Is it possible to estimate the amount of biodegradable? (3 methods)

This blog shall answer the question of whether it is possible to estimate the amount of biodegradable organic matter in the environment.

It shall also cover other areas such as:

  • Definition of biodegradable waste.
  • Process of biodegradation.
  • Biochemical oxygen demand.
  • Chemical oxygen demand.

Is it possible to estimate the amount of biodegradable?

Yes, the amount of biodegradable organic matter in a waste can be estimated. Biodegradation is an extensive process that requires different agents and different requirements.

Some factors affect the rate of biodegradation.

To understand the methods of estimating biodegradable organic waste, it is important we first look at the process of biodegradation.

What is biodegradation?

Biodegradation is the process by which natural organic materials are broken down into small particles, water, and carbon dioxide by microorganisms.

Some microorganisms produce methane instead of carbon dioxide, depending on the material broken down or their biological machinery.

The agents of biodegradation include:

  • Water.
  • Sunlight.
  • Temperature.
  • Bacteria.
  • Fungi.

Water.

This causes biodegradation by carrying the materials and causing mechanical breakdown.

Sunlight.

Some light wavelengths cause the mechanical breakdown of organic materials into smaller particles.

Temperature.

Temperature causes the expansion and contraction of organic materials.

This causes the material to experience stress which in return results in mechanical breakdown.

Bacteria.

Bacteria break down organic material through the process of respiration to form small particles which they use to acquire energy.

The most common and active bacteria include:

  • Pseudomonas.
  • Bacillus.
  • Mycobacteria.

Fungi.

They break down organic matter into small particles which they then assimilate into their body systems.

They include:

  • Yeasts.
  • Mushrooms
  • Molds.
  • Mildew.
  • Lichens.

Types of biodegradation.

Types of biodegradation include:

Aerobic biodegradation.

This entails bacteria and fungi breaking down organic matter by the use of oxygen.

The end products include water, carbon dioxide, small particles( small biomass), and energy.

This process is faster than anaerobic biodegradation.

Anaerobic biodegradation.

This entails the bacteria breaking down organic matter in the absence of oxygen.

The end products include water, methane gas, small particles ( small biomass), and energy.

This process is slower as compared to aerobic biodegradation although it is more efficient.

Steps of biodegradation.

Biodegradation occurs in three distinct steps:

  • Biodeterioration.
  • Bio-fragmentation.
  • Assimilation.

Biodeterioration.

This is the first stage of biodegradation.

Organic materials are mechanically broken down by light, water, and temperature into smaller particles that are easily acted upon by bacteria and fungi.

Bio-fragmentation.

This is the second stage of biodegradation.

Organic matter is broken down by bacteria and fungi, either aerobically or anaerobically.

Water, carbon dioxide, methane gas, energy, and small biomass are produced depending on the type of process.

Assimilation.

It’s the last stage of biodegradation.

Involves the uptake of biomass produced into the body system of the bacteria or fungi to be used in various biological processes.

Types of biodegradable wastes.

The following are the materials that can undergo biodegradation.

  • Food wastes.
  • Human waste.
  • Paper waste.
  • Animal waste.
  • Dead animals.
  • Dead plants.
  • Waxes and oils 
  • Organic alcohol.
  • Organic acids.
  • Natural rubbers.

Advantages of biodegradation.

Biodegradation has several advantages which include the following:

  • It cleans the environment of the wastes.
  • Applicable to a wide range of products.
  • It can be triggered through composting
  • It is cost-effective.
  • Results to soil enrichment with nutrients.
  • Used to produce bioenergy.
  • Biodegradation through fermentation has led to the manufacturing of drugs.
  • It leads to the production of organic acids and alcohol.

Disadvantages of biodegradation.

Biodegradation has several disadvantages which include:

  • This leads to wear and tear of organic-based materials such as clothes.
  • It takes a very long time to degrade waste.
  • When used to produce bioenergy, it requires a lot of biomass.
  • It is easily affected by contaminants such as oil and antibiotics.
  • It is only limited to organic matter.

Factors affecting biodegradation.

Biodegradation can be affected by several factors which include:

  • Temperature.
  • Biomass.
  • Fungal and bacterial concentration ( Microbial population).
  • Oxygen.
  • Contaminants.
  • Types of wastes.

Temperature.

Temperature affects biodegradation in two main ways:

Temperature causes the expansion and contraction of organic matter, this results in stress and therefore breaks matter into small particles that are readily acted upon by microorganisms.

Temperature also affects the rate of bacterial degradation.

When the temperatures are optimum, the rate of bacterial activities is at the peak, and therefore the rate of biodegradation increases.

When temperatures are too high, the bacterial cells are affected and maybe denatured, resulting in bacterial inactivity and a biodegradation rate lowers.

When temperatures are extremely low, bacterial cells are inactivated and become dormant. Their biological processes stop and therefore biodegradation rate also lowers.

Biomass.

This is the amount of biodegradable waste.

When biomass is high, biodegradation will take a longer time as compared to when the biomass is low.

Microbial population.

When there is a high concentration of microorganisms in a given area, the rate of biodegradation will be high, consequently, when the concentration of microorganisms is low, the rate of biodegradation will be below.

The rate of biodegradation in compost can be increased by introducing more strains of bacteria through soil and animal wastes.

Oxygen.

The concentration of oxygen affects degradation depending on the type of microorganism.

Some bacteria are anaerobic; they don’t use oxygen for respiration, as a result, they are affected by the presence of oxygen and therefore the rate of degradation lowers.

Some bacteria and fungi use oxygen for respiration. The presence of oxygen increases their biodegradation activity while the absence of oxygen decreases the rate of biodegradation.

Contaminants.

Contaminants such as oil and plastics affect the rate of biodegradation by reducing the activity of bacteria and fungi.

The presence of antibiotics and fungicides in the wastes also will affect bacterial and fungal activities hence reducing the rate of biodegradation.

Types of wastes.

The type of waste also affects the rate of biodegradation.

Some wastes such as sewage wastes and human wastes are degraded very easily and therefore take a shorter time.

Some wastes such as rubber, organic oils, and bioplastics take a longer time to be degraded.

What are the methods of estimating biodegradable waste?

Biodegradable wastes can be estimated through two main methods:

  • Biochemical Oxygen Demand (BOD).
  • Chemical Oxygen Demand (COD).

Biochemical Oxygen Demand (BOD).

According to an article, this is the measure of dissolved oxygen needed by aerobic organisms to break down the organic matter present in liquid waste at a given temperature.

It is usually expressed in milligrams of oxygen per liter of sample waste.

When the biochemical oxygen demand is high, it shows there’s a high concentration of organic waste in that sample.

This process is carried out in 2 methods.

Dilution method.

  • It involves the use of BOD glass or plastic bottles.
  • Sample waste is added to BOD bottles.
  • The dissolved oxygen is measured and recorded.
  • The waste is diluted using standard dilution water.
  • The dilations are dosed with seed microorganisms.
  • They are incubated for Five days at a 20⁰ Celsius temperature.
  • Control samples are set using dilution water blanks to test for any impurities in the dilution water used, the glucose glutamic acid is used to determine the quality of microbial seeds used.
  • Nitrification inhibitor is added to the dilutions to prevent oxidation of ammonia to nitrogen so that only oxygen demand will be recorded.
  • After 5 days of incubation, the oxygen used is recorded.

Manometric method.

This method measures oxygen demand due to carbonaceous oxidation. Ammonia oxidation is inhibited using nitrification inhibitors.

  • Waste samples are kept in a sealed bottle fitted with an electronic pressure sensor.
  • A substance for absorbing carbon dioxide is added to the container above the sample.
  • The sample is incubated at 20⁰ Celsius.
  • As oxygen is being consumed, carbon dioxide is released.
  • Carbon dioxide released is absorbed and pressure decreases.
  • As the pressure decreases, the sensor records and displays the amount of oxygen used.

Chemical Oxygen Demand (COD).

This is a measure of total oxygen required to oxidize materials in a waste solution.

It is expressed in the mass of oxygen used over the volume of solution.

It helps in determining the amount of organic matter in a waste.

This method uses oxidizing agents such as:

  • Potassium dichromate.
  • Potassium permanganate.

The process involves adding the oxidizing agent to the waste solution.

The agent reacts with organic matter, in a redox reaction to form dichromate or manganate ions.

The measure of dichromate or manganate ions determines the amount of organic matter in the waste.

The excess oxidizing agent in the waste is proof of the complete oxidation of organic matter.

Conclusion:

This blog has addressed the ways of determining the amount of biodegradable waste.

It has also covered areas such as; the biodegradation process, chemical oxygen demand, and biochemical Oxygen Demand processes.

For any questions or comments, use the comment section below.

Frequently Asked Questions (FAQs): Is it possible to estimate the amount of biodegradable?

Is it possible to estimate the amount of biodegradable? 

Yes, the amount of biodegradable waste can be determined using methods such as chemical oxygen demand and biochemical oxygen demand.

How is the biodegradability of wastewater measured?

It can be measured by determining the ratio of Biochemical Oxygen Demand (BOD) to chemical oxygen demand (COD).

What does BOD measure in wastewater treatment?

Biochemical Oxygen Demand measures the organic matter in waste by determining the oxygen used by the microorganisms in degrading the waste.

Citations.

Sawyer, Clair N. & McCarty, Perry L. Chemistry for Sanitary Engineers 2nd Ed. (1967) McGraw-Hill pp. 394–399

Clair N. Sawyer; Perry L. McCarty; Gene F. Parkin (2003). Chemistry for Environmental Engineering and Science (5th ed.). New York: McGraw-Hill

Lucas N, Bienaime C, Belloy C, Queneudec M, Silvestre F, Nava-Saucedo JE (September 2008). “Polymer biodegradation: mechanisms and estimation techniques”. Chemosphere. 73 (4): 429–42. doi:10.1016/j.chemosphere.2008.06.064

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