Best Practices Manual for Small Drinking Water Systems

All over the world the presence of arsenic in water sources for human consumption has been raising great concern in terms of public health since many epidemiologic studies confirm the potential carcinogenic effect of arsenic. Because arsenic removal is the most frequent option for safe drinking water, the development of more efficient and sustainable technologies is extremely important. Membrane separation processes are suitable for water treatment because they can provide an absolute barrier for bacteria and viruses, besides removing turbidity and colour. Their application is a promising technology in arsenic removal since it does not require the addition of chemical reagents nor the preliminary oxidation of arsenite required in conventional treatment options. However, since membrane technologies such as reverse osmosis can be a very expensive and unsustainable treatment option for small water supply systems, it becomes crucial that alternative methods are developed. This work presents a few conclusions based on a laboratorial study performed to evaluate the efficiency of arsenic removal using ultrafiltration, microfiltration and solar oxidation processes under different experimental conditions for relevant parameters. The results showed removal efficiencies higher than 90%. Key-words: safe drinking water, arsenic removal, membranes, public health.

In efforts to make package plants more compact, affordable and easier to operate and maintain, it has been noted that the design and performance of some of these plants containing conventional treatment processes is sometimes compromised if technical expertise in this regard is lacking. Generally, there are several risks associated with poorly designed treatment systems, including loss of production, poor safety and compromised equipment and process unit efficiency with associated higher operating and maintenance costs. These risks have more severe consequences in the case of desalination (including water reclamation and water re-use) package plants. The objective of this project is to develop a set of guidelines to assist municipalities, water treatment practitioners, designers and package plant manufacturers in the specification and design of appropriate unit processes and operating parameters to fit the influent water quality, operating environment and other special treatment requirements.

The University of Tennessee, Knoxville (UTK) received funding from the Bureau of Reclamation (Reclamation) in September 2013 to investigate a novel salt and organic removal technology. Using microbial electrolysis cell (MEC) technology and salt removal via capacitive deionization (CDI) to remove organic compounds present in produced water was investigated. This project was conducted in collaboration with CAP Holdings Company (CHC), which provided expertise in CDI technology. Converting soluble organic compounds via MEC was coupled to salt removal via CDI, providing a proof of principle for synergistic salt and organic removal. Hydrogen was generated by MEC from organic compounds and used to produce renewable electricity via a polymer electrolyte membrane (PEM) fuel cell , which was then used to power the CDI cell to achieve deionization.

Darigold operates a milk products facility in Lynden, Washington. Production processes include evaporation of milk, which generates what is referred to as condensate of whey (COW) water. COW water contains low molecular weight organic compounds including traces of lactic acid, alcohols, acetoin, and non-protein nitrogen (Möslang, 2017). COW water and non-contact cooling water from the Darigold Lynden facility are currently discharged to Outfall 001, which combines with stormwater and the City of Lynden’s wastewater treatment plant (WWTP) effluent discharge to the Nooksack River through the City’s outfall. Darigold’s discharge is regulated under National Pollutant Discharge Elimination System (NPDES) Permit No. WA0002470 administered by the Washington Department of Ecology (Ecology). In the future, Darigold’s COW Water and non-contact cooling water will be directly discharged to the Nooksack River in a new outfall pipe (Outfall 002) currently being constructed by the City.

This paper aims at analyzing the drinking water issue in the Mediterranean region, highlighting the principal problems and the appropriate technologies applicable in the different countries. The countries of this area are characterized by a huge variety from social, cultural, economic and environmental point of view. In particular, water distribution is inhomogeneous between the North, East, and South; even the type of water sources and the related quantity and quality problems differ country by country. Potable water comes from brackish and seawater, surface water, groundwater and water reservoirs with each source face different issues. The main problem of brackish and seawater for example is the high salinity and the contamination by disinfection byproducts, in addition to the microbiological and chemical contamination due to human activities that characterize also other surface water sources. Groundwater is also affected by human activity and it is not exempted from salinity because of the water intrusion. Moreover, water reservoirs are often contaminated by seasonal algal blooms. Technologies applied for drinking water treatment vary country by country. The paper presents the main treatment processes associated with the main water pollutants, according to the Mediterranean region. Case studies of drinking water treatment plants are also analyzed, presenting alternative technologies appropriate for specific contexts, among others. The characteristics of each specific context should be carefully analyzed in order to develop the most appropriate technologies; high-end technologies for drinking water treatment may not be applied equally to all countries or communities of the Mediterranean region.