Biological Foundations and Wastewater Treatment Essentials

Biological Foundations

Photosynthesis: Energy Capture

Photosynthesis is a vital process that enables plants to convert light energy into chemical energy. This fundamental process, crucial for life, relies on the presence of leaves and pigments to capture solar energy.

Cellular Structures & Nutrient Transport

Unicellular vs. Multicellular Organisms

Unicellular organisms are in direct contact with their external environment. In contrast, multicellular organisms do not have all their cells in direct contact with the outside world, facing challenges in spreading nutrients across individual cells.

Therefore, multicellular organisms require internal transport systems (like 'pipes' or circulatory systems) to distribute nutrients to all cells not in direct contact with the external environment. These systems also serve to bring nutrients into the organism and expel waste products (excretions).

Eukaryotic Cells

Eukaryotic cells consist of a membrane, a nucleus, and cytoplasm.

Prokaryotic Cells

Prokaryotic cells are simpler, typically consisting of a cell wall and lacking a membrane-bound nucleus or organelles.

Wastewater Treatment Processes

Primary Treatment

Primary treatment involves the separation of solid material in suspension and floating solids that were not retained in initial pretreatment stages. This process is completed through decantation, followed by flocculation and neutralization processes, or pH adjustment, to prepare the water for subsequent treatments.

Secondary Treatment

Secondary treatment is a set of biological processes, often including a secondary decanting system, designed to remove organic material present in wastewater. One common biological process used is the activated sludge process. This involves placing wastewater in large aerobic conditions, allowing naturally occurring bacteria (or added bacteria) to expedite the degradation of organic matter through oxidation processes.

Disinfection

Disinfection is the final treatment step, designed to prevent health problems caused by the existence of pathogenic bacteria and viruses in water. Its application depends on the effectiveness of previous treatments. Common processes include chlorination.

These processes often result in a concentrated liquid waste, referred to as mud or sludge. The subsequent treatments focus on managing this sludge.

Sludge Management

Sludge Thickening

The purpose of sludge thickening is to reduce its volume by eliminating most of the contained water. This facilitates subsequent handling and treatment. Thickeners, based on gravity or flotation devices, are commonly used for this process.

Sludge Stabilization

Sludge stabilization aims to remove organic material present in the sludge. This process can be performed through different routes: aerobic and anaerobic digestion. Aerobic digestion involves the oxidation of organic matter present in the sludge.