Wastewater is 99.99% water with amounts of dissolved or suspended solid matter. It contains a mixture of home sewage, industrial effluent, and groundwater that has penetrated into the sewers.
Fermentation process is one of the applications of the wastewater treatment. Wastewater is digested by enzymes released by microorganisms, during the wastewater disposal process. Organic solids are decomposed into non-toxic soluble chemicals and carbon dioxide.
The digested solids, often known as sludge, that accumulate in a wastewater treatment process, must be safely and effectively processed and disposed of. The goal of digestion is to lower the amount of organic matter in the solids, as well as the number of disease-causing microbes.
Can fermentation technology be used in wastewater treatment?
Aerobic degradation of raw wastewater
1- Application of Fermented Sludge in Nutrient Removal: Fermentation can provide a carbon source for nitrogen and phosphorus elimination. It is a tool for lowering the operational expenses of biological nutrient removal.
The elimination of nitrogen and phosphorus from wastewater effluents is critical for the protection of surface waters. High nutrient concentrations in rivers can induce eutrophication, oxygen depletion in the river, and algae development. As a result, it has been proposed as an efficient method of removing nutrients from wastewater.
2- Biological Nitrogen Removal: Biological nitrogen removal technologies can be integrated into both activated sludge and percolating filter plants. The general mechanism is based on nitrification (the conversion of ammonia to nitrite and nitrate), and denitrification (reduction of nitrate sequentially to nitrite, nitric oxide, nitrous oxide and nitrogen).
In general, biological denitrification methods recirculate nitrified wastewater as a source of nitrate. This means that complete elimination will never be possible. Only nitrate from the recirculated stream will be removed.
Sludge Anaerobic Digestion
However, anaerobic digestion is the most commonly used way of treating sludge. This can be accomplished by allowing the sludge to degrade in digesters, for many weeks under controlled settings. Digesters are closed tanks with provisions for mild agitation, the addition of sludge, and the emission of gases. Approximately 50% of biological matter is converted to gas, primarily methane.
Anaerobic Microbial Digestion typically consists of four steps:
1. Hydrolysis Extracellular (e.g., Cellulose)
2. Fermentation, which produces organic acids (VFAs), acetate, CO2, and H2.
3. Fermentation, which produces acetic acid (CH3COOH), H2 and O2.
4. Methanogenesis, which produces CH4, CO2, and H2O.
How does the fermentation process work?
The fermentation process occurs in two basic steps: hydrolysis and acidogenesis.
Extracellular enzymes break down long-chain molecules during hydrolysis into smaller dissolved molecules, which are then transformed to VFAs during the acidogenesis stage.
First, during hydrolysis, extracellular enzymes degrade water-insoluble biopolymers, such as carbohydrates, proteins, and lipids into water-soluble monomers, e.g., monosaccharide’s, amino acids, glycerine, fatty acids, which are then available to further degradation.
Different kinds of bacteria convert the intermediates of hydrolysis into acetic acid (CH3COOH), hydrogen (H2), carbon dioxide (CO2), organic acids, amino acids, and alcohol in the second stage. Some of these intermediate products (acetic acid, hydrogen, and carbon dioxide) can be directly utilized by methanogenic bacteria, but the majority of organic acids and alcohol are destroyed during acidogenesis into acetic acid, hydrogen, and carbon dioxide.
Only these compounds, as well as methanol, methylamine, and formate, can be converted into carbon dioxide and methane (CH4) by methanogenic bacteria, during the third and last phase, methane generation.
Advantages of fermentation technology in wastewater treatment
The production of biogas, which may be used as a source of energy, is a significant advantage of anaerobic fermentation. The ability of engineers to have absolute control over gaseous and liquid emissions, as well as the capability to recover and utilize methane gas generated as wastes degrade, is a significant advantage of anaerobic digestion over aerobic composting.
How can we assist?
Netsol Water offers a wide range of sophisticated wastewater treatment solutions, such as water softeners, wastewater treatment plants, sewage treatment plants, water treatment plants, RO Plants, as well as effluent treatment plants for various industries.