Wastewater treatability in the food and beverage industry – Treatment at the end of pipe is not cost-effective

By Alex Keen, President and CEO, ALTECH Group

Wastewater treatment is a concern in most industrial sectors, however, the food and beverage industry is potentially more concerned than most. With the pressure from municipalities of rising water charges and the application of sewer bylaw standards, the cost of water and wastewater measurably impacts the overall cost of production. At the same time, it is a fact that many countries in the world have adapted to water costs that are two and three times the costs in Canada. As water costs rise to reflect the requirements for infrastructure renewal, the food and beverage industry in Canada must respond with new technology applications to reduce and/or recycle water and treat wastewater streams.

Pressure on the Food and Beverage Industry

The food and beverage industry is traditionally a user of large volumes of water. In addition to water as a component of many products, it is a convenient, clean, and a relatively inexpensive resource. Because food materials are easily moved or quickly dissolved in water, it becomes an easily available solvent and method for conducting cleanups and other production needs. Since the company is only cleaning food debris, it is not generally considered hazardous by the generator. It is sometimes difficult for company staff to fully understand the impact of putting the water into the sewer.

With the rising costs of municipal infrastructure support, both for water and wastewater service delivery, and the provincial down loading of funding for some of these services, there is much more pressure on the municipality to cover its real costs of operation. With the involvement of private/public partnerships encouraged, there will be a further move to rising costs for these services.

It is not surprising, then, that municipalities are entering into structured programs of raising water rates. As well, municipalities are, perhaps, more aggressive at establishing surcharges for over-strength discharges.

Obviously, the cost to food companies, then, is twofold, namely, rising water charges and increases in wastewater surcharges. Finally, in some cases where residential and commercial development is restricted by the capacity of municipal wastewater treatment, the municipality may not allow over-strength agreements because it unfairly restricts the ability to approve new residential or commercial development which results in more tax revenue.

Pollution Prevention is the Key

Particularly in the food industry, treatment at the end of pipe is not cost-effective. The company must review practices upstream and practise pollution prevention or control at the source if it is going to find a cost-effective way to use water. Because water use is such a major component of production costs, ranging from 2% – 14%, this will be the secret to being more competitive in the future.

Implementing water recycling and reduction strategies has a two-pronged effect. Not only does it reduce municipal water charges, but it also reduces the cost of treatment and/or recycling equipment since hydraulic flow is the most influential factor in the cost.

There are a number of features of the food and beverage industry that make it practical to investigate smaller, treatment-at-source solutions. Production is usually a combination of high strength washouts and cleanups, combined with high-volume uses of water with low levels of contamination. To combine these streams is to increase the cost of treatment by diluting the high-strength contaminants in the larger volume of water.

First Step is Characterization

The first step is a complete characterization of wastewater from process operations in terms of flow rates and contaminant concentrations. Not only will this identify the process operations that contribute contaminants, it will help quantify the impact. This is especially important in developing a source control strategy. For example, with a quantitative analysis, controls at one or two operations can be calculated to determine if that is all that is needed to achieve compliance. The results of the characterization will provide the data to:

• Assess the potential for wastewater minimization through water reduction and/or reuse.
• Identify upstream options to minimize the contaminant concentrations and loadings.

The characterization is essential for providing a sound basis for the development of an overall treatment strategy that includes changes in procedures, treatment options at source, and any requirements for final treatment. Inexpensive options are the first consideration such as changes in procedure, water reduction opportunities, rerouting of sewers to contain high strength streams, etc.

Embrace Technology Improvements

With the easy to implement options completed, the baseline is set for financially rationalizing equipment-based improvements. The most cost-effective option is to ensure existing control equipment is optimized. For example, wastewater interceptors provide the cheapest form of separation of food materials that float or settle such as fats, oils and greases. However, flow rates through the interceptor often exceed the design capacity. Reducing or treating part of the flow upstream may be the secret to optimizing the existing interceptor for better performance on the rest of the effluent.

In most situations further treatment is required if discharge standards are to be achieved. In particular; there is not a good method of treatment for the soluble Biochemical Oxygen Demand (BOD) component of the wastewater. It is this parameter that causes the most problems for companies and creates financial hardship in terms of the sewer surcharges administered by the municipalities. The challenge, then, is to find new technological approaches that deal with the problem of BOD and are priced at a level that can demonstrate paybacks based on reductions in water charges and wastewater surcharges.

Membrane-based separations have been used in some industry process operations for some time, especially in the dairy or brewing industries. They have yet to gain acceptance in terms of treating waste waters. The challenge in application involves understanding the components of the waste process stream and the impact on membrane fouling in combination with the factors that maximize flow rate through the membranes. Membranes have specific impact on streams that have high BOD due to high total dissolved solids (TDS) such as sugars from confectionery products, juice manufacturing, and beverages. Membrane separations are ideal treatment options upstream where they can sometimes provide an extra payback in terms of reduced water usage.

Biological oxidation on a small scale is a more difficult problem. Most large food manufacturers with the room will install conventional biological systems. This approach requires the space and the scale of operation to support it, and it is expensive in capital and operating costs. Packaged biological treatment systems such as the CMS RotoDisc, the Zorch Sequencing Batch Reactors or the ALTECH System HydroKlean provide new, down-scaled options for installation of biotreatment with a small pack age inside the plant. With easy operation, the capital cost of such a plant can be compared to the elimination of the municipal wastewater surcharge and a payback analysis can be performed.

Payback Options

There are a number of factors that can have an impact on technology payback calculations, including:

Elimination of Bylaw Surcharge. Bylaw surcharges are often between $50,000 to $200,000. As these are direct costs to food companies and are likely to increase rather than decrease, they become an important part of the payback calculation for new equipment. As an added incentive, several municipalities offer a program that repays a portion of the capital back, based on past surcharges paid.

Reduction of Water Charges. Reduction in water usage through projects such as better collection of rinse waters, separating clean water streams from dirty ones, and the potential use of membranes ­ all can easily reduce water consumption by 30% – 50%. At approximately $0.95 per cubic metre (including water and sewer charge), this could amount to significant savings at low capital cost and have the added benefit of reducing the hydraulic flow and cost of final treatment.

Reduced Waste Transport Costs. The food industry generally has lower cost waste disposal options because the waste streams are generally considered to have some nutrient value where disposal options can include land application, livestock feed, composting, etc. However, many water streams are very dilute with BOD contaminants and the cost of haulage becomes expensive. Membrane applications have provided attractive pay backs by simply concentrating the waste and reducing haulage by as much as 80%.

There are substantial opportunities in the food industry to manage water and wastewater to reduce costs. It is a matter of carefully evaluating treatment at the source in combination with newer, lower cost technology applications.