CN100393636C

CN100393636C - Process for treating waste water of high concentration containing phosphorus

Info

Publication number: CN100393636C
Application number: CNB2005100323901A
Authority: CN
Inventors: 郭杰; 曾光明; 张盼月; 蒋剑虹
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2005-11-17
Filing date: 2005-11-17
Publication date: 2008-06-11
Anticipated expiration: 2025-11-17
Also published as: CN1792855A

Abstract

The present invention relates to a method for treating high concentration phosphorus-containing waste water. Phosphorus-containing waste water is filled into a crystallisation reactor which contains crystal seed tobermorite 5CaO.6SiO2.5H2O, the pH value is regulated to 8 to 8.5, medicines of zinc salts and ammonium salts are added, the molar ratio of Zn<2+> to NH4<+> to PO4<3-> in the waste water is 1: 1: 1, the mixture is thoroughly mixed and reacts for 30 min, phosphorus in the waste water is converted into ammonium phosphate zinc ZnNH4PO4.6H2O which is crystallized on the surface of the crystal seed, the solid-liquid separation is carried out, separated solid products are dewatered and dried to produce composite fertilizer, and yielding water which reach the standard is discharged. The method of the present invention has the advantages of low cost, simple processes, little sludge and good treatment efficiency, and fertilizer can be recycled.

Description

A kind of method of handling high-concentration phosphorus-containing wastewater

Technical field

The present invention is a kind of method of handling high-concentration phosphorus-containing wastewater, can remove the phosphate anion in the waste water effectively, and it is transferred in the ammonium phosphate zinc crystal that can be used as composite fertilizer.Be applicable to and handle as high density phosphorus-containing wastewaters such as sludge of sewage treatment plant digestion supernatant liquor, phosphorized waste water, phosphorus trade effluents.

Background technology

Removal of Phosphorus in Wastewater mainly contains biological process and physico-chemical process two big classes both at home and abroad.Biological process be fit to be handled low-concentration phosphorus-containing wastewater, and the value of waste water COD/P is greater than 30, and dephosphorization system could effectively be worked.Physico-chemical process is fit to handle high-concentration phosphorus-containing wastewater, traditionally, adopting many materialization treatment process is chemical precipitation method, mainly refer to use the metal ion of generation such as molysite, aluminium salt and lime and the sedimentary method of phosphate radical generation difficultly-soluble phosphates and removes phosphorus in the waste water.This method technology is simple, reliable, and can reach higher water outlet total phosphorus requirement.But because small deposit seeds quasi-equilibrium phenomenon (pseudoequilibrium), cause apparent solubility to amass and be much higher than true solubility product, in order to reach the formation condition of calcium phosphate precipitation, the precipitation by metallic ion agent concentration that need add is often greater than a normal solubility product 1-2 order of magnitude, therefore, medicament expense is with higher.In addition, the sludge quantity that also exist to produce is big, moisture percentage in sewage sludge is high, dehydration is difficult, be difficult to processing, be easy to generate shortcoming such as secondary pollution.

Summary of the invention

The technical problem to be solved in the present invention is these shortcomings that overcome traditional materialization treatment process, and a kind of crystallization process dephosphorization that utilizes is provided, the novel method of the processing high-concentration phosphorus-containing wastewater that cost is low, technology is simple, mud is few, recyclable farming is fertile, treatment effect is good.

Technical scheme of the present invention is:

A kind of method of handling high-concentration phosphorus-containing wastewater is characterized in that: phosphorus-containing wastewater is added be placed with crystal seed tobermorite 5CaO6SiO in it ₂5H ₂In the crystallization reactor of O, regulate pH value to 8～8.5, add zinc salt, ammonium salt medicament, make Zn in the waste water ²⁺, NH ₄ ⁺And PO ₄ ^3-Three's mol ratio is 1: 1: 1, thorough mixing, and reaction 30min is transformed into ammonium phosphate zinc ZnNH with the phosphorus in the waste water ₄PO ₄6H ₂The O crystallization is carried out solid-liquid separation at seed surface, and isolated solid product dehydrates the back and reclaims the water outlet qualified discharge as compound farming is fertile.

Described crystal seed tobermorite 5CaO6SiO ₂5H ₂The particle diameter of O is 1.0～1.5mm.

The crystallization reaction formula of zinc ammonium phosphate is as follows:

Zn ²⁺+PO ₄ ^3-+NH ₄ ⁺+6H ₂O→ZnNH ₄PO ₄·6H ₂O↓ (1)

The present invention is a kind of method of crystallization process dephosphorization, when waste water is alkalescence, Zn ²⁺, PO ₄ ^3-, NH ₄ ⁺, OH ^-Concentration is relatively low and when being metastable condition, the phosphorus in the sewage contacts with crystal seed in water, produces ammonium phosphate zinc at seed surface and separates out, and phosphorus concentration descends in the treating water thereby make.Because it only is that crystal seed becomes greatly that phosphorus is separated out at seed surface, therefore, the sludge quantity that produces in the treating processes is than coagulating sedimentation much less.Present method adopts tobermorite (5CaO6SiO ₂5H ₂O), can make ammonium phosphate zinc than the crystallization under the low ph condition, thereby save chemical reagent and associated cost that a part is regulated the pH value as the crystal seed of induced crystallization.

The needed zinc salt of present method can make from industrial utilising zinc containing waste residue, and China produces 320 000t industry cadmia every year approximately, therefrom extracts zinc, and the technology that is prepared into various zinc salts is ripe.So also can reduce a part of reagent cost.

Ammonium phosphate zinc is that the farming of a kind of composite slow release is fertile, not only contains nutritive elements such as N, P, also has trace elements zn, is specially adapted to the area that soil seriously lacks phosphorus and scarce zinc, a large amount of protective embankments field district that is produced as China's Jianghan Plain wetland cultivation.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Embodiment

Embodiment 1

Use the phosphorized waste water of certain refrigerator factory of this art breading, water quality is pH=7.2 before handling, PO ₄ ^3-=86.43mg/L, Zn ²⁺=18.71mg/L, COD=154mg/L, SS=106mg/L.Phosphorized waste water is added in the prilling tower, be placed with crystal seed tobermorite (5CaO6SiO in the tower ₂5H ₂O), add 20% NaOH solution, control pH value equals 8, adds 30% ZnCl simultaneously from the prilling tower bottom ₂Solution and 30% NH ₄Cl solution makes Zn in the prilling tower ²⁺, NH ₄ ⁺And PO ₄ ^3-Three's mol ratio is 1: 1: 1.Owing to can utilize original Zn in the waste water ²⁺Come crystallization PO ₄ ^3-So, saved a part of ZnCl ₂Medicament.Under the effect of pneumatic blending, waste water, medicament and crystal seed tobermorite thorough mixing in the prilling tower, behind the reaction 30min, the water outlet overflow enters solid-liquid separator.After solid-liquid separation, effluent quality is pH=7.9, PO ₄ ^3-=0.38mg/L, clearance are 99.56%; Zn ²⁺=1.26mg/L, clearance are 93.27%; COD=47mg/L, clearance are 69.48%; SS=58mg/L, clearance are 45.28%.

Effluent quality after the processing has reached the primary standard of integrated wastewater discharge standard GB8978-1996.Solid product dehydrates the back and reclaims as compound farming is fertile.

Embodiment 2

Use certain sludge of sewage treatment plant digestion supernatant liquor of this art breading, Analysis Results of Water Quality is before handling: pH=7.8; PO ₄ ^3-=108.64mg/L; NH ₄ ⁺=405mg/L; Ca ²⁺=137mg/L; Mg ²⁺=40mg/L; HCO ₃ ^-=2810mg/L is (with CaCO ₃Meter).To be placed with crystal seed tobermorite (5CaO6SiO in the tower in the above-mentioned waste water adding prilling tower ₂5H ₂O), in prilling tower, add KH ₂PO ₄Solution and ZnCl ₂Solution makes Zn ²⁺, NH ₄ ⁺And PO ₄ ^3-Three's mol ratio is 1: 1: 1.The NaOH solution of adding 20%, control pH value equals 8.3, PO in the waste water behind the reaction 30min ₄ ^3-, NH ₄ ⁺With Zn ²⁺Reaction generates ZnNH ₄PO ₄6H ₂The O crystallization is on crystal seed tobermorite surface, thereby effectively removed.

Handling the back Analysis Results of Water Quality is: pH=8.2; PO ₄ ^3-=0.44mg/L, clearance are 99.59%; NH ₄ ⁺=0.8mg/L, clearance is 99.8%, reaches integrated wastewater discharge standard.Solid product dehydrates the back and reclaims as compound farming is fertile.

Accompanying drawing 1 has provided the technical process of present method.Waste water, zinc salt medicament 1, ammonium salt medicament 2, sodium hydroxide 3 are entered in the prilling tower 4 by sump pump and dosing pump respectively, medicine system is realized adding the accurate control of dose and Ta Nei pH by nerve network controller and KMM programmable controller, can adapt to the wastewater treatment of different quality, different operating modes neatly, guarantee the water outlet requirement.

Air aeration reasonable in design and water-gas distribution plate have guaranteed that crystal seeds are in good fluidized in the prilling tower 4, and crystal seed has more completely with waste water and contact the carrying out of promotion crystallisation process.Prilling tower go out water mixed liquid through behind the solid-liquid separator 5, water is discharged from, solid product is again through whizzer 6 dehydrations, the crystallized product after the dehydration enters moisture eliminator 7 oven dry and removes remaining absorption capillary water, and is promptly recyclable for sale.Moisture eliminator is for being fit to crystal exsiccant loft drier.

Claims

1. method of handling high-concentration phosphorus-containing wastewater is characterized in that: phosphorus-containing wastewater is added be placed with crystal seed tobermorite 5CaO6SiO in it ₂5H ₂In the crystallization reactor of O, regulate pH value to 8～8.5, add zinc salt, ammonium salt medicament, make Zn in the waste water ²⁺, NH ₄ ⁺And PO ₄ ^3-Three's mol ratio is 1: 1: 1, thorough mixing, and reaction 30min is transformed into ammonium phosphate zinc ZnNH with the phosphorus in the waste water ₄PO ₄6H ₂The O crystallization is carried out solid-liquid separation at seed surface, and isolated solid product dehydrates the back and reclaims the water outlet qualified discharge as compound farming is fertile.

2. the method for processing high-concentration phosphorus-containing wastewater according to claim 1 is characterized in that: described crystal seed tobermorite 5CaO6SiO ₂5H ₂The particle diameter of O is 1.0～1.5mm.

3. the method for processing high-concentration phosphorus-containing wastewater according to claim 1 is characterized in that: described crystallization reactor is a prilling tower.