Graduate
  1. Physical Chemistry  1.1. Thermodynamics  1.1.1. Laws of Thermodynamics  1.1.2. Enthalpy and heat capacity  1.1.3. Entropy and free energy  1.1.4. Phase Equilibrium  1.1.5. Statistical thermodynamics  1.1.6. Thermodynamic cycle  1.1.7. Fugacity and activity  1.2. Quantum Chemistry  1.2.1. Principles of quantum mechanics  1.2.2. Schrödinger Equation  1.2.3. Particle in a box  1.2.4. Operators and eigenvalues  1.2.5. Atomic orbitals  1.2.6. Molecular orbital theory  1.2.7. Perturbation theory  1.2.8. Valence bond theory  1.2.9. Hybridization and chemical bonding  1.3. Chemical kinetics  1.3.1. Rate laws and reaction mechanisms  1.3.2. Collision theory  1.3.3. Transition state theory  1.3.4. Enzyme Kinetics  1.3.5. Chain Reactions and Polymerization  1.3.6. Photochemical reactions  1.4. Statistical mechanics  1.4.1. Partitioning functions  1.4.2. Molecular distribution functions  1.4.3. Boltzmann Distribution  1.4.4. Bose–Einstein and Fermi–Dirac statistics  1.5. Spectroscopy  1.5.1. Rotational Spectroscopy  1.5.2. Vibrational Spectroscopy  1.5.3. Electronic Spectroscopy  1.5.4. Nuclear magnetic resonance spectroscopy  1.5.5. Mass Spectrometry  1.5.6. Raman Spectroscopy  1.5.7. Electron paramagnetic resonance spectroscopy  1.6. Surface and colloidal chemistry  1.6.1. Absorption isotherm  1.6.2. Surface tension and wetting  1.6.3. Colloidal Stability  1.6.4. Catalysis  1.6.5. Emulsions and micelles  1.7. Electrochemistry  1.7.1. Nernst equation  1.7.2. Electrochemical cells  1.7.3. Conductivity and mobility  1.7.4. War  1.7.5. Fuel cells  1.7.6. Electrolysis
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic reactions  2.2. Spectroscopy and structural determination  2.2.1. UV-Vis Spectroscopy  2.2.2. IR Spectroscopy  2.2.3. NMR Spectroscopy  2.2.4. Mass Spectrometry  2.2.5. X-ray crystallography  2.3. Stereoscopic  2.3.1. Chirality and optical activity  2.3.2. Structural analysis  2.3.3. Geometrical isomerism  2.3.4. Dynamic Stereochemistry  2.4. Organometallic Chemistry  2.4.1. Organolithium and organomagnesium reagents  2.4.2. Palladium-catalyzed cross-coupling reactions  2.4.3. Transition Metal Complexes  2.4.4. Metal–carbon bond  2.5. Polymer chemistry  2.5.1. Polymerization mechanism  2.5.2. Polymer Characteristics  2.5.3. Biodegradable Polymer  2.5.4. Conducting polymer  2.5.5. Supramolecular polymers  2.6. Medicinal chemistry  2.6.1. Drug design and development  2.6.2. Pharmacokinetics and pharmacodynamics  2.6.3. Structure-activity relationships  2.6.4. Molecular docking and drug screening
  3. Inorganic chemistry  3.1. Coordination chemistry  3.1.1. Crystal field theory  3.1.2. Ligand field theory  3.1.3. Spectrochemical Series  3.1.4. Chelation and stability  3.2. Organometallic Chemistry  3.2.1. Metal Carbonyls  3.2.2. Catalysis by organometallic complexes  3.2.3. Metallocenes  3.3. Bio-inorganic chemistry  3.3.1. Metalloproteins and enzymes  3.3.2. The role of metals in biological systems  3.3.3. Metal ion transport and storage  3.4. Solid state chemistry  3.4.1. Crystal Structures  3.4.2. Band theory of solids  3.4.3. Superconductors  3.4.4. Defects in the crystal  3.5. Lanthanides and Actinides  3.5.1. Electronic configuration in lanthanides and actinides  3.5.2. Coordination chemistry of the lanthanides  3.5.3. Magnetic Properties of Lanthanides
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.2. Spectroscopic Techniques  4.2.1. Atomic absorption spectroscopy  4.2.2. X-ray diffraction  4.2.3. Inductively coupled plasma spectroscopy  4.3. Electroanalytical methods  4.3.1. Potentiometry  4.3.2. Voltammetry  4.3.3. Colometry  4.4. Mass Spectrometry  4.4.1. Ionization Technique  4.4.2. Fragmentation Pattern  4.5. Chemometrics  4.5.1. Multidisciplinary analysis  4.5.2. Machine Learning in Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.1.1. Force fields and energy minimization  5.1.2. Monte Carlo simulation in molecular dynamics simulations  5.2. Quantum chemical methods  5.2.1. Hartree–Fock theory  5.2.2. Density functional theory  5.2.3. Semi-empirical methods  5.3. Computational drug design  5.3.1. Molecular Docking  5.3.2. QSAR Modeling  5.3.3. Virtual Screening
  6. Biochemistry  6.1. Enzyme Kinetics  6.1.1. Michaelis-Menten kinetics  6.1.2. Inhibition mechanism  6.2. Metabolism and Bioenergetics  6.2.1. Glycolysis  6.2.2. Citric acid cycle  6.2.3. Electron transport chain  6.3. molecular Biology  6.3.1. DNA replication and repair  6.3.2. Protein synthesis  6.3.3. Gene Regulation  6.4. Structural Biochemistry  6.4.1. Protein Folding  6.4.2. Membrane Biophysics
  7. Environmental Chemistry  7.1. Atmospheric Chemistry  7.1.1. Greenhouse gases  7.1.2. Ozone depletion  7.1.3. Air pollutants and smoke  7.2. Water Chemistry  7.2.1. pH and water hardness  7.2.2. Wastewater treatment  7.2.3. Aquatic Chemistry  7.3. Soil Chemistry  7.3.1. Heavy metal contamination  7.3.2. Soil pH and Buffering  7.3.3. Nutrient cycling  7.4. Toxicology and Chemical Safety  7.4.1. Toxicokinetics  7.4.2. Risk Assessment in Toxicology and Chemical Safety in Environmental Chemistry  7.4.3. Effects of pollutants on the environment

Graduate → Environmental Chemistry → Water Chemistry ↓


Wastewater treatment


Introduction to wastewater treatment

Wastewater treatment is an important process in environmental chemistry that deals with the removal of contaminants and pollutants from water to make it safe for release into the environment or reuse. This process is essential to protect ecosystems and human health, ensuring that water quality meets health and safety standards.

Importance in environmental chemistry

In the field of environmental chemistry, wastewater treatment plays a vital role in reducing the negative effects of water pollution on the environment. Uncontrolled emissions of contaminants can lead to harmful ecological disruptions and health issues. Wastewater includes not only domestic sewage but also industrial effluents that require intensive treatment before being discharged. Understanding the chemistry behind these processes helps design effective treatment strategies.

Example: Sources of wastewater

Wastewater is generated from a number of sources including:

  • Residential areas (e.g., sewage, greywater)
  • Industrial activities (eg, chemical, pharmaceutical)
  • Agricultural runoff (e.g., fertilizers, pesticides)

Chemistry of wastewater

Wastewater contains a wide variety of chemical compounds that require attention. These compounds range from simple organic molecules to complex industrial chemicals. The main chemical components include:

  • Organic matter: Usually measured as biological oxygen demand (BOD) or chemical oxygen demand (COD).
  • Nutrients: Mainly nitrogen and phosphorus, which can cause eutrophication.
  • Toxic chemicals: Heavy metals such as lead (Pb), cadmium (Cd), and mercury (Hg), as well as synthetic organic compounds.
  • Pathogens: Bacteria, viruses and protozoa.

Major processes in wastewater treatment

1. Initial treatment

The goal of preliminary treatment is to remove large solids and debris from the wastewater. This is often achieved through screening and grit removal which prevents damage to downstream equipment.

Example: Screening process

The illustration above shows a simplified representation of the screening process, where large objects such as plastics and solids are removed from the water stream.

2. First aid

Primary treatment focuses on sedimentation, which causes suspended solids to settle out of the water. This process reduces the load on the secondary treatment stages. Most organic matter and grease are removed during this stage.

3. Secondary treatment

Secondary treatment involves biological processes that destroy organic matter using microorganisms. The most common method is activated sludge, where air and biological flocs of bacteria, fungi and protozoa are mixed with the sewage.

Example: Activated sludge process

The activated sludge process is based on aerobic bacteria that consume organic pollutants to form flocs that can be easily removed.

4. Tertiary treatment

In tertiary treatment, further purification is achieved by removing residual suspended solids, phosphorus, nitrogen and pathogenic microorganisms through chemical, physical and biological methods.

  • Chemical precipitation: Uses coagulating agents such as alum (Al_2(SO_4)_3) to remove phosphate.
  • Filtration: Uses sand filters or membrane technology.
  • Disinfection: Common methods include chlorination and the use of ultraviolet light.

Example: Membrane filtration

The above figure presents a simplified view of how certain particles can be separated from water by selective filtration.

Other advanced treatment methods

In addition to primary, secondary, and tertiary treatments, a number of advanced methods exist to target specific pollutants:

  • Advanced oxidation processes: Use strong oxidants such as ozone (O_3), hydrogen peroxide (H_2O_2), or ultraviolet light to break down pollutants.
  • Ion exchange: Removes specific ions such as Na^+ and Ca^2+ using a resin bed.

Wastewater treatment challenges

Many challenges exist in wastewater treatment, including emerging pollutants, energy consumption, and sludge management. Advanced research is focused on developing cost-effective, energy-efficient, and sustainable treatments.

Conclusion

Understanding the principles of wastewater treatment in water chemistry is essential to address modern-day environmental challenges. By taking advantage of chemical, biological, and physical treatment processes, we can effectively protect water resources and promote ecology and human health.


Graduate → 7.2.2


U
username
0%
completed in Graduate

← Prev (7.2.1)
pH and water hardness
Next (7.2.3) →
Aquatic Chemistry

Comments 



Wastewater treatment

https://www.chemistryelite.com/g/7.2.2?ceal=en