Impact of Different Combinations of Water Treatment Processes on the Concentration of Disinfection Byproducts and Their Precursors in Swimming Pool Water

Abstract

To mitigate microbial activity in swimming pools and to ensure hygienic safety for bathers, pool systems have a recirculating water system ensuring continuous water treatment and disinfection by chlorination. A major drawback associated with the use of chlorine as disinfectant is its potential to react with precursor substances present in pool water to form harmful disinfection byproducts (DBPs). In this study, different combinations of conventional and advanced treatment processes were applied to lower the concentration of DBPs and their precursors in pool water by using a pilot-scale swimming pool model operated under reproducible and fully controlled conditions. The quality of the pool water was determined after stationary concentrations of dissolved organic carbon (DOC) were reached. The relative removal of DOC (Δc c in −1) across the considered treatment trains ranged between 0.1 ± 2.9% and 7.70 ± 4.5%, where conventional water treatment (coagulation and sand filtration combined with granular activated carbon (GAC) filtration) was revealed to be the most effective. Microbial processes in the deeper, chlorine-free regions of the GAC filter have been found to play an important role in the degradation of organic substances. Almost all treatment combinations were capable of removing trihalomethanes to some degree and trichloramine and dichloroacetonitrile almost completely. However, the results demonstrated that effective removal of DBPs across the treatment train does not necessarily result in low DBP concentrations in the basin of a pool. This raises the importance of the DBP formation potential of the organic precursors, which has been shown to depend strongly on the treatment concept applied. Irrespective of the filtration technique employed, treatment combinations employing UV irradiation as a second treatment step revealed higher concentrations of volatile DBPs in the pool compared to those employing GAC filtration as a second treatment step. In the particular case of trichloramine, results confirm that its removal across the treatment train is not a feasible mitigation strategy because it cannot compensate for the fast formation in the basin.

Water loss in swimming pool filter backwashing processes in the Balearic Islands (Spain)

“…Their use for irrigating green areas, Water Policy Vol 00 No 0, 11 sprinkling grounds and tennis courts (very often located near a swimming pool), as well as flushing toilets is an easy solution that allows to dramatically reduce the environmental and economic costs (Wyczarska-Kokot, 2016). For instance, just filtering through granular activated carbon removes efficiently free chlorine and DBPs from the water, enabling its use in toilet flushing and other low-level applications (Skibinski et al, 2019). Advance membrane filtration technology, including micro-, ultra-and nanofiltration, offers better outcomes when applied to backwashing waters.…”

“…Conventional or traditional water treatment includes sedimentation, coagulation, sand and granular activated carbon filtration. Advanced procedures like membrane filtration (micro-, nano-or ultrafiltration) or ultraviolet irradiation are increasingly used for pool water treatment (Skibinski et al, 2016(Skibinski et al, , 2019. Simple purification processes, including a settling tank with a coagulant chamber and after a tank for intensive aeration, allow the backwash water to introduce into waters or the ground (Wyczarska-Kokot & Lempart, 2018).…”

“…Simple purification processes, including a settling tank with a coagulant chamber and after a tank for intensive aeration, allow the backwash water to introduce into waters or the ground (Wyczarska-Kokot & Lempart, 2018). The simple filtration with granular activated carbon effectively removes free chlorine and DBPs from the water, as demonstrated by Skibinski et al (Skibinski et al, 2019). That enables its use in toilet flushing and other low-level applications.…”

Systematic and data-driven literature review of the energy and indoor environmental performance of swimming facilities

“…Urine has a massive chloroform DBP formation potential (Berg et al, 2019) which is likely to end up in the pool's air (Berg et al, 2019). In addition, results have shown that removing the volatile DBP trichloramine across the water treatment train is not a feasible strategy due to the high formation rate in the pool (Skibinski et al, 2019). Thus, the ventilation concept and fresh air supply for the facility are crucial to reduce the negative health impacts for the occupants.…”

The Implementation of Multiple Linear Regression for Swimming Pool Facilities: Case Study at Jøa, Norway

“…The swimming facility at Jøa is a state-of-the-art swimming facility which complies with the Norwegian passive house standard [22]. It includes a ventilation heat recovery system equipped with a heat pump, as recommended in the literature [5,43], and conventional water treatment, which research has found to be the most effective water treatment train [44].…”