Kathryn S. Lowe

Influent Constituent Characteristics of the Modern Waste Stream from Single Sources: Literature Review

A literature review was conducted to assess the current status of knowledge on the composition of raw wastewater and primary treated effluent (i.e., septic tank effluent) from single source onsite wastewater systems. The overall goal of this research project is to characterize the extent of conventional constituents, microbial constituents, and organic wastewater contaminants in single source onsite raw wastewater and primary treated effluent to aid onsite wastewater system design and management. Information obtained was evaluated using cumulative frequency distributions to compare individual constituent concentrations in various waste streams and by using data qualifiers to enable assessment of parameters that might affect single source waste stream composition. To supplement information on the single source raw wastewater and primary treated effluent composition, state agencies responsible for onsite wastewater regulation were contacted to assess the prevalence of different system types installed and in operation. Selected demographics that capture differences in lifestyle habits that could affect raw wastewater composition were also assessed. A large amount of data was captured by this literature review, however information gaps were identified. The information presented here will be used to guide future project monitoring and assessment of modern raw wastewater waste streams. This title belongs to WERF Research Report Series ISBN: 9781843397731 (eBook)

STUMOD—a Tool for Predicting Fate and Transport of Nitrogen in Soil Treatment Units

A typical onsite wastewater treatment system consists of a septic tank and a soil treatment unit to treat wastewater before it is discharged through the vadose zone to an aquifer. A tool was developed for the purpose of predicting the fate and transport of nitrogen in soil treatment units (STUMOD or Soil Treatment Unit Model). STUMOD calculates nitrogen species concentrations and the fraction of total nitrogen reaching the aquifer or a specified soil depth. Input data include parameters for hydraulics and nutrient transport and transformation. An analytical solution is used to calculate the profile of pressure based on Darcy’s equation and the relationships between suction head, unsaturated hydraulic conductivity, and soil moisture. Chemical transport is based on simplification of the advection–dispersion equation. STUMOD is relatively simple to use but accounts for important processes such as ammonium sorption, nitrification, and denitrification. STUMOD accounts for the effect of soil moisture content (a surrogate for redox conditions) on nitrification and denitrification reactions. The model has provisions to handle the influence of temperature and organic carbon content on nitrogen transformation. Model outputs, generated based on input parameters obtained from extensive literature review, were compared to a numerical model and data from laboratory tests and field sites. Both measured data and STUMOD outputs show a relatively higher removal in clayey soils compared to sandy soils. Consistent with literature data for most soils, STUMOD predicted ammonium conversion to nitrate within the first foot below the trench infiltrative surface.

Influent Constituent Characteristics of the Modern Waste Stream from Single Sources

A literature review was conducted to assess the current status of knowledge on the composition of raw wastewater and primary treated effluent (i.e., septic tank effluent) from single source onsite wastewater systems. The overall goal of this research project is to characterize the extent of conventional constituents, microbial constituents, and organic wastewater contaminants in single source onsite raw wastewater and primary treated effluent to aid onsite wastewater system design and management. Information obtained was evaluated using cumulative frequency distributions to compare individual constituent concentrations in various waste streams and by using data qualifiers to enable assessment of parameters that might affect single source waste stream composition. To supplement information on the single source raw wastewater and primary treated effluent composition, state agencies responsible for onsite wastewater regulation were contacted to assess the prevalence of different system types installed and in operation. Selected demographics that capture differences in lifestyle habits that could affect raw wastewater composition were also assessed. A large amount of data was captured by this literature review, however information gaps were identified. The information presented here will be used to guide future project monitoring and assessment of modern raw wastewater waste streams. This title belongs to WERF Research Report Series . ISBN: 9781843393511 (Print) ISBN: 9781780403519 (eBook)

New Conceptual Model for Soil Treatment Units: Formation of Multiple Hydraulic Zones during Unsaturated Wastewater Infiltration.

Onsite wastewater treatment systems are commonly used in the United States to reclaim domestic wastewater. A distinct biomat forms at the infiltrative surface, causing resistance to flow and decreasing soil moisture below the biomat. To simulate these conditions, previous modeling studies have used a two-layer approach: a thin biomat layer (1-5 cm thick) and the native soil layer below the biomat. However, the effect of wastewater application extends below the biomat layer. We used numerical modeling supported by experimental data to justify a new conceptual model that includes an intermediate zone (IZ) below the biomat. The conceptual model was set up using Hydrus 2D and calibrated against soil moisture and water flux measurements. The estimated hydraulic conductivity value for the IZ was between biomat and the native soil. The IZ has important implications for wastewater treatment. When the IZ was not considered, a loading rate of 5 cm d resulted in an 8.5-cm ponding. With the IZ, the same loading rate resulted in a 9.5-cm ponding. Without the IZ, up to 3.1 cm d of wastewater could be applied without ponding; with the IZ, only up to 2.8 cm d could be applied without ponding. The IZ also plays a significant role in soil moisture distribution. Without the IZ, near-saturation conditions were observed only within the biomat, whereas near-saturation conditions extended below the biomat with the IZ. Accurate prediction of ponding is important to prevent surfacing of wastewater. The degree of water and air saturation influences pollutant treatment efficiency through residence time, volatility, and biochemical reactions.

Quantitative Tools to Determine the Expected Performance of Wastewater Soil Treatment Units Guidance Manual, Toolkit User's Guide and Visual-Graphic Tools

DEC1R06a: Development of Quantitative Tools to Determine the Expected Performance of Unit Process in Wastewater Treatment Units Onsite wastewater treatment system (OWTS) systems are an important part of the wastewater treatment and water management infrastructure in the U.S. Thus, proper OWTS selection, design, installation, operation and management are essential. While OWTS vary widely in their design and implementation, most systems are conventional OWTS that on the soil treatment unit (STU) for wastewater constituent treatment, hydraulic capacity, and eventual recharge to water resources. While there is considerable concern about potential water quality degradation associated with OWTS, current permitting and design focus mainly on ensuring that the hydraulic loading is not excessive. The STU provides an effective and sustainable means for wastewater reclamation, but occasional water quality degradation has been experienced. The likely cause for this is an incomplete understanding of treatment processes in various STUs, and the lack of available tools for assessing the performance of the STU. The overall goal of the project was to provide a toolkit to assess STU performance to enable evaluation and design of expected STU performance for important wastewater constituents over a relevant range of OWTS operating conditions. The toolkit is appropriate for a wide range of users, and includes an implementation protocol for different tools of varying complexity. Specific project objectives were to:   1. identify the best practices, available data, data gaps, and promising tools and techniques utilized in STU design and performance,   2. develop and test tools for performance-based STU design,   3. develop a protocol for using the tools,   4. refine the tools and protocol using data from laboratory studies, field sites, and numerical modeling, and   5. provide a final tool-kit and protocol to aid system designers and decision makers assess the expected STU performance. DEC1R06b: Quantitative Tools to Determine the Expected Performance of Unit Process in Wastewater Treatment Units: Toolkit Users Guide Onsite wastewater treatment systems (OWTS) are an important part of water management infrastructure in the United States. Thus, proper OWTS selection, design, installation, operation and management are essential. To aid this life-cycle, a toolkit was developed to enable evaluation and design of expected STU performance. The toolkit is comprised of this Guidance Manual, a companion Toolkit Users Guide, individual tools, and supplemental information. This framework provides detailed information to less experienced users while enabling more experienced users to start directly with STUMOD or other tool implementation referring to limited sections of the Guidance Manual or Users Guide. The toolkit was developed for a wide range of users faced with different needs of varying complexity when evaluating treatment of nitrogen, microbial pollutants (bacteria and virus), and organic wastewater contaminants (OWCs). Progressing through simple to more complex tools ultimately guides the user to the simplest tool that is appropriate, but discourages using a tool that is too simple for the decision at hand. The simplest tools include look-up tables and cumulative frequency distributions to direct the user to available pertinent information. Nomographs enable initial screening and quick insight into expected nitrogen removal based on the predicted output from STUMOD. Cumulative probability graphs illustrate modeling results in a risk-based framework while numerical model simulations demonstrate the usefulness of complex tools. Finally, two spreadsheet tools were developed for nitrogen transport, N-CALC and STUMOD, allowing the user to evaluate a range of STU operating conditions, soil hydraulics, and/or treatment parameters, as well as the relative influence of these factors on performance. DEC1R06c: Quantitative Tools to Determine the Expected Performance of Unit Process in Wastewater Treatment Units: Visual-Graphics Tools This file includes the visual-graphic tools: nomographs, cumulative probability graphs, and scenario illustrations. Chapter 1.0 includes nomographs illustrating the fraction of total-nitrogen remaining with depth. Chapter 2.0 includes cumulative probability graphs that illustrate the likely range of treatment outcomes. Chapter 3.0 includes HYDRUS simulation outputs that illustrate various operational scenarios. Finally, a list of visual-graphic tools is provided to aid in locating the visual-graphic tool of interest. This is a separate document that must be used in conjunction with the Guidance Manual and Users Guide. The companion Guidance Manual is organized into four Chapters describing the toolkit and providing guidance for tool selection and use. The fundamental assumptions that were incorporated and a detailed description of the tool development for these visual-graphic tools are provided in the companion Users Guide. Additional tools provided as separate files include STUMOD and N-CALC as MicrosoftTM Xcel files. This title belongs to WERF Research Report Series . In both the nomograph and the cumulative probability graphs, treatment information provided by these tools is based on data generated by numerical models that can incorporate complex and robust treatment and operating conditions. The parameters used for nomograph development are summarized in Table VG-1. Table VG-2 provides a definition for each parameter. Because the choices for representative OWTS conditions are limited, the user must decide how their OWTS system fits within the limited treatment estimations displayed by the graphics. Nomographs and cumulative probability graphs were developed for the following fixed operating conditions:   •Effluent Quality    ○Standard Effluent = representative of septic tank effluent (STE) as 60 mg-N L-1 as ammonium-nitrogen plus 1 mg-N L-1 as nitrate-nitrogen    ○Nitrified Effluent = representative of aerobically treated STE to achieve nitrogen reduction and transformation as 15 mg-N L-1 as nitrate-nitrogen   •Hydraulic Loading Rate (HLR)    ○2 cm d-1    ○5% Ksat   •Regional Temperature Range    ○Frigid/Cryic = Average Range 0 to 8 oC, Annual Mean 4.5 oC    ○Mesic = Average Range 8 to 15 oC, Annual Mean 11.5 oC    ○Thermic = Average Range 15 to 22 oC, Annual Mean 18.5 oC    ○Hyperthermic = Average Range 22 to 29 oC, Annual Mean 25.5 oC ISBN: 9781843393955 (eBook)

Soil Treatment Unit Performance as Affected by Hydraulic Loading Rate and Applied Effluent Quality

Treatment units, such as sand filters, textile media filters, and membrane bioreactors, are designed to enable higher or equivalent performance to a septic tank so that soil treatment can be accomplished at higher hydraulic loading rates and/or with less unsaturated soil depth. A field study was conducted to evaluate the performance of an overall treatment train with the soil treatment unit receiving effluent from three treatment units (septic tank [ST], ST with textile filter unit [TFU], and ST with membrane bioreactor [MBR]). The effluents from the three treatment units were applied to 18 in situ test cells at two hydraulic loading rates (2 or 8 cm/d). Each effluent was characterized and the effects of the effluent quality on the hydraulic and purification performance during soil treatment were studied. The treatment units achieved very different treatment efficiencies for organic matter, solids, nutrients, and bacteria (relative efficiency of ST 99% removal for total phosphorus and >87% removal of dissolved organic carbon after 60 cm of soil for each effluent quality. Nitrogen removal rates were ~60% in the TFU test cells and ~35% in the ST test cells. The treatment trains including a TFU or MBR, generally performed better with respect to purification and were less affected by HLR than the treatment train based on only a ST and soil treatment.