Women in Water Quality

Women’s contributions in water quality have revolutionized the thinking of society about how to interact with the Earth’s natural resources. This chapter covers four prominent women pioneers in water quality. Ellen Henrietta Swallow Richards, designated by Engineering News Record as “the first female environmental engineer,” developed the first state water quality standards in the late 1800s. Ruth Patrick, after whom the biodiversity tenet the Patrick Principle is named, matched the types and numbers of diatoms in water to the type and extent of water pollution and invented the diatometer to collect and measure those diatoms. Rachel Carson, credited as the catalyst for the environmental movement of the 1960s and 1970s that continues today, wrote extensively about the oceans in addition to authoring Silent Spring, an exposé on pesticides. “Her Deepness” oceanographer Sylvia Earle is working today to preserve the world’s oceans.

Urban areas increasingly face the challenge of effectively managing water resources to minimize both flooding and freshwater scarcity. Hydrometeorological consequences of climate change exacerbate the effects of surface sealing and increased runoff in urban areas, the overexploitation of available water resources, water pollution, and aging infrastructures. These issues highlight the need for new robust and reliable techniques to manage flooding and improve the quality of surface runoff. The effective integration of robust engineering and design standards, novel material technologies, and innovative blue-green infrastructure solutions can serve to reconnect the urban hydrologic cycle, enhancing the resilience of urban areas to climate change. Engineered blue-green-gray systems that combine urban waterways with functional vegetation, geo- or bio-based filter materials, and related technologies can create holistic systems for sustainable management of urban stormwater quantity and quality.

Pressures on water resources continue to rise with increasing population and diminishing local freshwater supplies. Use of locally available water sources can increase reliability and resilience of water supplies, particularly in areas prone to drought. Examples of local water supplies include roof runoff, stormwater, graywater, and treated wastewater. Conventionally, municipalities withdraw water from freshwater sources, treat that water to potable quality to meet urban water demand, and then treat and discharge wastewater. This approach results in substantial use of energy and consumables. Water is essentially imported and exported from local areas. An alternative is to use locally available water sources. This practice is gaining interest as an approach to minimize the import and export of water ensure reliable water sources, increase water supply resiliency, and promote energy efficiency. Local water sources are often supplied via decentralized water systems.

The immense global burden of infectious disease outbreaks and the need to establish prediction and prevention systems have been recognized by the World Health Organization (WHO), the National Institutes of Health (NIH), the United States Agency of International Development (USAID), the Bill and Melinda Gates Foundation, and the international scientific community. Despite multiple efforts, this infectious burden is still increasing. For example, it has been reported that between 1.5 and 12 million people die each year from waterborne diseases and diarrheal diseases are listed within the top 15 leading causes of death worldwide. Rapid population growth, climate change, natural disasters, immigration, globalization, and the corresponding sanitation and waste management challenges are expected to intensify the problem in the years to come.

The sewer-based paradigm for wastewater management at the global scale is not successful neither from a humanitarian nor from an environmental perspective. The systems are too expensive for the largest part of the global population. Source separation and resource recovery offer an alternative for sanitation and water pollution control. This chapter illustrates the importance but also the challenges of urine source separation for efficient nutrient removal and recovery.

Bioremediation is a sustainable environmental treatment technology that harnesses the natural metabolic activities of living organisms to remove contaminants within soil, sediment, and water environments. Bioremediation is generally accepted as being a more cost-effective and sustainable remediation strategy when compared to chemical-based or pump-and-treat systems. Bioremediation treatment strategies are traditionally categorized as either biostimulation or bioaugmentation. Biostimulation involves the stimulation of indigenous microorganisms that are capable of degrading contaminants of interest. This treatment approach relies on manipulating site conditions to promote the activity and/or proliferation of microorganisms that are known to metabolize target contaminants of concern in order to overcome rate-limiting metabolic processes. In general, biostimulation involves oxidation-reduction reactions wherein either an electron acceptor (e.g., O₂, Fe³⁺, or SO₄²⁻) is added to promote oxidative reduction of a contaminant or an electron donor (e.g., organic substrate) is added to reduce oxidized pollutants.

This chapter focuses on biofilms, a common mode of bacteria growth ubiquitous in aquatic environments. Recent developments on biofilm detachment theories are summarized, and previously overlooked biofilm phenomena are explored, including the promising algal mats in natural environments, problematic distribution system biofilms in engineering environments, and the interaction between biofilms and emerging contaminants such as nanoparticles and disinfection byproducts. The goal of this chapter is to further demonstrate the importance of biofilms in environmental engineering and provide new insights for future biofilm control and utilization.

The microbial ecology of tetrachloroethene (PCE)- and trichloroethene (TCE)-contaminated sites is complex. Fundamentally, accurate prediction of contaminant fate, the survival of dehalorespiring populations, and, thus, the performance of engineered bioremediation approaches at these sites are feasible only if the correct kinetic models are applied, and meaningful and mathematically independent parameter estimates are input into these models. A model that incorporates biomass inactivation at high chlorinated ethene concentrations, as well as the self-inhibitory and competitive inhibition effects that the elevated chlorinated ethene concentrations exert on dechlorination reactions, must be utilized to accurately predict dehalorespiring population substrate interactions and growth. The initial conditions used in batch laboratory kinetic assays, including the initial limiting substrate (S₀)-to-initial biomass concentration (X₀) ratio and the S₀-to-half-saturation constant (K_S) ratio, must be carefully selected to ensure that the parameter estimates are meaningful and independent. Kinetic assays conducted at appropriate S₀/X₀ and S₀/K_S ratios suggest that the substrate utilization kinetics of many PCE-to-dichloroethene (DCE) dehalorespirers are faster than those of Dehalococcoides mccartyi strains. Integration of mathematical simulations using appropriate dehalorespiration models and dehalorespiring co-culture experiments also showed that PCE-to-DCE dehalorespirers tend to outcompete D. mccartyi strains for higher chlorinated ethenes. Where dense nonaqueous-phase liquid (DNAPL) contamination is present, the fast substrate utilization kinetics of PCE-to-DCE dehalorespirers allow them to grow close to the DNAPL-water interface and control dissolution bioenhancement. Under excess electron donor conditions, D. mccartyi strains specialize in dehalorespiration of lesser chlorinated ethenes produced by PCE-to-DCE dehalorespirers. Maintenance of multiple dehalorespirers growing via complementary substrate interactions results in optimal utilization of electron equivalents, bioenhancement of DNAPL dissolution, and contaminant detoxification.

Veterinary pharmaceuticals, which are increasingly used in animal production practices, can enter surface and groundwater after land application of animal manures or animal wastewater. The presence of veterinary pharmaceuticals can result in negative environmental impacts including the proliferation of environmental antibiotic resistance and endocrine-disrupting effects in aquatic organisms. The efficacy of manure application strategies to limit the occurrence of veterinary pharmaceuticals in runoff and best management practices to remove these compounds from runoff prior to entering surface water should be investigated to mitigate the impact of these compounds on the environment.

Understanding the speciation of metal contaminants and their interactions with soils, sediments, and hazardous waste is critical both to predicting their mobility in the subsurface and to devising successful remediation approaches. Experimental-spectroscopic techniques and geochemical modeling can be coupled toward the study of metal interactions. This chapter will discuss contributions of infrared and X-ray-based techniques to study of the speciation of hexavalent chromium in two media: a Cr(VI)-contaminated soil from a plating facility and pure iron oxides—minerals that are abundant in natural soil environments, including the plating facility. The use of these techniques to inform treatment design and fate and transport models will be highlighted.