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