Characterization of Biotic and Abiotic Profiles of Greenhouse Evaporative Cooling System Fouling

Purpose: To characterize the microorganisms influencing greenhouse evaporative cooling system fouling as a prelude to designing a sustainable remediation scheme that would assist in reducing the heavy financial loss incurred by stakeholders due to deterioration of cooling pads.Methods: Samples of biofilms on evaporative cooling system pads were collected from various locations in Saudi Arabia and fixed with 5% formaldehyde. Light microscopy, scanning electron microscopy (SEM) and QWIN software were employed for the identification of different morphometric parameters of the constituent microbes. pH and conductivity were assessed using Pasport PS-2102 and PS-2116 sensors, respectively. Results: Different genera of cyanobacteria and diatom including Phormidium, Oscillatoria, Lyngbya, Navicula, Melosira and Gomphonema were identified and characterized, in addition to various types of bacteria and white crust fungus, Phanerochaete crysosporium. Total dissolved solids (TDS) values of 2641 ppm (conductivity, 5282 μS/cm) for Al-Rasheed, 2327.5 ppm (conductivity, 4655 μS/cm) for Sara, 3352 ppm (conductivity, 6704 μS/cm) for Dammam Municipality Greenhouse (DMG) and 61.5 ppm (conductivity, 123 μS/cm; pH 6.88) for KFUPM were obtained at 25°C. Conclusion: Various organisms, including cyanobacteria and diatoms, which have been implicated in the biofilms of evaporative cooling systems at different locations in Saudi Arabia, were characterized with the aid of morphometric parameters. Identifying the constituent microorganisms would aid in designing a sustainable remediation scheme that is expected to reduce the heavy financial cost incurred by stakeholders due to frequent replacement of evaporative cooling pads during routine maintenance.