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Case studies Wastewater treatment
Biological wastewater treatment Dalian, China
To manage the demands set for the plant, a biological treatment with fixed bed was chosen. The water first undergoes pre-treatment by screening and grit/grease removal. Primary sedimentation is done in 4 tanks with lamellar sedimentation.
The first step in the biological treatment consists of BOD, COD and SS removal in 12 Biofor filters. In these filters round expanded clay aggregates, Filtralite, is used as carrier for the biofilm. Process air blowers aerate the filters.
The second biofilter stage is nitrifiaction in 12 Biofor filters with the same surface area as in the first step. The filter media used in these filters is crushed Filtralite. Process air is supplied by blowers.
The treatment results are excellent:
Parameter
(all values in mg/l) |
Influent |
Effluent |
Effluent |
| |
Design |
Required |
Achieved |
| BOD5 |
216 |
< 10 |
3 |
| COD |
480 |
< 40 |
30 |
| SS |
350 |
< 10 |
8 |
| NH4-N |
|
< 5 |
1.1 |
About 40% of the treated water is disinfected by chlorine and used as recycle water for industrial use.
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