Water Technologies & Solutions case study

Find a contact near you by visiting www.suezwatertechnologies.com and clicking on “Contact Us.” *Trademark of SUEZ; may be registered in one or more countries. ©2017 SUEZ. All rights reserved.

E-CHBioPlus01_EN.docx Mar-13

BioPlus* and service programme gets biological wastewater plant back on trackchallenge A food processing plant producing margarine and other bakery additives contacted SUEZ to audit a newly purchased biological waste water plant because neither the plant operatives nor the commissioning engineering company were able to bring the new system to an acceptable level of operational performance.

This performance shortfall yielded excessive COD discharges attracting more than 200.000 €/y in local fines and taxes.

Since influent data records were incomplete, the first steps of the audit were to perform both an analytical characterisation and a microscopic examination.

The results of these showed:

• High total COD values, but low filtered COD values, indicating that excess emulsified organic material (FOG) had escaped the fat traps.

• Poor pH control in the waste plant influent (acidic).

• Dominance of hydrophobic filamentous bacteria (actinomycetes), yielding a glutinous foam layer on the surface of the active sludge.

• Poorly settling active sludge, with an inordinate amount of bacterial slime, indicating nutrient deficiency.

• Poor operation, despite extensive operator involvement, and little knowledge of the biological waste plant (a Sequencing Biological Reactor, or SBR).

Since the operational budget had been spent on fines and taxes, no money was available to upgrade the primary treatment, and so the Customer requested SUEZ to rectify the situation within a period of five weeks and subsequently define medium and long term operational policies.

Page 2 E-CHBioPlus01_EN.docx

solution Since the fat traps could not reduce high FOG loadings in the influent stream, SUEZ seeded the system with a BioPlus Grease-degrading product and dispersed the foam layer with a BioPlus grease solubilizer. Microscopic examination allowed monitoring and evaluation of the seeding process, and subsequent adjustments when required.

To increase settlability, the sequential batch reactor (SBR) was fed with KlarAid* CDP1303 coagulant at the end of the aeration period. In addition, sludge volumes were recalculated and the height of the effluent pump was adjusted to produce low solids effluent, while maintaining the required throughput.

Caustic was added to the influent stream and nutrients (phosphoric acid and ammonia) were better controlled by measuring residuals in the final effluent.

Operators were provided with thorough training, resulting in more efficient operation with far less involvement. Site personnel handled daily operations, whilst the service personnel of SUEZ provided operational instructions.

results After five weeks, the system had an efficiency of +98 % removal, produced less than 10 ppm TSS with less than 30 ppm COD in the final effluent (in contrast to an earlier + 350 ppm COD).

The SBR proved so stable that even occasional factory incidents (spill of a bulk of margarine), did not significantly affect the operations.

Finally, the application yielded a financial gain of more than 100.000 €/y (savings on taxes and fines), allowing the Customer to “save” for the final solution: an adequate pre-treatment preventing the FOG reaching the SBR treatment plant.