composition and concentrative properties of human urine

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NASACONTRACTOR

z

E

REPORT

COMPOSITION AND CONCENTRATIVE PROPERTIES OF HUMANURINE

Prepared by

MCDONNELLDOUGLASASTRONAUTICSCOMPANY

-

WESTERN DIVISION

Huntington Beach, Calif. 9 2 6 4 7 for LangZey ResearchCenter

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

WASHINGTON,

D. C.

JULY 1971

assified

OOblObl 1. Report No. NASA CR-l%2

2. GovernmentAccessionNo.

3. Recipient'sCatalog

4. Title and Subtitle

No.

5. ReportDate

July 1971

PROPERTIES HOF U"l WUtE

CON!?OSITION AND CONCENTRATIVE

6. Performing Organization Code

7. Author(s)

8. Performing Organization Report No.

DAC-61125-F

David F. Putnam

10. Work Unit No.

9. Performing Organization Name and Address

McDonnell Douglas Astronautics Company Advanced Biotechnology and Power Department Huntington Beach, California

11. Contract or Grant No.

NASI-~~S+ 13. Type of Report and Period Covered

12. SponsoringAgencyNameandAddress

I

National Aeronautics and Washington, D.C. 20546

Space

Administration

I

15. SupplementaryNotes

ContractorReport 14. SponsoringAgencyCode

16. Abstract

This report

defines

the

composition

of

typical

human

urine

and

presents

experimental

data on its chemical, physical,. engineering and concentrative properties. The effects of chemical

and

electrolytic

pretreatments

used

in

aerospace

applications

for

extraction

of potable water are included. The results are presented in tables and plots of unsmoothed data, empirical equations, and tables of nominal values. Sample calculations and examples illustrating

the

consideration

of

these

17. Key Words(Suggested by Author(s))

in

engineering

design

applications

18. Distribution Statement

Urine water reclamtion Concentrative properties of human urine Water reclamtion Physical properties of urine Electrolytic pretreatment of urine 19. Security Classif. (of this report)

data

Unclassified

20. Security Classif. (of this page)

- Unlimited

21. No. of Pages

Unclassified For sale by the National Technical InformationService, Springfield, Virginia 22151

I

22. Price*

$3.00

are

included.

CONTENTS

SUMMARY

................................... ................................ ...................................

1

INTRODUCTION

1

SYMBOLS

3

. . . . . . . . . . . . . . . . . . .5 ............................ 6 (k) .......................... 6

COMPOSITION O F HUMAN URINE RefractiveIndex(ni) Specific Conductivity

......................................... 7 Total Dissolved Solids (TDS) ....................... 7 Rapid Method for Chemical Oxygen Demand (C02D) . . . . . . . . 7 8 Chemical Oxygen Demand (COD) ..................... Total Kjeldahl Nitrogen (TKN) ...................... 9 Total Organic Carbon (TOC) . . . . . . . . . . . . . . . . . . . . . . .9 ELECTROLYTIC PRETREATMENT O F HUMAN URINE . . . . . 11

pH

PHYSICAL PROPERTIES O F HUMAN URINE CONCENTRATES

Example 1.

Example 2. Example 3.

.............................. 15 VaporCompressionSystem . . . . . . . . . . . . . . . 16 Vacuum Distillation System . . . . . . . . . . . . . . .1 7 R e v e r s e O s m o s i s S y s t e m . . . . . . . . . . . . . . . . . 17

Example 4. Miscellaneous Considerations

. . . . . . . . . . . . . . 17

........................... V a p o r P r e s s u r e ................................

Solute Weight Fraction

... Ill

19 20

iv

COMPOSITION AND CONCENTRATIVE PROPERTIES O F H U U N URINE

By David F. Putnam Advance Biotechnology and Power Department SUMMARY This report defines the composition of typical human urine and presents experimental data on

its chemical, physical, engineering, and concentrative

properties. The effects

of c h e m i c a l a n d e l e c t r o l y t i c p r e t r e a t m e n t s u s e d i n

a e r o s p a c e a p p l i c a t i o n s f o r e x t r a c t i o n of potable water are included. The results are presented in tables and plots equations, and tables

of unsmoothed data, empirical

of nominal values. Sample calculations and examples

i l l u s t r a t i n g the consideration of t h e s e d a t a in engineering design applications a r e included.

INTRODUCTION T h e r e c l a m a t i o n a n d r e u s e of w a t e r f r o m h u m a n u r i n e is m a n d a t o r y f o r long duration space missions due to the severe restrictions imposed on launch weight. Engineering studies show that the equivalent weight

of m o s t

urine purification equipment is significantly lower than the weight of drinking

as s t o r e d w a t e r , if no w a t e r r e c o v e r y

water that would have to be launched

s y s t e m w e r e u s e d ( R e f e r e n c e s 1 and 2). The many different urine purification systems that tion have at least one point in common:

are under investiga-

all m u s t deal with urine that b e c o m e s

p r o g r e s s i v e l y m o r e c o n c e n t r a t e d as drinking water is e x t r a c t e d ( R e f e r e n c e s

3 through 13). It is c l e a r , t h e r e f o r e ,

that knowledge of t h e c h e m i c a l a n d

p h y s i c a l p r o p e r t i e s of urine concentrates, for which there is very little reference information,

is r e q u i r e d f o r t h e s a t i s f a c t o r y a n a l y s i s a n d d e s i g n

of all u r i n e - p r o c e s s i n g s y s t e m s .

It is hoped that the data reported here will

fulfill this need. The 68 chemical constituents that comprise over in urihe are listed in decreasing order

99 p e r c e n t

o f the solutes

of concentration. A simplified analog

of typical urine is presented, consisting

1

of 42 chemical compounds. Data on

v a r i a t i o n s i n u r i n e c o m p o s i t i o n a r e p r e s e n t e d i n t e r m s of refractive index, specific conductivity,

pH, total dissolved solids, chemical oxygen demand

(standard and rapid methods), total Kjeldahl nitrogen, and total organic of urine is d e s c r i b e d , a mass balance

carbon. The electrolytic pretreatment

is p r e s e n t e d , a d i s c u s s i o n of t h e e l e c t r o c h e m i s t r y of t h e p r o c e s s is given, and a typical composition of e l e c t r o l y z e d u r i n e i s l i s t e d . T h e p h y s i c a l p r o p e r t i e s of u r i n e c o n c e n t r a t e s w e r e d e t e r m i n e d in the ranges 4 to 90 p e r c e n t solutes and 70 to140

degrees Fahrenheit. Both smoothed and unsmoothed

d a t a a r e p r e s e n t e d i n t a b l e s a n d p l o t s , w h i c h a r e g r o u p e d t o g e t h e r a t the back of this report. The physical property data presented are the following:

t o w a treart i o

solute weight fraction solute o s m o l a lpi trye s s u r e

vapor density

osmolarity

co s onlcuetneotpsrram etsioo stu n i cr e w c oant ecre n t rh ae t iaotn

of vaporization

h e a t ity of cos solution vis specific weight fraction heat

of precipitated solids

surface tension weight fraction

of e x t r aw c taet d er

specific conductivity refractive index

2

SYMBOLS

C

= solute concentration,

COD

= chemical oxygen demand, g/I or mg/e

COZD

= chemical oxygen demand (rapid method), g/J or mg/t.

C

=

cw

= water concentration, g of w a t e r p e r ml of urine

HW

= differential heat of dilution, BTU per

HS

= differential heat of solution, BTU per lb

HU

= differential heat of vaporization of urine, BTU per pound

P

g, of solutes per rnl

specificheat,BTU/lb

x

of u r i n e

F

lb of w a t e r i n c r e a s e of s o l u t e i n c r e a s e of

urine

k

=

L


specificconductivity,

mho-cm-1 or

pmho-cm'l of

water evaporated Lu


of

urine

=

differential heat of vaporization of w a t e r , B T U p e r water evaporated

M

= apparent average molecular weight

N

= number of m o l e s of solvent =

n

= numberof-moles

of s o l u t e p a r t i c l e s a s calculated from vapor pressure data and Raoult's Law

=

0

= osmolality, apparent g-moles

refractive index at

ww 18

of s o l u t ep a r t i c l e s

n.

I

pound of

=

ws M

70" F r e l a t i v e t o a i r f o r s o d i u m y e l l o w l i g h t of s o l u t e p a r t i c l e s p e r 1000 g of

water

Or

= osmolarity, apparent g-moles

of s o l u t e p a r t i c l e s p e r l i t e r

urine P

= v a p o r p r e s s u r e of urine concentrate, psia

p ::

= v a p o r p r e s s u r e of p u r e w a t e r , p s i a

3

of

PH

= hydrogen ion concentration, loglo

of t h e r e c r i p r o c a l m o l a r c o n c e n t r a t i o n of hydrogen ions (Hs) 10-PH = g - m o l e s of hydrogen ions liter Joules

R

=

s

= entropy,BTU/lb

T

= t e m p e r a t u r e ,d e g r e e sR a n k i n e ,F a h r e n h e i t ,o rK e l v i n

TDS

= total dissolved solids, g/Kg or mg/Kg

TKN

=

TOG

= total organic carbon, g/l or mg/l

gas constant,

8. 3144 g-mole x

x

O

cm3 -mo e

= weight of solvent, g

WP

= weight of p r e c i p i t a t e , g

ws

= weight of solutes, g

wu

= weight of u r i n e , g

X

=

1 -x

= water weight fraction,

X

= original solute weight fraction,

- x.

,

total Kjeldahl nitrogen, g/l or mg/l

ww

1

(Ht)

F

= m o l a r v o l u m e of w a t e r , 18

0

of the

solute weight fraction,

g of s o l u t e s p e r g of u r i n e g of w a t e r p e r g of u r i n e g of s o l u t e s p e r g of u r i n e ,

initially before concentration

=

original water weight fraction, initially before concentration

g of w a t e r p e r g of u r i n e ,

Y

= weight fraction of e x t r a c t e d w a t e r , g of w a t e r e x t r a c t e d f r o m

1-Y

= weight fraction of u n e x t r a c t e d w a t e r , g of w a t e r in urine conc e n t r a t e p e r g of initial water content before concentration

urine during concentration per concentration

= surfacetension,dynes-cm'

g of initial water content before

1

= dynamicviscosity,centipoise = o s m o t i cp r e s s u r e ,p s i a

P

=

density, g of u r i n e p e r ml of u r i n e

4

COMPOSITION O F HUMAN URINE The composition of human urine has been studied by many investigators and the quantities of 1 5 8 d i f f e r e n t c h e m i c a l c o n s t i t u e n t s a r e s u m m a r i z e d i n the NASA Bioastronautics Data Book (Reference 14). These constituents are b r o a d l y c a t e g o r i z e d as electrolytes, nitrogenous compounds, vitamins, hormones,organicacids,andmiscellaneousorganiccompounds.The

68

constituents that have individual maximum concentrations exceeding are listed in Table

10 m g / l

I i n d e c r e a s i n g o r d e r of concentration. These constituents

90 compounds

add up to about 36,800 mg/f in typical urine. The remaining total approximately 2 5 0 mg/B. For engineering analysis purposes

in water reclamation technologies, an

a b b r e v i a t e d l i s t of compounds is i n m o s t c a s e s m o r e t h a n a d e q u a t e t o c h a r a c terize human urine. This is

not to suggest that there is any substitute for

using real urine in the development and testing

of w a t e r r e c o v e r y s u b s y s t e m s :

rather, that it is convenient, and sufficiently accurate for most analyses, to u s e a s i m p l i f i e d v e r s i o n of the real thing.

An a n a l o g f o r r e a l u r i n e , c o n s i s t -

ing of 42 compounds, is presented in Table

11.

considered to be typical, and

The concentrations listed are

are based on the information in Table

m e a s u r e m e n t s p r e s e n t e d e l s e w h e r e in this report, and the results ous chemical analyses of u r i n e m a d e o v e r t h e l a s t developing water recovery subsystems. The

I, the

of n u m e r -

10 y e a r s i n t h e c o u r s e of

42 out of 158compoundsin

Table I1 account for over 98 p e r c e n t of the total solute concentration in urine. For most analyses and calculations, Table

I1 should serve as

starting point to develop an even more simplified analog such which shows the major categories

of ( 1 ) i n o r g a n i c s a l t s ,

compounds, and (4) organic ammonium salts broken

a convenient a s Table 111,

( 2 ) u r e a , ( 3 ) organic

down into content of

carbon,nitrogen,oxygen,hydrogen,andorganicsulfur. Some measurements that help to broadly categorize urine are presented in Table IV.

The measurements were made on

16 different batches of r a w ,

unconcentrated, nonpretreated urine, each containing about

40 l i t e r s c o m -

p o s i t e d f r o m 2 0 t o 30 m a l e s u b j e c t s . T h e t o t a l d i s s o l v e d s o l i d s ( T D S )

of the

batches ranged from 24.8 grams per kilogram to 37. 1 grams per kilogram.

5

The measurements selected were considered to be the most significant available for broadly categorizing urine. In addition to the directly meas-

k., pH,TDS, C02D, COD, TKN, and TOC, t h e r e a r e i' columns of n i t r o g e n a n d c a r b o n a s d e t e r m i n e d b y g a s a n a l y s i s i n the e l e c -

u r e dv a l u e s

of n

trolytic pretreatment process (see ELECTROLYTIC PRETREATMENT OF

HUMAN URINE). The agreement between the two different methods d e t e r m i n a t i o n is close for nitrogen, but not in Table IV a r e p l o t t e d i n F i g u r e s

of

s o close for carbon. The data

1 through 8 a g a i n s t TDS. Although

a

g e n e r a l l y i n c r e a s i n g t r e n d w i t h i n c r e a s i n g TDS is apparent for each p a r a m e t e r e x c e p t pH, there is considerable deviation from mean values. It is not known how much of the deviation is due to actual variations in the l e v e l of the measured quantities, and

how much is due to interferences and

side reactions involved in the method

of m e a s u r e m e n t . T h e p a r t i c u l a r

significance of e a c h m e a s u r e m e n t is discussed below. Refractive Index (ni)

F

The refractive index measurements in this section were made at 70" with a Bausch and Lomb refractometer calibrated for sodium yellow light relative to air. For

a d i s c u s s i o n of refractive index of aqueous solutions,

s e e R e f e r e n c e s 15 and16. solutions see References

For refractive index data on common binary 16 and 17.

The refractive index has been found to

have a s t r a i g h t - l i n e c o r r e l a t i o n ( F i g u r e 12) with solute weight fraction for most species in binary solution.

(X)

In addition, for many species the effects

of solute weight fraction on refractive index are additive. Specific Conductivity

(k)

Specific conductivity is a function of the ionic, species present in w a t e r . If the amount and identity

of each ionic solute is known, then the specific

conductivity of a solution can be calculated, as there

is a definite relation-

ship between ion concentration and specific conductivity for individual species. The specific conductivity, calculated for the urine listed

in Table 11,

assuming an activity coefficient of 0. 74 for each inorganic salt (Reference 17, p. D - 9 3 ) , is 18. 0 mmho-cm'l for the inorganic salts, and approximately 1. 5 mmho-cm-1 for the organic ammonium salts, for

a t o t a l of 19. 5 m m h o -

cm-1. This is very close to the values found in real urine (see Figure

6

2).

I

PH pH is a m e a s u r e of Ht and OH- ions. Usually, in the case low pH is caused by unbuffered organic acids, and high

of u r i n e ,

pH is caused by

unbuffered ammonium. Total Dissolved Solids (TDS)

as solute weight fraction,

TDS was determined in the same manner

i. e . , by drying samples at r o o m t e m p e r a t u r e w i t h a purge flow of -40" F dew point air.

TDS is r e p o r t e d in g r a m s p e r k i l o g r a m of solution and is

equal to solute weight fraction times

1000.

The TDS m e a s u r e m e n t c a n n o t

be expected to match a theoretical calcu1,ation of total dissolved solids based on a quantitative knowledge of t h e s p e c i e s p r e s e n t i n u r i n e , b e c a u s e

of

f a c t o r s s u c h a s v o l a t i l i z a t i o n of organic matter, mechanically occluded w a t e r , w a t e r of h y d r a t i o n , h y g r o s c o p i c p r o p e r t i e s of the residue, heat induced chemical decomposition, and oxidation effects. In the case

of u r i n e ,

d r y i n g a t r o o m t e m p e r a t u r e m i n i m i z e s t h e l o s s of h i g h v a p o r p r e s s u r e solutes such as NH4HC03, HC1, formic acid, amines and phenols; and r e s u l t s i n a TDS figure that is slightly higher than the theoretical value due mainly to water of hydration.

As a r u l e of thumb, it

value for raw urine in grams per kilogram

is felt that the

TDS

is approximately equal to the

theoretical concentraction in grams p e r l i t e r . Rapid Method for Chemical Oxygen Demand In this method,

a microsample is injected into

(C02D)

a heated combustion tube

( s e e R e f e r e n c e 18) through which C 0 2 i s flowing. Reducing materials react with the

CO 2 to f o r m CO, which is measured by an infrared analyzer.

A

generalized equation for oxidation by a combustion process for urine organics is C

~

b

H N

c

o d t ~ o 2 - a c o t2-b2 H2 O

+C

~

N

The oxidizing equation for C 0 2 is Ca Hb Nc Od t m C 0 2

-

7

( m t a ) CO

+

H20 t

z N2 C

~

When both Equations (1) and (2) are balanced in respect to oxygen, then n = m t a and the number of m o l e s of CO produced in Equation (2)

is equal to

(1). T h e r e s u l t s a r e

the number of oxygen atoms required in Equation

r e p o r t e d a s g r a m s p e r liter of oxygen and a r e t e r m e d "C02D". T h e m i x t u r e of o r g a n i c s i n u r i n e p e r T a b l e I1 a r e a p p r o x i m a t e l y r e p r e -

N2 02. The oxidation of t h i s m i x t u r e by C 0 2

s e n t e d by the equation C2 H6 would be

i f completeoxidationoccurred

Therefore, in this case,

would be approximatelyequal

the total organics in urine

w i t h no i n t e r f e r e n c e s , t o 90180 x CO D. 2

The efficiency of oxidation for a number of c o m p o u n d s a s r e p o r t e d i n R e f e r e n c e 18 i s as follows: Analyses of Known Solutions

CO,D, L

mg/l

Compound

Calcd

Found

Acetic acid Benzoic acid Oxalic acid Glycine Urea p-Nitroaniline Phenol Sucrose Acetone Ethanol Methanol Ammonium hydroxide Ammonium chloride

246 250 250 250 250 250 245 248 173 235 238 250 250

239 248 2 44 248 2 50 2 44 2 16 2 15 145 2 00 205 2 04 2 74

Oxidation Efficiency,

70

97. 2 99. 2 97. 6 99. 2 100.0 97. 6 88. 2 86. 7 83. 8 85. 1 86. 1 80. 6 109. 6

C h e m i c a l Oxygen Demand (COD) Chemicaloxygendemandisoftenusedasindication content of w a t e r( R e f e r e n c e

19).

of thetotalorganic

It i s a m e a s u r e of theamount

8

of

I

dichromatethat

is reducedbyoxidation

of theorganics.Typical

COD

v a l u e sf o rt h r e eo r g a n i cm a t e r i a l sa r ea sf o l l o w s : Item

COD

Lactose

0.84 g / g

(Measured)

Glucose

1. 07 g / g

(Theoretical, Reference 19)

Potassium Acid Phthalate

1.18 g/g

(Theoretical, Reference 19)

The oxidation of most organic compounds by dichromate is 95 to

100 p e r -

cent of the theoretical value. However, ammonia, urea, benzene, toluene, and pyridine a r e among the compounds that are not oxidized by dichromate. Since urine contains large amounts

of urea, ammonia and amines, its

COD

values would be expected to run considerably below the total organic content of urine, and the data presented in Table

IV bear this out.

Total Kjeldahl Nitrogen (TKN) T o t a l K j e l d a h l n i t r o g e n ( R e f e r e n c e 1 9 ) m e a s u r e s o r g a n i c n i t r o g e n i n the trinegative state and includes ammonia nitrogen.

TKNwouldbe

expected to

m e a s u r e e s s e n t i a l l y a l l of the nitrogen in raw urine. When the organics in rawurineareapproximatelyrepresentedbytheequation the total organics would be approximately equal

C

2

H

6 N 2 0 2’ t h e n

to 9 0 / 2 8 x TKN.

N i t r a t e a n d n i t r i t e n i t r o g e n a r e not m e a s u r e d by TKN a n d a r e not p r e s e n t to any appreciable extent in raw urine. However, in electrolyzed urine there can be high levels of nitrate present, and in this case

TKN does not indicate

total nitrogen. Total Organic Carbon (TOC) T h e t o t a l o r g a n i c c a r b o n m e a s u r e m e n t w a s m a d e w i t h a Beckman Model 915 Total Organic Carbon Analyzer (see Reference

20).

This instru-

ment complies with the ASTM tentative method D2579-T for the determination of o r g a n i c c a r b o n i n w a t e r a n d w a s t e w a t e r . swept into a catalytic combustion tube

A small-size water sample is

(95OOC) w h e r e all carbonaceous

m a t e r i a l i s oxidized to carbon dioxide. After removal

of the water vapor,

the C 0 2 is i n t r o d u c e d i n t o a n i n f r a r e d a n a l y z e r s e n s i t i z e d to m e a s u r e COz.

A parallel sample is then injected into

9

a second combustion tube

m a i n t a i n e d a t a l o w e r t e m p e r a t u r e (15OOC). inorganic carbonates and dissolved

By this procedure only

C 0 2 are liberated. They are swept into

the infrared analyzer where they are separately determined. The difference between the total carbon dioxide and the inorganic carbon dioxide is indicative of t h e o r g a n i c c a r b o n p r e s e n t

in the sample. The method measures

e s s e n t i a l l y a l l of t h e c a r b o n i n u r i n e .

When t h e o r g a n i c s i n u r i n e a r e

approximately represented by the equation C 2 H6 N 2 02, then the total organics in urine would be approximately equal to

10

9 0 / 2 4 x TOC.

ELECTROLYTIC PRETREATMENT OF

HUMAN URINE

By passing sufficient electricity through human urine, most

of the

dissolved organic compounds can be converted to hydrogen, oxygen, nitrogen,

a semipurified urine that contains primarily inorganic salts. These residual inorganic and carbon dioxide, which are outgassed, leaving behind

salts can be removed

by electrodialysis to produce potable water. The com-

p l e t e w a t e r r e c o v e r y p r o c e s s is t e r m e d e l e c t r o p u r i f i c a t i o n a n d a typical

mass balance is shown in Figure

9.

The overall electrochemical reaction

is approximately represented as follows:

X 0

3

+2

C 2 H6 N2 O2 t 11 H20

-.X304 t 17 Hz + 2N2

t 202 t 4C02

(4)

In this equation,

X 0 represents the inorganic compounds in raw urine, 3 C H N 0 representstheorganiccompoundsinrawurine,and X304 2 6 2 2 represents the inorganic compounds in electrolyzed urine. X represents

all atoms other than

C, H, N, and 0 and is considered to have an atomic

weight of approximately 30, which is about average for the composition of Table 11. The mechanism for the overall electrochemical reaction is not known, However, it is felt that chemical reactions involving hypochlorite, chlorate, perchlorate, and perhaps both nascent chlorine and nascent oxygen are prime importance. In actual practice,

a batch of urine consisting of approxi-

mately 4 l i t e r s i s c i r c u l a t e d t h r o u g h a n e l e c t r o l y s i s c e l l o p e r a t i n g a t c u r r e n t d e n s i t y in the range

2

2 0 0 to 300 mA/cm until the

TKN a r e e a c h r e d u c e d - t o l e s s t h a n

100 mg/L?.

urine during electrolysis is shown

in F i g u r e s 10,11,

The transient behavior

and a r e b a s e d o n c o r n p o s i t e d d a t a f r o m a p p r o x i m a t e l y

of the

1 2 , 13, 14 and15.

in Tables 11 and 111,

16 t e s t r u n s .

e s t i m a t e of t h e s a l t s r e m a i n i n g a f t e r e l e c t r o l y s i s i s s h o w n to sulfate and most

a

TOG, COD, and

These plots are estimates for the typical urine described

Essentially all organic material is

of

gone. The organic sulfur

An

in Table V. is converted

of the original chloride is converted to chlorate and

perchlorate.Figures16,

17, 18 and 19 c h a r a c t e r i z e e l e c t r o l y z e d u r i n e

t e r m s of refractive index, specific conductivity,

C o n s i d e r a b l e d e v i a t i o n f r o m m e a n v a l u e s is evident.

11

in

pH, and TDS respectively.

F i g u r e s 10 through 15 give some insight into the dynamics

of the organic

first few minutes of e l e c t r o l y s i s there is an induc-

removal process. In the

level drops about 10% ( F i g u r e 10).

tion period in which the chloride

s i o n of chloride to hypochlorite according to the following reaction

Converis

indicated: Anode:

- 6cl 6e -

6e

t 6HOH t

Cathode: 6Nat Mixing:

-

6C1-

(5)

(6)

6NaOH t 3H2

6NaOH t 3C12-3NaOC1

(7)

t 3NaC1 t 3 H 2 0

D u r i n g t h e f i r s t 3 h o u r s of e l e c t r o l y s i s , t h e o u t g a s s i n g of oxygen is low (Figure 14), indicating that little

if a n y e x c e s s w a t e r i s b e i n g e l e c t r o l y z e d .

T h e r a t i o of n i t r o g e n t o c a r b o n ( F i g u r e 1 5 ) i s h i g h e r t h a n t h e a v e r a g e v a l u e for urine, indicating that urea and other high-nitrogen organics are being oxidized in preference to low- and zero-nitrogen organics such as the organic acids. The fact that COD, which does not include urea, is decreasing (Figure 10) indicates that other organics besides urea are also being oxidized. Th2 primary chemical reaction appears to be hypochlorite oxidation, which, for urea,

is mainly as follows:

Oxidation: F12NCONH2 t 3NaOC 1

-

C 0 2 t N 2 t 3NaC1 t 2 H 2 0

( 5 ) , ( 6 ) , ( 7 ) , and ( 8 ) would

The overall reaction, combining Equations be as follows: Overall reaction:

€12NCONF12 t I I 2 O

-

Between hour 3 and hour 4 t h e chloride level drops, indicating concentration of hypochlorite and the preferential oxidation organiccompounds.Thedec.line

inpII

(9)

C 0 2 t N 2 t 3H2

ofa

a higher

new group of

( F i g u r e s 10 and 15) indicates that

ammonium ions are also being removed, leaving the organic acids unbuffered. By hour 4 the organic nitrogen

( T K N , Figure 1 0 ) has dropped to almost zero

and the nitrogen to carbon ratio (Figure 15) The nitrogen compounds that renlain

i s below t h e average value.

in solution a s z e r o TKN is approached

were identified as mainly nitrogen trichloride, NC13,

12

and nitrate ion,

N03

-

NC13 i s d e t e c t e d by TKN,but

NO3

-

is not.

NC1

is an end product of the 3 For simplicity, it is not

hypochlorite oxidation of u r e a ( R e f e r e n c e 21).

shown in Equation (8), w h i c h r e p r e s e n t s t h e p r i m a r y r e a c t i o n of hypochlorite with urea.

NC13 can be converted to

NO3- by hypochlorite as follows:

NC13 t HOC1 t 2 H 2 0 -NO3-

t 4C1- t 5Ht

(10)

I t w a s found that in low voltage electrolysis (current density

< 2 mA/cm2 )

l a r g e c o n c e n t r a t i o n s (-5 g / l ) of NO3- did occur, but in high voltage electroly s i s ( c u r r e n t d e n s i t y > 150 m A / c m 2 ) t h e NO3- concentration remained low (.

.

.

...........;

14

13

12

11

10

9

8

.... F .

I

.,

7

i

6

t i

0

0 .

5

8

4

I2

3

3

I

0

4

..

. : .

2

..... .

1

,

, .

JI_".^

.

. .

0

i

I

. . ,.,

3

4

TIME, HOURS

Figure 10.

COzD, COD, TKN, TOC, CI- a d pH of UrineDuringElectrolyticPretreatment

65

6

7

5.0

45

40

35

i

I

: . . . . I

.:

. '

:

I

30

.

. i I

i'.

,

..

. . *

I

I ..

I

! I

,

. . . . .

25

I

20

15

10

6

0

1

2

3

TIME, HOURS

Fiwre 11.

TDS and ni of UrineDuring Electrolytic PNtreStmWIt

66

4

6

6

1.3400

.X.

w

0

I

,,

,

. .

.

.

I

.

URINE

Cdl -H 0

...

UREA

1.3350

z

a U

w

METHANOL

1.3340

[I:

.-

c

1.3330 0

5

10

15

20

25

30

35

40

45

50

2.0 1.9

1.8

. .

1.7

>.

1.6

1.5

1.4

1.3

1.2

1.1 1.o

.9

.8

.7

.6

.5

i .4

.3 .2

1 I

0

,

!

2

3

4

TIME, HOURS

Fiwro 13.

Optical Density of Urine During Electrolytic Pretreatment

68

6

6

I

75

45

70

40

65

bp.

I

3

0 60

35

>

& N

I L

0 I-

z 55

30

5 50

25

I .

. .{

20

I

I.

j .;.i .

'I

' i

i 15

LL

10

0

5

2

3

4

TIME. HOURS

Figurn 14.

Composition of Gas Ou-t

During Electrdytic Pretreatment

69

5

I !

. . .

!

i..

.

.

1

> .

,

.

.

.

!

0 I-

?

~

..

t 2

LL

0

L I

0' .I.

.Z

j^ 2

3

4

6

6

TIME, HOURS

F i w r e 16.

Ratio of Nitragm to Carbonin Evolved Gas DuringElectrolyticPretreatment ~~ ~~

70

~~

7

1.3400

1.3390

1.3385

1.3380

1.3375

1. a 7 0

TDS, TOTAL DISSOLVED SOLIDS,g/kg

Fiwre 16.

Refnctive Indexof Electrolyzed Urine

TDS, TOTAL DISSOLVED SOLIDS, glkg

Figwe 17.

-if=

Conductivity of Electrolyzed Urine

v W

TDS, TOTAL DISSOLVED SOLIDS,g/kg

U

P

0

w

> A 0

40 1

a

st-. v)

0

t-

INITIAL TDS, TOTAL DISSOLVED SOLIDS,g/kg

Figurn 19.

Final Versus Initial TDS of Electrolyzed Urine

I

Fimre 20. T-S Diaaram of Vapor Compression Process

75

I

U

m

Figure

U U

..

Y, WEIGHT FRACTION OF EXTRACTED WATER

Figre

22.

Preaure Ratio as a Function of the Weight Fraction of Extracted Water

.............

-. .... . -_

........

..

.

0

.

L

m

.a2

..

".

-.c..

.84

.

- -.

"

- _.....".I-

.a6

.."_ ."

.88

."

. .. .

.90

Y,WEIGHT FRACTION OF EXTRACTEDWATER

Figure 23.

Boiling Point Rise a, a Function of the Weight Fraction of Extracted Water

i

"

.92

I

.94

..

.96

.9a

1 .oo

~

5,ocuJ .."

.-

..

.

........

""

_ _ ....

".

..

.

:

.

.

.

. . . . . . . -. . . . . . . . . . . . . . . . . . .

-.

"

.

.

,

f-::

f

.

.

- .-- .-

.

-

..

......

. . . . . . _. ..

.

,

.

. . .

... ."

....

".

..

,

.

.

PRETREATMENT .

i

i." ...

_

.......

ELECTROLYTIC

A PRETREATMENT .........

A

0

"

-

"

" "

.80

.84

......

.........

" . . l . " " " _

I _

.86

.88

.sa


Figrre

24.

Osmotic Pressure as a Function of the Weight Fraction of Extracted Water

".

. , " "

92

1 .

"

.9 4

.96

.98

1.oo

09 0


Figure

25.

Vdurne of Urine Concentrate Slurry as a Function of the Weight Fraction of Extracted Water


Figure

26.

Weight Fraction of Precipitated Sdidr as a Function of the Weight Fraction of Extracted Water

LL

0

UI

0 4

U

W

> 4

X.SOLUTE WEIGHT FRACTION Appmt Average Molecular Weightof Urine SoluteParticles

a '

P*, VAPOR PRESSURE OF WATER, PSlA

Figure 28. -

Logarithmic Plot of the Vapor Pressure of Urine Concentrates Versus theVapor Pressure of PureWater

~"

83

.1

DO195 .00190 BO185 .00180 .MI175 70

,001 .00165 .00160

-T'1 Figure 29.

RECIPROCAL URINE TEMPERATURE,

Semilogarithmic Plot of the Vapor Pressure of Urine concentrates Versus the Reciprocal of the Boiling Temperature

a4

T, URINE BOILING TEMPERATURE

F i w r e 30.

OF

Boiling PointRise as a Function of Boiling Temperature, Condensing Temperature,andSoluteWeightFraction ".

~

85

~

U

0 Lu 0

0

.1

.2

X. SOLUTE WEIGHT FRACTION

FiQlre 31.

BoilhgPoint Rim of Urine Concantrate

.3

A

.5

.6

.7

.8

.9

1 .o

X, SOLUTE WEIGHT FRACTION

Figure 32.

X, SOLUTE W E I G W FRACTION


Fiwn 34.

Water Concentration of Urine Concentrate

P I-

d

a W

I-

s


Solute b Water Ratio of kine Concentrate

X,SOLUTE WEIGHT FRACTION

Figurn 36.

Osmolality of Urine Concentmte


F i g r e 37.

Osmolarity of UrineConcentrate

w


Figure 38.

Ounotic Pressurn of Urine Concentrate

X. SOLUTE WEIGHT FRACTION

d

VI

-10

-6

"...

01'' 0

i1

..

2

.1

-.- . . . I. .

3

.

!

. ,

.

.3


Fipm 40.

Diffuentbl H a t of Solution of Urine Concmtrato

. , . . . .r .4

-

.

,

-5

.

.I . . . .6

..

..,....

.7

L

.... .8

..

;

:-, 9

. I . .

.: 1.o

35

...

"

.....

_ 7

. . . . . . .

.......

,"..

...

..............

.

.

,

.

....

0 0

I

4

"""""L

.1

2

.3

X.SOLUTE W E I G H TFRACTION

Figure41.

DifferentialHeat of Dilution of Urine Concentrae

A

_I_

A

.5

.6

1

!

.7

a

.

.

.

.

i . I

9

.: d

1 .O

X.SOLUTE WEIGHT FRACTION

Fiwn 42.

c

b W

W

01

z

>

0


W W


Figum

44.

wifiiconductivity of Urine Concsntnta

0 0

x. SOLUTE WEIGHT FRACTION

*

.

. ,

. 0

1

2

4

3

& SOLUTE TO WATER RATIO Fiwre 46.

Virority . I a Function of the Soluds to W-r

Ratio

. 7

c. 0

N

X. SOLUTE W I G H T FRACTION

Figurn 47.

1.m

.99 .98 .9?

.95

.w

I-.

0

w

U

0 2

0

.9a

L

>-

.0?


Fipm 48.

W w t Fraction of Water Extnctal From Urine

.6

.5

.4

.'

f I

"

.

.3

.2

.1

' . 0

.1

.2

.3

.5

.4


Fiwre 49.

Wei&t Fraction of Extracted Water Venus Solute Wei*

Fraction

.6

I.

. . . . . . .

.7

a

.

!

.9

. 1.o


0

al

-IQ

X,SOLUlX WEIGHT FRACTION

I

U

0

h
