An economic

assessment of

proteins recovery

from fish meal

effluents by

ultrafiltration

Maria Dina Afonsoa,

Javier Ferrerb and

Rodrigo Borquezb*&

aChemical Engineering Department, Instituto

Superior Tecnico, 1049-001 Lisbon, PortugalbChemical Engineering Department, Universidad de

Concepcion, POB 160-C, Correo 3, Concepcion,

Chile (Tel.: C56-41-204534; fax: C56-41-247491;

e-mail: rborquez@diq.udec.cl)

The main objective of this work was to assess the technical

and economical feasibility of proteins recovery from fish

meal effluents using crossflow membrane technology,

namely, ultrafiltration (UF) and nanofiltration (NF).

Mackerel processing effluents were pre-treated by micro-

filtration (MF cartridges battery of 80, 20 and 5 mm pore size)

followed by UF (membrane Carbosep M2, 15 kDa MWCO)

or NF (membrane Kerasep NanoN01A, 1 kDa MWCO). A

suitable treatment for the fish meal effluents consisted of a

MF pre-treatment followed by UF operating at 4 bar, 4 m/s,

natural pH and ambient temperature. UF yielded an average

permeation flux of 28 l/(m2 h),1 and 62% proteins rejection

for a volume reduction factor of 2.3. Both membranes fully

recovered their original permeabilities through an acidic/

basic washing cycle. The economic assessment of proteins

recovery from fish meal effluents by UF was accomplished

0924-2244/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.doi:10.1016/j.tifs.2004.02.008

* Corresponding author.1 1 l/(h m2)Z2.78!10K7 m/s.

for a production of 544 ton/yr of fish meal (66% protein

content), yielding a net present worth of 160!103 US$,

interest rate of return of 17% and payback time of 8 years.

q 2004 Elsevier Ltd. All rights reserved.

IntroductionWastewaters generated by fish meal industries contain a

high organic load and present high turbidity, strong greenish

yellow colour, and stinky odour. Therefore, they should not

be discharged without a suitable treatment in order to

prevent negative environmental impacts, and allow the

recovery of high added value products. Typically, a plant of

100 ton fish/h capacity generates 10–40 m3/h effluent with

protein loads of 0.5–20 g/l. However, protein concentration

is often too low to be economically recovered by classical

processes, such as evaporation or spray drying. An

alternative treatment for fish processing wastewaters is the

use of membrane separation processes, in particular

ultrafiltration (UF) and nanofiltration (NF). The advantages

of these processes over the conventional coagulation/floccu-

lation process are the good quality of the permeate which can

be recycled into the fish processing plant, as well as the

simultaneous recovery and concentration of soluble proteins.

The recovery of proteins from fisheries effluents by

membrane separation processes has been studied by several

authors (Afonso & Borquez, 2002a,b; Huang & Morrisey,

1998; Lin, Park, & Morrisey, 1995; Paredes & Borquez,

2001; Perez & Borquez, 1998). Membrane applications in

the seafood industry emerged in the early 1980s but the

number of published studies has shown a significant

increase in recent years. Almas (1985), Jaouen and

Quemeneur (1992) and Afonso and Borquez (2002a)

presented reviews on interesting applications of crossflow

membrane technology in the fisheries industry, e.g.

wastewater treatment and proteins recovery, production of

fish protein concentrates and hydrolysates, and down-stream

processing of biochemicals from marine raw materials. Lin

et al. (1995) pointed out that the wastewater from the first

washing in surimi production contains the highest concen-

trations of protein, non-protein nitrogen, fat, and ash,

besides a strong fishy odour, although it constitutes only

1.5% of total wastewater. Water recycle has become

important to surimi producers due to rising utility costs,

limited water resources, and pollution problems associated

to disposal. Jaouen and Quemeneur (1992) studied surimi

Trends in Food Science & Technology 15 (2004) 506–512

Viewpoint

M.D. Afonso et al. / Trends in Food Science & Technology 15 (2004) 506–512 507

wastewaters treatment, using different types of UF mem-

branes, namely, cellulose, polysulphone, and zirconium

oxide (10 kDa!MWCO!100 kDa). They analysed the

contribution of proteins adsorption upon membrane fouling

and membrane performance (permeation flux decline and

regeneration after cleaning) against the operating conditions

(transmembrane pressure and crossflow velocity). Huang

and Morrisey (1998) investigated the development of

membrane fouling during MF of surimi wash water with

the aim of recovering suspended myofibrillar proteins.

One of the interesting features of UF and NF in

comparison with other concentration processes lies in the

fact that water separation is energy efficient, since it is

carried out without phase change. Comparative energy

analyses of different concentration processes pointed out to

a theoretical ratio of 1:1100 between UF and single-stage

evaporation (Jaouen & Quemeneur, 1992). Nevertheless,

energy consumption is always higher than the theoretical

minimum, because crossflow velocity inside the membranes

must be high enough to minimise concentration polaris-

ation. This leads to a pressure drop increase (%25% of

transmembrane pressure), thus a higher pumping energy is

required and the actual energy ratio may increase up to two

orders of magnitude (ca. 200-fold in the present study).

Preliminary testing is essential to identify suitable

operating conditions (transmembrane pressure, crossflow

velocity and volume reduction factor), which will determine

the membrane type and pumps specifications, two important

parcels of the investment cost. Within this scope, the

purpose of this study was to determine suitable operating

conditions for UF/NF of fish meal effluents, with respect to

the permeation flux and proteins rejection, and thereby

assess the respective economic feasibility.

Performance of pressure-driven membrane processesConcentration polarisation and fouling (Andres,Alvarez, & Coca, 1991)

The permeation flux decline during pressure-driven

membrane processes (MF, UF, NF and reverse osmosis)

results from concentration polarisation and/or membrane

fouling phenomena.

Concentration polarisation is due to the membrane

permselectivity. Solutes are dragged to the membrane

surface by convective transport of the solvent, some of

which may pass through the membrane, whereas rejected

solutes accumulate in the membrane vicinity and may form

fairly viscous and gelatinous layers. The formation of a gel-

layer or secondary membrane reduces the permeation flux

and may also hinder the passage of low molecular weight

solutes.

Membrane fouling results from the deposition of

submicron particles, as well as crystallisation, precipitation

and adsorption of solutes on the membrane surface or inside

its pores. Fouling may be irreversible (e.g. proteins

adsorption) and its extent mainly depends on the membrane

nature and feed characteristics. The first means for

controlling this phenomenon is an adequate feed pre-

treatment and a careful choice of the membrane type.

Moreover, a module design providing suitable hydrodyn-

amic conditions for the particular application should be

chosen.

Effect of operating conditionsCrossflow velocity. Permeation flux increases for

increasing crossflow velocities, since the polarised layer

thickness decreases with increasing ‘fluid erosion’. How-

ever, it is well known that high crossflow velocities may

cause proteins denaturation and rupture, due to excessive

shear stress (Belhocine, Grib, Abdessmed, Comeau, &

Mameri, 1998; Huang & Morrisey, 1998; Lin et al., 1995).

Transmembrane pressure. Although the permeation flux

increases with transmembrane pressure increase at first, the

polarised layer thickness and the resistance to permeation

also increase, which may lead to a flux plateau for a given

pressure. The permeation flux cannot be further increased

once gel polarisation occurs and it may eventually decrease

with further pressure increase due to compaction of the gel

layer (Andres et al., 1991; Huang & Morrisey, 1998; Lin et

al., 1995).

Temperature. The membrane hydraulic permeability,

lpZJw/DPm, increases with the temperature increase due to

the viscosity decrease, whereas the intrinsic membrane

resistance, RZDPm=ðmJwÞ remains constant (Huang &

Morrisey, 1998). Usually, the permeation flux increases

3–4% per degree of temperature rise. The risk of denaturing

proteins contained in fisheries effluents advises the use of

moderate-low temperatures (Jaouen & Quemeneur, 1992).

Feed composition. Steady state flux drops with increas-

ing feed concentration, as more solute molecules accumu-

late in the polarised layer, increasing its thickness and

resistance to permeation. Obviously, concentration polaris-

ation cannot be fully eliminated in a concentration process,

it can only be minimised, e.g. by choosing suitable operating

conditions (Andres et al., 1991; Huang & Morrisey, 1998;

Lin et al., 1995; Tarleton & Wakeman, 1993, 1994;

Urkiaga, 1998).

Other feed characteristics, which affect membrane

performance, are the ionic strength and pH. The effects of

these parameters vary for different feed solutions and

membrane types (Huang & Morrisey, 1998; Tarleton &

Wakeman, 1993, 1994). They lead to changes in the

molecular conformation and/or aggregation of proteins,

ruling their adsorption on the membrane. The proteins

present minimal solubility near the isoelectric point, thus

promoting membrane fouling (Huang & Morrisey, 1998;

Lin et al., 1995; Paredes & Borquez, 2001).

Physical and chemical properties of the substances

present in the feed also play a role on the membrane

performance (Tarleton & Wakeman, 1993; Urkiaga, 1998).

For instance, particles size distribution determines the

occurrence of fouling inside the membrane pores. Moreover,

the solute geometry also affects the separation performance,

Fig. 1. Schematic diagram of Rhodia pilot unit.

M.D. Afonso et al. / Trends in Food Science & Technology 15 (2004) 506–512508

as well as its electrical charge, as this property may determine

the solute affinity for the membrane (adsorption).

At present, there is no general theory to predict

accurately the performance of UF/NF processes. NF can

be envisaged as a ‘tight’ UF, though it is also similar to

reverse osmosis as for the role of electrostatic forces in salts

separation, which are negligible for common UF.

Table 1. Characteristics of membranes Carbosep M2 andKerasep NanoN01A

Membrane Carbosep M2 Kerasep NanoN01A

Support Carbon Monolith Al2O3–TiO2

Membrane activelayer

ZrO2–TiO2 ZrO2 or TiO2

External diameter/length (mm)

10/1200 20/856

Number of channels 1 19Channel insidediameter (mm)

6 2.5

Membrane area (m2) 0.023 0.128pH 0–14 0–14Temperature Up to 100 8C Up to 100 8C

Materials and methodsExperimental set-up

A schematic diagram of the experimental set-up is shown

in Fig. 1. It consists of a pilot unit assembled by Rhodia and

equipped either with a Carbosep SC1 or a Kerasep K01

module. Valves V1 and V4 (purges) were kept closed,

whilst valve V2 remained open (closed loop). The

transmembrane pressure and feed flow rate were regulated

through valve V3 and the pump speed regulator.

A MF cartridges battery (Omnifilters of decreasing pore

sizes: 80, 20 and 5 mm) was used for the fish meal effluents

pre-treatment. The membranes tested (Rhodia-Orelis) were

Carbosep M2 (UF), monotubular, 15 kDa MWCO, with an

active layer of ZrO2–TiO2 on a carbon support, and Kerasep

NanoN01A (NF), tubular (19 channels), 1 kDa MWCO,

with an active layer of ZrO2 or TiO2 on a ceramic support.

Both membranes present high chemical and mechanical

resistances as shown in Table 1.

Pressure Up to 15 bar Up to10 barBurst pressure – 50 bar minimumSteam sterilisation at121 8C

Yes Yes

Sterilisation byoxidants

Yes Yes

Solvents Unaffected UnaffectedRadiation Unaffected –

Experimental procedureDistilled water permeated the UF and NF membranes at

transmembrane pressures in the range of 2–5 bar, in order to

measure the corresponding water permeation fluxes, Jw, and

determine the membranes hydraulic permeabilities, lp.

The effluents were collected from a fish meal factory

located in Talcahuano, Chile (Fig. 2), processing mackerel

by the time of the samples collection. Sample 1 was

collected from the original effluent (effluent from the gases

washing mixed with wastewaters from equipments spillings,

leakages and washings, piping leakages, evaporators con-

densates, etc.), whereas sample 2 was collected from the

dilute effluent (original effluent mixed with the refrigeration

water from the condenser prior to final disposal).

A gear pump pumped the effluents to the MF cartridges.

The microfiltrated effluents were kept in the refrigerator at

4 8C, and were brought to the ambient temperature before

being processed by UF/NF. Samples from both effluents,

Fig. 2. Schematic flowsheet of fish meal and oil manufacturing process (Almas, 1985).

M.D. Afonso et al. / Trends in Food Science & Technology 15 (2004) 506–512 509

before and after MF, were analysed for Total Solids (Drying

at 103–105 8C), Volatile Solids (Ignition at 550-600 8C),

Total Proteins (Organic Nitrogen—Kjeldahl distillation

method), Oil and Grease (Soxhlet extraction with diethyl

ether), and pH at 25 8C (ASTM, 1964).

UF/NF of microfiltrated fish meal effluents were

conducted in total recycle mode (concentrate and permeate

recycle into the feed tank to keep the feed composition

nearly constant) at 3–4 bar and crossflow velocity of

3–4 m/s, based on the manufacturer recommendations for

UF and due to pump limitations for NF (P!5 bar). The

concentration of the microfiltrated fish meal effluents by

UF/NF was carried out at 4 bar and 4 m/s, the most suitable

operating conditions determined for total recycle. Both

types of experiments (total recycle and concentration

modes) run at ambient temperature and natural pH. The

permeation flux, J, was measured throughout the exper-

iments, and samples from the concentrate and permeate

were collected for analysis, to determine the rejections, R,

with respect to the aforementioned parameters:

RZ ð1KCpermeate=CfeedÞ100%:

Results and discussionEffluents pre-treatment by MF

The characterisation of fish meal effluents before and

after the pre-treatment by MF is presented in Table 2.

Table 2. Characterisation of fish meal effluents, before and after microfi20 8C)

Sample 1 (original effluent)

Effluent MF effluent R (%)

Total solids (g/l) 24.0 21.0 12Volatile solids (g/l) 18.9 14.8 22Total proteins (g/l) 15.5 12.5 19Oil and grease (g/l) 1.21 0.07 94pH at 25 8C 6.5 6.5 –

The data show that a MF battery down to 5 mm pore size is

an efficient pre-treatment for fisheries effluents, as it

removes a significant fraction of oil and grease, which

otherwise could adsorb onto UF/NF membranes surfaces

leading to their permeation fluxes drop (membrane fouling).

UF/NF of microfiltrated effluentsThe hydraulic permeabilities of membranes Carbosep

M2 and Kerasep NanoN01A at ambient temperature were

37.5 and 32.9 l/(m2 h bar), respectively.

The data of UF/NF of fish meal effluents in total recycle

mode are displayed in Tables 3 and 4. The proteins rejection

in UF ranged 49–62% depending on the operating

conditions, whilst it is nearly constant, 66%, in NF. In

both cases, the highest proteins rejections were achieved at a

transmembrane pressure of 4 bar and a crossflow velocity of

4 m/s, therefore subsequent concentration runs were per-

formed at these operating conditions. For total recycle, the

permeation fluxes of UF/NF membranes decreased instantly

and steeply with respect to Jw, most likely due to adsorption

of proteins on the membranes surfaces and/or the formation

of a secondary (dynamic) membrane on their top layers. An

identical trend was also observed for the concentration runs

(Fig. 3). Despite the continuous permeation flux drop with

the volume reduction factor (VRF) increase, a trend to reach

a threshold was identified for both membranes at VRFR2.

ltration (average permeation flux of MF: 450 l/(m2 h) at 1 bar and

Sample 2 (dilute effluent)

Effluent MF effluent R (%)

24.4 24.0 28.2 7.2 125.7 5.1 110.9 0.5 446.3 6.3 –

Fig. 3. Permeation flux versus volume reduction factor (O-CarbosepM2 (15 kDa), 4 bar, 4 m/s, pHZ6.5, 21 8C, Cproteins feedZ12.5 g/l;D-Kerasep NanoN01A (1 kDa), 4 bar, 4 m/s, pHZ6.3, 25 8C,

Cproteins feedZ5.1 g/l).

Table 3. Ultrafiltration of microfiltrated effluent (membraneCarbosep M2, sample 1: Cproteins feedZ12.5 g/l, pHZ6.5, TZ21 8C)

DPm (bar) v (m/s) J (l/(m2 h)) Rproteins (%)

3 3 30.1 493 4 31.8 564 3 37.1 504 4 38.9 62

M.D. Afonso et al. / Trends in Food Science & Technology 15 (2004) 506–512510

Mameri et al. (1996) observed similar behaviours for the

permeation flux decline of a multi-channel ceramic

membrane.

The ‘overall similarity’ of UF and NF membranes

performance (permeation flux and proteins rejection), and

its ‘nearly constancy’ regardless the operating conditions,

corroborates the hypothesis of formation of a gel layer or

dynamic membrane on the inorganic membranes which

controls the separation process, dampening the operating

conditions effect.

The initial hydraulic permeabilities of UF/NF mem-

branes could not be restored by simple water washing.

However, they were fully recovered after an acid/basic

washing cycle. The irreversibility of the permeation flux

drop (with respect to Jw) was mainly due to membrane

fouling by proteins adsorption or formation of a sticky gel

layer on the membranes rather than typical concentration

polarisation (reversible phenomenon).

Industrial scale up and economic assessment(Afonso, Jaber, & Mohsen, 2004; Al-Wazzan, Safar,

Ebrahim, Burney, & Mesri, 2002; Filteau & Moss, 1997;

Harris, 1985; Jaouen & Quemeneur, 1992; Mameri et al.,

1996; Poullikkas, 2001; Van der Bruggen, Everaert, Wilms,

& Vandecasteele 2001;)

In this study, the highest permeation flux was achieved

by UF membrane Carbosep M2 at 4 bar, 4 m/s and ambient

temperature, after pre-treatment of fish meal effluents by

MF, thus the industrial scale up and economic assessment

focused on this situation. A treatment plant handling

10 m3/h of fish meal effluent containing 24.0 g/l of solids

and 15.5 g/l of proteins would generate 1 m3/h of

Table 4. Nanofiltration of microfiltrated effluent (membraneKerasep NanoN01A, sample 2: Cproteins feedZ5.1 g/l, pHZ6.3,TZ25 8C)

DPm (bar) v (m/s) J (l/(m2 h)) Rproteins

(%)a

3 3 22.3 663 4 25.7 634 3 26.7 664 4 32.0 66

a Proteins analysis is controversial as it measures organicnitrogen irrespective to MW ([Proteins]Z6.25([Organic N]).Thus, in this table, Rproteins actually refers to the rejection ofN-compounds with MWOMWCO (1 kDa). The permeatedcompounds (MW!1 kDa) comprise aminoacids and other non-protein nitrogen.

concentrate containing 170 g/l of solids and 112 g/l of

proteins (66% protein content, dry basis) (Fig. 4). The

concentrate stream would be recycled to the fish meal

processing through the evaporators, the inlet of which

should contain a protein concentration exceeding 80 g/l.

The plant would operate 200 days per year and 16 h daily.

The expected project life is 10 years and a linear

depreciation of the fixed-capital investment was assumed,

vanishing by the end of the tenth year. The treatment plant

specifications and costs are summarised in Tables 5 and 6.

Although the maximum VRF reached in this work was

2.3, it is clear from Fig. 3 that a flux plateau of 28 l/(m2 h)

was reached for VRFR2. To calculate the membrane area

required, a safety factor of 90% was assumed for the

average permeation flux at VRF of 10: AmZQp/JpZ9000

l/h/25 l/(m2 h)Z360 m2. The membranes price was provided

by Rhodia, Argentina: 1000 US$/m2!360 m2Z360,000

US$. Bearing in mind that a Carbosep M2 membrane has a

permeation area of 0.023 m2 and a cross-section area of

2.83!10K5 m2, 15,652 membranes would be required

corresponding to a total cross-section area of 0.443 m2 and

a total flow rate of 1.77 m3/s (6373 m3/h) at a crossflow

velocity of 4 m/s. Five pumps (and 5 spare ones) providing

maximum flow rate of 1500 m3/h and maximum pressure of

8 bar would match most of the plant energy requirements

(10!15,385 US$Z153,850 US$). The manufacture of the

pressure vessels (UF modules) and the purchase of valves,

piping and accessories was estimated as 143,810 US$. The

flux of the rotary filter was assumed to be half of the MF flux

(Table 2), i.e. 225 l/(m2 h). A standard rotary filter of 10 m2

area and 5 mm pore size working at 5 rpm (90,000 US$) would

be suitable to handle 10 m3/h offish meal effluent. To estimate

the feed tank capacity, 10 m3 (11,250 US$), a filling/drainage

time of 30 min was assumed, which is suitable to fill up and

activate the spare feed pumps in case of failure. The working

capital was assumed to be 10% of the fixed-capital

investment: 758,910 US$!10%Z75,891 US$. The revenue

from the fish meal produced (treatment plant concentrate after

evaporation) would be 0.170 ton/h!(16!200 h/yr)!600

US$/tonZ326,400 US$/yr.

The operating costs include membrane replacement,

chemicals, energy, labour, maintenance and depreciation.

The membrane replacement would take place every 5 years

Fig. 4. Treatment plant envisaged for the economic assessment.

M.D. Afonso et al. / Trends in Food Science & Technology 15 (2004) 506–512 511

(hence only once in 10 years), which is the common life-

span of inorganic membranes: 360,000 US$/10 yrZ36,000

US$/yr. The cost of chemicals for membrane cleaning

(NaOH 10 g/l, HNO3 5 ml/l) would be ð20 m3=d!10 kg=

m3 !0:25 US$=kgC20 m3=d!5 l=m3 !0:40 US$=lÞ! 200

d=yrZ18;000 US$=yr: The electric power to provide a

transmembrane pressure of 4 bar and to make-up for the

pressure losses due to friction at a recirculation velocity of

4 m/s would be zJpAmDPmCnAcsDPf Zð25!10K3=3600Þ

m=s ! 360 m2 ! 4 ! 105 PaC4 m=s!0:443 m2 ! 1 !105 PaZ1C177 kWz200 kW: The associated energy

cost would be 200 kW ! ð16!200 h=yrÞ ! 0:035

Table 5. Treatment plant specifications

Feed 10 m3/h of fish meal effluent; 24.0 g/lsolids; 15.5 g/l proteins

Concentrate 1 m3/h; 170 g/l solids; 112 g/l proteinsPermeate 9 m3/h; 7.8 g/l solids; 4.8 g/l proteinsExpected project life 10 yearsOperating time 200 days per year, two daily shifts of

8 hMembraneperformance and area

RTSZ63%; RproteinsZ62% (data at VRFZ2.3); JpZ25 l/(m2 h); AmZ360 m2

UF membranes life-span

5 years

Recirculation pumps PmaxZ8 bar; QmaxZ1500 m3/h

Rotary filter 10 m2, 5 mm, 5 rpmTank capacity 10 m3

Material ofconstruction

316 stainless steel

US$=ðkW hÞZ22; 400 US$=yr: Assuming two technicians

for the plant operation and quality control, the labour

cost would be (2!8!200 h/yr)!5 US$/hZ16,000

US$/yr. The maintenance was estimated as 5% of the

fixed-capital investment: 758,910 US$!5%Z37,946

US$/yr. The depreciation was assumed to be linear:

75,8910 US$!10%Z75,891 US$/yr. Membrane replace-

ment is one of the largest cost factor, in agreement

with other published works (Harris, 1985; Jaouen &

Quemeneur, 1992).

Table 6. Treatment plant costs

Fixed capital costs (US$)UF membranes 360,000UF modules, valves, piping and accessories 143,810Pumps 153,850Rotary filter 90,000Tank 11,250Working capital (US$)10% of fixed-capital costs 75,891Operating costs (US$/yr)Membrane replacement (20% annually) 36,000Chemicals (NaOH, HNO3) 18,000Electrical power (200 kW) 22,400Labour 16,000Maintenance 37,946Depreciation 75,891Revenue (US$/yr)170 kg/h of fish meal (66% protein content) 326,400

Table 7. Cash flow analysis and economic scenario of treatmentplant project

Cash flow analysis

Net present worth 160!103 US$Interest rate of return 17%Payback time 8 yearsEconomic scenario

Fish meal (66% proteincontent)

600 US$/ton

Discounting interest rate 12%Tax rate 15%

M.D. Afonso et al. / Trends in Food Science & Technology 15 (2004) 506–512512

As shown in Table 7, the project yielded a net present

worth2 of 160!103 US$, an interest rate of return of 17%,

and 8 years payback time for a fish meal price of 600 US$/

ton. The economic assessment revealed that the project is

economically feasible, i.e. the treatment plant pays for itself

if all assumptions hold. Moreover, a stricter legislation on

fish meal effluents disposal will provide further incentives to

the implementation of membrane processes for resources

recovery and reuse.

ConclusionsThe results obtained in this work showed that UF is a

promising separation process for the recovery and concen-

tration of proteins from fish meal effluents. A suitable

treatment for fish meal effluents consisted of a MF pre-

treatment (5 mm pore size), followed by UF (membrane

Carbosep M2, 15 kDa MWCO), operating at 4 bar and

4 m/s, which yielded a permeation flux of 28 l/(m2 h) and

proteins rejection of 62% for a volume reduction factor of

2.3. The integrated process comprising MF pre-treatment

and UF would enable 69% recovery of proteins allowing for

the productivity and revenue rise, besides a significant

reduction of environmental burdens. The economic assess-

ment yielded a net present worth of 160!103 US$, an

interest rate of return of 17%, and 8 years payback time.

Thus, UF of fish meal effluents is technically and

economically feasible for proteins recovery and pollution

reduction.

AcknowledgementsThis work was partly supported by the Regional

Government of Bio Bio, Chile, within the framework of

graduation thesis with regional impact. We thank the

technical staff of the Chemical Engineering Department of

Concepcion University for their support throughout the

experiments and chemical analysis, and Sociedad Pesquera

Landes for the samples collection and flowsheet provision.

2 NPWZP10

nZ0ðCFKIÞnð1CDRÞn ;

P10nZ0

ðCFKIÞnð1CIRRÞn Z0;

PPBTnZ0

ðCFKIÞnð1CDRÞn Z0 US$;

being NPW—net present worth; PBT—payback time; IRR—interestrate of return; DR—discounting interest rate; CF—present value ofcash flow after taxes; I—present value of total investment (fixed-capitalCworking capital); n—consecutive year number fromproject start.

References

Afonso, M. D., & Borquez, R. (2002a). Review of the treatment ofseafood processing wastewaters and recovery of proteins therein bymembrane separation processes—prospects of the ultrafiltration ofwastewaters from the fish meal industry. Desalination, 142, 29–45.

Afonso, M. D., & Borquez, R. (2002b). Nanofiltration of wastewatersfrom the fish meal industry. Desalination, 151, 131–138.

Afonso, M. D., Jaber, J. O., & Mohsen, M. S. (2004). Brackishgroundwater treatment by reverse osmosis in Jordan. Desalina-tion, 164, 157–161.

Almas, K. A. (1985). Applications of crossflow membrane technol-ogy in the fishing industry. Desalination, 53, 167–180.

Al-Wazzan, Y., Safar, M., Ebrahim, S., Burney, N., & Mesri, A.(2002). Desalting of subsurface water using spiral-wound reverseosmosis (RO) system: technical and economic assessment.Desalination, 143, 21–28.

American Society for Testing and Materials (1964). 1964 Book ofASTM standards with related material, Part 23—industrial water.Baltimore, USA: Atmospheric Analysis.

Andres, L. J., Alvarez, R., & Coca, J. (1991). Polarizacion deconcentracion en los procesos con membranas: aplicacion a laultrafiltracion. Ingenierıa Quımica, 263, 211–219.

Belhocine, D., Grib, H., Abdessmed, D., Comeau, Y., & Mameri, N.(1998). Optimization of plasma proteins concentration byultrafiltration. Journal of Membrane Science, 142, 159–171.

Filteau, G., & Moss, P. (1997). Ultra-low pressure RO membranes: ananalysis of performance and cost. Desalination, 113, 147–152.

Harris, J. L. (1985). Protein recovery from wheat starch factoryeffluent by ultrafiltration: an economic appraisal. Food andTechnology in Australia, 37(12), 564–567.

Huang, L., & Morrisey, M. T. (1998). Fouling of membranes duringmicrofiltration of surimi wash water: roles of pore blocking andsurfacecake formation. JournalofMembraneScience,144, 113–123.

Jaouen, P.,& Quemeneur, F. (1992).Membrane filtration for waste-waterprotein recovery. In G. M. Hall (Ed.), Fish processing technology (pp.212–248). London: Blackie Academic and Professional.

Lin, T. M., Park, J. W., & Morrisey, M. T. (1995). Recovered proteinand reconditioned water from surimi processing waste. Journalof Food Science, 60(1), 4–9.

Mameri, N., Abdessemed, D., Belhocine, D., Lounici, H., Gavach,C., Sandeaux, J., & Sandeaux, R. (1996). Treatment of fisherywashing water by ultrafiltration. Journal of Chemical Technologyand Biotechnology, 67(2), 169–175.

Paredes, H., & Borquez, R. (2001). Development of an alternativetreatment system for fishing industry waste waters usingultrafiltration. Latin American Applied Research, 31, 359–365.

Perez, H. & Borquez, R. (1998). Protein recovery from fishingindustry waste waters using ultrafiltration and microfiltration.Annals of International Symposium on Filtration and Separation,Las Palmas de Gran Canaria.

Poullikkas, A. (2001). Optimization algorithm for reverse osmosisdesalination economics. Desalination, 133, 75–81.

Tarleton, E. S., & Wakeman, R. J. (1993). Understanding flux declinein crossflow microfiltration: Part I—effects of particle and poresize. Transactions of the Institution of Chemical Engineers, PartA, 71, 399–410.

Tarleton, E. S., & Wakeman, R. J. (1994). Understanding flux declinein crossflow microfiltration: Part II—effects of process par-ameters. Transactions of the Institution of Chemical Engineers,Part A, 72, 431–440.

Urkiaga, A. (1998). Metodos de caracterizacion de membranas.Ingenierıa Quımica, 342, 191–198.

Van der Bruggen, B., Everaert, K., Wilms, D., & Vandecasteele, C.(2001). Application of nanofiltration for removal of pesticides,nitrate and hardness from ground water: rejection properties andeconomic evaluation. Journal of Membrane Science, 193, 239–248.