Food and beverage plants generally focus strongly on two objectives: Producing high-quality product in an efficient and well-run production facility and reducing/controlling costs in the process, while maintaining effective investment planning.
The latter includes investment avoidance where this is the best strategy. There is also an interrelationship between the various processing systems in most food plants. The same careful planning that goes into plant processing and water treatment must include the financial costs and implications that these operations will have on the handling or treating of plant effluent. High wastewater surcharges, or the need to construct a wastewater treatment plant, can often be eliminated or reduced, based on changes in the type of water treatment technology used; modifications to equipment operation and sanitation procedures; and addressing water minimization, reclamation and recirculation techniques.
It is important to make sure that any changes in operation will improve plant performance and further protect product quality.
This article will address the use of production facility audits to evaluate and quantify the impact that plant water treatment technologies and water management practices have on the following critical functions in a food processing and packaging plant. Included are case study examples that are primarily related to water treatment technology, with secondary emphasis on wastewater treatment and water reclamation.
What is an “Operational Audit?”
Are we truly safe from all organic and inorganic risks associated with the water supply? Foods must be able to withstand storage environments and maintain excellent shelf-life quality. Water treatment technology must resist fouling and avoid microbiologic vulnerability. A good audit will aim for a multiple barrier protection system for product water and often a total plant barrier where a pathogen such as Cryptosporidium is even a remote possibility.
Many plants pay twice for the water they use – once when they use it, and again when they dispose of it to the drain. The main disposal cost is usually the organic load in the water. Therefore, simply reducing the volume of water has a minimal effect. An audit can address changes that significantly reduce sewer surcharges, or establish a pre-treatment alternative to reduce costs by 50 percent or more.
Food plants rarely dispose of wastewater that contains serious contaminants. Plant operating practices can often be changed so that the wastewater volume and loading are far from being classified as a serious contributor to a municipal system.
There are a number of ways to look at an audit. It can be cast in the same light as a survey or a study. It can be an accounting of operational facts or it can be an audit with an ulterior motive.
That’s the audit we are discussing today – the audit with an ulterior motive. The motive can range from “are we ok?” to “are we missing an opportunity to do this job better?” The audit measures how the facility operates and identifies alternatives that either improve quality and performance, or keep the operation within regulatory compliance. The audit can be a troubleshooting tool, or can target cost savings or investment avoidance.
An audit should not be merely a checklist that includes use of observations alone. It must be based on data. Individuals or a team that has process system expertise should perform the audit. They should also have knowledge of the plant’s products, production standards, operating guidelines and start-up/ shutdown protocols. Where relevant, testing at the site should be performed, including analytic and microbiologic parameters.
Operational Audit Mind-Set
First, you must understand why you require an audit and what you hope to discover or accomplish. Secondly, who, or what team, will perform the audit?
The goal should be to improve system performance when you identify alternatives such as saving water, for example, so that you maximize production efficiency, ensure the highest product quality and increase operational control.
The audit team must be free to challenge standards and guidelines, and must be encouraged to think outside the box of conventional wisdom. Observations and checklists can be valuable, especially when they represent a new set of eyes, but a high-impact audit will require much more detail and data.
Audits are designed to address specific issues or to measure operating parameters. Typical operational audits address these common issues related to plant operation:
- Quality control/assurance and trademark protection
- Regulatory compliance
- Water conservation
- Selection of water and wastewater treatment technologies
- Wastewater characterization and biodegradability
- Reduction of plant effluent surcharges
- Cost reduction/Cost avoidance
- Higher Efficiency
- Plant Safety
Case Study Examples
The following three case studies discuss audits related to water treatment, wastewater treatment, water reclamation and plant operations.
Case Study 1
A large multi-beverage plant in Europe with seven production lines was using coagulation and reverse osmosis (RO) membrane technology for product water, cation exchangers for softening water used in heat exchange equipment and for rinsing operations, and aerobic wastewater treatment technology with natural tertiary polishing.
The plant had three issues that needed to be addressed by an audit. First, it had performance difficulties with wastewater treatment: Biochemical oxygen demand (BOD) removal was not at the normal high level prior to the tertiary stage. Second, regulatory compliance at the site required a maximum discharge BOD5 of 20 mg/L plus wastewater to meet many drinking water parameters. The chloride level in the discharge from the plant was borderline high and increasing. Third, the water treatment plant contained four carbon purifiers, one of which was experiencing periodic chlorine carry-through. Even when the plant changed the carbon bed, the chlorine would find its way through shortly after the recharge.
Tests confirmed that a new grade of “line lubricant” the plant was using was interfering with wastewater biodegradability. The plant had purchased a line lubricant that contained an inhibitor to reduce microbial growth, which it did quite well. However, when it washed over into the wastewater plant, it also slowed down the microbes there, which affected BOD and COD reductions. After the audit, the plant switched to a different product.
BOD5 reduction was returned to performance level at 99 percent. However, reducing the chloride level required two alternative approaches: RO water was used where it was not needed. This increased both the volume of water to the wastewater treatment plant and the chloride level of the wastewater. Correcting this, in addition to alternating between softened water and using complexed phosphates for some rinse water applications, resulted in compliance.
In the future, the plant would use RO water only where needed and strictly control water management to minimize chloride levels in the plant effluent.
Chlorine carry-through was traced to an error in carbon purifier design, where insufficient freeboard was allowed for proper backwashing of the carbon. This caused channeling of the carbon bed. The solution was to remove some carbon, creating the proper freeboard, and also to run the unit at a proper design flow of 1.0 gpm/ft3. The backwash rate was increased to 2 gpm/ft2.
Case Study 2
A large food plant in the United States with four production lines was using RO technology and support systems for production water, as well as water softening for water used in heat exchange equipment. The plant was not using wastewater treatment equipment, and had a BOD5 to drain at 2,000 mg/l+.
The plant had three issues that needed to be addressed by an audit. There were substantial sewer surcharges and compliance issues that resulted in the need for a complete wastewater treatment facility. It also had space and zoning limitations, and was considering a new site. The plant was targeted as a significant “user.”
There were concerns with microbial issues that surfaced periodically in the water treatment system. The water quality met all specifications, but servicing of the system was getting more critical. Lastly, there were also concerns with how various plant operations conformed to regulatory guidelines.
Municipal and plant data was confirmed relative to BOD/COD loading and volumes discharged. The plant was discharging a safe and easy-to-treat wastewater, which posed little concern to a municipal authority. Surcharges were weighed heavily toward strength of waste (BOD5), and an alternative was identified to pre-treat the wastewater for a 50 percent reduction in BOD5 before discharge. Other options included changing plant procedures for using heat exchange waters and disposing of solids.
Stainless steel carbon purifiers were to replace existing units that would not allow steam vapor sanitizing/stripping or hot water sanitizing. It is critical that granular activated carbon be in a vessel that allows easy-to-perform steam stripping of VOCs and hot water sanitizing so that an effective protocol can be developed to control microbes and reduce the buildup of organic contaminants.
The plant was well managed and in compliance with the regulation identified. Changes were initiated, but most were cosmetic and addressed storm water runoff.
Case Study 3
A large beverage plant in South America with six production lines was using coagulation water treatment technology and anaerobic wastewater treatment. The plant, which had an extensive sugar treatment process, was also using water softening for water used in heat exchange equipment and for rinsing requirements.
- Drawings (plant, plant site and function), operating data and laboratory results should be reviewed before starting an audit.
- Always get a complete water analysis (organic and inorganic) before starting the audit.
- On-site testing, particularly microbial, is critical to most water audits.
- Recommended actions should always improve plant operation and performance.
- Do not rule out avoiding a major investment in water or wastewater treatment systems as a result of a proactive audit.
- By doing the work described above in advance, an effective audit can usually be accomplished in two to three days, depending on the objectives.
- Whether by audit, survey, study or experience, never buy or select water treatment technology without a thorough understanding of the following.
- Water source or sources (multiple “sources” has become common).
- Water quality and volume needs for the various plant functions.
- The impact the technology selected will have on sewer surcharges and regulatory compliance.
- All investment and anticipated operating costs, and quick availability of support and services.
The Plant had Six Issues
The cost of water was extremely high; therefore, a reduction in water consumption was critical. In addition, the surface water supply posed a quality and safety threat to the plant.
There was too great a volume of wastewater to the existing anaerobic wastewater plant, necessitating a multi-million-dollar expansion of the system.
The plant was concerned with the quality and inconsistency of the incoming water supply, despite having a complete treatment plant for product water.
The plant needed to verify the risk-free status of the sugar treatment process (hot carbon) and make sure that the bottle-washing operation was delivering a clean and completely sanitary bottle.
The use of paper labels was fouling the bottle washing solutions, requiring frequent dumping of the caustic baths. These caustic solutions were as high as 3.5 percent sodium hydroxide, with additives for chelating and sequestering purposes. This created a huge impact on operating costs and a potential quality issue.
Dumping of caustic solutions was adversely affecting the anaerobic wastewater treatment plant despite neutralization. The plant was concerned with how the operation conformed to regulatory guidelines in a number of areas.
The audit confirmed that plant efforts to minimize unnecessary usage had been highly successful, and most processing systems were operating as designed because of a number of improvements contributed by the plant engineering and maintenance staffs.
The major use of water was in bottle washing and rinsing. This area accounted for better than 50 percent of the plant’s water consumption. It was also the main flow into the anaerobic waste treatment plant. A water reclamation system was installed, fully in accordance with compliance guidelines. Water usage was reduced by 75 percent. More important, the washing and rinsing operations were measurably improved in terms of bottle cleanliness. Microbial data confirmed that all agreed-to parameters had been achieved with a wide margin of safety.
The water reclamation system cut the flow of wastewater to the plant’s anaerobic wastewater treatment plant in half, but the BOD loading per day continued as before. Other measures were identified to reduce BOD loading via sugar treatment changes, but these were largely unnecessary. The anaerobic wastewater treatment plant operated much better with the more concentrated and consistent wastewater.
Label removal and caustic reclamation systems were identified that would accomplish two tasks.
With high recirculation flows, rapid straining out of labels before they could be “pulped” in the caustic bath improved machine performance and gave a cleaner caustic solution.
Caustic reclamation extended caustic life 300 percent (minimum), saving considerable money, as well as improving machine performance. An automated neutralization system was installed to protect the wastewater treatment plant.
The surface water supply was confirmed to be at risk to waterborne organisms, and a total plant barrier concept was introduced. All incoming water would be treated specifically to guard against pathogens of concern. Whether water was to be used for gardening, cooling, general purposes or even fire control stand-by, the barrier would be in effect at the plant inlet. For production purposes, the water would still be treated and subject to a multiple-barrier system.
These case studies show that the key to an effective audit is to approach it with an ulterior motive in mind. Using normal approaches to restrict or reduce water usage often means giving away a margin of safety – something that today’s food industry is determined not to do.
An audit should start with a specific objective and that objective should address a specific opportunity. It should be done by experienced personnel, and should always include an experienced plant engineer, operator or scientist.
Harry DeLonge is a consultant for US Filter’s Food & Beverage Market Team. He can be reached at DelongeH@usfilter.com.