Wading through water during a recent dairy visit made me very conscious of the vast amounts of water consumed and generated by the process. There has to be something we can do to improve performance in this regard.
The process obviously creates a few challenges when it comes to recycling the water used as the waste water requires specialized treatment as a result of the following issues:
- The presence of milk solids (e.g. protein, fat, carbohydrates, and lactose) in the untreated wastewater may have a significant organic content, biochemical oxygen demand (BOD), and chemical oxygen demand (COD).
- Whey may also contribute to high organic loads in wastewater.
- Salting activities during cheese production may result in high salinity levels in wastewater.
- The cleaning procedures results in wastewater containing acids, alkali, and detergents with a number of active ingredients, and disinfectants, including chlorine compounds, hydrogen peroxide, and quaternary ammonia compounds.
- Wastewater may have a significant microbiological load and may also contain pathogenic bacteria.
Prevention is much cheaper than cure. The IFS EHS guidelines recommend the following techniques to prevent the contamination of the wastewater stream:
Waste not, Want not.
Keep product losses to a minimum, these may be from spills, leaks, excessive changeovers, and shut downs through the adoption of good manufacturing procedures and facility maintenance;
Keep it Separate
Separate and collect product waste, including rinse waters and by-products, to facilitate recycling or further processing for subsequent use, sale, or disposal (e.g. whey and casein); separate streams as treatment options may vary and its always best to deal with the issue at source.
Stick to liquids
Install grids to reduce or avoid the introduction of solid materials into the wastewater drainage system;
Drain it away
Process and waste water drains should be separate in process areas and should discharge directly to a treatment plant and / or municipal sewerage system;
Pipes and tanks should be self–draining, product should always be drained before cleaning to minimize the amount of water needed for rinsing in the cleaning cycle.
Recycle, Re-use
Subject to food safety and quality requirements, recycle process water, including condensate from evaporation processes, for preheating and heat-recovery systems for heating and cooling processes, to minimize water and energy consumption;
"Green cleaning'
Adopt best-practice methods for facility cleaning, which may involve manual or automated Clean In Place (CIP) systems, using approved chemicals and / or detergents with minimal environmental impact and compatibility with subsequent wastewater treatment processes.
It is impractical to assume all waste water can be eliminated. There are a number of techniques for treating industrial process wastewater in this sector. We will discuss these options in future articles with the input of various FoodFocus fundi’s.
Bottom line: Dairy processing facilities use considerable quantities of potable water for processing and for cleaning of equipment, process areas, and vehicles. The amount of water going to the waste stream can be reduced and this should be an actively managed initiative – every drop does count – ask your accountant!
References
IFC EHS Industry sector guidelines - Dairy
http://www.ifc.org/wps/wcm/connect/534a1a8048855373af34ff6a6515bb18/Final%2B-%2BDairy%2BProcessing.pdf?MOD=AJPERES
