CN102167434A

CN102167434A - Method for recovering nitrogen and phosphorous from urine

Info

Publication number: CN102167434A
Application number: CN 201110037688
Authority: CN
Inventors: 董良飞; 张凤娥; 蒋健钗; 涂保华
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2011-02-15
Filing date: 2011-02-15
Publication date: 2011-08-31

Abstract

The invention belongs to the technical field of separation of domestic sewage sources and relates to a chemical method for urine treatment and recovery of nutrient elements, in particular to a method for recovering nitrogen and phosphorous from urine. The method comprises the following steps of: collecting fresh urine and then naturally covering and storing, and recovering nitrogen and phosphorus after the pH reaches above 9, wherein the pH can raise to 9 after the urine is stored for about 10 days according to the difference of seasons and environment temperatures, and the pH monitoring is subjected to the storage process; sampling and detecting the NH4+-N concentration and the PO43--P concentration, feeding Na2HPO4 and MgCl2 according to mol ratio of n(Mg): n(P): n(N) of 1.3: 1: 1, controlling the stirring speed of 100r/min and the reaction time of 10min, precipitating for 1h and then separating supernate to obtain the MAP (Magnesium Ammonium Phosphate) precipitate. In the invention, the phosphate and magnesium salts are fed according to certain mol ratio in accordance with the NH4<+>-N concentration and the PO4<3->-P concentration after the urine is hydrolyzed, the nitrogen and the phosphorus are furthest recovered in an MAP precipitate way by reasonably controlling reaction conditions so that the nitrogen and phosphorus contents are greatly reduced, and the recovery rate of the nitrogen and the phosphorus can reach up to about 95 percent.

Description

A kind of method that reclaims nitrogen in the urine, phosphorus

Technical field

The invention belongs to the sewage source separation technology field, relate to a kind of chemical process that urine is handled and nutritive element reclaims, refer in particular to a kind of method that reclaims nitrogen in the urine, phosphorus.

Background technology

Nitrogen in the waste water, phosphorus are the important elements that causes lake and sealing immediate offshore area eutrophication phenomenon, but also are important industry and agricultural resources; Therefore, removal and recovery nitrogen, phosphorus both can reach the purpose of protecting environment from different waste water, can accomplish the energy recovery utilization again, and its relevant recovery technology causes that people more and more pay attention to; Nitrogen in the municipal effluent, phosphorus concentration are lower usually, directly therefrom reclaim relatively more difficult nor economical; Nitrogen and phosphorus account for about 80% and 50% of nitrogen in the municipal effluent, phosphorus load respectively in the human urine, and the nitrogen in the human urine, phosphorus concentration are far above general municipal effluent, therefore, before urine enters water drain, at first carry out separated and collected and handle the technology of reuse (" source separation " technology) then, the effluent quality of present sewage work be can effectively improve on the one hand, and energy consumption and investment saved; Can also realize the recycle of nutritive substance on the other hand.

The research present for the treatment process of separated urine has: nitrated/the denitrification technology, the micro polluting substance technology is removed in nanofiltration, and directly as fertilizer sources is used, freezing decrement concentration technique, technology, stripping technology and struvite crystallization and ammonia adsorption technology etc. are preserved in acidifying; In these method and technologies, because ammoniomagnesium phosphate crystal technology (MAP, be called struvite again) can directly the nitrogen in the waste water, phosphorus be converted into available mineral manure simultaneously and become a kind of more promising treatment process, this technology is used widely in various high ammonia nitrogens or phosphorus-containing wastewater and is studied at present, as the leather trade effluent of mixing, the anaerobic digestion supernatant liquor, the mud supernatant liquor, percolate, the waste water etc. of raising pigs in addition, all these results of study show that all this technology can effectively remove and reclaim ammonia nitrogen and the phosphorus in the waste water; Although Ban etc. with this process application in from separated urine, reclaiming nitrogen, phosphorus, and obtained the effect of anticipation, but they have adopted freshly voided urine as research object on the one hand, and in the urine urea short period of time when condition is fit to can decompose and cause urine pH, nitrogen, the considerable change of phosphorus isoconcentration, on the other hand, for avoiding the adjusting of pH in the reaction process, they adopt the solid MgO that adds inconvenience as precipitation agent, have therefore influenced the efficient and the application of MAP technology.Reclaim the research of nitrogen, phosphorus in the source-separated urine recently with the MAP precipitator method, the good grade of rarely seen Zhao Qing of Harbin Institute of Technology delivered " the MAP crystallization process reclaims and remove the phosphorus in a urine " literary composition (environmental science, 2007.10), adopt and decompose the stable separated urine in back as object, with regard to factors such as Mg:P mol ratio, pH value in reaction, reaction times, sedimentation time and stirring velocitys the influence of MAP precipitated crystal technology is tested respectively, simultaneously formed product is analyzed, to determine its main component and crystal type; This research is research object with the urine after decomposing, and is target to reclaim and to remove phosphorus, adopts MgCl ₂6H ₂O solution is as the MAP crystallizing agent, and the phosphorus in the urine and the influence factor Mg/PO of part nitrogen are reclaimed in the MAP crystallization synchronously ₄ ^3--P mol ratio, reaction pH, reaction times, sedimentation time and stirring velocity etc. are carried out the lab scale test.The result shows, Mg/PO ₄ ^3--P mol ratio is important operating parameter, and when its mol ratio surpassed 1.3:1, the rate of recovery of phosphorus surpassed 95%, supernatant liquor residue PO ₄ ^3--P concentration is reacted the rate of recovery that pH can not obviously increase phosphorus less than 10mg/L and improve.

Summary of the invention

Fresh urine is weakly acidic, and pH is about 6-7, and main component has urea, calcium, magnesium, potassium, sodium, ammonia, phosphoric acid salt, carbonate, vitriol, muriate, organic substance, bacterium etc.; The biodegradable of high density urine is grown bacterium rapidly, and the result makes urine in the process of collecting and storing, and great variation takes place chemical ingredients; Because the urine hydrolysis generates ammonia and carbonic acid gas, makes pH rise to 9 rapidly, NH in the urine behind the hydrolysis-stable ₄ ⁺-N concentration can reach 8000mg/L, PO ₄ ^3--P concentration can reach 200mg/L, and the N/P mol ratio is greater than 50.Therefore, adopting the MAP precipitator method is that target must make and still remains a large amount of nitrogen in the urine to reclaim phosphorus, does not reach to pollute the whole requirement that control and resource reclaim.

The present invention is directed to the problems referred to above,,, and rationally control reaction conditions, make nitrogen, phosphorus reclaim with the sedimentary form of MAP to greatest extent by interpolation phosphoric acid salt and magnesium salts in conjunction with the urine N/P practical situation bigger than differing.

At first, should add a cover storage behind the fresh urine collecting, according to season and envrionment temperature difference, left and right sides pH can rise to 9 in about 10 days, and storage process is as the criterion with the pH monitoring, reaches the operation that can reclaim nitrogen, phosphorus more than 9; Sampling detects NH ₄ ⁺-N and PO ₄ ^3--P concentration, n (Mg): n (P): n (N)=1.3:1:1 adds Na in molar ratio ₂HPO ₄And MgCl ₂, the control stirring velocity is 100r/min, the reaction times is 10min, precipitates after 1 hour separation of supernatant to obtain the MAP throw out.

The present invention according to the urine hydrolysis after contained NH ₄ ⁺-N and PO ₄ ^3--P concentration, add phosphoric acid salt and magnesium salts by certain mol proportion, by reasonable control reaction conditions, make nitrogen, phosphorus reclaim with the sedimentary form of MAP to greatest extent, compare with prior art, not only reclaimed phosphorus, utilized the nitrogen that is rich in the urine simultaneously, make nitrogen, phosphorus all reduce significantly, nitrogen, phosphorous recovery are up to about 95%.

Further discover, fresh urine is diluted to 2 ~ 3 times, and pH value is controlled at 9.5 ~ 9.8, can further improve the organic efficiency of nitrogen, can reach 98%.

Embodiment

Example:

After the 10L freshly voided urine of Microdilution (diluting 2 times) is stored 10 days, measure NH ₄ ⁺-N content is 4350mg/L, PO ₄ ^3--P content 112mg/L, pH are 9.6, and n (Mg): n (P): n (N)=1.3:1:1 adds Na in molar ratio ₂HPO ₄12H ₂O and MgCl ₂6H ₂Each 1099g of O and 816g, the control stirring velocity is 100r/min, the reaction times is 10min, temperature of reaction be under 15 ℃ the condition precipitation after 1 hour separation of supernatant obtain the MAP throw out, remain NH in the supernatant liquor after measured ₄ ⁺The about 125mg/L of-N, PO ₄ ^3-The about 7mg/L of-P, nitrogen, phosphorous recovery are respectively 98% and 94%.

Claims

1. a method that reclaims nitrogen in the urine, phosphorus is characterized in that: will add a cover storage behind the fresh urine collecting, treat that the urine pH value reaches the operation that can reclaim nitrogen, phosphorus more than 9; Sampling detects NH ₄ ⁺-N and PO ₄ ^3--P concentration, n (Mg): n (P): n (N)=1.3:1:1 adds Na in molar ratio ₂HPO ₄And MgCl ₂, the control stirring velocity is 100r/min, the reaction times is 10min, precipitates after 1 hour separation of supernatant to obtain the MAP throw out.

2. a kind of method that reclaims nitrogen in the urine, phosphorus as claimed in claim 1 is characterized in that: fresh urine is diluted to 2 ~ 3 times, and pH value is controlled at 9.5 ~ 9.8.