Q.28 A biological process is involved in the ________ treatment of industrial effluent.
(A) primary (B) secondary (C) tertiary (D) quaternary
Biological Process in Industrial Effluent Treatment: MCQ Answer and Explanation
Biological processes play a key role in treating industrial effluent by breaking down organic pollutants. The correct answer to the multiple-choice question is (B) secondary. This stage uses microorganisms to degrade waste effectively.
Correct Answer
(B) secondary
Secondary treatment relies on biological methods like activated sludge and trickling filters, where bacteria consume organic matter in the effluent. This reduces biochemical oxygen demand (BOD) and makes water safer for discharge or further processing.
Primary Treatment
Primary treatment focuses on physical processes such as screening, sedimentation, and flotation to remove large solids, grit, oils, and floating debris. No biological activity occurs here; it prepares effluent mechanically for the next stage.
Secondary Treatment
This stage involves aerobic or anaerobic biological processes where microbes metabolize dissolved organics into biomass, carbon dioxide, and water. Common methods include activated sludge systems and biofilters, essential for industrial effluents high in organics like those from food processing or textiles.
Tertiary Treatment
Tertiary treatment employs chemical, physical, or advanced filtration methods like chlorination, coagulation, or membrane filtration to polish water by removing nutrients, metals, and pathogens. Biological elements may support it, but the focus is not primarily biological.
Quaternary Treatment
Quaternary treatment, when used, targets micropollutants like pharmaceuticals via advanced oxidation or adsorption, rarely standard in effluent plants. It goes beyond basic biological degradation and is not the main stage for biological processes.
