Executive Summary
The water shortage supply in Las Vegas is a major problem due to the city’s reliance on Lake Mead and Colorado Rivers, which are drying up due to droughts. The solution is wastewater reuse instead of drilling deeper into Lake Mead. The two approaches can be implemented, which include direct potable reuse (DPR) and indirect potable reuse (IPR). Both are effective and can be used to address the underlying issues, and the city should invest in IPR first and slowly move to DPR since the former is cheaper. Direct potable reuse ensures that the wastewater from the reclamation plant is treated with FAT through screening, membrane biological reactor, chloramine disinfection, reverse osmosis, and UV oxidation. After these processes, the wastewater is blended with raw water for further treatment. However, for IPR, wastewater is cleaned, after which it is added to the water reservoir.
Introduction
It is important to note that water is among the most valuable and essential resources for all forms of life. Human civilization depends on the water supply to survive and function properly. However, the droughts and other forms of climatic changes can deeply affect the sources of water supply for large urbanized centers. Such is the case with Las Vegas, which is faced with the problem of water shortage. Las Vegas should invest in and build wastewater management in the form of direct potable reuse (DPR) and indirect potable reuse (IPR).
Purpose Statement
The main purpose of the given assessment is to address the problem of water shortage in the city of Las Vegas by highlighting the creative and original solutions to the issue. Since the region of interest is heavily reliant on the water supplied by Lake Mead and the Colorado River, it is critical to decreasing the reliance on these reservoirs. The city needs to invest heavily into building a water supply system based on wastewater recycling and reusing.
Problem
The key problem of water shortage in Las Vegas is the reduction of water supply by the water sources, such as the Colorado River and Lake Mead. It is reported that “the period between 2000 and 2019 was also its driest stretch in more than 100 years of record-keeping, culminating in the unprecedented low water levels in Lake Mead” (Lai, 2022, para. 10). In addition, it should be noted that the project of drilling deeper into the lake is the current approach. It is stated that “the pipeline and pump projects cost more than $1.3 billion. Drilling began in 2014, amid projections that the lake level would continue to fall due to drought” (Associated Press, 2022, para. 11). In other words, the proposed solutions should be more original, creative, and innovative than further depending on the existing reservoirs.
Original and Creative Solutions: Wastewater Reuse
One should be aware of the fact that both IPR and DPR can their practical uses depending on the conditions, needs, and water specificities. In order to understand these differences, it is important to define these systems of potable reuse frameworks beforehand as shown in Figure 1 below. It is stated that “the introduction of purified water into an environmental buffer such … lake or river before the water is blended with a treated water supply system is called indirect potable reuse” (Davis, 2019, p. 1586). In other words, the wastewater is not directly introduced to the water distribution system, because it is relocated into a buffer before the treatment. For DPR, “the introduction of treated wastewater directly into a potable distribution system or into the raw water supply immediately upstream of the water treatment plant is called direct potable reuse” (Davis, 2019, p. 1586). Thus, unlike in IPR, the wastewater is directly relocated to the supply system, which can either go to the treatment plant or be distributed with the raw water.
With an ever-increasing population size as well as water demand in many regions of the United States, IPR and DPR are becoming plausible and feasible solutions. Additional factors include “water scarcity because of climate effects such as drought and seawater rise, as well as saltwater intrusion because of overdrawn potable water aquifers” (Davis, 2019, p. 1587). Although the drivers for IPR implementation vary across many regions, the high demand and low supply due to a multitude of factors are making IPR attractive. However, when it comes to DPR, “the amount of water supplied is relatively small compared to the communities” (Davis, 2019, p. 1589). Another explanation can include a high level of drought occurrence rates as well as an ever-improving technological sophistication in the identification and removal of major contaminants.
One of the key aspects of both IPR and DPR is centered around the strict adherence to national and local standards. The National Safe Drinking Water Act SDWA sets the core standard for the minimum requirements of drinking water. Although the act has no specific IPR-related or DPR-related standardization needs, the wastewater reused in both cases must adhere to the SDWA. The log removal value, or LRV, is an important standard of measurement for the finished water contaminant and pathogen concentration numbers, which tend to be in smaller ranges (Crini & Lichtfouse, 2018). Thus, various processes, such as membrane filtration or reverse osmosis, are evaluated and measured in accordance with their corresponding log removal values.
When it comes to potable reuse, the treatment process performance must be effective at all times over a long period. The contaminants which cause chronic health issues are more dangerous in this regard because the exposure is longitudinal (Davis, 2019). Therefore, the core design principles include reliability, redundancy, robustness, and resilience. In other words, a potable reuse system must be reliable in terms of consistent delivery of high-quality water. Redundancy refers to “the use of measures beyond minimum requirements to ensure that the treatment goals are reliably met, or that performance can be more reliably demonstrated” (Davis, 2019, p. 1592). Robustness determines the resistance to failures and capability to address a wide range of contaminants, whereas resilience is ensured through the treatment system’s adaptability to failure. In the case of design practices, both DPR and IRP must undergo treatment processes. It is stated that “full advanced treatment (FAT) trains typically consist of (1) microfiltration (MF), (2) reverse osmosis (RO), and (3) an ultraviolet light (UV)–based advanced oxidation process (AOP) with hydrogen peroxide” (Davis, 2019, p. 1594). In other words, FAT is a highly effective method of achieving the desirable log removal value and elimination of many contaminants.
Conclusion
In conclusion, the Las Vegas water shortage can be solved with the use of wastewater management in the form of DPR and IPR. Both can be effective in combination since Lake Mead can be utilized for IPR as an environmental buffer, whereas DPR can create more resilience to droughts since it is a closed system. Indirect potable reuse of wastewater uses an environmental buffer, but DPR uses the untreated water directly supplied upstream of the distribution system.
References
Associated Press. (2022). ‘The water is not there’: Drought forces Las Vegas to draw from deeper within Lake Mead. KTLA. Web.
Crini, G., & Lichtfouse, E. (2018). Advantages and disadvantages of techniques used for wastewater treatment. Environmental Chemistry Letters, 17, 145–155. Web.
Davis, M. (2019). Water and wastewater engineering: Design principles and practice (2nd ed.). McGraw Hill.
Lai, O. (2022). Is Las Vegas doing enough to combat water shortage? Earth.org. Web.