George Loomis

Evaluation of water quality functions of conventional and advanced soil-based onsite wastewater treatment systems.

Shallow narrow drainfields are assumed to provide better wastewater renovation than conventional drainfields and are used for protection of surface and ground water. To test this assumption, we evaluated the water quality functions of two advanced onsite wastewater treatment system (OWTS) drainfields-shallow narrow (SND) and Geomat (GEO)-and a conventional pipe and stone (P&S) drainfield over 12 mo using replicated ( = 3) intact soil mesocosms. The SND and GEO mesocosms received effluent from a single-pass sand filter, whereas the P&S received septic tank effluent. Between 97.1 and 100% of 5-d biochemical oxygen demand (BOD), fecal coliform bacteria, and total phosphorus (P) were removed in all drainfield types. Total nitrogen (N) removal averaged 12.0% for P&S, 4.8% for SND, and 5.4% for GEO. A mass balance analysis accounted for 95.1% (SND), 94.1% (GEO), and 87.6% (P&S) of N inputs. When the whole treatment train (excluding the septic tank) is considered, advanced systems, including sand filter pretreatment and SND or GEO soil-based treatment, removed 99.8 to 99.9% of BOD, 100% of fecal coliform bacteria and P, and 26.0 to 27.0% of N. In contrast, the conventional system removed 99.4% of BOD and 100% of fecal coliform bacteria and P but only 12.0% of N. All drainfield types performed similarly for most water quality functions despite differences in placement within the soil profile. However, inclusion of the pretreatment step in advanced system treatment trains results in better N removal than in conventional treatment systems despite higher drainfield N removal rates in the latter.

Hell and High Water: Diminished Septic System Performance in Coastal Regions Due to Climate Change.

Climate change may affect the ability of soil-based onsite wastewater treatment systems (OWTS) to treat wastewater in coastal regions of the Northeastern United States. Higher temperatures and water tables can affect treatment by reducing the volume of unsaturated soil and oxygen available for treatment, which may result in greater transport of pathogens, nutrients, and biochemical oxygen demand (BOD5) to groundwater, jeopardizing public and aquatic ecosystem health. The soil treatment area (STA) of an OWTS removes contaminants as wastewater percolates through the soil. Conventional STAs receive wastewater from the septic tank, with infiltration occurring deeper in the soil profile. In contrast, shallow narrow STAs receive pre-treated wastewater that infiltrates higher in the soil profile, which may make them more resilient to climate change. We used intact soil mesocosms to quantify the water quality functions of a conventional and two types of shallow narrow STAs under present climate (PC; 20°C) and climate change (CC; 25°C, 30 cm elevation in water table). Significantly greater removal of BOD5 was observed under CC for all STA types. Phosphorus removal decreased significantly from 75% (PC) to 66% (CC) in the conventional STA, and from 100% to 71–72% in shallow narrow STAs. No fecal coliform bacteria (FCB) were released under PC, whereas up to 17 and 20 CFU 100 mL-1 were released in conventional and shallow narrow STAs, respectively, under CC. Total N removal increased from 14% (PC) to 19% (CC) in the conventional STA, but decreased in shallow narrow STAs, from 6–7% to less than 3.0%. Differences in removal of FCB and total N were not significant. Leaching of N in excess of inputs was also observed in shallow narrow STAs under CC. Our results indicate that climate change can affect contaminant removal from wastewater, with effects dependent on the contaminant and STA type.

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)

Nitrifying and Denitrifying Bacterial Communities in Advanced Nitrogen-Removal Onsite Wastewater Treatment Systems

Advanced N-removal onsite wastewater treatment systems (OWTS) rely on nitrification and denitrification to remove N from wastewater. Despite their use to reduce N contamination, we know little about microbial communities controlling N removal in these systems. We used quantitative polymerase chain reaction and high-throughput sequencing targeting nitrous oxide reductase () and bacterial ammonia monooxygenase () to determine the size, structure, and composition of communities containing these genes. We analyzed water samples from three advanced N-removal technologies in 38 systems in five towns in Rhode Island in August 2016, and in nine systems from one town in June, August, and October 2016. Abundance of ranged from 9.1 × 10 to 9 × 10 copies L and differed among technologies and over time, whereas bacterial abundance ranged from 0 to 1.9 × 10 copies L and was not different among technologies or over time. Richness and diversity of -but not -differed over time, with median Shannon diversity indices ranging from 2.61 in October to 4.53 in August. We observed weak community similarity patterns driven by geography and technology in The most abundant and containing bacteria were associated with water distribution and municipal wastewater treatment plants, such as and species. Our results show that communities in N-removal OWTS technologies differ slightly in terms of size and diversity as a function of time, but not geography, whereas communities are similar across time, technology, and geography. Furthermore, community composition appears to be stable across technologies, geography, and time for .

Comparison of N 2 O Emissions and Gene Abundances between Wastewater Nitrogen Removal Systems

Biological nitrogen removal (BNR) systems are increasingly used in the United States in both centralized wastewater treatment plants (WWTPs) and decentralized advanced onsite wastewater treatment systems (OWTS) to reduce N discharged in wastewater effluent. However, the potential for BNR systems to be sources of nitrous oxide (NO), a potent greenhouse gas, needs to be evaluated to assess their environmental impact. We quantified and compared NO emissions from BNR systems at a WWTP (Fields Point, Providence, RI) and three types of advanced OWTS (Orenco Advantex AX 20, SeptiTech Series D, and Bio-Microbics MicroFAST) in nine Rhode Island residences ( = 3 per type) using cavity ring-down spectroscopy. We also used quantitative polymerase chain reaction to determine the abundance of genes from nitrifying () and denitrifying () microorganisms that may be producing NO in these systems. Nitrous oxide fluxes ranged from -4 × 10 to 3 × 10 µmol NO m s and in general followed the order: centralized WWTP > Advantex > SeptiTech > FAST. In contrast, when NO emissions were normalized by population served and area of treatment tanks, all systems had overlapping ranges. In general, the emissions of NO accounted for a small fraction (<1%) of N removed. There was no significant relationship between the abundance of or genes and NO emissions. This preliminary analysis highlights the need to evaluate NO emissions from wastewater systems as a wider range of technologies are adopted. A better understanding of the mechanisms of NO emissions will also allow us to better manage systems to minimize emissions.

OPERATION AND MAINTENANCE SERVICE PROVIDER PROGRAM

The Operation and Maintenance (O&M) Service Provider Program is being established to set standards of using best practices for onsite wastewater treatment system service visits. The focus of these materials is single-family residential systems. Through routine service visits and proper maintenance, onsite wastewater treatment systems are a permanent and effective part of our wastewater treatment infrastructure.