Microeco MidTerms Lab

• Water is a natural resource with limited and uneven distribution in time and space
• All forms of life and all human activities are dependent on water
• Modern industrial development and urbanization have resulted in the formation of large urban areas, industrial zones and the development of intensive agriculture
• This has increased the need for water, but also the growth of urban and industrial discharges into rivers without any prior treatment, thereby reducing the possibility of self-purification (auto purification) of water
• The need for clean water, today is considered as one of the biggest problems OF the global environment
• According to the World Health Organization, an estimated 5 million people die each year from the consumption of contaminated water
• Physico-chemical and microbiological analysis are the prime consideration to assess the quality of water for its best utilization like drinking, irrigation, and industrial purpose and helpful in understanding the complex processes, interaction between the climatic and biological processes in the water
• Materials


  • samples of water from different sources
  • polyethylene bottle
  • pH paper/pH meter
  • thermometer
  • visual/color kit
  • beaker
• Procedures

  
  

  1. Prepare a Sampling and Analysis Plan (SAP) which describes the sampling locations, numbers and types of samples to be collected, and the quality control requirements of the project.
• 2. Check with the laboratory before collecting samples to ensure that sampling

  equipment, preservatives, and procedures for sample collection are acceptable.

  It is best to obtain sampling supplies directly from the laboratory performing

  the analyses. Gather all equipment and supplies necessary for the project.
• 3. Using polyethylene bottle or plastic bottle, collect at least 500 ml of samples in drinking fountain, pond/river, and bottled water. Wear gloves when collecting samples.
• 4.Deliver or ship samples to the laboratory to ensure that holding times are met. Holding time starts at sample collection and ends at preparation and/or analysis. Be sure to allow time for the laboratory to process the samples.
• 5. Conduct the different physico-chemical tests below. Complete the table and analyze the results of the experiment.
• Microbiological contamination is a major water-quality problem worldwide
• Coliforms


  Faecal contamination-related microorganisms, e.g. Escherichia coli (E. coli)
• Coliforms as indicator


  To determine the level of microbial contamination in the test water samples
• Membrane filtration technique


  A widely used analytical procedure to detect, identify, and count indicator microorganisms in the water samples and hence to determine the quality and safety of the water

  
• The water sample must be collected in a sterile sealed sample bottle

  
• Do not rinse the bottles before taking samples
• Do not touch the inside of the sample bottle or the inside of the cap, to avoid contamination
• Always collect cold or room-temperature water. Never sample hot water for microbial examination

  
• Disinfect the work area and gloved hands with 70% ethanol
• Prepare a serial dilution of water samples


  1. 10-fold dilution (1:10)

  2. 100-fold dilution (1:100)

  3. 1000-fold dilution (1:1000)

  
• Assemble the filtration apparatus


  Put together the funnel, suction flask, and vacuum pump
• Label the bottom of LB agar plates


  1. Name of the sample

  2. Dilution

  3. Date of experiment

  4. Class

  5. Group number
• CFU (Colony-Forming Units)


  The number of viable bacterial cells in a sample
• Calculate the count per 100 ml


  CFU/100 ml = No. of CFU counted x 100 / Volume of sample filtered in ml
• Report the results as CFU per 100 ml of sample
• Discard all agar plates into the designated container with 10% chlorine bleach or discard them into the biohazard bag for autoclave processing afterwards