Many utilities considering indirect potable reuse want to know if ultraviolet (UV) peroxide treatment for NDMA
will remove other xenobiotic contaminants. Endocrine disrupting compounds (EDCs),
pharmaceuticals and personal care products (PPCPs) are presently unregulated contaminants with
poorly understood human health and ecological effects that occur with great consistency in
wastewater effluents. This study evaluated the ability of UV peroxide to reduce EDCs and PPCPs
when applied at the dose needed to control NDMA. Pilot testing occurred at the City of San Diego's 30-MGD North City Water Reclamation Plant
(NCWRP) located in San Diego, California. The NCWRP consists of bar screening, grit removal,
primary clarification, aeration, secondary clarification, filtration, demineralization with
electrodialysis reversal (EDR), and disinfection. A process flow diagram of NCWRP showing the
major unit operations is provided.
A side stream of filtered effluent was fed to a pilot consisting of a Zenon ZeeWeed 500 UF
membrane system, a dual stage RO membrane system, and a Trojan Technologies Inc.
UVLogic8AL30 low pressure high output (LPHO) UV lamp system. Hydrogen peroxide was added
with a static mixer at the inlet pipe to the UV reactor. An overall schematic of the pilot train is provided, along with a picture of the UV reactor and the specifications for
the Trojan UV system. NDMA as well as EDC and PPCP compounds were spiked into the UV reactor influent during the
pilot study. The specific EDC and PPCP compounds selected for spiking were chosen based on the
following criteria: high likelihood of occurrence in prior monitoring results; provision of a
broad range of physical and chemical properties; and, amenability to a single solid-phase
extraction LC/MS/MS analysis (Vanderford, 2003). A brief description of the target chemicals
utilized in the study is provided. NDMA was spiked to approximate 800 ng/L and
EDC/PPCP compounds were spiked between 280 and 990 ng/L. Positive and negative control
samples were associated with each experiment. The bench-scale UV collimated beam apparatus, consisting of a low-pressure UV
lamp housed within a 6.6 cm diameter collimating tube, was used to characterize the delivered dose
of the pilot-scale system. An International Light™ calibrated radiometer (IL1400) was used to
measure the UV intensity at the surface of 150-mL water samples contained within a petri dish and
uniformly placed below the collimator. These water samples were collected from the pilot facility
and fortified with NDMA to achieve a uniform high initial concentration of approximately 1000
ng/L. Analysis of the NDMA concentration of these samples after different UV exposure periods
was used to generate a dose-response curve. This curve is then utilized to characterize the delivered
dose of the pilot system by comparing the log reduction achieved with the pilot facility to the
corresponding dose of the collimated beam curve. Includes 5 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 420 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 7 |
| Published : | 06/01/2006 |
