This review includes many types of physical and biological treatment technologies, with the common feature of utilizing primarily natural processes or components for the treatment function, whether the system is aquatic or soil-based.Onsite systems have traditionally been very simple, passive systems that make use of soil or aquatic processes, although some of the components can be technologically advanced. For this reason, it is difficult to make a distinct separation of the topics covered in this review, and considerable overlap should be expected. WETLAND SYSTEMSGeneral. There are many types of constructed wetlands that are used to treat many different types of wastewaters. Some topics are specific to particular application and have been placed in subsequent sections. Some of the topics that are of general interest to the field of constructed wetland treatment are presented in this section.Understanding of predictive modeling and design of constructed wetlands continues to advance. The effect of treating detention time and first-order rate coefficients as distributed variables was explored (Kadlec, 2003a). Distributed parameter values can create modeling artifacts that obscure physical interpretations.The tanks-in-series model was shown to better accommodate distributed parameters than the typical plug-flow model. Tanner and Kadlec (2003) also studied nitrogen removal in experimental subsurface flow wetland mesocosms receiving four different 1192 organic wastewater with contrasting COD:N ratios and forms of N. Results were compared to models of oxygen requirements for the observed nitrification/denitrification and oxygen transfer rates. Results were not entirely consistent with current models of nitrogen removal in wetlands, and possible alternate pathways with lower oxygen requirements were discussed.Wetlands have been used in New Zealand to treat effluent from waste stabilization pond treatment systems for a number of applications, including sewage, dairy farm and swine wastewaters. Performance of these systems was reviewed and practical management issues, such as plant maintenance, wildlife management, hydraulic design, and pretreatment, were discussed (Tanner and Sukias, 2003). Knight et al (2003b) presented an extensive discussion of mosquito control issues in constructed wetlands and the tradeoffs between mosquito control and constructed wetland technology efficiency. Mosquito control strategies and design alternatives are presented, as well as recommendations for basic research to better resolve the conflict between constructed wetland design and their reputation for being mosquito-friendly habitat. The potential for production of greenhouse gases by constructed wetlands has received attention. Nitrous oxide (N 2 O) flux was measured over a two-year period from constructed wetlands treating wastewater (Johansson et al., 2003). Large temporal and spatial variations were observed. Emission factors calculated according to IPCC methods from the data were considerably lower than default factors provided by t...
Water quality standards programs in the United States and other countries are based on designated uses (DUs), which are linked to criteria that specify maximum pollutant levels and other characteristics that are thresholds for waterbody compliance with regulatory goals. Most DUs are similar to certain provisioning ecosystem goods and services (EGS), such as drinking water supply and recreation (e.g., boating, fishing). Absent in the DU concept are supporting or regulating services, which results in disjointed and often ineffective aquatic ecosystem protection and restoration strategies. The focus on discrete sets of water quality parameters in the DU concept can often result in the appearance of conflicting DUs, resulting in poor provisioning of certain DUs. We present a framework that uses EGS to provide a more holistic assessment of DUs and to help inform best management practices that could result in fuller attainment of DUs while providing greater provisioning of desired goods and services. Two case studies are discussed, demonstrating some of the issues with the DU concept, how it is implemented in the United States, and how the EGS framework can provide a crosswalk between the DU paradigm and stakeholder goals for a watershed. A process is presented that could help regulatory agencies and stakeholders make better use of the EGS framework in DU decisions, including watershed protection and restoration. The EGS framework presented here, coupled with a watershed stakeholder process focused on developing an integrative management strategy based on the framework, could help achieve multiple beneficial uses in an aquatic system. Integr Environ Assess Manag 2019;15:808–818. © 2019 SETAC.
The current emphasis on informed voluntary compliance with recommended best management practices -rather than regulation and enforcement -requires a new approach to watershed planning and management. In addition, many regulatory programs (e.g., TMDLs, Phase II Stormwater, Source Water Protection) depend on promoting and implementing voluntary actions. Protecting and restoring water resources by mandating compliance with laws and regulations is necessary in many cases, but public agencies do not have the resources to adequately address water quality problems nationwide. States have identified more than 20,000 water bodies, including almost 300,000 miles of rivers and streams and more than seven million acres of lakes, as too polluted for fishing and swimming.Many current watershed planning and management approaches involve detailed assessments and process-heavy stakeholder meetings before any action is actually undertaken. While assessments and broad-based stakeholder buy-in are ultimately required, much time and momentum can be lost while scientists analyze conditions and stakeholders attend meetingssometimes for months or even years.The business community moves much quicker. Time lags between product conception, development, and marketing is now measured in weeks. The corporate community is focused on rapid, targeted implementation, not months of pre-project analyses and development of an entire five-year plan before taking action. Many of our watershed problems stem from fairly well-known conditions at identifiable land tracts in the watershed. Working with land owners and land managers (e.g., farmers, developers, city street department staff, loggers) early in the planning process -while the stakeholder meetings are commencing -can help jump start implementation efforts and achieve water quality improvements before the assessment, planning, and management process has run its course. Early action creates, builds, and sustains momentum during that process and generates an atmosphere of progress, community and stakeholder interest, and overall support. This presentation takes a look at what the business community is hearing about planning and links it directly to the watershed approach. Lessons from management consultants Tom Peters, Stephen Covey, Brian Quinn, and Henry Mintzberg are matched to startlingly similar advice from the Center for Watershed Protection, the US EPA Office of Water and watershed experts from federal, state and private organizations. Recommendations to focus on action and avoid "paralysis by analysis" may provide a refreshing perspective for those burdened with the minutiae and sometimes drudgery of the often interminable planning process.
The Clean Water Act of 1972 required states to adopt policies and implementation procedures for preventing the loss of existing water body uses, disallowing water quality degradation except when clear economic and/or social benefits could be identified, and prohibiting any permanent degradation in certain pristine waters. States have largely adopted antidegradation policies, but few have devised -or are using -specific procedures for reviewing the potential for water quality degradation when permit applications or other proposals that may impact water resources are considered. Conservation groups are reviewing state antidegradation policies and implementation procedures, and are beginning to pursue court action to force states and US EPA to formalize antidegradation permit review processes, water quality studies comparing baseline conditions and expected changes caused by new or expanded activities, and the identification of expected social and/or economic benefits.
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