Water Recovery from Urban Wastewater for Irrigation using Ultrafiltration and Nanofiltration: Optimization and Performance

Abstract

The shortcomings of conventional processes for treating urban wastewater subjected to secondary treatment, in order to use this water for irrigation, are well known. Alternative advanced treatment techniques are required instead. This study aims to use single-stage ultrafiltration (UF) or nanofiltration (NF) membrane processes to produce irrigation water from biologically treated urban wastewater. For this purpose, the effects of four process variables (membrane type, cross flow velocity, temperature, and transmembrane pressure) on process performance parameters (permeate flux, concentrations/removal efficiencies of contaminants) are analyzed through Taguchi experiment design. Temperature and membrane type are found to have the biggest effect on UF, whereas the membrane type is the most significant variable for the NF. Moreover, the use of membrane permeate for landscaping and agricultural irrigation based on optimal conditions is assessed with reference to the criteria imposed by national regulation/international guidelines. Water in various quality categories is produced using different settings for 28 distinct specific parameters with reference to the membrane type, process performance, and the irrigation method. The results indicate that single-stage UF or NF membranes with high recovery rates can be used for wastewater subjected to secondary treatment, to recover irrigation water at low pressure and high water permeate flux.

Datacentric Similarity Matching of Emergent Stigmergic Clustering to Fractional Factorial Vectoring: A Case for Leaner-and-Greener Wastewater Recycling

“…The four factors (Table 1 of ref. [62]) are briefly re-stated here and re-coded for convenience, accordingly, to aid in the data analysis that follows: (1) membrane type (A), (2) cross-flow velocity (B), (3) temperature (C) and (4) transmembrane pressure (D).…”

“…At any rate, it is noted that optimizing water quality is a challenging task because of the ever-present influence and extent of uncertainty in the influx water volume [61]. A new tactic to optimize water recycling efficiency, which is chiefly intended for irrigation purposes, is to allow ultrafiltration and nanofiltration processes to compete with each other against a particular outcome [62]. Then, the most appropriate process is selected, thus achieving an optimal filtering performance.…”

“…The operational demands are anticipated to impose limited access to the wastewater treatment facility for lengthy experiments to be conducted, since they would incur noticeable downtime losses. Non-linear OAs have been recommended to formulate the experimental recipes for the examined controlling factors in a published study [62]. This is because filtration phenomena may introduce curvature dependencies into the multivariate input-output relationships; non-linear OAs offer a minimum-effort opportunity to capture strong deviations from linearity.…”

“…This is because filtration phenomena may introduce curvature dependencies into the multivariate input-output relationships; non-linear OAs offer a minimum-effort opportunity to capture strong deviations from linearity. Moreover, lone replicates are planned for both the tested filtration processes in order to succeed in gaining additional resource and time savings [62]. Running the trials in the saturation mode, the experimenter aspires to extract the maximum information from the implemented OA scheme [66].…”