Wastewater and Waste Management Fundamentals

Posted on Aug 24, 2025 in Geology

Wastewater Treatment Plant (WWTP)

A Wastewater Treatment Plant (WWTP) is a facility where a set of purification and treatment systems are applied to wastewater. The goal is to enable its reuse, decontamination, and safe disposal into the environment or directly into the sea, without risks to health.

WWTP Schematic

Water Line:

  • Pretreatment
  • Primary Treatment
  • Secondary Treatment
  • Tertiary Treatment
  • Disinfection

Sludge Line:

  • Sludge Thickening
  • Sludge Stabilization

Key Definitions and Procedures

Population

In the context of a study, ‘population’ refers to the entire phenomenon or group of elements under consideration.

Sample Preservation

Samples must be stored at low temperatures (4°C) or with stabilizing reagents to ensure their integrity. They must be sealed and perfectly identified. The time from collection to delivery should be minimal.

Random Sampling Procedures

Methods include using a four-quadrant random numbers table and simple random sampling.

Osmosis

Osmosis is a physicochemical phenomenon related to water behavior, where water moves from an area of low solute (salt) concentration to an area of high solute concentration, and vice versa, across a semi-permeable membrane.

Reverse Osmosis

In reverse osmosis, water from an area of high solute concentration passes to an area of low solute concentration by applying external pressure. For example, seawater can be desalinated, allowing only water (not salt) to pass through a membrane, making it potable.

Applications:

  • Desalination
  • Hardness reduction
  • Effluent decontamination and treatment
  • Nitrate reduction
  • Odor elimination from water
  • Industrial uses
  • High-quality water production

Residue

Residue refers to the fraction of elements that are not profitable and therefore must be treated and disposed of to prevent health or environmental problems.

Waste Classification

  • Household Waste: Waste from households and/or communities.
  • Industrial Waste: Originates from manufacturing or raw material processing.
  • Hospital Waste: Typically classified as hazardous waste; can be organic or inorganic.
  • Commercial Waste: From exhibitions, offices, shops, etc., composed of organic remains like fruit, vegetables, cardboard, and paper.
  • Urban Waste: For populations, includes waste from parks and gardens, discarded furniture, and similar items.
  • Space Debris: Objects and artificial fragments of human origin that are no longer useful and are in Earth orbit.

Waste Management

Project Stages

  1. Inventory and data collection, including applicable regulations.
  2. Diagnosis.
  3. Development of alternatives and selection of the best applicable alternative.

Waste Management Principles

Waste management aims to minimize the amount of waste sent to landfills. These efforts include:

  • Recycling
  • Converting waste to energy
  • Designing products that use less material
  • Legislation mandating manufacturers to take responsibility for product and packaging disposal costs.

The ‘4 Rs’ of Waste Management:

  • Reduce
  • Reuse
  • Recycle
  • Recover

Waste Management Process Stages

Collection, Sorting, Storage, Transportation, Treatment, Recovery, Disposal.

Landfills

Landfills are sites where waste is ultimately deposited. They can be controlled or uncontrolled.

Ideal Location Criteria:

  • Stable geological material
  • Impermeable soil
  • Away from groundwater and surface water currents
  • Consideration of wind direction
  • Away from residential areas/stocks
  • No significant impact on the landscape

Waste Disposal Procedures

  • Incineration
  • Recovery
  • Reuse/Recycling