Stagnation leads to short-term fluctuations in the effluent water quality of biofilters: A problem for greywater reuse?

Abstract

Highlights A greywater treatment system was monitored with automated flow cytometry and turbidity. Stagnation in biological activated carbon filter led to peaks in total cell concentration and turbidity. Strong correlation was observed between TCC and turbidity. Stagnation did not lead to increase of opportunistic pathogens in the biofilter's effluent.

Sensor setpoints that ensure compliance with microbial water quality targets for membrane bioreactor and chlorination treatment in on-site water reuse systems

“…Online monitoring of turbidity is recommended by several WRFs, and others have reported strong correlations between turbidity and the total cell concentration determined by flow cytometry (intact cells + damaged cells) (Hess et al, 2021). We assume that the lack of correlation between turbidity and ICC is due to the low ICC concentrations in the tested MBR+chlorine systems compared to concentrations reported by Hess et al (2021) (~1 order of magnitude higher) who studied an MBR system without chlorine disinfection.…”

Automatic optimization of temporal monitoring schemes dealing with daily water contaminant concentration patterns

“…56 For example, contaminants in surface water and both treated and untreated wastewaters can be highly affected by variations in environmental conditions (e.g., some metals, nitrogen-species, photolabile compounds and microbiological indicators are affected by diurnal light intensity variation 7,57,58 ), impulse-like contaminant releases, especially in small catchments, 15,50 and daily changes during wastewater treatment. 14,17,59,60 For this reason, traditional sampling schemes might not be appropriate, while the use of the proposed algorithms could be beneficial, allowing the presence of unexpected concentrations to be identified, which could warrant further investigation.…”

“…8,11,[13][14][15] However, compared to electrochemical sensors, these new instruments are characterized by non-negligible capital and operating costs and the need for increased maintenance in case of high sampling frequencies. 5,11 While high monitoring frequencies using such instruments have uncovered relevant contaminant concentration fluctuations, 3,9,16,17 such intensive campaigns are not sustainable by water utilities or environmental protection agencies for long periods due to budget constraints. Hence, sampling frequencies are arbitrarily reduced by the operators to limit costs, having legislative compliance as the only constraint for the sampling frequency selection.…”

“…While high monitoring frequencies using such instruments have uncovered relevant contaminant concentration fluctuations, 3,9,16,17 such intensive campaigns are not sustainable by water utilities or environmental protection agencies for long periods due to budget constraints. Hence, sampling frequencies are arbitrarily reduced by the operators to limit costs, having legislative compliance as the only constraint for the sampling frequency selection.…”

Automated flow cytometry as a tool to obtain a fine-grain picture of marine prokaryote community structure along an entire oceanographic cruise

“…Even though the OC-300 is in the market since 2017, to our knowledge there are only three publications based on its use, two of them about monitoring microbial abundance in biofuel cultures (Haberkorn et al, 2021), and bioreactor performance (Hess et al, 2021), and the third one focus on the identification of outlying observations with machine learning (Russo et al, 2021). It seems that the potential of the OC-300 for environmental monitoring, particularly in seawater, is still unexploited.…”