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Natural Organic Matter in SA Waters: Characterisation and treatability- our capabilities
“Sustainable water resource”
Nanotechnology and Water Sustainability Unit (NanoWS @ UNISA)
Multi-disciplinary research unit focussing on:
• nanotechnology (nanomaterials) for water treatment• advanced water treatment technologies (membranes)• optimisation of conventional water treatment technologies• water reuse, wastewater reclamation, “new water” from AMD
The researchers in the group and collaborators include materials scientists, analytical chemists, applied chemists, nanoscience research specialists, materials engineers, biosciences engineers, water and environmental engineers
RESEARCH FOCUS AREAS
• Nanostructured Membranes, Composites and nanocomposites
• Toxicology, nanotoxicology and development of analytical methods and protocols
• Urban Water Cycle (Water reclamation, reuse, NOM, and drinking water treatment)
• Bioremediation and analysis (Constructed wetlands and biotoxins analysis)
• Community Engagement (Training)
STRUCTURE OF NOM
CHEMICAL DESCRIPTION OF NOM FRACTIONS
(i) Hydrophobic acid:
carboxylic acids of five to nine
carbons, one and two-ring aromatic carboxylic acids, aromatic acids, one and two-ring phenols and tannins.
(ii) Hydrophobic base:
are proteins with one and two-ring aromatic amines except for pyridine and high molecular weight alkyl.
(iii) Hydrophobic neutral:
a mixture of hydrocarbon and carboxyl compounds.
(iv) Hydrophilic acid:
aliphatic acids of less than five carbons, hydroxyl acids, sugars, low molecular weight alkyl monocarboxylic acids and dicarboxylic acids.
(v) Hydrophilic base:
Amphoteric proteinaceous materials containing amino acids, amino sugars, peptides and proteins.
(vi) Hydrophilic neutral:
aliphatic amides, alcohols, aldehydes, esters, polysaccharides and ketones with less than five carbons.
NOM IN THE ENVIRONMENT
Terpenoid
Humic Acid
Amino Sugars
3-Acetonedicarboxylic acid
Tannic acid
D-xylose
Hydrophobic HPO
Transphilic TPI
Hydrophilic HPI
Natural Organic Matter (NOM)
NOM IN THE WATER TREATMENT TRAINFerric Disinfectio
n
Coagulation Flocculation Effluent
HPIHPO
DBPs
Disinfection byproducts (Health and social).
Colour, undesirable taste and odour (water quality).
Corrosion of distribution network (Costs).
High disinfectant demand (Costs).
Eutrophication (Environmental)
What do we need to know about NOM to understand its treatability?
• DOC concentration at source
• Charge load
How much coagulant do we need?
• Zeta potential (charge removal)
• Membrane fouling
How do we optimise the
process?
• Fractionation• No idea! (yet)
How much DOC will remain?
What DBPs will form?
NOM CHARACTERIZATION
Isolation and/or concentration of NOM from source waters.
Fractionation into groups (fractions) of compounds with similar physical or chemical characteristics.
To identify which fractions dominates the NOM.Develop and employ methods to remove
problematic fractions.
Use of NOM fractions to investigate the effects of NOM on various water treatment processes and health effects.
CHARACTERIZATION OF NOM
NOM FRACTIONATION
• Hydrophobic NOM• High aromatic content• High UV254
Humic
• Hydrophilic NOM• Less aromatic
(aliphatic)• Lower UV254
Non-Humic
Dissolved organic carbon
C18 CN/NH2
HPOTPI
HPI
HPI Fraction
NaOH NaOH
HPO Fraction
TPI Fraction
NOM sample
FRACTIONATION OF NOM (PRAM)
DISINFECTION BY-PRODUCT FORMATION (POTENTIAL)
NOM + free chlorine THMs + HAAs + cyanogen halides + other DBPs
SIMULTANEOUS FEEM ABSORBANCE
TYPICAL RAW SURFACE WATER FEEM