of feed

(1)

(6- 4

8 kg). Thus,

^{the risks}

of feed

intake increase

depending

^on^seasonal

influences penalized

^more

the

females,

not restricted

during early growth.

For

production

in batches of

separated

^sexes

(D!smouLm, 19 6 9 - 1971 ),

seasonal feed restric- tions can be

accompanied by

^a

preferential

choice of cereals : maize in the castrates,

barley

^{in the}

females.

Survey

^on

^the monitoring

of

an

aeration processed

^waste

disposal ^unit treating

^a

^mixture

of swine and cattle

manure

J. SENNELIER,

^P.^POULET,

J.-P.

^RAYNAUD

Station de R et D. Vétérinaire et Nutrition animale,

Pfizer

International, B.P.

42,

37400 Amboise

f3iologie appliquée, Option Hygiène

^de[’Environnement, Institut Universitaire de

Teclanologie,

3îooo Tours

We are

presenting

the results of the

handling

^of^a^waste

disposal

^unit

(aeration process) treating

^amixture of swine and cattle waste. This study ^wasundertaken to obtain an

acceptable

effluent and to

improve

^the

efficiency

of this unit. It was demonstrated that the

following

^measures

had to be followed for a

good processing :

i) Screening

^to^retain^non

biodegradable

crude fibres

(important

^if

dairy cattle).

^{It is}^not

necessary ^to^use^toofine a screen ^{as we}found that there was

practically

^nondifference between

a qoo and 600^screen.

)

Sufficient

quantity

ôf^{water to}ôbtainâ^diluted^manure.^{In this}ûnit,^wefound that the decantation was disturbed when over 9

g/1

^{of total}

suspended

^solids^were

present

in the oxidation tanks. With a maximum

sludge

load of 35

kg

^of

ROD s/ day,

the volume of water varied between 3

0

and 50

m 3 /day.

3 )

^A^correctconcentration of oxygen in the oxidation tanks and ^asufficient flow of the return

sludge.

^After

studying

the evolution of the microflora involved in the

nitrogen cycle,

^of

the different forms of

nitrogen

in the effluent and of the concentrations of dissolved oxygen obtained in the oxidation

tanks,

^{we were}^able^to^determine^an

optimum operating

time for the compressor

(the

average

temperature

^{of the}^{water :}

i 7 o C)

^of

6 5

p. ^tooi. e.

IS.6 hours/day.

We estimated the

operating

^{cost at}⁸⁶

F/day.

^{This is}^a

high figure,

^{but if}^weestimate the maximum

possible

^total

pollution given by

^swine

only,

^{it is}

comparable

^to

already published

costs ^onsimilar units : 33 F for i swine from

weaning

^to

of feed

(6- 4

8 kg). Thus,

of feed

depending

influences penalized

females,

during early growth.

production

separated

(D!smouLm, 19 6 9 - 1971 ),

accompanied by

preferential

barley

Survey

the monitoring

of

aeration processed

disposal unit treating

mixture

of swine and cattle

J. SENNELIER,

J.-P.

Pfizer

42,

f3iologie appliquée, Option Hygiène

Teclanologie,

presenting

handling

disposal

(aeration process) treating

acceptable

improve

efficiency

following

good processing :

i) Screening

biodegradable

(important

dairy cattle).

practically

)

quantity

g/1

suspended

present

sludge

kg

ROD s/ day,

m 3 /day.

3

)

sludge.

studying

nitrogen cycle,

nitrogen

tanks,

optimum operating

(the

temperature

i 7 o C)

6 5

IS.6 hours/day.

operating

F/day.

high figure,

possible

pollution given by

only,

comparable

already published

weaning

slaughter.

^the monitoring

disposal ^unit treating

^mixture