The costs for reducing biofouling depend on the method selected to do so.

There is a number of references that address this topic available. Biofouling formation and also techniques to reduce biofouling effects are reported.

Just to cite a few:

http://www.sciencedirect.com/science/article/pii/S1383586600001568

http://www.sciencedirect.com/science/article/pii/S0011916403004144

http://www.sciencedirect.com/science/article/pii/S0011916402007646

http://www.sciencedirect.com/science/article/pii/S0011916402002606

http://www.sciencedirect.com/science/article/pii/S0376738803002461

http://www.sciencedirect.com/science/article/pii/S0376738803001649

http://www.sciencedirect.com/science/article/pii/S0011916404900185

I hope this helps.

Regards.

Fouling is a complex phenomena and biofouling is even more complicated. You can find a review on the fouling in bioreactors in the paper attached. To reduce the fouling phenomena, you have to work below a critical flux as shown in the figure 14. In these conditions, you will delay the TMP jump that leads to a rapid fouling of the membrane.

Regards.

Article Fouling in membrane bioreactors used in wastewater treatment

Very complex machanism. The major fouling mechanisms mostly studies included pore blocking (large organic molecules can block the pores of the membranes), inorganic scaling (inorganic compounds (i.e., CaCO3) deposites on the membrane surface, sorption of MLSS sludge on membrane surface, adsoprtion of organic material and microbial by products (i.e., EPS, SMP) on membarne surface and within the pores. Selecting a proper SRT allows degradation of EPS and eliminates excessive generation of SMPs.