Fact Sheet: Disinfection Alternatives
Disinfection of wastewater protects the public from potential
exposure to pathogenic microorganisms that would otherwise be present in
wastewater effluent that is discharged into waterbodies that may be used
for recreation or drinking water. Wastewater disinfection has
traditionally been accomplished using some form of chlorination. In
fact, more than 60% of the 20,000 municipal wastewater treatment plants
in North America use chlorination as the primary method of disinfecting
effluent. Although an effective disinfectant, chlorine (and related
compounds) has come under increased scrutiny because of regulatory,
safety, and security issues. Many treatment facilities are now
considering disinfection alternatives to be used either solely or in
combination with traditional chlorination for the treatment of effluent
into sensitive receiving waters.
For treatment facilities in search of an alternative to liquid
chlorine disinfection, there are a few technologies from which to
choose. One such technology gaining acceptance in many treatment
facilities is ultraviolet (UV) disinfection. WERF has funded several
projects looking at various aspects of UV disinfection methods. Our
research has shown it to be a cost-effective alternative, as well as an
effective disinfection method for such resistant pathogens as Cryptosporidium. Other options for disinfection,
such as ultrasonic and ozonation disinfection, show a good deal of
promise, as well. These technologies, however, are particularly
energy-intensive and are not yet cost effective for most facilities.
WERF also is examining new technologies, including the use of tin oxide
anodes to electrochemically generate disinfectants in
Fate and Persistence of Pathogens Subjected to
Disinfection (stock no.
98HHE2) Investigates the fate and persistence of bacteria,
viruses, and protozoan pathogens subjected to disinfection to determine
how each responds to various disinfection techniques and to provide
guidance on the disinfection processes most likely to result in optimal
Identifying and Communicating the Benefits and Risks of
Disinfecting Wet Weather Flows (stock no. 00HHE6) Improves the understanding
and communication of the benefits and risks of wet weather flow
disinfection related to aquatic life and human health. Also defines
effective disinfection control programs.
Oxidation Reduction Potential vs. Residual Control of
Chlorine (stock no.
99WWF6) Compiles results of a literature review on oxidation
reduction potential (ORP) sensors, membrane sensors, and automatic
chemistry systems. Side by side tests of all three technologies were
conducted to identify the drawbacks, advantages, and overall strengths
and weaknesses of both ORP and residual chlorine
Disinfection of Wastewater Effluent: Pros and Cons of
Technologies (project no. 04-HHE-4, ongoing) Will develop a
single document that presents the pros and cons and costs of various
technical options for wastewater disinfection that can be used by
wastewater professionals to evaluate and select the appropriate
technology for their application.
Impacts of Disinfectant Selection on Health Risk From
Pathogens in Effluent (stock no. 99HHE1) Provides a
detailed characterization of the effects of disinfectants on common
wastewater bacteria, in terms of their initial response to disinfectant
exposure, changes in bacterial community post-exposure, and nature and
extent of bacterial physiological damage resulting from exposure to
disinfectants. Also provides a quantitative assessment of risks of viral
infection associated with application or omission of disinfection as
part of municipal wastewater treatment and offers recommendations
regarding the circumstances under which wastewater disinfection should
Numerical and Experimental Characterizations of Dose
Distributions in UV Disinfection Systems (stock no. 99CTS2UR) Applies newly developed
tools for estimation of the dose distribution in UV disinfection
systems. The results of this research should enable the regulatory
community to develop a rational, scientifically based protocol for
design and regulation of these disinfection systems. WERF can only
provide limited information on this project to protect patent
The Effect of Upstream Treatment Processes on UV Disinfection
Performance (stock no.
D93012) This report is a comprehensive document evaluating the
effect of a wide variety of upstream treatment processes on UV
disinfection efficiency. It provides information for operators,
consultants, and design engineers on process changes for enhancement of
UV disinfection, and also provides guidance for new process
Understanding Viability of Pathogens During
Disinfection (stock no.
00HHE1) Improves the fundamental understanding of disinfectant
reactivity on pathogen and indicator organism viability and clarifies
the species-specific response to chlorination. This will lead to
improvements in disinfection processes to protect public health. WERF
can only provide limited information on this project to protect patent
Comparison of UV Irradiation to Chlorination: Guidance for
Achieving Optimal UV Performance (stock no. D43008) Compares the biocidal
efficiencies of UV irradiation and chlorination using secondary
effluents of varying quality, assesses the efficiency of UV inactivation
of total and fecal coliforms, investigates the effect of suspended
solids and particle size distribution on UV disinfection of secondary
wastewater effluent, evaluates existing UV disinfection models and
presents a newly developed model, and compares the economic feasibility
of UV irradiation with that of chlorination/dechlorination.
Optimization of Vortex Separator Removal Efficiencies for CSO
Treatment (stock no.
D41002) Investigates the degree of contaminant removal
achievable through the modification of vortex combined sewer overflow
(CSO) control devices. This research specifically uses dissolved air
flotation, UV disinfection, and chemical addition.
Inactivation of Pathogens by UV
Technologies (stock no.
00CTS9CO) Determines whether design parameters currently used
for low UV irradiation disinfection systems are applicable for high
intensity and pulsed UV systems.
Phase II: Development and Implementation of a Pilot-Scale Tin
Oxide Disinfection System (project
no. 02-CTS-6, ongoing) Evaluates the effect of common water
quality parameters on tin oxide anode effectiveness, evaluates the
specific mechanisms of oxidation and disinfection with tin oxide anode
systems, and characterizes the impact of reactor configuration and anode
processing techniques on the type and kinetics of production of reactive
A Risk-Based Approach to Optimize Filtration and Disinfection
Systems (project no. 04-HHE-5, ongoing) Will develop risk-based
criteria for the design and operation of wastewater filtration and
disinfection systems that will minimize health risks posed by pathogens
occluded in effluent particles.