CN103951112A

CN103951112A - Method for removing heavy metals in wastewater phosphorus recovery product

Info

Publication number: CN103951112A
Application number: CN201410197757.4A
Authority: CN
Inventors: 叶志隆; 邓玉君; 陈少华; 叶欣; 林向宇; 张召基
Original assignee: Institute of Urban Environment of CAS
Current assignee: Institute of Urban Environment of CAS
Priority date: 2014-05-13
Filing date: 2014-05-13
Publication date: 2014-07-30
Anticipated expiration: 2034-05-13
Also published as: CN103951112B

Abstract

The invention relates to a method for removing heavy metals in a wastewater phosphorus recovery product, belonging to the fields of water pollution control and resource regeneration, particularly a method for lowering ecological environment risk of a phosphorus recovery product. The method comprises the following steps: pretreating to remove suspended and colloidal organic substances in phosphorus-containing wastewater, and carrying out solid-liquid separation; regulating the pH value of the supernate to 8.0-11.0, adding a certain ratio of magnesium source or calcium source to perform magnesium ammonium phosphate or calcium phosphate crystallizing precipitation reaction, and adding alkali to control the pH value of the reaction at 8.0-11.0 until the reaction finishes; and carrying out solid-liquid separation to obtain the precipitate phosphorus recovery product. The steps can be carried out to remove the heavy metals in the wastewater phosphorus recovery product. On the premise of ensuring the phosphorus recovery yield, the method can achieve the goal of removing heavy metals by removing the suspended and colloidal organic substances in the wastewater, thereby lowering the ecological environment risk which can be caused by the phosphorus recovery product.

Description

A kind of method of removing heavy metal in phosphorus in waste water recovery product

Technical field

The invention belongs to water pollution control and resource recovery field, be phosphorus-containing wastewater carry out phosphorus reclaim time a kind of method of removing heavy metal in product.

Background technology

A large amount of existence of Phosphorus From Wastewater are the one of the main reasons of body eutrophication, and quality of water environment is caused to serious negative impact, have become one of current great environmental problem.Phosphorus is the indispensable nutritive elements of all life forms, is also important industrial chemicals, the particularly finiteness of occurring in nature phosphorus ore resource, and the recycle that makes to realize phosphor resource is very necessary.It is the important way of alleviating water pollution and phosphor resource shortage that the phosphorus of waste water reclaims.At present, the main technique reclaiming from phosphorus in waste water such as breeding wastewater, municipal sludge anaerobic supernatants is magnesium ammonium phosphate (MgNH ₄pO ₄6H ₂and calcium phosphate (Ca O) ₅(PO ₄) ₃(OH), Ca ₃(PO ₄) ₂xH ₂o etc.) crystalline deposit technique, the magnesium ammonium phosphate of recovery and calcium phosphate are good slow release fertilizers, can directly apply to agriculture production.

In the rich phosphorus waste water such as livestock breeding wastewater, municipal sludge anaerobic supernatant, contain suspension and the dissolved organic matter that concentration is higher, in the time that reclaiming, condenses because system potential variation is organic in phosphorus, mix with magnesium ammonium phosphate and calcium phosphate crystal, be difficult to separate, affect the quality of phosphorus recovery product.Meanwhile, also contain the heavy metal of various different shapes in the waste water such as livestock breeding wastewater, municipal sludge anaerobic supernatant, these heavy metals easily, by absorption, ion-exchange, complexing and the organic chelating body that forms, are mixed in phosphorus and reclaim in product, are difficult to separate.Research shows, even if the heavy metal concentration concentration in chemical fertilizer is very little, also can produce bio-toxicity, can be absorbed by hydrobiont, enrichment, in food chain, transmits, final harm humans health.Given this, when research and development phosphorus in waste water reclaims, the removal method of heavy metal, reduces the Ecological Environment Risk that reclaims fertilizer, and the popularization of reclaiming for phosphorus in waste water has important using value.

Summary of the invention

While recovery for phosphorus in waste water such as livestock breeding wastewater, municipal sludge anaerobic supernatants, the heavy metals such as Cu, Cr, As, Pb mix in product, are difficult to the problem of separation, the invention provides a kind of removal method of phosphorus in waste water recovery product heavy metal.Described method realizes in the following way: first adopt pre-treating process (as coagulation, filtration, membrane filtration etc.) to remove suspension and the colloidality organic matter in phosphorus-containing wastewater, then solid-liquid separation; The pH value of supernatant liquor is adjusted to 8.0-11.0, adds a certain proportion of magnesium source (as MgCl ₂, MgSO ₄, bittern etc.) or calcium source (Ca Cl ₂deng) carry out magnesium ammonium phosphate or calcium phosphate crystal precipitin reaction, control the pH value stabilization reacting at 8.0-11.0 until reaction finishes by adding alkali (as NaOH, KOH); By solid-liquid separation, the throw out of recovery is phosphorus and reclaims product.Can remove phosphorus in waste water by above-mentioned steps and reclaim the heavy metal in product.

Phosphorus in waste water provided by the present invention reclaims the removal method of product heavy metal, ensureing that phosphorus reclaims under the prerequisite of productive rate, by the organic matter of suspension and colloidality in removal waste water, reach the object of removal heavy metal, reduce phosphorus and reclaim the Ecological Environment Risk that product may cause, improve the quality of product simultaneously.

Embodiment

embodiment 1:

Certain livestock breeding wastewater, initial pH value 6.7, suspended solids 1570 mg/L, NH ₄ ⁺and PO ₄ ^3-concentration is respectively 920 mg/L and 103 mg/L, heavy metal Cu 15 mg/L, Cr 0.8 mg/L, Zn 30 mg/L, Cd 1 mg/L, Pb 0.4 mg/L, As 2.5 mg/L.First polymerize aluminum chloride (PAC) flocculation agent that adds 12 mg/L carries out coagulation pre-treatment to breeding wastewater, fully stirs, and then leaves standstill and filters.Get the supernatant liquor after filtration, add NaOH and adjust pH value to 9.2, fully stir, then add the Mg of 100 mg/L ²⁺carry out ammoniomagnesium phosphate crystal reaction, control pH value stabilization 9.2.After 40 min, stop stirring, leave standstill 20 min, collect bottoms, dry rear preservation.After testing, suspended solids 10 mg/L in product, heavy metal Cu 0.006 mg/Kg, Cr do not detect, Zn 0.02 mg/ Kg, Cd do not detect, Pb does not detect, As does not detect.

embodiment 2:

Certain municipal sludge anaerobic supernatant, initial pH value 7.2, suspended solids 2500 mg/L, NH ₄ ⁺and PO ₄ ^3-concentration is respectively 850 mg/L and 150mg/L, heavy metal Cu 8 mg/L, Cr 2.5 mg/L, Zn 10 mg/L, Cd 0.9 mg/L, Pb 3.5 mg/L, As 2 mg/L.Adopt nanofiltration membrane to carry out pre-treatment to waste water.Get the supernatant liquor after nanofiltration, add NaOH and adjust pH value to 9.0, fully stir, then add the Mg of 140mg/L ²⁺carry out ammoniomagnesium phosphate crystal reaction, control pH value stabilization 9.0.After 30 min, stop stirring, leave standstill 20 min, collect bottoms, after lyophilize, preserve.After testing, suspended solids 5 mg/L in product, heavy metal Cu 0.005 mg/Kg, Cr do not detect, Zn 0.01 mg/ Kg, Cd do not detect, Pb does not detect, As does not detect.

embodiment 3:

Certain livestock breeding wastewater, initial pH value 7.1, suspended solids 2310 mg/L, NH ₄ ⁺and PO ₄ ^3-concentration is respectively 1080 mg/L and 86 mg/L, heavy metal Cu 35 mg/L, Cr 0.5 mg/L, Zn 35 mg/L, Cd 0.08 mg/L, Pb 1.0 mg/L, As 5.5 mg/L.First polyacrylamide (PAM) flocculation agent that adds 10 mg/L carries out coagulation pre-treatment to breeding wastewater, fully stirs, and then leaves standstill and filters.Get the supernatant liquor after filtration, add NaOH and adjust pH value to 9.5, fully stir, then add the Mg of 80 mg/L ²⁺carry out ammoniomagnesium phosphate crystal reaction, control pH value stabilization 9.5.After 25 min, stop stirring, leave standstill 20 min, collect bottoms, dry rear preservation.After testing, suspended solids 6 mg/L in product, heavy metal Cu 0.002 mg/Kg, Cr do not detect, Zn 0.005 mg/ Kg, Cd do not detect, Pb does not detect, As does not detect.

Claims

1. remove the method that phosphorus in waste water reclaims heavy metal in product, it is characterized in that described method steps is: first adopt pre-treating process (as coagulation, filtration, membrane filtration etc.) to remove suspension and the colloidality organic matter in phosphorus-containing wastewater, then solid-liquid separation; The pH value of supernatant liquor is adjusted to 8.0-11.0, adds a certain proportion of magnesium source (as MgCl ₂, MgSO ₄, bittern etc.) or calcium source (CaCl ₂deng) carry out magnesium ammonium phosphate or calcium phosphate crystal precipitin reaction, control the pH value stabilization reacting at 8.0-11.0 until reaction finishes by adding alkali (as NaOH, KOH); Solid-liquid separation again, the throw out of recovery is phosphorus and reclaims product.

2. a kind of method of removing heavy metal in phosphorus in waste water recovery product according to claim 1, is characterized in that described phosphorus recovery process is magnesium ammonium phosphate (MgNH ₄pO ₄6H ₂and calcium phosphate (Ca O) ₅(PO ₄) ₃(OH), Ca ₃(PO ₄) ₂xH ₂o and derivative thereof) crystalline deposit technique.

3. a kind of method of removing heavy metal in phosphorus in waste water recovery product according to claim 1, is characterized in that described heavy metal includes, but are not limited to: copper (Cu), chromium (Cr), zinc (Zn), cadmium (Cd), plumbous (Pb), arsenic (As).

4. a kind of method of removing heavy metal in phosphorus in waste water recovery product according to claim 1, is characterized in that the organic matter in described waste water is suspension and colloidality organic matter.

5. a kind of method of removing phosphorus in waste water and reclaiming heavy metal in product according to claim 1, is characterized in that suspension in described phosphorus-containing wastewater and the pre-treating process of colloidality organic matter can be following independent method or Combination of Methods: coagulation, filtration, membrane filtration (micro-filtration, ultrafiltration, nanofiltration), air supporting, precipitation, charge neutrality.