Photocatalysis of Titanium Dioxide for Water Disinfection: Challenges and Future Perspectives

Table 1

Microorganisms found in contaminated waters.

Microorganisms	Orgnismal features	Potential health effects	Sources of contamination
Cryptosporidium	A single-celled protozoan parasite	Gastrointestinal illness (e.g., diarrhoea, gastroenteritis, vomiting, cramps)	Human and animal faecal waste
Giardia lamblia	A single-celled protozoan parasite	Gastrointestinal illness (e.g., diarrhoea, gastroenteritis, vomiting, cramps)	Human and animal faecal waste
Legionella	Gram-negative bacterium	Legionnaire’s disease, a type of pneumonia	Found naturally in water and multiplies in heating systems
Coliforms (including faecal coliform and E. coli)	Gram-negative, rod-shaped bacteria	Not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present	Coliforms are naturally present in the environment, as well as faeces; faecal coliforms and E. coli only come from human and animal faecal waste.
Vibrio	Gram-negative, rod-shaped bacteria	Gastroenteritis	Human and animal faecal waste
Shigella	Gram-negative, rod-shaped bacteria	Bacillary dysentery or shigellosis	Human and animal faecal waste
Helicobacter pylori	Gram-negative, spiral-shaped bacteria	stomach ulcers	An emerging water-borne bacterium, possibly due to human faecal waste
Clostridium perfringens	Gram-positive, rod-shaped bacteria	Gastrointestinal illness (e.g., diarrhoea, cramps)	Human and animal faecal waste
Enterococci	Gram-positive, ovoid or round bacteria	Gastroenteritis	Human and animal faecal waste
Salmonella	Gram-negative, rod-shaped bacteria	Gastroenteritis	Human and animal faecal waste
Viruses (enteric)	Virus	Gastrointestinal illness (e.g., diarrhoea, vomiting, cramps)	Human and animal faecal waste