Water and Wastewater Use in the Food Processing Industry PDF Print E-mail
Written by North Carolina Division of Environment and Natural Resources   
Tuesday, 06 July 2010 08:40
Article Index
Water and Wastewater Use in the Food Processing Industry
Fruit and Dairy Processing
Meat and Poultry Processing
Grain Processing for Oils
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(This is Chapter 5 from the Water Efficiency Manual, available from the Alliance for Water Efficiency

Water and Wastewater Use in the Food Processing Industry*

The following sections discuss major water using and waste generating processes in fruit, vegetable, dairy, meat, poultry, and oil processing. The information is provided to help food processing managers evaluate water use performance and consider additional water efficiency measures. In the absence of water use data, wastewater (hydraulic) loadings information is presented as a reference for water use.

Fruit and Vegetable Processing
The fruit and vegetable processing indus- tries may be described as consisting of two segments: fresh pack and processing. The former collects crops and field packs them into lug boxes or bulk bins for shipment to a produce finishing plant. Crops are cooled to preserve integrity and fumigated or treated to control insect infesta- tion or microbial disease development. The processing segment, or packers, includes all unit operations, extending the shelf life of food being processed and adding value through produce modification to satisfy market niches.

The fresh pack segment of the industry shares unit operations with the processing segment. These operations are the sorting/trimming, washing, grading, and packing lines. But after the packing lines, additional unit operations may add to the waste generating scheme for the processing segment alone. Additional operations may include combinations of peeling, stemming, snipping, pitting, trimming, chopping, and blanching. In some instances, the final product is dehydrated (e.g., chopped onions). In others, it is packaged and processed. Processing can include one treatment or a combination of several treatments (e.g., acidifying, brining, freezing, or cooking).

Major water use and waste generation points associated with the fruit and vegetable industry include the washing steps for raw and processed produce, peeling and pitting practices, blanching, fluming the produce after blanching, sorting, and conveying the product within the plant. Reducing size, coring, slicing, dicing, pureeing, and juicing process steps, as well as filling and sanitizing activities after processing, also contribute to the wastestream.

Wastewater Characterization
Major wastewater characteristics to be considered for the vegetable and fruit processing industry are the wide ranges of wastewater volume and the concentrations of organic materials. Wastewater characteristics can be influenced by a number of factors such as the commodity processed, the process unit operations used, the daily-production performance level, and the seasonal variation, e.g., growing condition and crop age at harvest. Figure 34 presents historical data collected from raw wastewater discharged from the vegetable and fruit processing industry.

Figure 34. Representative Wastewater Loadings Per Ton of Product Associated with Typical Vegetable and Fruit Raw Products

Flow Flow Flow
Crop (1,000 gal/ton) minimum (1,000 gal/ton) mean (1,000 gal/ton) maximum
Vegetable products
Asparagus 1.9 8.5 29.0
Bean, snap 1.3 4.2 11.2
Broccoli 4.1 9.2 21.0
Carrot 1.2 3.3 7.1
Cauliflower 12.0 17.0 24.0
Pea 1.9 5.4 14.0
Pickle 1.4 3.5 11.0
Potato, sweet 0.4 2.2 9.7
Potato, white 1.9 3.6 6.6
Spinach 3.2 8.8 23.0
Squash 1.1 6.0 22.0
Tomato, peeled 1.3 2.2 3.7
Tomato, product 1.1 1.6 2.4
Fruit Products
Apple 0.2 2.4 13.0
Apricot 2.5 5.6 14.0
Berry 1.8 3.5 9.1
Cherry 1.2 3.9 14.0
Citrus 0.3 3.0 9.3
Peach 1.4 3.0 6.3
Pear 1.6 3.6 7.7
Pineapple 2.6 2.7 3.8
Pumpkin 0.4 2.9 11.0

Water Use and Wastewater Sources
In the processing environment for vegetable and fruit material handling, heating, cooling, and packaging, there are six major contributing point sources for waste. These sources are the following operations: (1) raw produce washing, grading, and trimming, (2) washing after steam/lye peeling and/or size reducing, (3) blanching and fluming, (4) filling, (5) sanitation/plant cleanup, and (6) pro- cessed product cooling. Plant manage- ment practices greatly influence process operation efficiency relative to final product yield and waste quantity gener- ated. (Refer to Figure 34 for industrial variability.)

Water Use and Waste Minimization
Ideally, considerable waste reduction can be achieved if harvesting equipment permits additional stems, leaves, and culled materials to remain in the field during harvest. If crop washing, grading, and trimming can occur in the field, then additional soil and food residues will remain at the farm. Realistically, most such wastes are being handled at vegetable and fruit processing plant sites. Primary waste-management strategies used by this industry are water conservation and waste-solids separation.

Water use by the vegetable and fruit processing industry is essential to the washing, heating, and cooling of food products. But the industry has adopted a number of practices, showing heightened sensitivity to the need for water conservation:

  1. Use of air flotation units to remove suspended debris from raw crop materials
  2. Recovery and reuse of process water throughout the processing plant.
  3. Decrease of water volume use in peeling and pitting operations, as well as decrease of raw product losses.
  4. Separation of waste process streams at their sources, for potential by-product use.
  5. Countercurrent reuse of wash and flume/cooling waters.
  6. Separation of low and high strength wastestreams.
  7. Installation of low-volume, high- pressure cleanup systems.
  8. Conversion from water to steam blanching.
  9. Use of air cooling after blanching.

* Excerpts from "Waste Management and Utilization In Food Production and Process," CAST, October 1995.


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