Pilot-scale evaluation of semi-passive treatment technologies for the treatment of septage under temperate climate conditions.

Population growth in rural Canada has resulted in an increase in municipal septage generation, which could overload existing treatment facilities that rely on biological treatment approaches. To address concerns associated with potential shock loading of these systems, three semi-passive wastewater treatment technologies were compared at the pilot-scale to identify a suitable approach to augment the capacity of an existing wastewater stabilization pond facility in rural Ontario. Two of these technologies, the BioDome and BioCord systems, were commercially available systems that make use of biofilm technology to improve treatment performance and enhance the robustness to temperature and hydraulic loading fluctuations. The third approach involved the use of the natural filtration capacity of zebra mussels to improve effluent quality. The three technologies were assessed against a control for reductions in regulated wastewater parameters with an emphasis on nutrient (ammonia/ammonium, orthophosphate) reductions, air cycling, energy consumption, and performance following exposure to anoxic conditions. The BioCord system was the only technology that was found to significantly outperform the control, exhibiting reductions of 69%, 47%, 77% and 81% for NH3/NH4+, TN, COD and TSS, respectively. The BioCord system also had the lowest maintenance and energy requirements, likely due to its design, which provided the biofilm with optimal oxygen and substrate contact. Consequently, the BioCord system could develop a more stable, heterogeneous microbial population and maintain high levels of activity in its biofilm, even during periods of extended anaerobic conditions. This also suggested that the BioCord system would require less aeration, and hence a lower energy expenditure, than the other systems. Furthermore, the BioCord system showed the fastest rates of recovery, reaching significant levels of parameter reductions within one week of system re-initiation.

Multivariate statistical analysis of water chemistry conditions in three wastewater stabilization ponds with algae blooms and pH fluctuations.

The wastewater stabilization ponds (WSPs) at a wastewater treatment facility in eastern Ontario, Canada, have experienced excessive algae growth and high pH levels in the summer months. A full range of parameters were sampled from the system and the chemical dynamics in the three WSPs were assessed through multivariate statistical analysis. The study presents a novel approach for exploratory analysis of a comprehensive water chemistry dataset, incorporating principal components analysis (PCA) and principal components (PC) and partial least squares (PLS) regressions. The analyses showed strong correlations between chl-a and sunlight, temperature, organic matter, and nutrients, and weak and negative correlations between chl-a and pH and chl-a and DO. PCA reduced the data from 19 to 8 variables, with a good fit to the original data matrix (similarity measure of 0.73). Multivariate regressions to model system pH in terms of these key parameters were performed on the reduced variable set and the PCs generated, for which strong fits (R(2) > 0.79 with all data) were observed. The methodologies presented in this study are applicable to a wide range of natural and engineered systems where a large number of water chemistry parameters are monitored resulting in the generation of large data sets.