferric chloride obtains potassium hydroxide solution and poly-ferric chloride solution respectively.2) potassium hydroxide solution and the poly-ferric chloride solution mol ratio according to 3: 1 is successively added to the medicament filler place of water factory's mixed cell tubular static mixer front end, and added amount of chemical is for to count 40mg/L with the throwing amount of poly-ferric chloride.3) after potassium hydroxide solution and poly-ferric chloride solution add to the water, the In situ FeO that reaction generates
xH
yAdsorbable more phosphorus has adsorbed the In situ FeO of phosphorus
xH
yFurther take off steady cohesion in the coagulation unit, and final remove by precipitation, filtering unit, heavy back water tp removal rate significantly improves to 75%, filter cycle stretch-out to 24 hour.
Embodiment 3
Certain regeneration water factory is the water source with the municipal wastewater treatment plant secondary effluent, and the treatment process of employing is that waterpower hybrid reaction-tube settling-submerged ultrafiltration filters.Phosphorus content is 5mg/L in the former water, and turbidity 30NTU, the flocculation agent of employing are ferric sulfate, flocculation agent throwing amount is 60mg/L, but treatment effect is undesirable, shows as heavy back water, filter back water turbidity is higher, heavy back water tp removal rate only is 50%, and the ultra-filtration membrane backwash cycle is 20 hours.
Adopt method reinforced phosphor-removing of the present invention: the 1) dissolving under fully stirring with calcium hydroxide and ferric sulfate obtains aqua calcis and ferrum sulfuricum oxydatum solutum respectively.2) aqua calcis and the ferrum sulfuricum oxydatum solutum mol ratio according to 1: 1 is added simultaneously to the medicament filler place of water factory's mixed cell tubular static mixer front end, and added amount of chemical is for to count 60mg/L with the throwing amount of ferric sulfate.3) after aqua calcis and ferrum sulfuricum oxydatum solutum add to the water, the In situ FeO that reaction generates
xH
yAdsorbable more phosphorus has adsorbed the In situ FeO of phosphorus
xH
yFurther take off steady cohesion in the coagulation unit, and final remove by precipitation, filtering unit, heavy back water tp removal rate significantly improves to 70%, ultra-filtration membrane backwash cycle stretch-out to 24 hour.