Treatment performance of advanced onsite wastewater treatment systems in the Otsego Lake watershed

Transcription

1 Treatment performance of advanced onsite wastewater treatment systems in the Otsego Lake watershed Submitted by: Holly Waterfield SUNY Oneonta Biological Field Station 5838 State Highway 80 Cooperstown, NY Funding provided by NYSDEC grant #49298.

2 EXECUTIVE SUMMARY This report documents the treatment performance of four advanced onsite wastewater treatment systems based on monitoring during the summers of 2008 through All four systems are installed in the Otsego Lake watershed; three were installed as part of a NYS DEC grant to demonstrate the use of advanced onsite wastewater treatment systems. Three systems have been monitored since 2008 (Waterfield and Kessler 2009, Waterfield 2010, Waterfield 2011); OWTS 1 and OWTS 2, funded by the grant, and the UIC system (serving BFS Upland Interpretive Center). Another system, also funded by the grant, was installed in the spring of 2009 at the BFS Thayer Farm; this system serves three buildings; the Hop House, Boat House, and a rented residence. Many of these enhanced treatment technologies are new the region, and thus are unfamiliar to industry professionals, regulators, and residents. For this reason, a DEC grant was sought and obtained to fund a demonstration project to install and monitor the treatment performance of six shared advanced treatment systems. The scope of the grant has since been amended, changing the total number of treatment systems to four, with the last installed in early 2011 to serve SUNY Oneonta s newly renovated Cooperstown Campus, which houses the Biological Field Station and the Cooperstown Graduate Program. The grant did not fund the installation of the system, though the treatment technologies used were chosen by the demonstration project s coordinators. Treatment performance was assessed based on the following analyses: biochemical oxygen demand (BOD or CBOD), total suspended solids (TSS), nitrate (NO 3 ), ammonium (NH 3 ), and total phosphorus (TP). Systems were sampled a total of about 31 occasions, though all four systems weren t necessarily sampled on each collection date. Detailed analysis of each system s performance is provided in the System Performance, Operation, and Maintenance section of the report. Overall, treatment systems performed well, but mainly because they were actively managed and serviced by qualified professionals. The systems incorporating textile filters received the most consistent use with the incoming effluent being of typical household strength (higher than the other systems monitored). Outgoing effluent from these units was of the highest quality, achieved the best nitrogen transformation rates, and was the least variable of the systems monitored. The aerobic treatment unit (ATU) serving the UIC produced effluent of consistent quality, though the system saw very low use compared to its designed capacity. It handled typical UIC functions and events (field trips, workshops, etc.) and long periods of low use very well without compromising effluent quality. The foam filter s treatment was most variable of the four systems and produced effluent of lower quality than the other units. The configuration and dosing regime of this system may play a role in the variability observed throughout this monitoring program. In the end, most treatment performance issues were improved by communicating with the trained service provider contracted for each system. As the manufacturer s recommend, regular maintenance is needed in order for these systems to operate as they are intended and produce high quality effluent. Homeowners should be encouraged (and potentially regulated) to prioritize such maintenance as they would for other major investments (heating systems, vehicles, etc.).

3 Treatment performance of advanced onsite wastewater treatment systems in the Otsego Lake watershed, Holly Waterfield 3 INTRODUCTION This report serves to document the treatment performance of four advanced onsite wastewater treatment systems monitored during the summers of 2008 through All four systems are installed in the Otsego Lake watershed; three were installed as part of a NYS DEC grant to demonstrate the use of advanced onsite wastewater treatment systems. Three systems have been monitored since 2008 (Waterfield and Kessler 2009, Waterfield 2010, Waterfield 2011); OWTS 1 and OWTS 2, funded by the grant, and the UIC system (serving BFS Upland Interpretive Center). Another system, also funded by the grant, was installed in the spring of 2009 at the BFS Thayer Farm. This system serves three buildings; the Hop House, Boat House, and a rented residence. Due to operation and maintenance issues, OWTS 2 was not monitored in 2010 or Treatment performance was assessed based on the following analyses: biochemical oxygen demand (BOD or CBOD), total suspended solids (TSS), nitrate (NO 3 ), ammonium (NH 4 ), and total phosphorus (TP). Otsego Lake is located in northern Otsego County, New York. According to the historical overview by Harman, et al. (1997), the monitoring of Otsego Lake s water quality dates back to a 1935 NYS Department of Environmental Conservation (DEC) study. Routine water quality monitoring efforts began subsequent to the establishment of the Biological Field Station (BFS) in 1968 (Harman, et al. 1997). Comparisons to these and other historical datasets had shown overall decreasing water quality conditions, noting in particular increased phosphorous concentrations likely tied to loading from watershed activities (agriculture, road maintenance, onsite wastewater treatment, etc.). Onsite wastewater treatment (septic) systems are estimated to contribute only 7% of the total phosphorus load (Albright 1996), though the combination of the bio-available form and time of greatest loading at the height of the growing season is likely to lead to stimulation of algal production (Harman, et al. 1997). The cascading effects of such nutrient loading on the lake s ecosystem are far-reaching, and began to concern lake users and the Village of Cooperstown, which uses Otsego Lake as its source of drinking water. In 1985, the Village implemented public Health Law 1100 in order to give them legal grounds to protect the lake as their source of drinking water (Harman, et al. 1997). Additional actions to curb further water quality degradation in the lake culminated in the formation of a watershed management plan in 1998, which identified nutrient loading as the greatest threat to the health of Otsego Lake. Wastewater treatment via onsite treatment systems were listed second on a prioritized list of action areas (Anonymous 1998), and efforts to manage the effectiveness of these treatment systems began with a 2004 inventory of all systems in the established Lake Shore Protection District followed by the inception of the inspection program in 2005 (Anonymous 2007). Under the program, any system found to be in failing condition is to be replaced within one calendar year. Such replacement systems generally make use of advanced or enhanced treatment technologies due to conditions that constrain the use of 2 Funding provided by NYSDEC grant # Research Support Specialist, SUNY Oneonta Biological Field Station

4 conventional designs, such as setback to the lake or a tributary, soil depth to bedrock or groundwater, percolation rate, etc. Many of these enhanced treatment technologies are new the region, and thus are unfamiliar to industry professionals, regulators, and residents. For this reason, a DEC grant was sought and obtained to fund a demonstration project to install and monitor the treatment performance of six shared advanced treatment systems. The scope of the grant has since been amended, changing the total number of treatment systems to three, with the last installed in December of Biochemical oxygen demand (BOD or CBOD) and total suspended solids (TSS) are typical metrics used to characterize the strength of residential wastewater (Crites and Tchobanoglous 1998). BOD is an analysis used to determine the relative oxygen requirements of wastewater, effluents, and polluted waters, by measuring the oxygen utilized during a given incubation period (APHA 1992). It is expected that organic material is broken down as wastewater progresses through a treatment system, thus decreasing the oxygen requirements of highly-treated wastewater and in turn resulting in lower BOD concentrations over the course of the treatment system (APHA 1992). TSS analysis measures the total amount of suspended or dissolved solids in wastewater. Solids may negatively affect water quality for drinking or bathing and potentially clog a drain field. As with BOD, the amount of solids in treated effluent should be lower than that of raw wastewater (APHA 1992). Nitrate and ammonia concentrations will provide insight into the physio-chemical conditions along the treatment train, as the transformations between various nitrogen forms are dependent on oxygen availability, alkalinity, temperature, and the presence of specific bacterial populations. Nitrogen is a dynamic component of wastewater treatment systems, which are often designed to facilitate specific transformations of nitrogen species. Advanced treatment systems most often incorporate a secondary treatment step that involves aerating the wastewater in order to create favorable conditions for the bacterial transformation of ammonia to nitrate, called nitrification. Nitrogen can be completely removed from the waste stream through the process of denitrification, during which nitrate is converted to nitrogen gas (N 2 ), which is released to the atmosphere. Nitrification is generally considered the most limiting step of this overall nitrogen removal process, as it supplies the nitrate that is converted to N 2 gas. Phosphorus, as previously mentioned, is the nutrient of greatest concern with regards to vulnerable freshwater bodies. The removal of phosphorus from the waste stream prior to subsurface disposal will be of great benefit to lake management efforts should the technologies installed prove to be successful. The nutrient removal units installed in all four systems are of the same, or very similar design, sourced from a single manufacturer. Phosphorus removal occurs via adsorption of P onto active sites of an iron-oxide based reactive media; this design results in the gradual reduction in performance as active adsorption sites on the media surface become occupied. Eventually the adsorption capacity of the media is exhausted and the media must be replaced in order to restore the treatment unit s ability to effectively reduce the phosphorus concentration leaving the treatment system

5 METHODS AND MATERIALS Four onsite wastewater treatment systems (OWTS) were monitored in this study and are illustrated and described in Figure 1; these include the systems serving the SUNY Oneonta BFS Thayer Farm Upland Interpretive Center (UIC) and Hop House (HH) and two shared homeowner systems, OWTS 1 and 2. The UIC system has relatively high treatment capacity, as the UIC was built to accommodate large groups for field trips and meetings. However, typical water usage is relatively low due to the short duration of most events (<4 hours); actual flow has not been measured. The system was installed and use commenced in fall of The system has been in continuous operation, though initially the main tank was not sealed adequately and as a result proper function did not begin until fall of Use of this facility increased during the summers of 2009 and 2010, when typical BFS operations were moved temporarily to the Thayer Farm. A period of intensive use occurred in 2011 and is reflected in the performance results. OWTS1 and OWTS2 are located within 100 feet of the western shore of Otsego Lake off of State Highway 80, and are used mainly on weekends during the summer. Each system is shared by two adjacent residences and they are designed to receive daily flows of 440 gallons and 550 gallons respectively. Actual flow for OWTS1 was not measured. Flow through OWTS2 was measured by the service provider. OWTS1 has been in use since 1 June OWTS2 has been in use since 1 June 2007; this system was not monitored in 2010 or 2011 due to operational issues, which have since been resolved. The HH system was installed at the BFS Thayer Farm to serve the Hop House (BFS temporary main offices and labs), the Thayer Boat House, and the Thayer Farm House (a residential rental) and operation began in April 2009 with waste from the Hop House and Farm House. Flow from the Boat House began in August The system receives consistent domestic flow from the Farm House, which is anticipated to be beneficial to the treatment system especially during the winter months, which is a low-occupancy period at the BFS. Preliminary sampling efforts were conducted during the summer of 2007 in order to assess the concentrations of various chemical and nutrient parameters. Regular grab samples were collected between May and August 2008, and June through September Weekly samples were collected between 9 June and 13 August 2010 and 6 June and 3 August During each sampling event, approximately 600 ml of wastewater were collected following each treatment component of all systems. Each sample site is shown in Figure 1 as S#. Samples were tested for BOD 5 using methods summarized by Green (2004). This method involves determining initial dissolved oxygen (DO) concentration of the sample and nutrient buffer followed by incubation at 20 C for five days and determination of the final DO concentration. Samples were diluted to obtain target DO values such that the 5-day DO concentration would be lower than the initial by at least 2 mg/l but with a final concentration greater than 1 mg/l. These conditions were not always achieved, thus valid BOD values were not obtained for every sample collected. Because a nitrification inhibitor is used during incubation, results are presented as values of CBOD, and are associated with the carbonaceous oxygen demand rather than the total oxygen demand (APHA 1992). Overall CBOD reduction rates for each secondary treatment unit (OWTS 1, 2 and HH filters, UIC 1-3) were calculated based on the average CBOD concentrations observed over the monitoring period, presented in Table

6 Figure 1. Onsite wastewater treatment system configurations. S# indicates a sampling point. A) The UIC system is comprised of a 2-compartment tank, a phosphorus removal unit, a pump tank, and gravel bed drainfield. Wastewater is circulated and aerated in the first chamber (UIC1 and 2), and settles in the clarification chamber for final solids settling (UIC3). It then flows through the phosphorus removal unit, on to a pump chamber (UIC4), from which it is pumped in to the drain field. B) OWTS1 provides primary treatment in a septic tank and processing tank (PTE) which flow into an equalization tank, then to a pump tank where the wastewater is pumped and sprayed over an open-cell foam media filter (BFE). In this case the foam media filter aerates the wastewater and provides surface area for beneficial bacteria, increasing organic digestion. 25% of flow is returned to the headworks of the processing tank to facilitate the removal of nitrogen from the waste stream, and 50% flows to the P removal unit (PRE) and on to the drainfield via gravity. C) OWTS2 provides primary treatment in 2 septic tanks which flow to a two-compartment processing tank. Effluent flows from the processing tank to a pump tank which periodically doses a textile media filter. Filter-effluent (AXE) is split between the processing tank (PTE) and the P removal unit (PRE). A portion of effluent from the textile media filter is returned to the processing tank to facilitate the removal of nitrogen from the waste stream. D) HH provides primary treatment in 2 septic tanks (STE) which flow to a two-compartment processing tank (PTE). Effluent is pumped from the processing tank to a textile media filter. Filter-effluent (AXE) is split between the processing tank (PTE) and the P removal unit (PRE). A portion of effluent from the textile media filter is returned to the processing tank to facilitate the removal of nitrogen from the waste stream

7 Total suspended solids (TSS) concentration was determined according to the standard method (APHA 1992). A recorded volume of wastewater was filtered through a rinsed, dried, pre-weighed glass fiber filter. Filters were dried for a minimum of 24 hours at 105 C in a gravimetric oven and then removed to a desiccator to cool before being weighed. The concentration of solids in each sample was calculated from the weight of the filtered solids and the volume of sample filtered; concentrations are reported in mg solids/l. Overall TSS reduction rates for each secondary treatment unit (OWTS 1, 2 and HH filters, UIC 1-3) were calculated based on the average TSS concentrations observed over the monitoring period, presented in Table 6. Total phosphorus concentrations were determined using the ascorbic acid following persulfate digestion method run on a Lachat QuikChem FIA+ Water Analyzer (Laio and Marten 2001). Nitrate and ammonia concentrations were also determined for most samples, using Lachat-approved methods (Pritzlaff 2003, Liao 2001). All reduction and transformation rate estimates are calculated based on average concentrations observed over the duration of the monitoring period (Table 6). Total nitrogen concentrations were not determined and are not presented here due to incomplete oxidation of ammonia to nitrate during the digestion process, which results in underestimation of TN concentration. SYSTEM PERFORMANCE, OPERATION, AND MAINTENTANCE Monitoring results for each sampling location in all treatment systems are presented in tabular and graphical form for all parameters monitored (Tables 1-6, Figures 2-5). The tables summarize the testing results for each year ( ) and over the entire monitoring period, including calculated standard error and the sample size. Figures for CBOD, TSS, TP and NO 3 /NH 4 include standard error bars. The overall performance of the systems can be assessed by comparing the first stage of treatment with the last. Typical CBOD concentrations associated with raw wastewater vary greatly ( mg/l) depending on per capita water usage and inputs of solids to the system (i.e. garbage grinder waste) (Crites and Tchobanoglous 1998). The industry standard for BOD 5 and TSS in effluent from secondary treatment units is 30 mg/l (NSF 2007). Each system will be discussed individually in the following sections; the treatment performance of each is assessed in addition to a description of operation and maintenance issues encountered over the course of the monitoring period. At the time of installation and design, phosphorus removal units were available from single manufacturer, and so the same treatment unit is used in all four systems; the results obtained for each treatment system expose the same performance and maintenance issues for this specific treatment unit, which are addressed in the last section, Phosphorus Removal Components

8 Table 1. Average carbonaceous biochemical oxygen demand (CBOD)in mg/l determined for onsite wastewater treatment systems between 2008 and 2011, with calculated standard error (SE), sample size (n) for 2008 through 2011 and over the entire monitoring period. Site Carbonaceous Biochemical Oxygen Demand overall average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n UIC UIC UIC UIC OWTS1 PTE OWTS1 BFE OWTS1 PRE OWTS2 PTE OWTS2 AXE OWTS2 PRE HH STE HH PTE HH AXE HH PRE CBOD (mg/l) Carbonaceous Biochemical Oxygen Demand UIC OWTS1 OWTS2 HH Site Figure 2. Average carbonaceous biochemical oxygen demand (CBOD) in mg/l determined for onsite wastewater treatments systems. Bars indicate standard error

9 Table 2. Average total suspended solids (TSS)in mg/l determined for onsite wastewater treatment systems between 2008 and 2011, with calculated standard error (SE), sample size (n) for 2008 through 2011 and over the entire monitoring period. Site Total Suspended Solids overall average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n UIC UIC UIC UIC OWTS1 PTE OWTS1 BFE OWTS1 PRE OWTS2 PTE OWTS2 AXE OWTS2 PRE HH STE HH PTE HH AXE HH PRE Total Suspended Solids (mg/l) Total Suspended Solids UIC OWTS1 OWTS2 HH Site Figure 3. Average total suspended solids (TSS) in mg/l determined for onsite wastewater treatments systems. Bars indicate standard error

10 Table 3. Average nitrate concentration in mg/l determined for onsite wastewater treatment systems between 2008 and 2011, with calculated standard error (SE), sample size (n) for 2008 through 2011 and over the entire monitoring period. Sample Nitrate overall average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n UIC UIC UIC UIC OWTS1 PTE OWTS1 BFE OWTS1 PRE OWTS2 PTE OWTS2 AXE OWTS2 PRE HH STE HH PTE HH AXE HH PRE Table 4. Average ammonium (NH4)in mg/l determined for onsite wastewater treatment systems between 2008 and 2011, with calculated standard error (SE), sample size (n) for 2008 through 2011 and over the entire monitoring period. Ammonium Sample overall average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n UIC UIC UIC UIC OWTS1 PTE OWTS1 BFE OWTS1 PRE OWTS2 PTE OWTS2 AXE OWTS2 PRE HH STE HH PTE HH AXE HH PRE

11 Ammonia (mg/l) Nitrate (mg/l) Concentration mg N/L UIC OWTS1 OWTS2 HH Site Figure 4. Average nitrate and ammonium concentrations in mg/l determined for onsite wastewater treatments systems. Bars indicate standard error

12 Table 5. Average total phosphorus concenration (TP)in mg/l determined for onsite wastewater treatment systems between 2008 and 2011, with calculated standard error (SE), sample size (n) for 2008 through 2011 and over the entire monitoring period. Site Total Phosphorus overall average +\- SE n average +\- SE n average +\- SE n average +\- SE n average +\- SE n UIC UIC UIC UIC OWTS1 PTE OWTS1 BFE OWTS1 PRE OWTS2 PTE OWTS2 AXE OWTS2 PRE HH STE HH PTE HH AXE HH PRE Total Phosphorus (mg/l) Total Phosphorus UIC OWTS1 OWTS2 HH Site Figure 5. Average total phosphorus (TP) in mg/l determined for onsite wastewater treatments systems. Bars indicate standard error

13 Table 6. Average rates of removal or reduction for CBOD, TSS, TP, NH 4, and Nitrogen calculated for each onsite wastewater treatment system overall and for each year 2008 through 2011, with sample size (n). System CBOD TSS TP NH 4 Decrease N Removal % n % n % n % n % UIC 22 31/ / / / / / / / /5 1 5/4 15 OWTS / / / / / / OWTS / / / /6 74 9/ / HH / / / / / /6 99 5/

14 Upland Interpretive Center (UIC) Typical flow through the system was greatly below the design flow capacity for the majority of the monitoring period; throughout the monitoring period the system produced high quality effluent, meeting the NSF Standard 40 for Class 1 ATUs (30mg/L CBOD and TSS). In 2010 the system saw more consistent usage and monitoring results indicate enhanced reduction of CBOD and TSS, with high quality effluent produced (final CBOD < 11 mg/l, TSS = 11 mg/l). In 2011, the system experienced a period of intense use, which may have been beyond the treatment capacity of the system. Though this period was relatively short in comparison to the monitoring period (10 days of use by 19 individuals), average 2011 effluent CBOD and TSS concentrations increased substantially, to 54 mg/l and 22 mg/l, respectively (Tables 1 and 2). Over the 4-year monitoring period, the system proved to handle long periods of low usage well. The size of the system is able to accommodate sporadic short-duration heavy-use events without noticeable influence on the quality of final effluent. Though nitrogen reduction is not a priority of treatment in the Otsego Lake watershed s wastewater management program, the nitrogen transformations that take place in advanced treatment systems are notable and give insight into the conditions within the treatment system. The final effluent from the UIC system contains relatively high nitrate to ammonium ratio, indicating that the aeration provided in the unit is sufficient for nitrification to take place. System-wide over the 4-year period, nitrogen was reduced by 37%; better removal rates occurred during years where use of the system was higher (without exceeding the design-capacity) (Table 6). Operational Notes The only major issue encountered with the UIC system was related to its installation. The mid-seam of the 3-compartment tank was not properly sealed at the time of installation. For the first season of its use, the full operating level was never attained (i.e. the tank remained approximately half-full). The problem was not immediately diagnosed because of the low use of the system during non-summer months. Following repair the system has maintained an appropriate operating level. The blower/aerator by design runs full-time (24/7) and has had no mechanical problems to date. The microbiological inoculant must be replaced on occasion; this doesn t seem to be critical in the overall functionality of the system. As with all four monitored systems, the nutrient removal unit s reactive media must be replaced regularly to maintain high phosphorus removal rates and sufficiently low final P concentrations. This is likely more important for units serving systems in close proximity to P-limited water bodies. Onsite Wastewater Treatment System 1 (OWTS 1) The configuration of this system seems to be less robust than others for seasonal-use situations, due in large part to the above-ground installation of the media filter combined with summer-only use and the long start-up time for the microbiological community that lives in and on the foam media. The foam media comprising the filter in this system is susceptible to settling over time, especially during periods of freeze and thaw. This particular system is installed above ground, and therefore is subjected more extreme temperature variation than its below-ground counterparts. Extreme temperature fluctuations and long period of dormancy (without nutrient, carbon, and water supply) also influence the microbial community, contributing to the long

15 period of time required for treatment performance to reach a consistent level following dormant periods. Treatment performance of this particular installation did not meet the manufacturer s expectation (Jowett 2010) nor was it consistent with the results of other field testing studies (ETV 2003, MASSTC 2004). This discrepancy is likely due to the difference in both configuration and actual use of the system. Treatment of BOD and TSS improved steadily over the duration of the monitoring program and treatment proved to be enhanced by spring maintenance to combat settling of the foam media that may have occurred during the winter. BOD and TSS concentrations averaged 43 and 33 mg/l, respectively, following treatment in the foam filter. This does not meet the industry standard of 30 mg/l for each parameter (for secondary treatment performance as Class 1 Aerobic Treatment Unit, media filter, etc), though the system was likely still in the start-up phase for the majority of the monitoring period each summer. Monitoring protocols used in this study are also different than those used by the National Sanitation Foundation when testing advanced treatment systems again performance criteria (NSF 2007). Nitrogen concentrations were in line with the other systems monitored, though the incoming ammonium concentration was generally greater than the other systems. This is likely due to the fact that the system was being used on a regular basis and with water conservation in mind, producing a more concentrated waste. Over the entire monitoring period, nitrogen removal averaged about 33%. The reduction of ammonium concentration before and after treatment by the foam filter unit (54%) was less than that achieved by the other systems; this indicates a less effective conversion of ammonium to nitrate within the foam filter itself. Following a service visit in early 2010, the ammonium reduction rate increased (to 77%), indicating that the environment within the filter was better suited to facilitate the nitrification process. Operational Notes Operation and maintenance issues were related to settling of the foam media over time. Spring maintenance was effective at restoring the treatment performance for all parameters. This servicing involved redistribution of the foam to restore the original packing density and eliminate any preferential flow paths that had allowed wastewater to short-circuit the media. Ideally, wastewater should trickle in a thin film through and around the foam cubes. Odor coming from this system was also a major issue for the property owners, though it was a design flaw that did not directly impact the treatment performance and was independent of the manufacturers of the treatment components. Three sources of odor were identified; one was the system s vent stack, another was the lid of the equalization tank, which receives processing tank effluent (mix of septic tank of effluent and foam filter effluent), and the third was the electrical conduit connecting the pump vault to the control panel. All three sources were remedied, though these should be considered by the design engineer prior to installation. The vent stack was extended above the roof-line in order to physically move it away from the patio and deck areas of the two camps served by the system. This pipe was also capped with a carbonfilter assembly to reduce the final odor. The equalization tank s cover is of poor design and does not provide an air-tight or water-tight seal at the surface. The odor was greatly reduced by weighting the lid down; ideally, this lid should be replaced with a model that will provide a more secure seal. The conduit from the pump vault to the control panel was left unsealed by the installer, and so proved to be the preferential flow path for gas exchange. This conduit was

16 sealed with a caulking agent, eliminating the odor problem. All-in-all, while the odor problem did not directly affect treatment performance, public perception and acceptance of advanced treatment systems can be negatively impacted by such oversights. Onsite Wastewater Treatment System 2 (OWTS 2) Overall treatment performance met expectations in 2008 and most of the 2009 monitoring period compared to the performance of other systems of this type. Prior to the operational problems that began in 2009, OWTS 2 produced high quality effluent containing less than 15 mg/l BOD and TSS on average (Tables 1 and 2) with nitrogen removal between 42 and 50% (Table 6). As a result of the operational issues and subsequent maintenance that was required this system was not monitored in 2010 or Operational Notes This system experienced periods of poor treatment unrelated to the design or the treatment processes employed in the system. One of the camps served by the system underwent major renovations, during which time electrical power to the system was inadvertently shut off; this system does not operate by gravity-flow, and so relies on timers, switches, and pumps for proper cycling of wastewater between the treatment components. Although no one was living in the renovated camp, the other camp served by the system was still occupied and sending wastewater to the system. Wastewater was not treated properly and resulted in fouling of the nutrient removal device. The problem persisted though 2011 due to lack of communication between the main service provider to the system and the homeowner, as well as between the main service provider and the manufacturer/service provider for the nutrient removal unit. This issue highlights a number of areas where more work is needed to ensure that advanced treatment systems are operating properly and to the best of their ability; (1) the need for effective communication between involved parties (regulators, homeowners, and service providers) to ensure that maintenance contracts are in place and carried out according to the manufacturer s guideline (2) the challenges associated with effectively operating a shared system and (3) the need for homeowners to be aware of the system s function and operation. All users of the structure must be aware of good practices for disposal of wastes in the system this includes tenants, contractors, guests, etc. These systems are highly engineered and treatment often relies on the presence of beneficial microbial communities. Disposal of chemicals, paints, disinfectants, etc. can reduce or eliminate the populations of such microbes and may also cause fouling of or reduced longevity of other physical and mechanical components of the system (e.g. textile fabrics, coarse filters, pumps, etc.). Hop House (HH) Treatment performance has consistently been at a high level and no major maintenance issues have occurred to date aside from the high media replacement rate for the nutrient removal unit. Incoming waste was of typical strength ( mg/l) for American households. CBOD and TSS concentrations averaged 3 mg/l following treatment in the textile filter (Tables 1 and 2); this is an exceptional level of treatment and standard error indicates a low degree of variability with respect to fluctuations in the concentration of these two parameters. Ammonium concentration was reduced to less than 1 mg/l on average (Table 4), a 99% reduction from the septic tank effluent to textile filter effluent. Nitrogen removal averaged around 34%, which is

17 lower than seen in OWTS 2, and may be enhanced by altering the system dosing cycles based on the actual flow received; this is discussed further in the Operational Notes. Operational Notes No major treatment or mechanical issues were encountered during the monitoring period; all pumps and controls are functioning properly. This particular system has a larger design capacity than a typical residential situation (the Hop House and Boat House are served in addition to a residence); however, the actual flow through the system has generally been less than anticipated. Actual flow through the system can be calculated, but to date this information has not been used to adjust the rate at which wastewater is cycled from the processing tank to the textile filter. As a result, the textile filter is dosed more often than is necessary to adequately treat the waste and therefore the processing tank does not consistently maintain an anaerobic environment to facilitate denitrification (final step of nitrogen removal) of effluent coming in from the textile filter. Treatment would be enhanced by increased oversight of the system by the service provider. Phosphorus Removal Components The nutrient removal devices are designed to remove phosphorus from the wastewater via chemical adsorption of phosphorus onto the surface of a reactive porous media. Over time the active sites are occupied by adsorbed phosphorus and the efficiency declines until no active sites remain. These work well but require frequent replacement in order to maintain high degree of phosphorus removal, as a result of the relatively small volume of reactive media in each unit. Larger media canisters would reduce the frequency of media replacements. The size of each unit was not scaled to correspond to the designed treatment capacity of the system with which it was installed. In the case of the Hop House system, following replacement of the reactive media, acceptable treatment was documented for less than 3 months before the adsorptive capacity of the media was reached. Frequent sampling and analysis for total phosphorus concentration is the only way to determine the efficacy of each unit; it is unlikely that such sampling would be done more than once per year in a typical residential situation. Treatment Technologies CONCLUSIONS Media Filters (Textile, Foam, Dosing Regime) Textile filters provided the most consistent and effective treatment of the three types installed in the demonstration systems. CBOD and TSS were consistently below 15 mg/l and showed little variation over the sampling period under normal operating conditions. The filter media are arranged in hanging sheets, and so are not subject to settling or compaction over time; it seems that this arrangement, combined with an insulated cover and below-ground installation, result in a short start-up period at the beginning of the occupancy season. The foam filter s performance was variable and frequently fluctuated above the industry standard for this class of system. When installed for seasonal use, spring maintenance is needed to ensure that the media is properly distributed in the baskets, as settling may have occurred due

18 to freeze and thaw during the winter. A long period of time (upwards of 8 weeks in some cases) was required at the start of each summer occupancy season for the establishment of a sufficient microbial community such that consistent and acceptable treatment was documented. Microbial populations are greatly reduced during periods without flow (i.e. winter) and are likely further reduced during periods of extreme cold. This should be considered in the design process if this technology is to be used at other seasonal installations; installing the media filter underground may provide enough thermal buffering to reduce the temperature fluctuation and in so doing, reduce the settling and start-up period. Differences observed in the treatment performance of the foam and textile filters may be related more to the dosing regimens rather than the ability of either media to provide a favorable treatment environment. Dosing regimes are typically based on either time or demand (flow). A Timed Cycle: A predetermined volume is dosed at a regular time interval. Both systems incorporating textile filters (OWTS 2 and HH) were time-dosed (a requirement of the manufacturer). o Storage capacity is built-in to allow for holding of wastewater for later processing based on default schedule o Flow is distributed over a 24-hour period Eliminates potential inundation of treatment components and the drainfield; Holds water during high-use periods (shower-time, laundry, etc.) Cycles wastewater throughout the day and night, providing consistent flows to the treatment technologies and the drainfield during lower-use periods Allows for alternation between unsaturated and saturated flow, and thus, aerobic and anaerobic conditions Facilitates gas exchange Facilitates activity of both aerobic and anaerobic microbial populations together yield more effective and complete breakdown of wastewater constituents o Floats detect high-flow conditions and can trigger the over-ride of default timing cycle to more quickly process wastewater, accommodating extreme events without compromising the integrity of system components. o In seasonal-use or weekend-use situations, cycling of wastewater between a processing tank and the filter continues even during periods where no new water enters the system, maintaining nutrient and water supply to the microbial populations. Demand (flow through the system): A predetermined volume is transferred every time that specific volume accumulates in a dosing chamber. The foam filter (OWTS 1) operated on demand-dosing. o During high flow periods, wastewater may be dosed without a time delay in order to keep up with incoming flow. This may result in the inundation of subsequent treatment components (such as a nutrient removal device) that have a limited volume capacity and require a longer period of time for wastewater to pass through

19 o During periods with little or no use, no water is dosed to the filter unit, potentially resulting in a reduction in the microbial population.. Aerobic Treatment Unit The aerobic treatment unit (ATU) serving the UIC produced effluent of consistent quality, though the system saw very low use compared to its designed capacity. CBOD and TSS were generally below 15 mg/l and nitrogen was removed at moderate rates. It handled typical UIC functions and events (field trips, workshops, etc.) and long periods of low use very well without compromising effluent quality. Phosphorus Removal Devices The effective life-span of the reactive media within the phosphorus removal devices was disappointing, especially given the cost of the units and fees associated with media replacement. These units work well but require frequent replacement in order to maintain high degree of phosphorus removal as a result of the relatively small volume of reactive media in each unit. Larger media canisters would reduce the frequency of media replacements. In order to adequately address the need for phosphorus removal in certain locales, a more affordable, longer-lasting design is essential. Monitoring Procedures Sampling protocols can influence the observed treatment performance and varies with the type and configuration of each system. Comparisons between monitoring and assessment efforts should acknowledge such details. Grab samples are likely to be more variable and have a higher associated standard error if the quality of effluent is variable over the course of a day. Composite samples capture the range of conditions encountered throughout the day, providing flow-weighted results of effluent quality produced by the system. The potential for sampling protocol to influence results will vary with the configuration of the system. o Some systems continuously mix wastewater and yield more consistent results over the course of a 24-hour period, whereas a system with discrete treatment components will experience variation over the course of a day, depending on use of the system, in which case a grab sample may yield non-representative results if such factors are not considered. Sufficient sample size should allow for a range of conditions to be encountered, providing an average that is representative of the effluent quality that typically leaves the system, though this cannot be guaranteed. Lessons Learned Oversight of Operation & Maintenance Communications with service providers and manufacturers resulted in remedied issues and increased treatment performance. Vigilance in the maintenance of advanced treatment systems is of the utmost importance if these systems are to be relied upon to reduce human

20 impacts to sensitive environments, especially considering that the vast majority of systems are not monitored once they are installed, as they were with this project. Property Owner Awareness & Proper Use Homeowners, as the primary users of such systems, are the key to ensuring proper use and maintenance. Steps should be taken to stress the importance of their participation as a means of protecting their investment in addition to protecting public health and their surrounding environment. In a few instances, as outlined in the system performance section of this report, operational issues occurred due to a lack of communication between the property owners of shared systems, or between the property owners and others that were renting or working on the property. Owners failed to recognize the importance of informing the other users as to the requirements of the system (i.e. electrical power) and best practices for disposal of materials to the system. REFERENCES Albright, M.F. and H.A. Waterfield Evaluation of phosphorus removal media for use in onsite wastewater treatment. In: 42 nd Ann. Rept. (2009). SUNY Oneonta Bio. Fld. Sta. Cooperstown, NY. Albright, M.F., L.P. Sohaki, and W.N. Harman Hydrological and nutrient budgets for Otsego Lake, N.Y. and relationships between land form/use and export rates of its subbasins. Occ. Paper #29, SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta. Anonymous A plan for the management of the Otsego Lake watershed. Prepared by: Otsego Lake Watershed Council. Anonymous A plan for the management of the Otsego Lake watershed. Prepared by: Otsego Lake Watershed Council (1998). Updated by the Otsego County Water Quality Coordinating Committee. APHA, AWWA, WPCF Standard methods for the examination of water and wastewater, 17 th ed. American Public Health Association. Washington, DC. Crites, R. and G. Tchobanoglous Small and Decentralized Wastewater Management Systems. McGraw-Hill, p183 Environmental Technology Verification Program (ETV) ETV Joint Verification Statement: Waterloo Biofilter Model 4-Bedroom. National Sanitation Foundation and US Environmental Protection Agency. Green, L Standard Operating Procedure 011: Biochemical Oxygen Demand (BOD) Procedure. University of Rhode Island Watershed Watch. Harman, W.N The state of Otsego Lake Occ. Paper #30, SUNY Oneonta Bio. Fld. Sta., SUNY Oneonta