Wastewater and Water Quality Concepts

• Lecture covers water and wastewater topics

Learning Outcomes

• Understand and discuss the Hydrological Cycle
• Gain knowledge about Wastewater
• Understand Physical Parameters of water
• Learn about Chemical Parameters of water
• Explore Biological Characteristics of water
• Study Wastewater disposal methods
• Learn about Self-Purification of Natural Streams

Introduction

• Ensuring safe and sufficient water is increasingly challenging due to population growth and environmental degradation.
• Part of the solution involves reducing pollution and managing wastewater more effectively.
• A circular, sustainable economy reduces ecosystem contamination and increases wastewater treatment, recycling, and safe reuse for water, energy, and nutrients.
• Water pollution is rising throughout the water cycle because of population growth, urbanization, and economic development, leading to increased wastewater quantities and pollution loads globally.
• Industry and agriculture often cause water pollution; intensified use of fertilizers, pesticides, and untreated wastewater pollutes both groundwater and surface water, and factories may discharge waste directly into water courses.
• Wastewater management needs serious attention, as safely reused wastewater can be a sustainable source of water, energy, nutrients, and other valuable materials.
• Untreated wastewater impacts cities, particularly in urban areas where it is often discharged into drainage channels or water bodies, leading to environmental contamination in densely-populated zones.

Water

• One of nature's abundant compounds
• Covers approximately ¾ of the Earth's surface
• 97% of the total quantity of water is in the oceans and saline bodies of water
• Over 2% is tied up in polar ice caps and glaciers and in atmosphere and as soil moisture
• 0.62% of water found in fresh, rivers and groundwater supplies irregularly and non-uniformly distributed over the vast of the world

Hydrological Cycle

• Evaporation occurs due to solar radiation.
• Water molecules become atmospheric vapor.
• Atmospheric water condenses, falls as rain/snow.
• Water flows into streams/lakes/soil.

Wastewater Composition

• Wastewater is used water impacted by domestic, industrial, and commercial activities
• It consists of 99.9% water, with 0.1% being the removed matter.
• The 0.1% contains organic matter, microorganisms, and inorganic compounds.

Industrial Wastewater

• Effluent is discharged from a particular industry.
• The quality and quantity varies depending on the industry type, raw materials, processes, and housekeeping.
• Characteristics differ across industries.

Physical Parameters

• Suspended solids may be inorganic or organic particles.
• Turbidity measures the absorption/scattering of light by materials in water.
• Color is visible.
• Taste and odor come from gases released by organic matter decomposition.
• A temperature increase enhances activity.

Chemical Parameters

• Total dissolved solids (TDS) can be organic or inorganic.
• Alkalinity is water's ability to neutralize acids.
• Hardness relates to dissolved divalent metallic cations like Ca++ and Mg++.
• Fluoride comes from igneous and sedimentary rocks.
• Inorganic salts can be from industrial wastes.
• pH is an essential parameter for waters and wastewater.
• Dissolved Oxygen
• COD
• BOD

Biological Characteristics

• Suspended Solids: Contribute to sludge deposits and anaerobic conditions.
• Organics (Biodegradable): Principally carbohydrates, proteins and fats contribute to BOD.
• Refractory Organics (Non-biodegradable): Phenols, fertilizers, and pesticides not easily removed, harm the biological community, and hinder biological treatment.
• Pathogens: Cause waterborne diseases like cholera, dysentery, and typhoid which are transmitted by pathogenic organisms.
• Nutrients: Phosphates/Nitrates contribute to Eutrophication of static water bodies.
• Dissolved Inorganic Solids: Excess salts of sodium and calcium need removal for domestic & industrial water use.
• Heavy metals: Nickel, Manganese, Lead, Chromium, Cadmium, Zinc, Copper, and Iron Mercury, in higher concentrations, are detrimental for aquatic life.

Disposal of Wastewater

• There are natural methods, such as disposal by dilution.
• Artificial methods include primary and secondary treatment.

Self-Purification of Natural Streams

• When wastewater or effluent enters a natural stream, the organic matter converts into substances like ammonia, nitrates, sulfates, and carbon dioxide through cateria action.
• During oxidation, the natural water's oxygen content is used leading to oxygen deficiency.
• Once excess organic matter is stabilized, the normal cycle involves self-purification, with dissolved oxygen replenished via reaeration by atmospheric oxygen.

Test your knowledge of wastewater composition, water quality parameters, and environmental impacts. This quiz covers topics such as turbidity, taste and odor, and self-purification processes in streams. Explore the challenges of growing populations and the importance of sustainable wastewater management.