Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
Industrial Wastewater – Potentials for Cost-Reduction Through Inplant Measures
Prof. Dr.-Ing. Ute Austermann-Haun
Fachhochschule Lippe und Hoexter, Detmold, Germany.
Wastewater treatment is expensive. Thus, one central target must be the prevention of
wastewater production. This can be achieved by the training of the staff, by water-saving
fittings, by dry cleaning instead of wet cleaning, or by the multiple usage of water.
However, not only the reduction of water consumption, but also the reduction of
wastewater loads is crucial for the reduction of costs, as in most cases highly polluted
wastewater means that parts of the product (milk, fat, beer e.g.) are at the wrong place.
All measures start with registering all water consumption sites in the respective company.
Then, specific index parameters like the specific water consumption or specific loads are
determined for each step of production, which gives an overview of the company. Every
process stage must be observed separately. The comparison with reference literature will
already show at which point in the company the water losses are extreme and at which
point in the company water saving steps will have to start.
Several examples are presented, for instance breweries or companies from the paper and
beverage industries.
1
Process-integrated Environment Protection
Process-integrated measures of environmental protection pursue several aims:
-
Minimisation of the consumption of resources and energy, with water being one of
these resources,
-
Higher product yield and improved product quality, if possible,
-
Reduction of the waste to be disposed, of the wastewater amounts, and of the
wastewater loads.
The target must be to achieve economically sound solutions with these measures.
The reduction of the wastewater amount and wastewater loads through in-plant
measures is useful, particularly prior to the planning of a wastewater treatment plant or a
preliminary treatment plant. With these measures, the costs and fees for the water
supply, the wastewater treatment, and the investment costs for wastewater treatment can
be reduced. Moreover, they lead to an improvement of the general yield through the
reduction of production losses or to the saving of operation materials.
1
Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
Production-integrated measures have different emphases (Rosenwinkel und Nagy, 2000):
-
Multiple use of non-avoidable process water, washing water, and rinsing water
-
Closure of cycles
-
Substance regain
-
Utilisation
The crucial prerequisite for any efficient production-integrated environmental protection is
always the following procedure: Creation of a production scheme with all locations where
wastewater is produced. Creation of a water balance with careful stock-taking of the
current situation. To achieve this, it is often necessary to install water-meters, to take
wastewater samples, and to analyse the samples in regard to their organic loads. The
production-related water amounts and load gained in this way – for instance L/t fruit,
m³/purification cycle, m³/1000 L beverage – must first be compared with data from
reference literature to produce initial clues on how big the saving potential is. Afterwards,
suggestions for in-plant measures can be formulated. The experiences of different
companies and industrial branches are transferable here (water-saving fittings, lye regain,
etc.) Analyses of the economic feasibility will then show the potential of the productionintegrated environmental protection measures.
General options are the employment of production technologies with low or even no usage
of water (air cooling instead of water cooling, dry cleaning), resource regain or retention
from the wastewater (gaining of animal feed from pomace and marc), and the installation
of circuits, that is the multiple usage (flume water and washing water circuit, lye circuit,
cooling water cycles, utilisation of exhaust vapours in the flume water cycle).
A simple measure which can also be realised in small companies is the filtration of the
freshly produced wastewater, for instance in the production of French fries, to gain animal
feed and to reduce the wastewater load.
Table 1 shows some simple and effective measures from the soft drinks industry as
example of the beverage industry in general.
2
Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
Table 1. In-plant measures (Austermann-Haun and Rosenwinkel, 2000; ATV-M766,
1999)
General operation
Water pipes and fittings as
well as fresh-water usage
Yard and vehicle cleaning
Fruit and vegetable transport
and washing
Aroma and concentrate unit
Fining
Filtration
Briefing of the staff, creation of a sense of responsibility; explaining
the saving measures and giving advice on how these measures can
be realised;
Prevention of production losses;
Installation and control of water meters at all crucial company
implements (water amount balance));
Repair and removal of leaking implements and leakages;
Planning of production and cleaning sequences;
Recording and evaluation of relevant processing and production
data
Usage of reducing adapters, small hose diameters, water-saving
valves;
Installation of user-friendly fittings (for instance ball valves);
Utilisation of suitable circuit water, exhaust vapour condensates, etc.
Implementation of water circuits;
Usage of cooled-down exhaust vapour condensate, cooling water;
Strainer, if necessary settling tank for earthy components and sand
Control, retention and re-use of exhaust vapour condensate, for
instance as washing water or flume water;
Installation of cooling water circuits;
Prevention production losses through exhaust vapours
Pulp filtration;
Feeding of pulp into the digesters of municipal wastewater treatment
plants,
agricultural utilisation, composting with ensuing utilisation in
landscaping;
Preliminary treatment of the fining tanks with exhaust vapour
condensate
Dry discharge of the filtering agents;
Avoidance of production residues in the filter plants;
Collection and utilisation of first and after runnings of the
production;
Selection of suitable filter media;
Optimisation of filtering periods
3
Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
Fruit juice processing/Syrup
chamber, Premix preliminary
dosing device
Storage
Filling
Prevention of losses, complete emptying of containers, avoiding
intermediate cleaning during the working day (as far as possible),
running as few changes as possible
Preliminary treatment of the storage tanks with exhaust vapour
condensates;
Usage of CIP cleaning;
Large container sizes to reduce the flushing water amounts
Collection and utilisation of first and after runnings of the
production;
Avoidance of trickling losses;
Drinking water and service water Stacking of the water produced during regeneration for even discharge;
processing
Utilisation of concentrate from the reverse osmosis plant, for instance for
the flume or washing water demand;
Equipping the reverse osmosis desalination plants with powerful
membranes; membrane replacement in cases of decreasing performance;
Usage of heavy-duty resins with optimised washing water demand for ion
exchangers;
Eco-friendly disinfection
Cleaning and disinfection of the
production plant and the
production halls
Usage of high-pressure cleaners;
Dry cleaning, for instance with compressed air;
Wet cleaning with exhaust vapour condensate;
Economical usage and selection of suitable cleaning and disinfection
agents (N, P, S, AOX, biological degradability;
Usage of tank cleaning devices and water-saving valves;
Circuit cleaning (CIP)
Bottle and crate washing units
Installation of pulsating injections, switching-off of pumps in downtime and
breaks;
Lye stacking, lye processing, for instance sedimentation and re-use;
Evenly dosed discharge can lead to the neutralisation of the total
wastewater without additional consumption of chemicals;
Optimisation of temperature and lye concentration
Syrup chamber
Prevention of losses; complete emptying of containers; as few changes as
possible
Heat and cold production,
cooling
Condensate recirculation; usage of recooling towers; installation of cooling
water circuits
2
Examples of Industrial Applications
2.1
Brewery Wastewater
As part of a research project, one of the aims was to further reduce the wastewater load in
a brewery and thus to find new and higher standards for this industry in Germany.
4
Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
Different measures were taken, which all had an impact on the operation costs and on the
wastewater treatment.
2.1.1
Cleaning and Disinfection Agents
First, the cleaning and disinfection amounts used need to be determined. In one brewery,
the consumption control, that is the controlled issuing to the person in charge for the
respective production area after signing the issue document, led to a reduction of the
cleaning and disinfection agents by 60 %.
If cleaning and disinfection agents are used in larger amounts, the cleaning agents used
should be checked for their biological degradability in cases where there is an in-house
wastewater treatment plant, in order to calculate the maximum permissible amounts for
usage in the company. The change to cleaning and disinfection agents which are more
easily degradable will have an impact on the biological degradability, expressed as
COD:BOD5 ratio and the contents of AOX, EDTA, NTA and P. This in turn will have a
positive effect on the residual COD in the effluent of the WWTP and possibly also on the
sludge amount due to P precipitation.
It should be checked to which degree phosphoric acid could be replaced by hydrochloric
acid. In one brewery, the consumption of phosphoric acid was reduced to a minimum, so
that the P concentration could be reduced from 60 mg/L to < 20 mg/L.
Bottle washing lye is increasingly soiled through the continued feeding of beverage
residues, labels, glue and other fouling; in the end, it will have to be exchanged
completely. State of the art for lye processing are methods like screening and
sedimentation, where the lye is cleaned of all dirt in particle form. In this method,
however, the dissolved components will accumulate. An alternative is the continuous
processing of lyes with membranes.
The optimisation of the contact time of the cleaning lye in the bottle washing machine can
be reached by subdividing the cleaning into three lye baths in line:
1st bath: as pre-heating stage, soaking function for labels and foulings in the bottle,
2nd bath: as proper cleaning stage,
3rd bath: final rinsing of the bottles (Pluta and Krause, 1999).
The lye of the baths is circulated. With the help of the lye processing, the pollution load
discharged into the wastewater can be reduced. Via the automatic measuring and control
of the lye concentration, the optimal low lye concentration can be defined and set (Pluta
and Krause, 1999), which will reduce the lye entrainment.
2.1.2
Bottle Equipment
The wastewater-relevant in-plant measures can go so far that the product or its packaging
can be influenced.
5
Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
Bottle washing machines run at pH-values of 12 and above if lye cleaning is used. At such
values, the heavy metals contained in the bottle equipment, that is in the labels, are
commonly dissolved. In one brewery, the neck labels of the premium beers were changed
from aluminium to paper, which reduced the aluminium concentration from 12 mg/L to
2,35 mg/L in the total wastewater.
Analyses of the bottle labels in one brewery showed that they released AOX. By using
printing ink with a reduced AOX contents, and by substituting conveyor belt lubricants on
alkyl amine basis with lubricants on tenside basis, the AOX values in the effluent of the
in-house wastewater treatment plant could be reduced by 40 down to 70 g/L.
2.2
Fruit Juice Companies
2.2.1
Cleaning of the Pipelines
As part of a diploma paper, the author examined whether any savings are possible if the
existing pipelines are no longer cleaned with water, but by using a so-called pig (Figure1).
Figure1. Pig body (Company Guth, Landau, Germany)
In that company, fruit juice concentrate, fruit juice puree and juices from tropical regions
(for instance concentrates from fruit such as oranges, passion fruits, pineapples, bananas)
are delivered in tank trucks. From the tank trucks, pipes lead to the respective storage
tanks. From the storage tanks, the concentrates are conveyed to the bottling plants. After a
tank truck has been emptied, the pipeline must be cleaned before another vehicle delivers
another concentrate. The company is equipped with two parallel plants. In the first, the
pipelines are conventionally rinsed with water, in the second, the cleaning is carried out
with pigs. There is a pig station, from which the pig is introduced into the pipeline. The
pig is propelled with water. Before the next concentrate, puree or juice can pass through
the pipeline, the water still contained in the pipe must be removed. This is achieved by
using a second pig, which is pressed through the pipe with the next product.
6
Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
Within the diploma paper, the two cleaning methods were compared. The following
aspects were measured and compared: water amounts, wastewater loads (COD, BOD5),
viscosity of the fruit juices and purees as Brix contents. Then, the saving potential was
determined. By determining the different viscosity degrees, the gained measuring results
were transferred to other products.
By using the pig for cleaning the pipe, the water consumption was reduced by approx. 90
% compared to conventional rinsing of the pipes. The reduced production losses led to a
reduction of the COD load in the wastewater of more than 95 %, which allows for
dramatic saving potentials in the wastewater treatment.
The following conditions are necessary for using this method: a pig station, pipelines with
constant inner diameters and pipe bend radii which are at least twice as high as the pipe
diameter, so that the pig can pass the bent pipeline.
The savings for freshwater, wastewater and reduced production losses were determined.
Interestingly, about 85 % of the savings were due to the lower losses of the expensive
concentrates. For the company in question, the annual savings amounted to approximately
20.000 €/a.
2.2.2
Tank Cleaning
Within the same diploma paper, different methods of tank cleaning were compared:
manual tank cleaning and an automatic tank cleaning plant, a CIP plant, which stands for
cleaning in place.
The cleaning programme of the CIP plant comprised in this case: preliminary rinsing,
alkaline cleaning, intermediate rinsing, acidic cleaning and disinfection, secondary rinsing.
In order to reduce the freshwater consumption, it is recommended to use at least one tank
to stack the secondary rinsing water, the contents of which can in the following cleaning
be used as preliminary rinsing water. In the stacked cleaning, the used cleaning agents are
collected and re-used as often as possible. With the help of an automatic concentration
control with conductivity meters, underdoses and overdoses of cleaning agents are
prevented. The comparison in the mentioned diploma paper of a CIP cleaning controlled
in this way with a conventional manual cleaning showed that the water consumption was
lower by a factor of 4.5.
The water consumption can also be reduced in an already installed and controlled CIP
plant by optimising the water rinsing times. Here, it is recommended to take samples in
regular intervals and to examine their pollution load. Thus, it becomes possible to gain
information about the necessary rinsing periods. When analysing the optimisation of a CIP
cleaning plant in one brewery, Wagner (1999) found that the water consumption could be
reduced by 46 %.
7
Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
2.3
Corrugated Cardboard Paper Industry
In Germany, the corrugated cardboard paper industry produced a total of 3.5 million tons
in 1997, which made for a share of approx. 90 % of all packaging paper produced. The
freshwater consumption in this branch can be reduced that far that only as much water is
used as is evaporated during the drying process of the paper. In these cases with closed
circuits, the freshwater needed amounts to only 5 m³/t of paper.
As the actual water demand is much higher, the wastewater from the paper industry is
commonly treated biologically in an anaerobic plant with a topped aerobic plant. The
treated wastewater is conveyed back to the paper production, so that a closed circuit is
created.
The process scheme looks like this: freshwater  paper production  anaerobic stage 
aerobic stage  secondary clarifier  pH-value setting  sand filter  paper production.
One problem is the accumulation of calcium in the wastewater, which leads to calcium
concentrations between 500 and 1200 mg/l. Thus, there occur unavoidable precipitations
in the anaerobic process. 20-60 % of the dissolved calcium ions are precipitated there. The
total precipitation ratios range from 70 to 90 %. However, the calcium precipitation is
considerably lower if the calcium concentration in the effluent to the wastewater treatment
plant is below 300 mg/l. Due to this problem, some of the bigger producers of corrugated
cardboard have opened the circuits again to such an extent that the precipitation reactions
are controllable. Yet, the production-integrated wastewater treatment is indispensable for
economic reasons.
3
Financial Support in North Rhine-Westphalia
The federal land of North Rhine-Westphalia (NRW) supports the execution of the socalled PIUS Check (PIUS = production-integrated environmental protection). It works
like this: together with a consultant, for instance from an engineering firm, a company
turns to the Efficiency Agency of NRW. The consultant examines the company in regard
to the water and energy consumption, creates production-specific index parameters, and
determines the saving potential. Based on these findings, a catalogue of measures is
created which lists the different options of realising the water and energy saving measures.
The Efficiency Agency NRW, that is the land of North Rhine-Westphalia, covers up to 70
% of the consultancy fees. If the company wants to realise innovative methods, it is
possible that the operation processes are also financially supported by the land.
Table 2 shows the present balance of this relatively new way. The part-financing of the
consulting should be emulated, as many companies are made wary of this topic only
through this entry point, which then introduces further actions.
8
Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
Table 2. Development and potential of the PIUS® Check in North Rhine-Westphalia,
State January 2005 (Efficiency Agency NRW, 2005)
Number
Investments
Annual savings in the
production process
Annual saving of resources,
example: water
Annual saving of resources;
example: energy
4
Hitherto realised
projects
103
16,9 Mio. €
4,2 Mio. €
Long-term total potential of
all projects (estimated)
264
43,5 Mio. €
10,7 Mio. €
665.430 m³
1,7 Mio. m³
29,5 GWh
75,8 GWh
Reference Literature
ATV-M 766 (1999): Abwasser der Erfrischungsgetränke-, der Fruchtsaft-Industrie und der
Mineralbrunnen, Januar 1999, ISBN 3-933693-70-5
Austermann-Haun, U.; Rosenwinkel, K.-H. (2000): Fruchtsaftfabriken und Erfrischungsgetränkeherstellung. Kapitel 13 in ATV-Handbuch Industrieabwasser, Band
„Lebensmittelindustrie“, 4. Auflage, Verlag Ernst & Sohn, Berlin, S. 279
Efficiency Agency NRW (2005): www.efanrw.de
Hamm, U. (1999): Wasserkreisläufe von Verpackungspapierfabriken. Wochenblatt für
Papierfabrikation, H. 5, 1999, S. 303-306
Pluta, H.-J.; Krause, S. (1998): Abwässer aus der Flaschen- und Behälterreinigung und der
Desinfektion in der Nahrungs- und Getränkeindustrie. FuE-Vorhaben 102 06 520, im
Auftrag des Umweltbundesamtes, WaBoLu Heft 2 ISSN 0175-4211
Rosenwinkel, K.-H.; Nagy, J. (2000): Produktionsintegrierter Umweltschutz in der
Lebensmittelindustrie.
in:
ATV-Handbuch
Industrieabwasser,
Band
„Lebensmittelindustrie“, 4. Auflage, Verlag Ernst & Sohn, Berlin, S. 35-42
Rosenwinkel, K.-H.; Seyfried, C.F.; Kunst, S.; Austermann-Haun, U. (1996): Bau und
Betrieb einer Anlage zur anaeroben Vorbehandlung von Abwasser aus der Fruchtsaftindustrie. Abschlußbericht des Forschungsvorhabens 02 WA 89068 des
Bundesministeriums für Forschung und Technologie
Wagner, D. (1999): Einsparpotentiale bei CIP-Anlagen. Handbuch zum 32.
Technologischen Seminar Weihenstephan, 1999, Unternehmensberatung Weihenstephan
GmbH
9
Water & Waste Conference, June 3-6, 2007, Assiut university, Egypt.
Address of the Author:
Prof. Dr.-Ing. Ute Austermann-Haun
Fachhochschule Lippe und Hoexter
FB Bauingenieurwesen
Labor fuer Siedlungswasserwirtschaft
Emilienstraße 45
32756 Detmold
Germany
Tel. +49 5231 769 827; Fax: +49 5231 769 819,
E-mail: ute.austermann-haun@fh-luh.de
10