Conference Agenda

Farms and agro-industrial processes generate wastewater that may exceed discharge quality criteria bringing risks to the environment. In maple syrup production, wastewater from equipment washing is strongly alkaline or acidic due to the characteristics of the soaps. To limit the impacts associated to wastewater management, it is necessary to assess treatment strategies that are simple, efficient, cost-effective, and adaptable to the sector. This study aimed to validate the manual neutralization as a strategy for treating wastewater from the reverse osmosis machine washing processes in maple industry. A wastewater characterization was conducted in 2022-2023 covering 56 alkaline washes and 14 acidic washes. Parameters such as pH, conductivity, phosphorus, suspended solids, biochemical oxygen demand, and total nitrogen were monitored at 5-minute intervals up to 20 minutes or the end of each wash. Three neutralizing agents were proposed for neutralization citric acid, sodium hydroxide and sodium bicarbonate. A calculation tool was developed to determine the required neutralizing agent quantity based on soap type, amount, and solution volume used in the washes. For alkaline washes, the critical volume accumulation time for neutralization occurs within the first 15 minutes, while for acidic washes, it extends beyond 25 minutes. A subset of characterization samples was used to validate the tool's accuracy, achieving a pH range of 6 to 9.5 (regulation limits) after neutralization process. The validation of the tool will continue throughout 2024 in 4 maples facilities, with results to be presented subsequently.

Bacterial resistance in human and animal waste streams has been identified as a major concern for the environment and human health. While it is commonly understood that the presence of antibiotics (above minimum selective concentrations) drive selection of Antibiotic Resistant Bacteria (ARBs) and Antibiotic Resistance Genes (ARGs), increasing evidence suggests that environmental conditions may also significantly effect the selection and proliferation of resistance genes. In the present study shotgun metagenomic Next Generation Sequencing (NGS) and open source bioinformatic tools, in tandem with High Performance Computing (HPC), were used to investigate the water chemistry effects of three different biological treatments (macrophyte engineered floating wetland, duckweed, and algae) on corresponding microbial diversity and resistance in wastewater. Mesocosms (in triplicate per treatment) were studied over a 100 day growth period. TP, pH, DO, COD, and heavy metals were measured throughout the study. The results showed significant ( p < 0.05) treatment effect on water chemistry and nutrients (TP, pH, DO, COD, and heavy metals), as well as, microbial taxonomy, ARGs, Mobile Genetic Elements (MGEs), and Metal Resistant Genes (MRGs). Strong correlation (r > 0.7, p < 0.05) was found to exist between key water parameters and microbial diversity (and resistance). The results suggest that water chemistry parameters play a critical role in microbial diversity and genetic selection. The results support further investigation into the implementation of engineered biological treatment systems to alter microbial water column microbial resistance.

In Canada, the extremely high concentrations of dissolved organic and inorganic material in surface waters make potable water production very challenging. Unfortunately, nanofiltration (NF) membranes, widely utilized to purify these sources, experience serious fouling, increasing the associated cost. A comprehensive investigation of NF fouling is necessary to prevent or mitigate this phenomenon and increase access to NF technology, especially for small and remote communities. We conducted analytical, spectroscopic, and chromatographic experiments on water and fouled NF membrane samples from a water treatment pilot plant supplied by a challenging water source (Assiniboine River) at Brandon, MB. NF hydrogel-like foulant was ~97% organic. The mechanically removed foulant (MRF) comprised similar fractions of low molecular weight & building blocks (<1 kDa; 28.3%), humic substances (1–20 kDa; 38.7%), and biopolymers (>20 kDa; 33.1%). However, part of the foulant, mostly hydrophobic and 95.4% low molecular weight & building blocks, remained strongly attached to the NF membrane surface and pores, implying this would be difficult to clean. Also, calcium and magnesium (water hardness) bridge the organic substances, promoting NF fouling. Likely, the higher biopolymer fraction in the MRF caused most of the fouling. Researchers have associated some of those biopolymers with a microbiological origin. Thus, the microbes found in water and NF foulant may be contributing significantly to the fouling development by producing or shedding the polymers. We are currently performing deep-amplicon sequencing and Nanopore metagenomics on microbial DNA to identify the microbial community composition and its possible influence on the NF foulant formation.