Lesson 2 - Cleaning Systems and Control
This lesson explores the concepts of hygienic design and the Cleaning-in-Place (CIP) systems in the brewery. We examine the nature of soils, the chemicals used to remove them and how we can validate cleaning effectiveness. We also consider the optimisation of modern cleaning systems within the brewery.
Environmental Optimisation
It is important that when we discuss environmental optimisation related to CIP, we need to consider water use and energy, effluent reduction, and the undesirableness of the compounds that are dumped. Sustainability is high on the global brewing agenda and cleaning is one of the focus areas.
Water use
Water reduction is a stated sustainable development goal amongst all the large brewing organisations globally, with brewery use of < 3 hL/hL possible. Reduction in cleaning water is an ongoing focus to help reach that goal.
The high-pressure but low-volume cleaning rotary jets in fermenters can play a big role in this, reducing water use by over 50% compared to the traditional continuously spraying spray balls. This is due to the more precise coverage of these devices. Also, a lot of soil can be removed by mechanical action in the pre-rinse stage, allowing a shortening of the overall cycle in the main cleaning stages.
The optimisation of spray ball devices is also possible through the use of burst rinsing. This allows for the emptying of the water reservoir that collects at the bottom of the vessel, which would otherwise reduce mechanical cleaning in this area. Burst rinsing allows time for the detergent to dissolve the soil, increasing the efficiency of the clean
An animation illustrating this key point can be viewed here (Note, this is for illustrative purposes only and is not a recommendation or endorsement of the supplier’s product):
New plant equipment is more hygienically designed now, allowing for easier and more efficient cleaning, resulting in further water saving opportunities.
Effluent and energy reduction
A reduction in CIP water use will allow a consequential reduction in effluent volume. Pressure sensors in the vessels using rotary jet technology allow optimisation of the mechanical cleaning energy, and thus, overall water use.
At the CIP plant, operation is monitored by sensors to alert for and prevent accidental discharge from draining, which results in pH change with consequent effluent penalties. This also allows determination of optimal cleaning cycles, and for implementation and monitoring of energy reduction initiatives, for example, temperature reduction on hot CIP’s and burst rinsing.
Increasingly, CIP detergent formulations are being optimised to develop more powerful and efficient products, with lower effluent footprint. We have seen the removal of many compounds from detergents and sanitising agents over the years, to make them more environmentally friendly. ECA (Electro-Chemical Activation) water has been proposed as a more eco-friendly replacement for chlorine sanitisers. In the ECA system, hypochlorous acid (HOCl) is produced from salt containing water, eliminating the need for the environmentally damaging and toxic elemental chlorine gas.
Soil sludge accumulating in large CIP tanks has been successfully concentrated and dewatered using decanter centrifugation. This allows for solids disposal and reduces wastewater COD, or chemical oxidation demand.
COD is a measurement of the oxygen required to oxidise soluble and particulate organic matter in the wastewater.
The most significant reduction of effluent can be achieved by installing a partial or full wastewater treatment plant at the brewery, prior to discharge into the municipal sewer. The capital investment is large; however, payback can be quick in certain territories, especially if biogas is collected for energy production.