Causes of Excessive Organic Matter in Wastewater

Excessive organic matter in wastewater, typically measured as high BOD (Biochemical Oxygen Demand) or COD (Chemical Oxygen Demand), poses significant environmental risks like oxygen depletion and eutrophication. Key causes include:

Municipal Sources:

Food Waste: Improper disposal of cooking oils, fats, greases (FOG), and solid food scraps down drains adds substantial organic load.

Human Waste: High concentrations of fecal matter and urine are primary contributors.

Household Chemicals: Certain soaps, detergents, and personal care products contain organic compounds.

Industrial Discharges:

Food & Beverage Processing: Effluents from dairies, breweries, slaughterhouses, canneries, and sugar refineries are rich in sugars, starches, proteins, and fats.

Pulp & Paper Mills: Releases lignin, cellulose, and other wood-derived organics.

Chemical & Pharmaceutical Manufacturing: Can discharge solvents, raw materials, and complex organic by-products.

Textile & Tanneries: Use and release dyes, oils, and organic processing chemicals.

Agricultural Runoff:

Animal Manure: Runoff from livestock farms carries high loads of nitrogenous and carbonaceous organic matter.

Pesticides & Fertilizers: Some contain organic compounds that contribute to the load.

Crop Residues: Decomposing plant material can wash into water systems.

Infiltration/Inflow (I/I) & System Failures:

Stormwater Inflow: Heavy rain can dilute wastewater, reducing treatment time and washing organic debris (like leaves) into sewers.

Septic System Leakage: Failing systems leak untreated sewage into groundwater or surface water.

Sewer Leaks & Cross-Connections: Allow groundwater infiltration (diluting flow) or direct contamination.

Inadequate Treatment:

Overloaded Plants: Hydraulic or organic overload prevents sufficient biological treatment time.

Process Failures: Malfunctions in aeration, settling tanks, or biological processes reduce removal efficiency.

Understanding these diverse sources is crucial for developing targeted strategies – source control, pretreatment programs for industries, improved agricultural practices, infrastructure upgrades, and optimized wastewater treatment – to reduce organic pollution and protect water quality.