Identification of Microorganisms in Wastewater Systems

Course: ENV 4005L – Environmental Engineering Laboratory II

Lab Type: Group Laboratory

Role: Microscopy, organism identification, interpretation

Tools: SWIFT M10T-MCS Optical Microscope, digital imaging system

Skills: Environmental monitoring, wastewater diagnostics, applied microbiology, microscopy, data interpretation

Overview

This laboratory investigation focused on the identification and classification of microorganisms commonly found in activated-sludge wastewater treatment systems. Using optical microscopy and comparative analysis, the lab simulated real-world conditions where microbial communities act as biological indicators of system performance, oxygenation, and sludge maturity.

Rather than relying on chemical sensors alone, wastewater operators frequently assess sludge health through microbial composition. This lab emphasized how engineers can use qualitative biological diagnostics to support operational decisions such as aeration control, nutrient balance, and sludge retention time.

Methodology

A laboratory culture representative of wastewater microbial communities was prepared on glass slides using pipettes and cover slips. Samples were examined under a compound optical microscope (SWIFT M10T-MCS series) at magnifications ranging from 40× to 1000×.

Illumination intensity and iris diaphragm settings were adjusted to optimize contrast and depth of field. Still images and videos were captured using the microscope’s digital imaging system and later compared against published photomicrographs and reference literature to confirm organism identification.

Results

Distinct microbial species were observed across multiple samples, each offering diagnostic insight into sludge conditions:

Microorganism	Features & Behavior	Interpretation
Euglena	Green flagellate capable of photosynthesis and heterotrophy	Presence indicates high organic load or unstable conditions
Rotifer	Ciliated metazoan feeding on decomposing matter	Suggests mature sludge and healthy oxygenation
Vorticella	Bell-shaped ciliate attached to bacterial flocs	Found in systems with high DO and good settling performance
Blepharisma	Pink ciliate protozoan; predatory	Common under moderate to high organic load
Stentor	Trumpet-shaped protozoan, slow-moving	Sign of stable, low-BOD, oxygen-rich environment
Water Bear (Tardigrade)	Multicellular, eight-legged micro-animal	Indicates well-aerated, mature sludge with stable conditions

Engineering Significance

This lab demonstrated how microscopic observations translate into macro-scale process understanding. Shifts from flagellate-dominated communities toward rotifers and stalked ciliates reflect transitions from young, unstable sludge to mature, well-functioning systems.

Such biological diagnostics are routinely used in wastewater treatment plants to:

• Identify early signs of process imbalance

• Supplement or validate sensor data

• Inform aeration and sludge age adjustments

Reflection

This experiment strengthened my ability to connect microbial ecology with engineering decision-making. Beyond organism identification, the lab emphasized microscopy as a practical monitoring tool, reinforcing skills such as depth focusing, contrast optimization, and digital documentation.

The experience highlighted how applied environmental microbiology supports reliable, real-time wastewater system diagnostics, a perspective directly relevant to environmental monitoring and treatment operations.