Jim Morran

Long term case study of MIEX pre-treatment in drinking water; understanding NOM removal

Removal of natural organic matter (NOM) is a key requirement to improve drinking water quality. This study compared the removal of NOM with, and without, the patented magnetic ion exchange process for removal of dissolved organic carbon (MIEX DOC) as a pre-treatment to microfiltration or conventional coagulation treatment over a 2 year period. A range of techniques were used to characterise the NOM of the raw and treated waters. MIEX pre-treatment produced water with lower concentration of dissolved organic carbon (DOC) and lower specific UV absorbance (SUVA). The processes incorporating MIEX also produced more consistent water quality and were less affected by changes in the concentration and character of the raw water DOC. The very hydrophobic acid fraction (VHA) was the dominant NOM component in the raw water and was best removed by MIEX pre-treatment, regardless of the raw water VHA concentration. MIEX pre-treatment also produced water with lower weight average apparent molecular weight (AMW) and with the greatest reduction in complexity and range of NOM. A strong correlation was found between the VHA content and weight average AMW confirming that the VHA fraction was a major component of the NOM for both the raw water and treated waters.

Removal of MIB and geosmin using granular activated carbon with and without MIEX pre-treatment.

This study assessed the impact of MIEX pre-treatment, followed by either coagulation or microfiltration (MF), on the effectiveness of pilot granular activated carbon (GAC) filters for the removal of the taste and odour compounds, 2-methylisoborneol (MIB) and geosmin, from a surface drinking water source over a 2-year period. Complete removal of MIB and geosmin was achieved by all GAC filters for the first 10 months, suggesting that the available adsorption capacity was sufficient to compensate for differences in dissolved organic carbon (DOC) entering the GAC filters. Reduction of empty bed contact time (EBCT), in all but one GAC filter, resulted in breakthrough of spiked MIB and geosmin, with initial results inconclusive regarding the impact of MIEX pre-treatment. MIB and geosmin removal increased over the ensuing 12 months until complete removal of both MIB and geosmin was again achieved in all but one GAC filter, which had been pre-chlorinated. Autoclaving and washing the GAC filters had minimal impact on geosmin removal but reduced MIB removal by 30% in all but the pre-chlorinated filter, confirming that biodegradation impacted MIB removal. The impact of biodegradation was greater than any impact on GAC adsorption arising from DOC differences due to MIEX pre-treatment. It is not clear whether, at a lower initial EBCT, MIEX pre-treatment may have impacted on the adsorption capacity of the virgin GAC. The GAC filter maintained at the longer EBCT, which was also pre-chlorinated, completely removed MIB and geosmin for the period of the study, suggesting that the greater adsorption capacity was compensating for any decrease in biological degradation.

Drought to flood: A comparative assessment of four parallel surface water treatments during the 2010–2012 inflows to the Murray–Darling Basin, South Australia

Four treatment processes; conventional coagulation, magnetic ion exchange (MIEX)/coagulation, with and without granular activated carbon (GAC), and membrane treatment combining microfiltration (MF) and nanofiltration (NF), were operated in parallel using the same source water from the Murray-Darling basin in South Australia. During the two year study, high levels of natural organic matter and turbidity arising from floods affecting the Murray-Darling basin in 2010-2012 challenged the four processes. The comparative study indicated that all four processes could effectively meet basic water quality guidelines of turbidity and colour despite challenging source water quality but that the more advanced treatments improved overall organic and bacterial removal. Interestingly, the high organics and turbidity arising from the floods resulted in improved treatment efficiency for all treatments incorporating coagulation to the extent that, despite flood conditions, treated water quality could remain comparatively constant provided that the process was operated and optimised effectively.

Comparison of coagulation and MIEX pre-treatment processes for bacterial and turbidity removal, utilizing real-time optical monitoring techniques

Jar testing and flow cytometry were used in conjunction with photometric dispersion analysis (PDA) to assess conventional alum coagulation with and without magnetic ion exchange (MIEX) pre-treatment for turbidity and bacterial removal capacity. Treatment assessment included powdered activated carbon (PAC) and pre-chlorination of the MIEX-treated raw water. Floc particles were subjected to shear forces after settling and re-suspended to gauge bacterial release potential, floc breakage and re-aggregation. MIEX in conjunction with alum coagulation achieved improved coagulation as measured by PDA but did not increase bacterial log removal value (LRV) in comparison with conventional coagulation. Pre-chlorination and PAC addition were seen to improve bacterial removal and coagulation, respectively, but were less effective for bacterial LRVs when they were used in conjunction during coagulation.

Chemometric approaches to data assessment for a long-term case study of MIEX pretreatment performance

Abstract A specifically designed pilot plant facility located at the Mount Pleasant Water Treatment Plant in South Australia was used to investigate the efficiencies of several drinking water treatment processes, including (1) magnetic ion exchange (MIEX) as a pretreatment followed by conventional coagulation treatment, (2) conventional coagulation at pilot the plant alone, (3) MIEX followed by microfiltration (MF), and (4) MF alone. Dissolved organic matter (DOM) removal efficiency of the treatment processes and more importantly the treated water quality was assessed using dissolved organic carbon (DOC) measurement and together with the changes in the chromophoric organics character based on their molecular weight profiles determined by high-performance size exclusion chromatography (HPSEC) were also reported. Cluster analyses (CAs) were performed using the HPSEC peak area (after separated by peak fitting), and supported by DOC, UV absorbance at 254 nm, and SUVA in order to compare treatment efficiencies...

Guidance manual for the minimisation of NDMA and other nitrosamines in drinking and recycled water.

N-nitrosodimethylamine (NDMA) is a nitrogen-containing organic compound that has known carcinogenic properties. NDMA has been a health concern for some industries for a number of years as it is used in rubber formulations, as a fire retardant, antioxidant, additive for lubricants and softener of copolymers; it is also a degradation product of dimethylhydrazine, an additive to rocket fuel. Most people are exposed to NDMA via a number of diverse routes including cigarette smoke (actively or passively) and processed foods, for example smoked meat products. However, it has only come to the attention of the international water industry since it was recognised as a disinfection by-product (DBP) of chloramination or chlorination in the presence of ammonia. The aim of this guidance manual is to answer commonly asked questions about this emerging issue, such as: This Guidance Manual has a companion document, Generic Management Plan for Nitrosamines in Drinking Water which provides provide background information on the group of organic contaminants, nitrosamines. This title is Co-published with WaterRA . ISBN: 9781780406237 (eBook) ISBN: 9781780406220 (Print)