Bublienko N.O., Semenova O.I., Kulbachuk O.O.
National university of food technology, Ukraine
Treatment waste water of sugar
industry with using of methane fermentation
The
sugar industry is the one of the most important branches of agro-industrial
complex of state. But sugar production connected with different ecological problems.
One of them is the creation of waste water. The most dangerous is the concentrate
waste water of III category. BOD5 of them can range from 3200 to
7500 mg O2/dm3. Usually, for the sewage treatment use
disposal fields on the sugar plants, but they didn’t provide necessary separation
efficiency. The beginning of the decay, descent pollution soil, underground
water and air are connected with the regular throw down of waste water on
disposal fields.
The
methane fermentation is the best way in ecological and economical sides. Almost
all of the organic matters can be used as substrate for this anaerobic method
of treatment. The deep of treatment can be reached 95% with using methane fermentation.
The application of the methane fermentation for treatment waste water is
expedient. It gives an opportunity to decrease the concentration of pollution
and to increase the effect of this process with using of biogas and biomass enriched
biologically active substance.
The
waste water of III category from sugar industry with COD 3789 mg O2/dm3
was subjected to process fermentation by the research worker of
Biochemical and Ecological Control department of National University of Food
Technology of Ukraine. The methane treatment of waste water was carried out
with the temperature of 45 oC. It is the first significance of
thermophile diapason of temperature. The dose of everyday loading of reactor
with the periodical regime was 25 and 50% from total volume of cultural medium.
The results of the investigation are shown in table 1.
Table
1
Separation efficiency and gas-generation during
periodical fermentation wastewater depending on loading doses
|
Loading dose, % |
CODending mg Î2/dm3 |
Amount of biogas and ÑÍ4 concentration |
Deep of fermentation, % |
|||
|
dm3/ dm3 waste water |
dm3/g CODload |
dm3/g CODferm |
ÑÍ4, % |
|||
|
25 |
110 |
3,5 |
0,28 |
0,29 |
72 |
97,10 |
|
50 |
170 |
3,2 |
0,25 |
0,26 |
70 |
95,51 |
Time
of the fermentation of third category waste water from sugar factory (25 and 50
% of loading dose) was 3 days. The data shows a direct correlation between time
of fermentation and the concentration of pollutants in the effluent.
The
most intensive process of contaminants transformation and gas-generation was observed
in exponential and stationary growth phases (Fig. 1). A clear relationship
between the process of synthesis and purification of biogas we can see from the
figure 1. The largest production of biogas was observed at the maximum using of nutrients from waste water.
Fermentation time, days
Fig.1. Biogas synthesis and COD reduction during
periodic fermentation of sugar waste water
The
intensity of treatment processes and gas-generation reduced with increasing of
loading dose. That confirms the classical idea of microorganisms’ activity in the
conditions of increasing of pollution substances.
Cultivation
terms and loading dose for the negative-filling-up mode fermentation was the same
as for the periodic fermentation (Table 2).
Table
2
Separation efficiency and gas-generation during
negative-filling-up fermentation of waste water depending from the loading dose
|
Loading dose, % |
CODending mg Î2/dm3 |
Amount of biogas and ÑÍ4 concentration |
Deep of fermentation, % |
|||
|
dm3/ dm3 waste water |
dm3/g CODload |
dm3/g CODferm |
ÑÍ4, % |
|||
|
25 |
80 |
3 |
0,3 |
0,29 |
70 |
97,89 |
|
50 |
120 |
2,9 |
0,22 |
0,2 |
69 |
96,83 |
The
greater part of pollution is utilized during fermentation process, but
significant quantity of them stays in the culture medium. The data shows that
increasing of the dose loading leads to a decrease of the depth of fermentation.
A system cannot transform some rather significant portion of organic matter at
high doses of loading in allotted time.
It
shows that the negatively-filling-up fermentation process provides more effective
biotransformation of contaminants than periodic. Depth reaches 97.89% and
significantly improves wastewater. For the final disposal of contaminated
substances from wastewater used traditional aerobic fermentation.
Thus,
using of integrate anaerobic-aerobic technology will help to solve the problem
of treatment of concentrate waste water from sugar plants.