Hazard Analysis and Critical Control Points
The Australian Drinking Water Guidelines (ADWG) are the authoritative reference document when it comes to the management of drinking water in Australia.One of the concepts contained within the ADWG is the management concept of Hazard Analysis and Critical Control Points (HACCP).
HACCP is a risk management system designed for NASA in the United States to oversee elements of the space program, and its principles have been adopted internationally for control of hazards in the food and beverage manufacturing industry.
It is also a useful system for the management of drinking water.
The first component of the HACCP is the Hazard Analysis.
The purpose of the hazard analysis is to identify any hazards that could potentially impact the supply of good quality drinking water to the consumers.Hazards include any biological, chemical, physical or radiological agent that has the potential to cause the drinking water to be unsafe for human consumption.
Examples from each of these categories are provided below.
It is worth noting that different drinking water quality hazards will be present at different locations. Therefore, the hazard analysis, as well as the preventative measures put in place to address these hazards, will also be different.
Critical Control Points
Points throughout the system which may present significant risk from hazards should be designated as Critical Control Points.
A critical control point is a point within a system where control can be applied and which is essential in order to eliminate or reduce risk to the system.
A critical control point has specific operational requirements:
It must have measurable parameters for which Critical Limits may be set to easily define whether the preventative measures in place are working;
It must be easily monitored and measurements taken frequently enough to recognise any system failures in a timely manner;
Procedures can be implemented at the control point to correct deviations from the critical limits.
A chlorine dosing point with sample points and online monitoring is an excellent example of a critical control point.Limits may be set above and below which the chlorine residual is allowed to fluctuate and monitoring is easily achieved with online instrumentation and field sampling. Water pH and turbidity can also be monitored to ensure these aspects also don’t impact on chlorine dosing efficacy.
Variable speed drive dosing pumps can be used to ensure the correct disinfection dose is adhered to and alarm systems can be put in place to warn the operator when the system may be deviating out of control
Critical Control Points in practice
To give you an example of critical control points in action, you can see in the diagram below a conventional water treatment plant sourcing their water from a river.
Throughout the treatment process, operators are constantly performing water quality testing to determine the characteristics of the water, comparing these results to set points (critical limits), and making adjustments to optimise the final water quality supplied by the system.
Each of these points, can be considered a critical control point, whether it be the output of the sediment tank, the output of the sand filters, or the output of the chlorine dosing point.
Another example of a water treatment and supply system is provided below.
As you can see, the water treatment process is different from the one above, because the hazard analysis has identified different hazards to drinking water quality.
Despite this, water quality parameters are measured throughout the system at critical control points, and adjustments to treatment processes are undertaken at these critical control points.
Critical control points in the diagram above could include the groundwater pump, after the bag filters, and after the chlorine dosing point. Water quality testing undertaken in the community to verify the drinking water is acceptable for consumption is not a critical control point, because at this point it is too late for you to be able to make an adjustment to the process to optimise water quality.
Although this article has been examining the use of HACCP with regards to drinking water, the concept applies equally well to wastewater treatment as well.
Why don’t you take some time today to think about the critical control points at your own workplace, and what aspects define them as CCP’s? Remember, it has to be a point in the system where you can measure something against a set threshold, and somewhere you can make a process adjustment in response to this.