An electrochemical advanced oxidation process (EAOP) for the inactivation ofRhizoctonia solaniin fertigation solutions

Abstract

Boron-doped diamond anodes and stainless-steel cathodes were employed in an electrochemical flow cell and evaluated for inactivation efficacy on the plant pathogen Rhizoctonia solani J.G. Kühn [Thanatephorus cucumeris (A.B. Frank) Donk] in hydroponic fertigation water. The electrochemical system showed promise as an electrochemical advanced oxidation process (EAOP) in that significant reductions in R. solani (AG-8) were achieved; however, to achieve complete inactivation the system required supplemental chloride (20 mg L−1), while using 9.09 mA cm−2. The chloride allowed for low levels of free chlorine (≤0.17 mg L−1) that were more active in the bulk solution, complementing the electrode surface EAOP reactions. Perchlorate production was an initial concern but was found to be negligible under the conditions tested. Small but significant increases in nitrate, ammonium, and sulphate were observed following treatment. These increases are hypothesized to originate from the degradation of proteins and amino acids released during pathogen cell disruption.

Electrolytic Disinfection of Irrigation Water for Intensive Crop Production in Greenhouses as Demonstrated on Tomatoes (Solanum lycopersicum Mill)

“…Although F. oxysporum and R. solani can be killed at 14 mg L −1 for 6 min and 12 mg L −1 /L for 10 min contact time, respectively, phytotoxicity occurs [55]. Lévesque et al [2] demonstrated the inactivation efficacy of electrochemical disinfection in hydroponic irrigation water contaminated with mycelial suspensions of R. solani. Thereby, 1.14 mA cm −2 for a contact time of 6 min in the presence of fertilizer resulted a notable but not complete inactivation of R. solani.…”

“…Water is a fundamental element in greenhouse crop production, but its availability is increasingly limited mainly due to climate change, overexploitation of aquatic ecosystems and contamination of water sources [1]. Irrigation systems in protected agriculture face the challenge of ensuring water supply and at the same time adapting to the needs of new legislative and social restrictions by governments that increasingly limit the amount of fresh water available for crop production [2][3][4]. A conscious handling and use of the resource water, especially its reuse, poses a challenge for farmers and gardeners to meet this demand.…”

A Conceptual Framework for Incorporation of Composting in Closed-Loop Urban Controlled Environment Agriculture

“…This risk may not be tenable with many producers and a sterilization step may be required. However, it should be noted that several of the mineralization processes (e.g., ozonation, electrochemical oxidation) can achieve this goal [211][212][213].…”

“…Recent studies on electrochemical oxidation techniques have also been shown to inactivate pathogens while mineralizing organic matter in the hydroponic nutrient solution [212,213]. Although a wide variety of pathogen control techniques are available [219], the prospect of simultaneously managing pathogens and mineralizing organic matter makes ozonation and electrochemical oxidation technologies very appealing in the context of the current discussion.…”