Page 66 - FoodFocusThailand No.209 AUGUST 2023

SOURCE OF ENGINEER

WHO, but it can be contaminated from water feed pipe or water • Reverse Osmosis (RO) can filter particles larger than
storage systems in the facility. Hence, water quality improvement 0.0001 micron and uses high pressure of 30-60 bar, which
are recommended, such as sediment filtration or addition of enables it to filter extremely small contaminants such as
chlorine to ensure the minimum presence of free chlorine within nitrate, fluoride, sulfate, chloride, and heavy metal.
the water outlet system of no less than 0.2 mg/L. Nevertheless, a precaution to be noted is that raw water
Water for food production refers to the water intended to must not contain an excessive amount of suspension,
be used as food ingredient or in the processes where potential mineral, or chemical as it will accelerate the deterioration of
contact with ready-to-eat food or contamination may occur. the filtration membrane. Additionally, no presence of free
These are, for instance, the final cleaning of fresh vegetables chlorine should be detected in raw water as it can weaken
or fruit for preparing as ready-to-eat food like salad, flushing and damage the filtration membrane, especially aromatic
water of pipelines for packing and remaining water in pipeline polyamide and thin-film composite membranes. Hence,
systems before packing which are directly in contact with food pressure, filtration rate, and conductivity rate in filtered water
as well as cleaning or disinfection water of packaging with a should be constantly measured to ensure periodic efficacy
risk contamination into the products. According to relevant laws assessment of the filtration system.
and standards, the quality of these waters must comply with 2. Water softening relies on cation resin to completely
the requirements stipulated in the notifications of the Ministry remove water hardness caused by bicarbonate, salt, or
2+
2+
of Public Health No.61 B.E.2525 (AD 1982), No.135 B.E.2534 sulfate of calcium (Ca ) and magnesium (Mg ). Raw water
(AD 1991), No.316 B.E.2553 (AD 2010) Re: Potable Water in should have standard levels of pH, total solids, and
Completely Sealed Container, and No.416 B.E.2563 (AD 2020) contaminants with negative ion such as nitrate, fluoride, and
Re: Prescription of Quality Requirements, Standards, sulfate because cation resin is not capable of filtering these
Regulations, Conditions, and Methods for Food Inspection and substances. If the substances in the initial raw water exceed
Analysis for Microbiological Pathogens. The water production the established standards, it is recommended to shift to the
processes that adhere to these standards may implicate the RO system instead as it can remove these contaminants.
following methods to ensure improved quality of running water Raw water should also have at least 0.2-0.5 ppm of free
or water for general consumption: chlorine to prevent microbial accumulation on resin, which
1. Membrane Filtration will accelerate untimely deterioration of the resin. Therefore,
• Micro Filtration (MF) can filter particles larger than 0.1 every resin maintenance routine should at least comprise
micron and bacteria, but it cannot filter virus. Since MF can constant checkup of filtration rate, turbidity level, and free
function with low water pressure, it does not require any chlorine amount to ensure the effectiveness of water
electrical power. The filtration membrane can be cleaned easily. filtration substances. If any irregularity is detected, cleaning
Raw water that is passed into the filtration system should have and regeneration or replacement of cation resin may be
a turbidity level similar to that of running water, which is not required.
higher than 5 NTU. The maintenance routines may include, for 3. Deionization (DI) is a system that removes all ions
example, constant monitoring of filtration rate, turbidity level, from solutions, providing purified water without minerals,
and bacterial contamination in treated water to ensure that the which is not suitable for consumption but can be very useful
efficacy of filtration membranes is constantly assessed. in food, medicine, cosmetics, and electronics industries. The
Cleaning or replacement of membrane must be carried out as processes involved in the production of deionized water are
soon as any irregularity is detected. similar to those in the water softening system. Deionization,
• Ultra Filtration (UF) is similar to MF but can filter particles however, applies both cation resin and anion resin for filtration
that are larger than 0.01 micron, including bacteria and virus. of water and removal of positive and negative ions from
This system applies pressure of no more than 10 bar. The water. Cation resin is positively charged with ions, such as
quality of raw water and maintenance routines are similar to H , which cling themselves to resin beads’ surfaces and
+
those of the MF system. can remove positive ions in solutions. Anion resin, on the
• Nano Filtration (NF) can filter particles larger than 0.001 other hand, is negatively charged with ions, such as
-
micron, thus allowing some minerals to cross over as a result. OH , which also attach themselves to resin beads’ surfaces
The NF system operates on 20-40 bar of pressure, and the and can remove negative ions. Although water deionization
quality of raw water and maintenance routines are similar to system can completely remove all ions, it does not work for
those of the MF and UF systems. microbial filtration, which needs to be carried out by UV
filtration in the final step instead. This technique requires the
same maintenance routines as those of the water softening
system.
Water intended for industrial application needs to meet
the hygiene and quality requirements dictated by law. It must
have the same quality as that of potable water. A major key
that guarantees constantly purified water is to adhere to
relevant sanitary principles to control external contaminants
from upstream to downstream flow, including maintenance
and monitoring routines of water container’s hygiene, water
quality, and water feed system to assess any potential
contamination.

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