4.1 History of Water and Wastewater Treatment Regulatory Issues across the World4.2 Design Principles for Sustainable Treatment Systems4.3 Preliminary and Primary Treatment4.4 Secondary Treatment4.5 Tertiary Treatment4.6 Emerging Technologies4.7 Residual Management4.8 Portable Water Purification Kit4.9 Requirements of Electrical, Instrumentation and Mechanical Equipment in Water and Wastewater Treatment to Achieve SustainabilityReferences