Control of filamentous organisms in food‐processing wastewater treatment by intermittent aeration and selectors

Abstract

Various measures were tested at a full-scale wastewater treatment plant to control sludge bulking by type 0041 and 0675 filamentous microorganisms, instigated by highly variable wastewater loadings from a food-processing facility. Intermittent aeration on a 1-h on 1-h off basis was found to effect a marginal improvement in sludge settling characteristics, as reflected by about an 11-36% reduction in the Sludge Volume Index (SVI) to 118 cm À3 g À1 . At BOD loadings of 1500 kg d À1 which marginally exceeded the design capacity of the plant of 1200 kg d À1, SVI rose sharply to 230 cm À3 g À1 in less than a week. The anoxic selector effected a reduction in SVI to 170 cm À3 g À1 within 3 weeks of operation at temperatures of 8-12°C. The aerobic selector was most effective, reducing SVIs further to 79 cm À3 g À1 in 2 weeks. Sludge settleablity was found to be inversely proportional to the aerobic selector food-to-microorganism ratio. The optimum aerobic selector loading was found to be 1.8-2.7 kgBOD 5 kgMLVSS d À1, with corresponding SVIs in the range of 80-120 cm À3 g À1.

An overview and analysis of site remediation technologies

“…These contaminants include heavy metals, radionuclides, chlorinated solvents, petroleum hydrocarbons, PCBs, PAHs, organophosphate insecticides, explosives, and surfactants (Nedunuri et al, 2000).…”

“…It may be employed in activated sludge, rotating biological contactors, trickling filters and biological lagoons (FRTR, 1999n). Many configurations may promote aeration including jets to blow air into the water or mechanical aeration devices that propel water droplets through the air (Nakhla and Lugowski, 2003).…”

The Treatability Study of High Strength Pet Food Wastewater: A Continuous Flow Aerobic System Performance Evaluation

“…Table 2 shows that the average SVI values for both stages are between 62.5 and 72.5 ml g -1 TSS, which are better than those reported by other researchers. SVI measurements during the treatment of high oil and grease wastewater were 65-117 ml g -1 [10], while SVI was 159-207 ml g -1 during the regular operation of food-processing wastewater treatment [17]. The current low SVI measurement indicated that the sludge settled well, which verified the limitation of the clarifier performance.…”

Microbial Ecological Model of Filamentous Bulking and Mechanisms

“…However, because of the complexity of composition and biochemical reactions in activated sludge mixed liquid, the hysteresis of biochemical reactions for the reaction conditions and the technical difficulty in determining accurately some compositions, it is very difficult to solve this problem only through experiment. Fortunately, some scholars (Taylor and Williams 1975;Smouse 1980;Lau et al 1984;Hermanowicz 1987;Van Niekerk et al 1988;Kappeler and Brodmann 1995;Jenné et al 2002;Nakhla & Lugowski 2003) have made theoretical and experimental studies on this problem. Many kinds of mathematical models and simulation methods have been applied to study the activated sludge floc and microenvironment (Scuras et al 1998;Martins et al 2004b).…”