Biological Fixed Film Systems

Abstract

Mark W. Fitch, Adriel Lam, Robert Segar INTRODUCTION Overview The work reviewed here was published during the catalogue/issue year 1999 and described research involving biofilms treating pollutants. This review explicitly excludes research in medical biofilms, dental biofilms, biofilms causing corrosion and biofilm formation in drinking water treatment and distribution systems. Anaerobic biofilm treatment system research is not reviewed here although a set of references is provided. However, the authors have included coverage of denitrification in traditional biofilm treatment systems. Similarly, biofilm systems for the treatment of air pollutants is reviewed in the Gaseous Emissions from Wastewater Facilities section of this issue. Coverage The references catalogued here are divided on the basis of fundamental research area or reactor type. Fundamental research into biofilms is presented in two sections, characterization/measurement and growth/modeling. References related to models of specific processes are included in the section on that technology. The reactor types which are covered are trickling filters, rotating biological contactors, fluidized bed biofilters (including airlift bioreactors), submerged bed bioreactors (including moving bed and floating bed bioreactors), biological activated carbon, membrane bioreactors, and immobilized cell bioreactors. Thereafter, innovative reactors which are not easily classified are presented, and an additional section on biofilms on sand, soil, and sediment is given. Reviews and Reactor Comparisons Stickler (1999) offered a review on the formation and maturation of biofilms, with emphasis on community coordination. Another review, with 35 references and written in Chinese, discussed biofilm formation, influencing factors, structure, composition, chemical and physical characteristics, biochemistry, and antibiotic resistance (Wang et al., 1999b). Barker and Stuckey (1999) reviewed soluble microbial products from wastewater treatment including the relation between such products and treatment processes. A review of small treatment systems (2,000 100,000 gpd) with nutrient removal requirements in Florida listed the estimated achievable performance limits for various suspendedand attached-growth technologies (Foess et al., 1999). Of the technologies studied, submerged biofilters and rotating biological contactors were ranked last as nutrient removal alternatives for these low flow plants. Four biological processes were compared for