Conceptual Approach / Experiments

Experiment 1: Algae pond

Hypothesis

The algae will take up the minerals from the urine and absorb most of the suspended N,P and K. After harvesting the algae, the algae must be dried so they can be used as a (solid) fertilizer or as food for husbandry.

Working method

  • First a shallow pond has to be made. This could be made of thick plastic within a circular wooden frame. We have to create a climate in the pond with the circumstances as locally encountered. I.e. it must be possible to simulate the temperature, irradiance, etc of Nairobi when that is the subject of our algal study.
  • When the basin is ready, the basin will be filled with fresh urine diluted with (rain)water. The layer of liquid in de pond will be kept at 0,1 meter to allow sufficient light to reach the bottom. The most important value to be found is the time that the algae need to consume the minerals (K, N and F) coming from the urine in the water. At regular intervals samples have to be taken and analyzed.
    * When the experiment is started the algae need an adaptation time before they will start absorbing the minerals. When the algae stop increasing, they have used most minerals in the water. Again the water quality has to be measured.
  • At this stage the algae can be collected and dried. Some algae species are easier to harvest then others. Spirulina for example should cause no big harvesting problems.

Example

We will test a pond that can treat the collected urine of 6 persons during 3 days. Therefore we will ask 6 persons to collect their urine in a plastic bottle. We expect to collect a little over 1 liter of urine per person per day, less than the daily average of 1,5 liter as they often will be out during day time, so in total we may collect 6 liter per day.
We assume that the urine has to be diluted with water to create a good base for algal growth. We expect to use between 4 and 9 parts of (rain)water on 1 part urine to create optimal circumstances for the algal growth. Especially in the adaptation phase the dilution can not be to strong.
In case the dilution is 1 to 4, the contend of the pond is 3x6x5= 90 liter, the diameter of a 10 cm deep pond should be 1,25 meter. In case the dilution is 1 to 9, the contend of the pond is 3x6x10=180 liter, the 10 cm deep pond has a diameter of 1.5 meters. As we have constructed a pond of 2 meter diameter, we should convince more people to donate their daily urine! From now the algae will do the work. The only thing still to do is to avoid extreme conditions, such as high or low temperatures.

Requirements

  • a basin
  • a light source
  • heater
  • (Fresh) urine
  • (different types of) algae
  • rain water
  • We need different gauges for pH, Ec, light and temperature
  • we also need a way to detect and gauge phosphorus, nitrogen and potassium
  • mixer (something that will make the water move all time and bring air in)

Things that has to be done before starting this experiment

  • the basin
  • temperature
  • light
  • space to place the experiment
  • mixer
  • heater
  • most difficult items
    • We have to find one or more potential algae species that are best suited for our project. This could possibly be a Spirulina or Green algae.
    • We still need the different types of gauges for: Ph, light, phosphorus, nitrogen and potassium.

Results

October 18 2004, Planning general set up
October 23 2004, A well insulated pond is constructed. Its diameter is 2 meters. As available daylight at the chosen spot is poor, we rely on electric lighting. See Report10/23/04

Conceptual Approach / Experiments

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Page last modified on May 16, 2006, at 07:56 PM