Production of demineralized water for use in thermal power stations by advanced treatment of secondary wastewater effluent

Comparison of cooling tower blowdown and enhanced make up water treatment to minimize cooling water footprint

When water supply restrictions increasingly escalate to water supply risks, developing strategies to minimize the water footprint of wet cooling systems becomes crucial. This study compares two water engineering approaches to minimize the water footprint of a recirculating evaporative cooling tower (CT): (1) reusing cooling tower blowdown and (2) producing demineralized water to increase the cycles of concentration (CoC) of the CT. Our techno-economic analysis across various scenarios and CT settings reveals that reusing blowdown (option 1) is the most feasible approach for an industrial cooling system currently operating at CoCs of > 3, discharging blowdown with a conductivity of 2 mS/cm and a total organic carbon (TOC) concentration of approximately 20 mg/L. Compared to enhanced make up treatment, blowdown reuse allows higher water savings (13 %) and involves lower implementation and operation costs. Pilot scale trials validated the feasibility of both approaches. Blowdown and enhanced make up treatment included biologically activated carbon filtration, ultrafiltration and reverse osmosis, producing high-quality permeate, suitable for (re)use as CT make up or within other processes. The blowdown treatment reached a product quality of 80 μS/cm conductivity and 70 μg/L TOC, make up treatment 20 μS/cm in conductivity and 60 μg/L TOC, respectively. The study's findings underscore the viability of blowdown reuse as a cost-effective and efficient strategy to minimize the water footprint of cooling systems under increasing water scarcity conditions.

Water Demineralization by Membrane Distillation Utilizing Cooling Water From Municipal Waste Incinerator

The membrane distillation performance was studied for production of demineralized water from surface water (river). Hot water from cooling water system of municipal waste incinerator was considered as an energy source for membrane distillation. The integration of membrane installation with such cooling water system allows to re-use up to 18 kW per 1 m2 of the membranes. The studies were performed with the application of polypropylene capillary membranes Accurel PP S6/2. The membrane modules were supplied with the feed heated to a temperature of 310 K and 330 K. The permeate fl ux obtained for these temperatures was 2.8 and 9.7 L/m2 h, and the distillate conductivity was 6 and 4 S/cm, respectively. The water demineralisation process was carried out for 1200 h without module cleaning. The behaviour of the permeate fl ux and distillate conductivity indicate that used membranes maintained their non-wettability over tested period. The performed SEM-EDS examinations confi rmed, that the deposits did not fi ll the pores and were mainly formed on the membrane surface. The scaling intensity was defi nitely smaller for lower temperature (310 K) of the feed. The amorphous deposits containing beside Ca also substantial amounts of the Si were mainly formed under these conditions, whereas at higher feed temperature dominated CaCO3 scaling.

Water consumption management in polyethylene terephthalate (PET) bottles washing process via wastewater pretreatment and reuse

The increasing recycling of polyethylene terephthalate (PET) bottles requires more and more fresh water during washing the bottles. The post-washing wastewater is often treated as effluent, whereas it could be reused in the technological process after appropriate pretreatment. In this paper, coagulation together with flocculation is proposed for use in the pretreatment of the wastewater arising during PET bottles washing. Five flocculants and six coagulants were tested. The turbidity and total organic carbon (TOC) were reduced by up to 98% and 69%, respectively. Out of the tested flocculants, Praestol 611 BC at a dose of 2 mg/dm³ had the best performances. The best coagulant in TOC reduction was PIX-123. As for turbidity reduction, ALS was the best, but PIX-123 was comparable, and therefore, PIX-123 was indicated as most suitable in simultaneous reduction of TOC and turbidity. The coagulation and flocculation together reduced the amount of pollutants and contaminants in the post-washing wastewater to the levels allowing the water to be reused in the washing process, which could bring both economical and ecological benefits.

A modified MBR system with post advanced purification for domestic water supply system in 180-day CELSS: Construction, pollutant removal and water allocation

Water supply was vital to people's life, especially inside Controlled Ecological Life Support System (CELSS) for long-term space exploration. A platform of 4-person-180-day integrated experiment inside a CELSS including 6 cabins called 'SPACEnter' was established in Shenzhen, China. Based on this platform, a Membrane Bio-Reactor (MBR) system configuring post advanced purification, including I-MBR, II-MBR, nanofiltration (NF), reverse osmosis (RO), ion-exchange (IE), polyiodide disinfection (PI) and mineralization (MC) stages, used as a Domestic Water Supply System (DWSS) to guarantee crew's daily life was constructed. The performance of DWSS to treat the real plant cabin's condensate water was examined during continuously 180-day experiment. The long-term operation results showed that, though the influent pollutant load changed as the experiment processing, the system exhibited stable performance on pollutants removal with average effluent TOC＜0.5 mg/L, NH₄⁺-N＜0.02 mg/L, NO₃^--N＜0.25 mg/L, NO₂^--N＜0.001 mg/L, and displayed good capacity for controlling the trace metal ions and microorganism. The effluent through such modified MBR system was sufficiently allocated as hygiene water and potable water, and the average value was 39.69 and 10.93 L/d, respectively. The consumption of the modified MBR process was within the designed allowable scope. The outcomes of this study will be helpful for facilitating future applications of MBR as bio-based water supply technology in the CELSS.