Why Pretreatment Is Discussed for RO on Cooling Tower Blowdown
Desalination through reverse osmosis (RO) of cooling tower blowdown water streams has been increasing over the years, and recycling of cooling tower blowdown streams using RO has specific challenges in view of the fouling characteristics associated with water in open recirculating cooling systems [S2]. A review is dedicated to recovery of cooling tower blowdown water through reverse osmosis (RO), covering water parameters affecting membrane fouling and pretreatment schemes [S4].
Ultrafiltration as a Documented Pretreatment
Recycling of blowdown water from cooling towers through ultrafiltration followed by reverse osmosis has seen progressive development in industrial applications over the years [S1]. This pairing is described in the literature as a configuration in which ultrafiltration is placed ahead of the RO stage, with the combined train noted as having seen progressive development in industrial applications [S1]. The exact excerpt identifies ultrafiltration followed by reverse osmosis as a sequence that has been progressively developed in industrial applications for blowdown recycling [S1].
Why Blowdown Is a Challenging RO Feed
Recycling of cooling tower blowdown streams using RO has specific challenges in view of the fouling characteristics associated with water in open recirculating cooling systems [S2]. Recovery of cooling tower blowdown water through reverse osmosis (RO) is presented as a review of water parameters affecting membrane fouling and pretreatment schemes [S4]. The framing of pretreatment for blowdown-to-RO duty is therefore tied directly to the fouling characteristics of open recirculating cooling systems and to the water parameters that affect membrane fouling [S2][S4].
Parallel and Adjacent Evidence on Pretreatment
Recovery of cooling tower blowdown water for reuse includes the investigation of different types of pretreatment prior to nanofiltration and reverse osmosis, indicating that pretreatment type is selected upstream of the membrane stage [S5]. Control of mineral scale deposition in cooling systems is listed among the related water-treatment topics, intersecting with pretreatment design for RO reuse [S5]. Removal of conditioning chemicals from cooling tower water in constructed wetlands is listed as a related topic, intersecting with the fouling and pretreatment drivers for cooling water [S5]. A critical review of treatment technologies for cooling water blowdown is listed among the related water-treatment topics [S5].
Treatment Technologies Covered in the Broader Literature
Membrane treatment of side-stream cooling tower water for reduction of water usage is listed in the related work [S5]. Membrane distillation of industrial cooling tower blowdown water is listed in the related work [S5]. Zero Liquid Discharge and water reuse in recirculating cooling towers at power facilities is listed as a review and case study analysis in the related work [S5]. Chloride removal from recycled cooling water using ultra-high lime with aluminum process is listed in the related work [S5]. Cooling water use in thermoelectric power generation and its associated challenges for addressing the water-energy nexus is listed in the related work [S5].
Summary of the Evidence Base
The excerpts that directly address pretreatment for RO on cooling tower blowdown identify ultrafiltration followed by reverse osmosis as a sequence that has been progressively developed in industrial applications for blowdown recycling [S1], identify specific fouling challenges associated with water in open recirculating cooling systems as the driver for pretreatment selection [S2], and frame the topic as a review of water parameters affecting membrane fouling and pretreatment schemes [S4]. Adjacent entries in the related-work list also point to investigation of different types of pretreatment prior to nanofiltration and reverse osmosis for blowdown reuse [S5].