Question Solid Waste

1. Lectures in Solid Waste Treatment, SS 2021Dr.
1. Give some kinds of waste which are biodegradable and can be used for
composting or fermentation
Materials that can get broken easily by microorganisms in the environment
such as: Paper, Clothes, Banana peels, fruit, cardboard, vegetables, etc
2. Which components of biowaste are DOS (Degradable organic substances),
which are NOS ? Give some examples…..
DOS: Are the substances that can be easily decomposed by natural agents like
water, oxygen, ultraviolet rays of the sun, acid rains, micro-organisms etc.
Examples: banana, dead leaf, fats, proteins.
NOS: Are those materials which cannot be broken down or decomposed into the
soil by natural agents. These substances consist of plastic materials, metal
scraps, aluminum cans and bottles, hazardous chemicals.
3. Explain the difference between Oxo-degradable and Bio-degradable. Which is
the more eco- friendly material?
Oxi-degradable: Oxo-degradable material quickly fragment into smaller and smaller
pieces, but don’t break down at the molecular or polymer level like biodegradable.
Even though the whole degradation process itself is accelerated.
Bio-degradable: Material which after a certain period of time (in general 6 months) will
be transformed in a compost, biomass or water.
4. How can you determine the usability of compost ? Give 3 examples of testing
methods….
For the compost to be usable it has to be physically, chemically and biologically
suitable and that’s include having no visible plastics, solids and glass particles, also it
should only include raw materials without any chemical effects.
5. Why is it important maintaining the temperature of composting process at
thermophilic range over a period of 2 or 3 weeks ? How can you stop too high
temperatures?
It is important for the thermophilic microbes accelerated reproduction, and for certain
substances to be fully biodegraded and the temperature is kept at this level (no higher)
by cooling.
6. For waste gas treatment of a composting plant a biofilter is needed.. Calculate
area and volume of the biofilter for following parameters:
waste gas: 60 000 m³/h,
temperature: 35°C
humidity: 82% r.w.
Area= 60 00/120 = 50 m2
Volume = 6000/100= 60 m3
Which filter materials do you recommend in this case ?
Critical properties of media material include (1) porosity, (2) moisture holding capacity,
(3) nutrient content, and (4) slow decomposition.