Lucas-Parmer: Lab 7

EES 4102C Wastewater Microbiology

Lab #7: Characterization of Industrial Wastewater

Introduction

Wastes brought to landfills are subjected to either groundwater underflow or infiltration from rain water. As water collects throughout the waste in the landfill, it tends to pick up a variety of inorganic and organic compounds. This then flows out of the wastes to accumulate at the bottom of the landfill resulting in contaminated water known to us as leachate. Given that Municipal landfill leachate is high in concentrations of dissolved heavy metals, organic and inorganic compounds. This all can cause variations in dissolved oxygen, pH, and turbidity. When treatment plants take the leachate, they need to know if the treatment plant can handle the leachate without pre-treatment or if it needs to be pre-treated beforehand.

Methods and materials

Even though we can look at many aspects of leachate, we are focusing on Specific oxygen uptake rate (SOUR), dissolved oxygen, turbidity, and pH.

Specific Oxygen Uptake Rate (SOUR) was found by first and formost making sure to calibrate the DO meter. We then needed to get about two-300 mL BOD bottle, this was then used to collect varied samples of leachate to wastewater volumes. The volumes can be reported like:

100% leachate and 1% (v/v) leachate:wastewater
100% leachate and 3% (v/v) leachate:wastewater
100% leachate and 5% (v/v) leachate:wastewater
100% leachate and 10% (v/v) leachate:wastewater
100% leachate and 20% (v/v) leachate:wastewater
100% leachate and 50% (v/v) leachate:wastewater
100% leachate and 75% (v/v) leachate:wastewater

Start with the leachate:wastewater mix first! not the 100% leachate. We then filled only half the container as we aerated the sample thoroughly by shaking then place on a stir plate with a stir bar to continue aeration. Now that we have added some aeration we need to fill up the rest of the BOD bottle to just below overflowing with sample. Be sure to immediately insert DO meter and displace enough of the sample to fill top of bottle. This is to isolate contents from the atmosphere. You have to add some movement to the DO probe but very slight to make sure you don’t add too much oxygen back in. After Meter has stabilized, record initial DO (mg/L). Record DO concentration in 2-10 second intervals over a 5 minute period, or until DO becomes stabilized. Then just repeat for given samples.

Now for DO we have to making sure the meter is set to DO (mg/L) mode, rinse the probe with distilled water before each time you make a measurement just to keep contamination at a minimum. Dip the rinsed DO probe into testing solution and stir very slowly! Wait till stable and record the value. Now repeat in triplicates.

Turbidity is a bit tricky with the numbering but very easy to actually do. Turbidity is the measurement that tends to go hand-and-hand with water clarity. To do this you need a handy dandy turbidimeter. Wash the sample bottle in the machine with that of your sample of interest just to minimize contamination. Then fill the vile with your sample and place in the machine. Turn the vile ever so slightly in a 360 degree rotation and pay attention to the smallest number that is displaced. This is to stop the variations in the sample bottle. Repeat in triplicates

We end our experiment with finding pH, This is the total amount of Hydrogen ions in a given sample. The higher the Hydrogen concentrations, the lower the pH. So grab your pH meter and rinse the tip between your measurements. To test the pH, dip the probe into your sample and stir slightly around until giving you a stable number. Now just repeat in triplicates.

Results