Information Sheets for Water Treatment Operators submission

ID:

This submission reflects the views of

Organisation Name:

Department of Health Victoria

Please identify the best term to describe the Organisation:

Government Department – State / Territory

Personal Details

Specific questions for Public Consultation – Information Sheets for Water Treatment Operators

Specific Comments:

question_1

‘the application of multiple barriers (section 3.3.1), which helps ensure that a failure of one barrier may be compensated by the effective operation of the remaining barriers, thus minimising the likelihood of contaminants passing through the entire treatment system and being present in sufficient amounts to cause harm to consumers’

This statement seems to infer that only engineered treatment systems can form part of the multiple barrier approach and that redundancy is required in the treatment plant. The multiple barrier approach should be applied from catchment to tap (i.e. catchment protection is a barrier).

question_2

This section describes that treatment is usually divided into two groups, disinfection and physical removal. However information sheets have only been provided for disinfection. Information sheets should be included in ADWG for other treatment processes such as media and membrane filtration. Media filtration in particular is utilised in hundreds of drinking water supplies acrossAustraliaand in many cases is the only treatment barrier utilised by water suppliers to manage protozoan risks.

question_3

Consideration should be given as to whether this information sheet is needed, as it may be misleading if viewed in isolation. If it is to be retained, the subsequent comments are provided for consideration.

‘In all cases disinfection should be treated as a critical control point (CCP) (see section 3.3.2 for more information on critical control points). This means the failure of the disinfection process would lead to the water being unsafe to drink.’

question_4

Clarification should be provided in relation to the statement: ‘Despite the limitations, disinfectants are an important and widely used process in the production of safe drinking water and are generally the first barrier selected in ensuring the delivery of safe water to customers.’ Generally a physical removal process such as filtration would precede disinfection. Refer to comments above in relation to the need to publish information sheets on filtration.
Suggest moving ‘temperature’ from the bullet points under ‘characteristics of the water supply system’ to the fourth bullet point under ‘the quality of the source water’ (page 2).

question_5

Suggest deleting ‘Table IS1.1 Examples of Ct values for 99% (2 log) inactivation of various microorganisms by disinfectants’ as it is a duplication of information provided in the subsequent fact sheets.

question_6

Suggest deleting discussion relating to the required UV doses for pathogen reduction as this is a duplication of information provided in the UV fact sheet.
Also suggest discussing the importance of using a UV system that is validated in accordance with the requirements of the USEPA Ultraviolet disinfection guidance manual for the final long term 2 enhanced surface water treatment rule (UVDGM) (2006).

The UVDGM is considered the most authoritative guidance document and therefore should be adopted for validation of UV reactors. The UVDGM is considered to have superseded the DVGW (DVGW 2006a, 2006b, 2006c), NSF (NSF International 2004), ONORM (ONORM (Austrian Standards Institute) 2001, 2003) and NWRI guidelines (National Water Research Institute 2012), because unlike the UVDGM, these guidelines do not deal comprehensively with concepts such as uncertainty and bias between challenge test microorganisms and target pathogens.

question_8

Suggest including particle shielding as a factor affecting disinfection. Turbidity is already included in the table describing operational monitoring parameters.

pH and temperature should be added as parameters that should be monitored operationally for chlorine dioxide and ozone (noting that between pH 6-8.5 it will probably not be an issue for disinfection by chlorine dioxide).

Operational monitoring parameters listed for ‘ultraviolet irradiation’ should be amended to ‘Turbidity, UV absorbance or UVT’. UV absorbance is related to UV transmissivity (by the equation A = log₁₀ (1/T)), and as a result, typically only one is monitored (generally UVT).

It should be made clear in this section that the table summarising the operational parameters which should be monitored for common disinfectants only relates to those parameters which might impact on the effectiveness of disinfection. The table does not include all operational parameters which should be monitored for these treatment processes (i.e. those which need to be monitored to demonstrate the effectiveness of disinfection). If this table is viewed in isolation, this could cause confusion. To make it more clear, a summary table under a new sub-heading (e.g. Operational Monitoring), which includes all relevant operational monitoring parameters for each disinfectant could be included.

question_9

Where does the requirement to achieve a chlorine CT of 15 come from? This section seems to indicate that a CT of 15 must be achieved; however a scientific reference has not been included. This CT is also mentioned in the chlorine fact sheet.

question_10

We suggest that context be provided around the initial sentence in this section - ‘Disinfection should not be compromised to control disinfection by-products’. Alternatively this sentence could be deleted as it is explained in greater detail later in the information sheet.

question_11

This section is not particularly useful as it just states numerous CTs that have been published. It would be more useful to have a discussion around the fact that numerous studies have been published on the effectiveness of chlorine at reducing several different pathogens (the range of published CTs could be included). Then it would be appropriate to discuss why certain CTs are more appropriate than others, for instance the USEPA (1991) CTs should be applied for Giardia reduction.
‘The Ct values should be considered as indicative only, and suitable safety factors should be applied to ensure adequate disinfection’. This information sheet should provide the CT values that should be applied by the industry. If there is to be consistency within the industry, the ADWG as the authoritative guidance document must specify the appropriate CTs. In addition this statement is misleading as some of the CTs specified in the table have already had safety factors applied.
Table IS 1.3.1. This table should be expanded to provide the required CTs across a range of log reduction values (LRVs) (for instance 1-4 LRV). The USEPA tables are a good example. This is important as some schemes may require more or less than 2 LRV.
The recent publication by Keegan et al (Keegan, A., S. Wati and B Robinson. 2012. Chlor(am)ine disinfection of human pathogenic viruses in recycled water (#62M-2114). Prepared by the Australian Water Quality Centre for the Smart Water Fund, Victoria.), should be reviewed and if applicable the CTs in this fact sheet should be updated. In general the Keegan et al (2012) report validates the Black et al (2009) CTs.
Clarification should be provided in relation to the statement ‘at the typical chlorine Cts used in Australian drinking water supplies, which are usually at least 15 mg/L.min…’. Is this based on evidence and can a reference be provided?

question_12

Suggest reviewing the Keegan et al (2012) report specifically for the discussion on the effects of turbidity on chlorine disinfection.
It would be useful to provide context for the following sentence ‘Relationships with other parameters such as colour have also not been determined’

question_17

It would be useful to include a summary table or list in this section of typical operational monitoring parameters which should be monitored when chlorine is used to disinfect drinking water supplies (e.g. CT, pH, temperature, turbidity, instantaneous flow rate, tank hydraulic volume/level).

If free chlorine is the active disinfectant, free chlorine analysers must be used to monitor the disinfection process. It may be useful to include a short paragraph in this section on instruments used to measure disinfection effectiveness for chlorination. For example, the following text could be included[1]:

Oxidation Reduction Potential (ORP) meters cannot be used to measure disinfection effectiveness for chlorination. Studies have demonstrated that chlorination effectiveness is not well predicted with ORP measurements and that ORP does not vary in direct proportion to chlorine residual. Furthermore, calculation of residual concentration from measured millivolts can result in large errors of +/- 30 per cent.

[1] Reference: State ofVictoria, Department of Health (2013) Guidelines for validating treatment processes for pathogen reduction: Supporting Class A recycled water schemes inVictoria.

question_18

question_19

Paragraph 3. This section is not particularly useful as it just states numerous CTs that have been published. It would be more useful to have a discussion around the fact that numerous studies have been published on the effectiveness of chloramines at reducing several different pathogens (the range of published CTs could be included). Then it would be appropriate to discuss why certain CTs are more appropriate than others, for instance the USEPA (1991) CTs should be applied for Giardia reduction.

question_19

‘The Ct values should be considered as indicative only, and suitable safety factors should be applied to ensure adequate disinfection’. This fact sheet should provide the CT values that should be applied by the industry. If there is to be consistency within the industry, the ADWG as the authoritative guidance document must specify the appropriate CTs. In addition this statement is misleading as some of the CTs specified in the table have already had safety factors applied.
Table IS 1.5.1. This table should be expanded to provide the required CTs across a range of log reduction values (LRVs) (for instance 1-4 LRV). The USEPA tables are a good example. This is important as some schemes may require more or less than 2 LRV.
Suggest removing the CT for Cryptosporidium in table IS 1.5.1, as even with Note 4 the table is likely to be misconstrued.

question_25

It would be useful to include a summary table or list in this section of typical operational monitoring parameters which should be monitored when chloramine is used to disinfect drinking water supplies (e.g. CT, chlorine to ammonia ratio, pH, temperature, turbidity, instantaneous flow rate, tank hydraulic volume/level).

question_27

Paragraph 2. This section is not particularly useful as it just states numerous CTs that have been published. It would be more useful to have a discussion around the fact that numerous studies have been published on the effectiveness of chlorine dioxide at reducing several different pathogens (the range of published CTs could be included). Then it would be appropriate to discuss why certain CTs are more appropriate than others, for instance the USEPA (1999) CTs should be applied for enteric virus reduction. Is the discussion relating to the effectiveness of chlorine dioxide relevant?
It is unclear why the NZ MoH CTs for Cryptosporidium have been adopted. Consideration should be given to the CTs published by the USEPA (2010)[1].
‘The Ct values should be considered as indicative only, and suitable safety factors should be applied to ensure adequate disinfection’. This fact sheet should provide the CT values that should be applied by the industry. If there is to be consistency within the industry, the ADWG as the authoritative guidance document must specify the appropriate CTs. In addition this statement is misleading as some of the CTs specified in the table have already had safety factors applied.
Table IS 1.6.1. This table should be expanded to provide the required CTs across a range of log reduction values (LRVs) (for instance 1-4 LRV). The USEPA tables are a good example. This is important as some schemes may require more or less than 2 LRV.

[1] USEPA (2010). Long term 2 enhanced surface water treatment rule toolbox guidance manual, edited by USEPA Office of Water.

question_31

Suggest including the statement which was included in the other chlorine-based disinfection fact sheets, that advises to not reduce disinfection as a way of reducing by-product formation.

question_33

It would be useful to include a summary table or list in this section of typical operational monitoring parameters which should be monitored when chlorine dioxide is used to disinfect drinking water supplies.

question_35

Table IS 1.7.1. This table should be expanded to provide the required CTs across a range of log reduction values (LRVs) (for instance 1-4 LRV). The USEPA tables are a good example. This is important as some schemes may require more or less than 2 LRV.
We note that the ozone CTs stated are not accompanied by the qualifying statement used for the chlorine based disinfectants?

‘The Ct values should be considered as indicative only, and suitable safety factors should be applied to ensure adequate disinfection’

We support this approach and do not agree that such a qualifying statement should be included anywhere in the document. This document, where possible, should always specify the required CTs.

It is unclear why the NZ MoH CTs for Cryptosporidium been adopted. Consideration should be given to adopting the CTs published by the USEPA (2010[1]).

[1] USEPA (2010). Long term 2 enhanced surface water treatment rule toolbox guidance manual, edited by USEPA Office of Water.

question_41

It would be useful to include a summary table or list in this section of typical operational monitoring parameters which should be monitored when ozone used to disinfect drinking water supplies.

question_43

This section should discuss the approach to validation and should reference the approach described in the USEPA UVDGM (as previously discussed above).
Provide a dose table for the major pathogen groups (bacteria, protozoa and viruses) as per USEPA UVDGM.

question_49

Include lamp age and UV intensity in the list of recommended operational monitoring parameters.

General Comments

Comments:

Thank you for the opportunity to submit comments as part of the public consultation process for the ‘information sheets for water treatment operators’.

The department supports the development of the ‘information sheets for water treatment operators’ as they will promote greater consistency in the operation of water treatment processes.

The department also encourages the National Health and Medical Research Council to develop an information sheet on filtration.

If you would like to discuss any aspects of this submission, please contact the Water Program on 1300 761 874.

NHMRC Public Consultations

Information Sheets for Water Treatment Operators submission