James E. Alleman, Professor of Environmental Engineering
School of Civil Engineering
West Lafayette, Indiana 47907-1284
The Science and ‘art’ of wastewater engineering stretches only slightly beyond one hundred years. Within this period, the applied technology has certainly made significantstrides in promoting disease control and environmental protection. Fixed-film treatment unquestionably plays an important role in this history, particularly since it represented the original biological mechanism. Beginning with options like the trickling filter, intermittent filter and contact bed, fixed-film systems dominated the technology of wastewater treatment for several decades. And althoughthis status has subsequently been assumed by suspended growth process, there is unquestionably a resurgence of interest in fixed-film applications.
Given the relative historical significance, and projected future of fixed-film systems, a chronological review of the associated progressive developments should be both interesting and informative. This paper will, therefore, explore the genealogybehind our current fixed-film technology, condensing the relevant yesteryear literature into twenty-five year increments. While attempting to limit this synopsis to a reasonable length, every effort has been made to facilitate a thorough documentation of the associated literature.
1850 - 1875
As described by the classic Dickens tale in 1859, "It was the best of times, it was the worst oftimes. . ." (1) This literary image poignantly portrays a mid-nineteenth century era freshly endowed with the blessings of an Industrial Revolution, yet virtually helpless in the face of rampant, epidemic disease. Cholera, alone, flared through the British Isles in four deadly outbreaks within one terrifying ten year period. (2) Without question, these problems with communicable disease provide a sadreflection on the existing deficiencies in environmental sanitation. However, the concurrent infancy of bacteriology yielded only vague clues regarding the dangerous correlation between fecal contamination and disease transmission. Existing efforts towards sewage disposal, let alone treatment, were virtually non-existent. (3) Certainly it was fortuitous, then, that legislation (i.e., the NuisanceRemoval Act) was enacted in 1858 to control sewage discharge, albeit more so a function of safeguarding aesthetics rather than a perceived health hazard. (4) This emphasis quickly shifted towards disease control, though, following Dr. John Snow’s monumental publication on epidemiology within the same year. (2, 4, 5).
England shortly organized a series of Royal Committees (6, 7, 8) charged withthe study of problems relating to sewage disposal and treatment. Their initial findings categorized the existing state-of-the-art according to chemical precipitation, filtration and irrigation, with the latter two procedures generally associated with land treatment. While land systems carried a traditional background extending several centuries (4, 9), some of the other available options wererather curious. One such precipitation procedure, the ABC process, employed a bizarre mixture of alum, blood and clay. (4, 10).
None of the available treatment mechanisms were, however, recognized as biologically-related systems. Hence, Dr. Alexander Mueller’s demonstration in 1865 that sewage could be purified by living organisms in a filtration column provided a major revelation. (11) Dr.Mueller, a prominent City Chemist of Berlin, subsequently patented his biological purification process several years later. Unquestionably avant-garde, neither the patent nor the fundamental concept attracted much attention, though.
In 1868, one of the Commission members, Sir Edward Frankland, began an epic study of filtration performance on raw London sewage in laboratory columns packed with...