Impressive results obtained with new inorganic coagulant

Norlex Chemicals full-scale test with Norfloc NF1 resulted in more stable operation and plant capacity for Danish WWTP Damhusåen.

Summary

Client: Damhusåen WWTP (BIOFOS)

Product: Norfloc NF1 inorganic coagulant based on nanotechnology

Project: Full-scale test with Norfloc on line A.

Results: Better / faster settling, Higher SS, Less foam, more stable operation – also during heavy rain events, increased plant capacity, less chemical sludge.

Background

Norlex Chemicals has, in collaboration with Biofos, performed a fullscale testing with Norfloc NF1 on one of Damhusåen WWTP 4 lines, line A, where line B, C and D were used as a comparison basis.

Challenges

Damhusåen WWTP has for longer periods experienced problems with the plants general sludge properties, especially during heavy rain events, where the sludge mirror in the clarification tanks would rise, resulting in bulking sludge, low SS in the return sludge (7 kg/m3 in line A) and contaminated outlet from the clarification tanks.

Goals

The goal of the test was to see if the general sludge properties of line A could be improved. Biofos wishes to be able to handle up to 10.000 m3/h (design flow capacity), without the sludge mirror level reaching 2 meters.

Results

Better/ Faster settling (lower SVI)

SV30: 27.04.2020

SV30: 04.05.2020

SVI (SLUDGE VOLUME INDEX)

Higher SS in return sludge

Before treatment started: average 7 kg/m3
After treatment with Norfloc NF1: average 13 kg/m3

With Norfloc NF1: Line A bioreactors 07.05 (notice the tank without aeration has foam)

Without Norfloc NF1: Line B bioreactors 07.05 (notice the tank without aeration still has dense foam)

Hydraulics – Sludge blanket during heavy rain events

More stable operating conditions – also during heavy rain events

Flow event at 10.000 m3/h

Sludge blanket for lines with Norfloc NF1 versus line with ferric chloride during heavy rain events.

The graph shows clearly that the sludge levels for line A with Norfloc NF1 (blue) are kept much more stable compared to lines with ferric chloride (orange), where sludge levels rise above 200 cm and result in sludge escape (bulking) from the clarification to the outlet and restriction in the flow to the biology (incoming water partly directed to reservoirs).

If ongoing rain, this will lead to a bypass situation when reservoirs are full.

Conclusion

All of the above listing results indicate better sludge properties in general in line A, therefore increased plant capacity due to better settling and less chemical sludge.