treatment of wastewater from the meat industry applying integrated membrane systems

www.elsevier.com/locate/procbio

Process Biochemistry 40 (2005) 1339–1346

Treatment of wastewater from the meat industry

applying integrated membrane systems

Jolanta Bohdziewicz*, Ewa Sroka

Institute of Water and Wastewater Engineering, Silesian University of Technology ul.

Konarskiego 18, 44-100 Gliwice, Poland

Received 5 December 2003; accepted 8 June 2004

Abstract

The paper presents investigations into the treatment of wastewater from the meat industry applying three hybrid processes in the following

combinations: ultrafiltration–reverse osmosis, coagulation–reverse osmosis, coagulation–ultrafiltration–reverse osmosis. Neither coagulation

nor ultrafiltration enabled a sufficient removal of pollutants from the wastewater, which, as a result, could not be discharged into receiving

water due to elevated pollution indices. However, an additional treatment by means of reverse osmosis made it possible for the wastewater to

be reused in the production cycle of a plant.

# 2004 Elsevier Ltd. All rights reserved.

Keywords: Membranes; Ultrafiltration; Reverse osmosis; Coagulant; Wastewater produced by the meat industry

1. Introduction

Industrial wastewater components show different degrees

of environmental nuisance and contamination hazard due to

their chemical characteristics as well as excessive concen-

tration [1].

Therefore, the treatment of wastewater, which is parti-

cularly hazardous to the environment, requires a number of

complementary techniques that sufficiently remove pollu-

tants and enable the wastewater to be discharged into

receiving water or be reused for industrial purposes.

Membrane processes can eliminate shortcomings, which

are characteristic of the traditional methods of wastewater

treatment. Due to their selectivity and high effectiveness,

they can replace traditional techniques or may operate

together in combinations as hybrid systems [1].

The meat industry is a branch of the food industry, which

causes degradation of the environment to a large extent. The

wastewater produced in it contains a variety of organic and

E-mail address: [email protected].

* Corresponding author. Tel.: +48-32-237-1698; fax: +48-32-237-1047.

E-mail address: [email protected] (J. Bohdziewicz),

[email protected] (E. Sroka).

0032-9592/$ – see front matter # 2004 Elsevier Ltd. All rights reserved.

doi:10.1016/j.procbio.2004.06.023

inorganic pollutants, has a high concentration of etheric

extract, suspended and biogenic matter as well as variable

concentrations. In this research, we aimed at treating it,

applying three systems that combined: ultrafiltration–

reverse osmosis, chemical precipitation–reverse osmosis

and chemical precipitation–ultrafiltration–reverse osmosis.

2. Apparatus

Ultrafiltration was carried out applying a SEPA CF-HP

pressure apparatus equipped with a plate-and-frame module

produced by Osmonics, membrane active area — 155 cm2.

The system operated in the crossflow mode.

Reverse osmosis was conducted in a GH 100–400 high-

pressure apparatus, capacity — 400 cm3, produced by the

same company. The system operated in the dead-end mode

on flat membranes whose active area was 36.3 cm2.

3. Materials

The wastewater was sampled from the Meat-Processing

Plant ‘‘UNILANG’’ in Wrzosowa (southern Poland), whose

J. Bohdziewicz, E. Sroka / Process Biochemistry 40 (2005) 1339–13461340

Table 1

Pollution indices of raw wastewater

Pollution indices Concentration of pollution in raw

wastewater (mg/dm3)

Load pollution (kg/d) (mean value) Permissible standards (mg/dm3) [2]

Range Mean value

COD 2650–6720 4685 309.2 150

BOD5 1200–3800 2500 126.8 30

Total nitrogen 49–287 198 13 30

Total phosphate 15–70 32 2.1 5*

Total suspension 112–1743 396 26.1 50

* For a wastewater treatment plant whose daily flow is below 2000 m3.

Table 2

Characteristics of ultrafiltration and osmotic membranes used in the tests [3]

Membrane type Retention

R (%)

Nominal molecular

weight (cut-off) (K)

Operating pressure DP (MPa) pH Max.

temperature T (8C)Recommended Maximum

HN – 10–50 0.35 2.07 0.5–13 100

HZ – 50–100 0.17 1.38 0.5–13 100

DS-CQ – 15–30 – 0.35 2–8 30

DS-GH 2K – 2 – 2.7 2–11 90

DS-GH 8K – 8 – 2.7 2–11 90

SS-10 98* – 2.76 6.90 2–8 50

* 0.5% sodium chloride.

activity covers the slaughter and processing of pigs. It was

characterized by considerable pollutant load, substantial

amounts of suspended matter and high concentrations of

total nitrogen and phosphorus. The values of the basic and

eutrophic pollution indices ranged widely during the whole

production cycle. The characteristics of the wastewater are

presented in Table 1.

Table 3

Condition for polysulphone membranes preparation

4. Coagulant

The research employed four technical coagulants ALF

(Al3+:Fe3+, 4:1); PAC (Al2O3-15.5%, Cl-20%); PAX (Al2O3,

Cl�-210 g/kg); PIX 113 (Fe2(SO4)3 Feog, 12.8%, Fe2+,

0.7%, H2SO4, 1%], which were added to the wastewater

in the form of 1 wt.%. aqueous solution. The basic reagent

dosages were calculated on the basis of a chemical reaction

of phosphates. The process of coagulation with the basic

dosage of the coagulant as well as its 100% and 200% excess

was carried out at 18–20 8C, pH of the wastewater being

6.4–7.6. The fast stirring time was 45 s, while the time of

slow stirring and sedimentation was 30 min each. The choice

of a coagulant was assessed on the basis of a decrease in

COD and phosphorus concentration in the purified waste-

water [7,8].

Membrane

symbol

Polymer concentration

in casting solution

(wt.%)

Amount of solvent

(DMF) in casting

solution (cm3)

PSf-12 12 92.6

PSf-15 15 89.4

Conditions for membrane preparation: temperature of casting solution, 291–

293 K; solvent evaporation time, 5 s; gelating agent, water; gelation time,

900 s; temperature of gelation, 278–280 K; thickness of cast film, 0.2 mm.

5. Membranes

The membranes used in the pressure driven membrane

operations produced by American company Osmonics are as

follows: two flat polysulphone ultrafiltration membranes

SEPA-H designated as HN and HZ, DS-CQ cellulose mem-

brane, two DS-GH 2K and DS-GH 8K composite mem-

branes and one SS-10 membrane for reverse osmosis made

of cellulose acetate. Table 2 shows the operating conditions

and separation characteristics recommended by the manu-

facturer of the membranes.

We also used two ultrafiltration membranes prepared by

in this laboratory: PSf-12 and PSf-15. They were produced

from casting solutions containing 12% wt. polysulphone

(PSf-12) and 15% wt. polysulphone (PSf-15) applying the

method of phase separation (Table 3).

6. Methods and analysis

Prior to the main tests, the transport properties of the

applied ultrafiltration and osmotic membranes and separa-

tion characteristics of PSf-12 and PSf-15 ultrafiltration

membranes were determined.

In the next stage of the research, the wastewater was

treated in a system combining ultrafiltration and reverse

osmosis. Ultrafiltration was used to remove organic and

colloidal macromolecular substances. The processes which

used HN and HZ membranes were carried out at transmem-

J. Bohdziewicz, E. Sroka / Process Biochemistry 40 (2005) 1339–1346 1341

Fig. 1. Dependence of volume water flux on transmembrane pressure for

ultrafiltration membranes.

brane pressures recommended by the manufacturer, which in

the case of DSCQ, DSGH-2K, DSGH-8K, PSf-12 and PSf-

15 membranes, this was 0.3 MPa. The linear flow velocity of

the filtered medium over the membrane surface was 2m/s

each time. Next, the permeate was additionally treated by

means of reverse osmosis on the SS-10 membrane removing

mineral matter and low molecular organics which formed in

the wastewater. The operating parameters of the process

were: transmembrane pressure, 2.0 MPa; stirring rate,

200 rpm.

The wastewater was also treated by replacing ultrafiltra-

tion with coagulation, which was additionally followed by

reverse osmosis after the wastewater was filtered through a

sand bed. The applied transmembrane pressure was 2.0 MPa

and the stirring rate 200 rpm.

In the last stage of the research, the wastewater was

treated applying coagulation, ultrafiltration and reverse

osmosis. Ultrafiltration of the wastewater, which followed

coagulation with 200% excess of PIX, was carried out on

DSCQ, DSGH-2K, DSGH-8K, PSf-12 and PSf-15 mem-

branes using the assumed operating parameters. Ultrafiltra-

tion permeates were additionally treated with reverse

osmosis.

Each time, before it was treated, the raw wastewater was

pre-treated in a fat separator.

The effectiveness of the treatment in all unit processes

was assessed on the basis of a decrease in pollution indices

of the wastewater, such as COD, BOD5, concentration of

biogenic substances and in the case of membrane operations,

permeates fluxes were determined.

The concentrations of total nitrogen, phosphorus and

COD were determined by means of the tests, which used

an SQ118 photometer produced by Merck [4]. BOD5 was

assayed employing the respiratory measurement method

with OxiTOP measuring cylinders produced by WTW

[5], the dry matter of the deposit was determined by means

of the gravimetric method [6], whereas oxygen concentra-

tion, pH and temperature were measured with a microcom-

puter CX — 315 pH/oxygen meter produced by

ELMETRON.


SS-10 osmotic membrane.

7. Results and discussion

7.1. Determination of transport and separation properties

of the ultrafiltration and osmotic membranes used in the

tests

The tests started with determination of transport proper-

ties of the membranes by finding the dependence of the

volume deionized water flux on transmembrane pressure. It

was observed that in all cases, the water fluxes increased

with increasing transmembrane pressure, and the correla-

tions obtained were rectilinear (Figs. 1 and 2).

As far as ultrafiltration membranes are concerned, the

highest increase in ultrafiltration rate over the pressure range

of 0.1–0.3 MPa was observed for the DS-CQ ultrafiltration

membrane whose volume water flux increased 2.2-fold

under these conditions. The DSGH-2K membrane was

characterized by the lowest performance for which the

volume water flux was 0.31 � 10�5 m3/m2 s at D = 0.3 MPa.

Before they were tested, PSf-12 and PSf-15 polysulphone

membranes were preliminary conditioned which consisted

in filtering deionized water at a pressure of 0.3 MPa and a

temperature of 293 K until a constant volume water flux was

achieved (9–12 h).

The transport properties of the membranes are illustrated

in Fig. 3.

Similarly to the commercial membranes, also in the case

of these membranes, the volume water flux increased with

increasing pressure and was the highest for the pressure of

0.3 MPa. It was 5.3 � 10�5 m3/m2 s for PSf-12, while for

PSf-15 it was higher by 43% and amounted to 2.3 �10�5 m3/m2 s.

As for the osmotic membrane, the dependence of the

volume water flux on transmembrane pressure was also

rectilinear and at 2.0 MPa the flux oscillated around 0.55

� 10�5 m3/m2 s.

Table 4 contains equations describing the dependence of

the volume water flux on the applied transmembrane pres-

sure for all tested membranes.

Determination of the separation properties of those mem-

branes consisted of determining their cut-off, applying a



PSf-12 and PSf-15 polysulphone membranes.

Table 4

Equations describing dependence of volume water flux on applied trans-

membrane pressure

Membrane type Function

Jw = f(x) Jw (m3/m2 s)

Coefficient of

correlation

HN 23.45x 0.976

DSGH-2K 1.0857x 0.9616

DSGH-8K 10.743x 0.9793

DSCQ 2.8071x 0.9645

PSf-12% 18.171x 0.9727

PSf-15% 4.4643x 0.998

Fig. 5. Dependence of volume permeate flux on its recovery during

ultrafiltration treatment of wastewater.

dextran whose molecular weight and concentration were

200,000 and 5g/dm3, respectively. The samples of permeates

and feed were analyzed by means of a gel permeation

chromatograph produced by Shimadzu.

The obtained dependence of dextran retention coeffi-

cients on their molar mass enabled the determination of

cut-off values of the tested membranes. It has been found

that the membrane of more compact structure (PSf-15) has a

cut-off of 80,000 and PSf-12 of 90,000 (Fig. 4).

7.2. Treatment of wastewater in the hybrid system of

ultrafiltration and reverse osmosis

The first stage of the investigations dealt with the treat-

ment of wastewater in the system of ultrafiltration and

reverse osmosis.

Fig. 4. Cumulative fraction of molecular weights in dextran samples.

Raw wastewater was introduced into the ultrafiltration

module after fat separation, flotation and filtration through a

sand filter whose grain size was 0.2–0.4 mm. Ultrafiltration

was carried out on six ultrafiltration membranes, which

differed in their polymer type and the compactness of the

structure, and thus different cut-off values ranging over

2000–100,000.

Fig. 5 presents dependences of the volume permeate

fluxes on recovery during ultrafiltration applying different

membranes.

Table 5 contains equations describing the dependence of

the volume permeate flux on its recovery. The equations

were of logarithmic function and the high correlation coef-

ficients indicate the proper selection of the equations for the

results obtained.

The HN membrane was the most efficient. Its permeate

flux decreased by 12%, recovery being 50%. It was, how-

ever, four times lower in comparison with the water flux.

Decisively lower filtration velocities were found for the

remaining membranes. The volume permeate fluxes

obtained were from two to four times lower under the same

conditions (50% recovery of the permeate and the same

process parameters).

However, the effectiveness of the processes depends not

only on membrane performance but also the degree of

contaminant removal. Depending on the type of membrane

applied, different degrees of decrease in particular pollution

indices, e.g. COD, BOD5, phosphorus and total nitrogen

(Fig. 6) were found.

Table 5

Equations describing the dependence of volume permeate flux on its

recovery during ultrafiltration treatment of wastewater

Membrane type Function

Jp = f(x) Jp (m3/m2 s)

Coefficient of

correlation

HN �0.0678 ln(x) + 1.9169 0.9326

HZ �0.1419 ln(x) + 1.6446 0.9726

DSGH-8K �0.1432 ln(x) + 1.8052 0.8965

DSCQ �0.098 ln(x) + 1.2625 0.9336

PSf-12% �0.00771 ln(x) + 1.4882 0.9007

PSf-15% �3E � 06x + 0.2081 0.9339


Fig. 6. Influence of ultrafiltration membrane on removal degree of pollu-

tants from wastewater.

Fig. 7. Dependence of volume permeate flux on its recovery during reverse

osmosis of wastewater after ultrafiltration treatment.

The highest retention coefficients of nitrogen and phos-

phorus, and the highest removal degrees of COD and BOD5

were obtained when the DS-CQ membrane was applied.

They were 58%, 85.9%, 84.6% and 81.5%, respectively. A

similar degree of wastewater purification was achieved in

ultrafiltration carried out on HN membrane. Nevertheless,

the degrees obtained in both cases were not sufficient to

allow the wastewater to be discharged into receiving water,

let alone be reused in the production cycle. For this reason,

Table 6

Equations describing dependence of volume permeate flux on its recovery degre

Feeding solution (nadawa) Function

Permeate after UF on HN membrane �0.0389 l

Permeate after UF on HZ membrane �0.0367 l

Permeate after UFon DSGH-8K membrane �0.0416 l

Permeate after UFon DSCQ membrane �0.0212 l

Permeate after UF on PSf 12 membrane �0.0328 l

Permeate after UF on PSf 15 membrane �0.0309 l

Table 7

Pollution indices of wastewater after it was additionally treated in the system comb

Pollution indices Unit Raw wastewater Wastewater after ultra

Concentration (mg/dm

COD mgO2/dm3 2284 355.0

BOD5 mgO2/dm3 1900 350.0

Total nitrogen mg/dm3 285.0 40.0

Total phosphate mg/dm3 25.5 10.6

the obtained ultrafiltration permeates obtained were addi-

tionally purified by applying reverse osmosis.

Fig. 7 illustrates dependences of the changes in the

volume permeate fluxes on recovery in this process. The

decrease in filtration velocity for HN, HZ and DSGH-8K

membranes was similar and reached 11%, 11% and 13%,

respectively, while for DSCQ, it decreased almost two-fold

and equalled 6% (16% recovery of the permeate). PSf-12

and PSf-25 membranes also displayed a two-fold decrease in

the velocity of wastewater filtration compared to the water

flux.

Similarly to ultrafiltration, the dependence of the volume

permeate flux on its recovery during reverse osmosis was of

logarithmic function (Table 6). The high correlation coeffi-

cients indicate the proper selection of the equations for the

obtained results.

Table 7 shows the final characteristics of the wastewater

treated in the hybrid system of both processes: ultrafiltration

and reverse osmosis. In the first process, the HN membrane

was used because, while it had similar separation properties

to DSCQ, it displayed a decisively better performance.

The results obtained indicate that the wastewater addi-

tionally treated by reverse osmosis can be reused in the

production cycle.

7.3. Treatment of wastewater in the hybrid system of

coagulation and reverse osmosis

Since ultrafiltration (see 7.2) did not produce a satisfac-

tory degree of wastewater purification, it was replaced with

coagulation.

Figs. 8 and 9 show the results of the selection of a

coagulant and its optimum concentration. The highest

removal degree was obtained for PIX at 200% excess of

its basic dosage, i.e. for the concentration of 19.0 g coagu-

lant/g phosphorus. It enabled a decrease in COD and BOD5

by 96.5% and 62.6%, respectively, and amounted to:

e during reverse osmosis applying the SS-10 membrane

Jp = f(x) Jp (m3/m2 s) Coefficient of correlation

n(x) + 0.763 0.8991

n(x) + 0.6763 0.8461

n(x) + 0.6634 0.8159

n(x) + 0.7015 0.8684

n(x) + 0.6221 0.7854

n(x) + 0.5574 0.8372

ining ultrafiltration (HN membrane) and reverse osmosis (SS-10 membrane)

filtration process Wastewater after RO process

3) Retention R (%) Concentration (mg/dm3) Retention R (%)

84.5 4.0 99.8

81.6 3.9 99.8

86.0 2.5 99.1

57.6 0 100.0


Fig. 8. Dependence of COD removal degree on type and dosage of

coagulant. Fig. 9. Dependence of phosphorus removal degree on type and dosage of

coagulant.

662.0 mgO2/dm3 and 200.0 mgO2/dm3. The concentrations

of phosphorus and total nitrogen in the purified wastewater

decreased by 95.7% and 64%, and were 2.5 mg/dm3 and

150 mg/dm3, respectively. Similar removal degrees for both

phosphorus and COD were obtained when using coagulant

ALF with its 200% excess of the basic dosage and the

concentration of 3.45 g coagulant/g phosphorus. PIX, how-

ever, was chosen for further tests because it was more

efficient in removing colour and suspended matter which

significantly affected the effectiveness of reverse osmosis.

The results obtained indicated that wastewater treatment

through coagulation, similar to ultrafiltration, did not enable

sufficient removal of pollutants, and the wastewater could

not be discharged into receiving water. Except for phos-

phorus, all pollution indices exceeded permissible standards.

A comparison of the effectiveness of coagulation and ultra-

filtration showed a similar degree of pollutant removal.

Thus, following coagulation, the wastewater was filtered

on a sand filter in order to remove suspended matter and

subsequently introduced into the osmotic module. The

effectiveness of the wastewater treatment in the system of

chemical precipitation – reverse osmosis – is presented in

Table 8.

The volume permeate flux obtained during reverse osmo-

sis oscillated around 0.43 � 10-5 m3/m2 s and was lower by

37% compared to reverse osmosis of the wastewater after

ultrafiltration treatment (see 7.2).

7.4. Treatment of wastewater in the hybrid system

combining coagulation, ultrafiltration and reverse osmosis

The final stage of the research dealt with treating the

wastewater in the hybrid system combining coagulation,

Table 8

Effectiveness of wastewater treatment in the system combining coagulation and

Pollution indices Unit Raw wastewater Wastewater after coag

Concentration (mg/dm

COD mgO2/dm3 2700 662.0

BOD5 mgO2/dm3 1800 540.0

Total nitrogen mg/dm3 420.0 150.0

Total phosphate mg/dm3 27.8 2.5

ultrafiltration and reverse osmosis. The introduction of

ultrafiltration after the wastewater was treated chemically

and before its additional treatment through reverse osmosis

aimed at obtaining a satisfactory removal degree of pollu-

tants so that the wastewater could be discharged into receiv-

ing water.

The wastewater, after its preliminary coagulation with

200% excess of coagulant PIX (coagulation was carried out

as in 7.3), was subsequently treated on DSCQ, DSGH-K,

DSGH-8K, and PSf-12 and PSf-15 membranes. Due to

technical reasons, HN and HZ membranes were not used

in this system.

The dependence of the volume permeate fluxes on recov-

ery (Fig. 10) were determined and described with mathe-

matical equations (Table 9).

Among the tested membranes, DSCQ displayed the

highest volume permeate flux. The permeate fluxes at

30% recovery egree increased by 25.7% for PSf-12 to

74.6% for DSCQ (DP = 0.3 MPa) and were 0.8 m3/m2 s

and 1.3 m3/m2 s, respectively, compared to the flux obtained

during ultrafiltration of the raw wastewater.

Table 9 shows equations describing dependences of the

volume fluxes on the degree of permeate recovery. They

were of logarithmic function.

The highest removal degrees of tested contaminants were

observed during ultrafiltration carried out on DSCQ and PSf-

15 membranes (Fig. 11). They were: COD, 70.6% and

65.5%; BOD5, 72.7% and 62.5%; total nitrogen, 64% and

67%; phosphorus, 98.2% and 96%, respectively. DSCQ,

however, was considered as more favourable because it

displayed a higher volume permeate flux. As for the remain-

ing membranes, the degrees of contaminant removal were

found to be lower by several per cent.

reverse osmosis

ulation process Wastewater after RO process

3) Retention R (%) Concentration (mg/dm3) Retention R (%)

87.5 4.00 99.9

70.0 3.98 99.3

49.0 1.16 98.8

91.0 0.0 100


Fig. 10. Dependence of volume permeate flux on its recovery during

ultrafiltration of the wastewater coagulated by means of different ultrafil-

tration membranes.

Table 9

Equations describing dependence of volume permeate flux on the degree of

permeate recovery during ultrafiltration of wastewater after coagulation

Membrane

type

Function

Jp = f(x) Jp (m3/m2 s)

Coefficient of

correlation

DSGH-2K �0.0604 ln(x) + 0.9533 0.811

DSGH-8K �0.1546 ln(x) + 2.0314 0.8489

DSCQ �0.407 ln(x) + 4.9369 0.9639

PSf-12% �0 0938 ln(x) + 1.6628 0.9109

PSf-15% �0.0621 ln(x) + 1.0219 0.8524

Fig. 11. Influence of ultrafiltration membrane type on the degree of removal

of contaminants from wastewater.

Fig. 12. Dependences of volume permeate flux on recovery degree in the

process of reverse osmosis (feed-wastewater after coagulation and ultra-

filtration).

The purified wastewater had the following pollution

indices, DSCQ: COD — 159 mgO2/dm3, BOD5 —

130 mgO2/dm3, total nitrogen — 52.7 mg/dm2, phosphorus

— 0.1 mg/dm3; PSf-15: COD — 165 mgO2/dm3, BOD5 —

Table 10

Equations describing the dependence of volume permeate flux on recovery degr

Feeding solution (nadawa) Function

Permeate after UF on DSGH-2K membrane �0.0442

Permeate after UF on DSGH-8K membrane �0.0812

Permeate after UF on DSCQ membrane �0.0173

Permeate after UF on PSf-12 membrane �0.0194

Permeate after UF on PSf-15 membrane �0.0155

140 mgO2/dm3, total nitrogen — 48 mg/dm3, phosphorus —

0.1 mg/dm3. The remaining membranes showed even lower

degrees of contaminant removal. Thus, it can be clearly

noticed that the additional ultrafiltration treatment of the

wastewater after coagulation did not produce the desired

effect and the wastewater still could not be discharged into

receiving water. Except for phosphorus, all determined

pollution indices exceeded permissible standards.

Therefore, the wastewater was additionally treated apply-

ing reverse osmosis. The process was carried out at

a pressure of 2.0 MPa and a stirring rate of 200 rpm.

Fig. 12 illustrates the dependences of the changes in the

volume permeate fluxes on the recovery degree when the

wastewater treated with high-pressure filtration was pre-

treated via coagulation and ultrafiltration on different mem-

branes. The equations describing this dependence are pre-

sented in Table 10.

It has been found that the highest volume permeate flux

(0.67 m3/m2 s) (16% of permeate recovery) was obtained in

the process of reverse osmosis when the wastewater was

filtered after coagulation and ultrafiltration applying the

DSCQ membrane.

Below is presented the compilation of results of waste-

water treatment effectiveness in the hybrid system combin-

ing coagulation, ultrafiltration (on DSCQ) and reverse

osmosis (Table 11).

The obtained results showed that the wastewater purified

in this system can be reused in the production cycle.

Fig. 13 compares the volume permeate fluxes obtained in

reverse osmosis of the wastewater pre-treated by various

methods: ultrafiltration, coagulation and in the system com-

bining both these processes.

ee in the process of reverse osmosis

Jp = f(x) Jp (m3/m2 s) Coefficient of correlation

ln(x) + 0.884 0.9654

ln(x) + 1.0448 0.9128

ln(x) + 0.8129 0.8989

ln(x) + 0.628 0.9351

ln(x) + 0.6368 0.9351


Table 11

Effectiveness of wastewater treatment in the system combining coagulation, ultrafiltration (on DSCQ) and reverse osmosis

Pollution indices Unit Raw wastewater Wastewater after

coagulation process

Wastewater after

ultrafiltration process

Wastewater after

RO process

Concentration

(mg/dm3)

Retention

R (%)

Concentration

(mg/dm3)

Retention

R (%)

Concentration

(mg/dm3)

Retention

R (%)

COD mgO2/dm3 2839 542.0 80.1 159.0 94.4 3.5 99.9

BOD5 mgO2/dm3 1890 490.0 74.1 130.0 93.1 3.1 99.8

Total nitrogen mg/dm3 447.5 144.9 67.6 52.7 88.2 0.9 99.7

Total phosphate mg/dm3 27.6 3.4 87.7 0.1 99.6 0.0 100

Fig. 13. Dependence of volume permeate flux on recovery degree of

permeate in the process of reverse osmosis of the wastewater pre-treated

by various methods.

It has been found that after 6 h of reverse osmosis at 16%

permeate recovery the volume permeate fluxes obtained

during filtration of the wastewater pre-treated in the unit

process of ultrafiltration and in the system combining coa-

gulation and ultrafiltration were similar and amounted to

0.66 � 10�5 m3/m2 s and 0.68 � 10�5 m3/m2 s. It has also

been observed that the decreases in volume fluxes were

negligible and reached 5%.

A decisively lower filtration velocity was obtained in the

system in which the wastewater underwent high-pressure

filtration after it had been pre-treated in the process of

coagulation and subsequent filtration on a sand bed. The

obtained volume permeate flux was lower by 37% and

oscillated around 0.43 � 10�5 m3/m2 s. This may probably

be explained by the presence of suspended matter in the

feed, which was not removed to a sufficient extent during

filtration on the sand bed.

8. Conclusions

The investigations showed that the pressure driven mem-

brane operations can be applied to the treatment of the

wastewater from the meat industry. It has been found that

the degree of wastewater purification, both after unit ultra-

filtration and coagulation, as well as combined together, is

too low for the wastewater to be discharged into receiving

water. Additional treatment with reverse osmosis enables it

to be reused in the production cycle.

The system combining ultrafiltration and reverse osmosis

was found to be the most favourable. The treatment effec-

tiveness and the volume permeate flux obtained during

reverse osmosis were similar to the effectiveness and filtra-

tion velocity obtained in RO in the hybrid system of coa-

gulation, ultrafiltration and reverse osmosis.

The application of additional treatment of coagulation

prior to ultrafiltration did not enable a sufficient removal of

contaminant load and the wastewater could not be dis-

charged into receiving water.

In the case of both approaches, the additional treatment of

the wastewater in the RO process made reuse in the produc-

tion cycle possible.

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