On-site Sewage Systems Research Articles

Estimation of greenhouse gases from sewage from on-site sewage management system

Reducing greenhouse gases (GHGs) emissions plays an important role in preventing global warming and climate change. It is generally known that domestic wastewater management activities are significant contributors to the emissions due to its biological process that produces methane, nitrous oxide, and carbon dioxide. Various studies related to GHGs emissions from this sector have been conducted. However, only limited studies focused on the on-site sewage treatment. Since 72% of total existing wastewater treatment facilities in Indonesia are on-site systems, this study attempted to estimate GHGs emissions from each component in the system using the IPCC method. Depok City was chosen as the study case and the estimation was limited to on-site treatment tank, wastewater collection tank, and fecal sludge treatment system. Our study estimated that the total annual emissions from the on-site sewage system in Depok City were 232.45 Gg CO2eq, consisted of 232.39 Gg CO2eq of on-site emissions and 0.0662 Gg CO2eq of off-site emissions. Among the system component, direct emissions from the on-site treatment such as septic tanks is the highest contributor to the total emission (70% followed by direct emission from fecal sludge treatment plant (19%). Through scenario evaluations, this study suggests that converting private septic tanks into the communal type is the most effective strategy in reducing total GHGs emissions from on-site wastewater treatment systems.

Artificial intelligence based monitoring system for onsite septic systems failure

An onsite sewage system (OSS) is a complex system that takes advantage of nature's biological processes to remove harmful pathogens from wastewater and reintroduces clean water back into the natural water cycle. However, the failure of an OSS can contaminate drinking water, surface water and release hazardous pathogen and chemicals creating hazardous conditions within the local environment. This research aims to provide an artificial intelligence (AI) solution using machine learning (ML) algorithms such as logistic regression (LR), random forest classifier, and K-nearest neighbors (KNN) to understand and examine the underlying factors that could cause septic failures. Septic records from 1970 to 2019 were collected from five different counties across the State of Indiana and ML algorithms were applied to predict areas of possible septic failures. The algorithms demonstrated accuracy of approximately 80% in prediction of OSS failures. Such algorithms can assist state and county health departments in alerting homeowners of impending failures. Such an approach has the ability to not only prevent failures but also in the maintenance of a safe environment for communities reliant of OSSs. This approach was implemented and tested in the Indiana State Department of Health (ISDH).

Anthropogenic markers for source tracking of fecal contamination in Bayou Lafourche: a major drinking water source in Southeast Louisiana, USA

Abstract Bayou Lafourche, which is the sole drinking water source for 300,000 people in Louisiana, has failed to consistently meet its designated use criteria set by the Louisiana Department of Environmental Quality (LDEQ). This resulted in a total maximum daily load to be imposed on the Bayou by the Environmental Protection Agency (EPA). These designated use water quality criteria include fecal coliform (FC) levels for drinking water source, primary contact recreation, and secondary contact recreation. The goal of this study was to identify and enumerate anthropogenic nonpoint source FC contamination from malfunctioning home sewage systems in the Bayou's watershed. Thirty-four sites along the Bayou were selected for the study. Samples were analyzed for optical brightener ratios, FC CFU/100 mL (mFC), Escherichia coli, and three human markers, including human polyomavirus BK, the Archaeon Methanobrevibacter smithii, and the human-associated Brevibacterioides HF 183 eubacteria. Frequencies of sites with all three anthropogenic molecular markers are considered positive for human fecal contamination. This study provided data to address the problem of malfunctioning on-site sewage systems in the Bayou Lafourche watershed.

Fecal coliform concentrations in effluent from ultraviolet disinfection units installed in onsite wastewater treatment systems.

Ultraviolet disinfection (UVD) units enhance onsite sewage systems (OSSs) in areas where conventional treatment is limited by site characteristics. Although UVD units are efficacious under testing conditions, few studies have considered their effectiveness when installed. This study used a mixed-methods approach to examine UVD unit effluent quality and determine the association between UV bulb status and fecal coliform levels. Samples from UVD units and pump chambers were tested for bacterial and physiochemical parameters. Field data were supplemented with data from retrospective compliance samples. A multivariate Tobit regression model predicted that the geometric mean (GM) fecal coliform concentration was 122% higher when the UV bulb was deficient than when it was not deficient, adjusted for other OSS deficiencies (95% CI: 36-428, p-value <0.001). The predicted GM fecal coliform concentration in malfunctioning UVD unit effluent (745 CFU/100 mL) exceeded field compliance standards (400 CFU/100 mL), and the odds of exceedance were 7.48 times higher when the UV bulb was deficient, adjusted for other OSS deficiencies (95% CI: 4.03-13.9, p-value <0.001). Despite limitations in the characterization of UV dose, the results validate the importance of UVD units to reduce bacterial loads and the need for further research into their field effectiveness.

Chemical and isotopic composition of nitrogen and boron in septic tank wastewater samples

Most of earth’s population depends on onsite sewage systems to dispose of their wastewater to the environment. Samples used to estimate contaminant transport in the environment have typically been collected from nitrogen loads external to the septic tank. Here we characterize the isotopes of boron, nitrate–nitrogen and nitrate–oxygen in partially clarified liquid collected directly from within septic tanks located in Florida. Among other parameters, total Kjeldahl nitrogen (TKN) and total boron were also evaluated. Nitrate–nitrogen isotopes from three samples ranged from +1.25 to +10.00‰, and boron isotopes from five samples ranged from +8.8 to +31.3‰. Nitrate–oxygen isotopes ranged from −3.23 to +19.96‰ and were indicative of an anoxic environment. On average, residential septic tanks were found to contain 96 µg L−1 total boron and 63 mg L−1 TKN. Utilizing isotopes of boron, among other parameters, our findings show that the partially clarified liquid in septic tanks contains a distinguishable δ11B signature.

Standardised survey method for identifying catchment risks to water quality

This paper describes the development and application of a systematic methodology to identify and quantify risks in drinking water and recreational catchments. The methodology assesses microbial and chemical contaminants from both diffuse and point sources within a catchment using Escherichia coli, protozoan pathogens and chemicals (including fuel and pesticides) as index contaminants. Hazard source information is gathered by a defined sanitary survey process involving use of a software tool which groups hazards into six types: sewage infrastructure, on-site sewage systems, industrial, stormwater, agriculture and recreational sites. The survey estimates the likelihood of the site affecting catchment water quality, and the potential consequences, enabling the calculation of risk for individual sites. These risks are integrated to calculate a cumulative risk for each sub-catchment and the whole catchment. The cumulative risks process accounts for the proportion of potential input sources surveyed and for transfer of contaminants from upstream to downstream sub-catchments. The output risk matrices show the relative risk sources for each of the index contaminants, highlighting those with the greatest impact on water quality at a sub-catchment and catchment level. Verification of the sanitary survey assessments and prioritisation is achieved by comparison with water quality data and microbial source tracking.

Political Trust and Perceptions of the Quality of Institutional Arrangements – how do they influence the public's acceptance of environmental rules

AbstractThis paper investigates the relationship between political trust and the acceptability of government regulations in the environmental field. We hypothesise that trust in particular authorities and perceptions of the quality of institutional arrangements are important predictors of rule acceptance, which we assume is important for the long‐term legitimacy of the regulatory system. We explore the validity of this hypothesis using the case of homeowners with on‐site sewage systems (OSSs), i.e. small‐scale systems treating sewage from one or a few households that contribute to eutrophication and data was gathered through a questionnaire sent to randomly selected homeowners with OSS in Sweden. The results support propositions that political trust indeed is an important factor explaining homeowners' acceptability of governmental regulations. Political trust is in turn influenced by homeowners' perceptions of authorities being environmentally effective and impartial when enforcing rules, as well as by positive experiences of authority contacts. Policy makers and officials should thus use trust‐building approaches and factors underpinning trust such as those investigated in this study to increase rule acceptance and, in the longer‐run, pro‐environmental behaviour. Copyright © 2015 John Wiley &amp; Sons, Ltd and ERP Environment

On-Site Sewage Systems from Good to Bad to…? Swedish Experiences with Institutional Change and Technological Dependencies 1900 to 2010

Even though technological advances have occurred during recent decades today’s nutrient loading from Swedish on-site sewage systems (OSSs) is much higher than in the 1940s, despite a decreased rural population and the existence of potentially far better technologies than the existing inadequate installations. The objective of this paper is first, to explain this situation as the result of co-evolution of technology and institutions, which has resulted in a very stable conservation. Second, to properly understand how such stable configurations may change, the paper investigates how a power-distributional theory of incremental institutional change might complement the previous analysis and open up the thinking about how seemingly stable configurations may change endogenously. The analysis reveals how shifts in the distribution of power, i.e., public and private actors’ resources and tools to use in interaction with other actors, have influenced the direction of technological and institutional development. We conclude that the sequencing of events has been important; the series of choices made foremost between the 1950s and 1990s caused both institutional and technical lock-in effects that have been increasingly difficult to break out from. Despite parallel and later incremental developments, improvement in the environmental outcome is not yet seen on the large scale.

Influence of interventions and internal motivation on Swedish homeowners’ change of on-site sewage systems

This article reports results from a questionnaire administered to Swedish homeowners (N=1481) investigating factors that influence them, as users and owners of on-site sewage systems (OSS), to environmentally improve their OSS. Social and psychological factors were based on previous research into pro-environmental and compliance behaviors and a previous interview study. The results suggest that the most important motives are to benefit, to act when outcomes are fair, and to avoid inconvenience. Less important motives are to act when outcomes are fair and to act of concern for the environment. Perceived efficacy in decreasing the environmental impacts of current OSS, when the OSS is changed, and perceived ability to change their OSS are also among the strongest predictors of readiness to change OSS. However, among homeowners who changed their OSS to do ones duty and achieve long-term safety were ranked highest. The results support the expectations of goal-framing theory that motives related to “gain” would be focal in situations of unfavorable cost–benefit ratios. Similarly, the importance of fair outcomes and efficacious rules is consistent with general findings in research on social dilemmas.

Indiana's Network for Tracking of Onsite Sewage Systems (iTOSS): Indiana State Department of Health's Data System for Managing Onsite Sewage System Data

Indiana's Network for Tracking of Onsite Sewage Systems (iTOSS): Indiana State Department of Health's Data System for Managing Onsite Sewage System Data

Category 4b Demonstration for Pathogen Impaired Tributaries to Puget Sound in Kitsap County, Washington

Section 303(d) of the Clean Water Act (CWA) and the US Environmental Protection Agency’s (USEPA’s) supporting regulations in 40 CFR Part 130.7 require states to develop lists of waterbodies impaired by a pollutant and needing a Total Maximum Daily Load (TMDL) (i.e., the Section 303(d) list) and to prepare a TMDL for each waterbody/pollutant combination. USEPA’s regulations also recognize that other pollution control requirements may obviate the need for a TMDL. These alternatives to TMDLs are commonly referred to as Category 4b waters as described in USEPA’s Integrated Reporting Guidance for Sections 303(d), 305(b), and 314 of the CWA. The Washington Department of Ecology (Ecology) 2008 Integrated Report has placed 14 pathogen (fecal coliform) impaired creeks that flow to Puget Sound in Category 4b. The foundation of Ecology’s Category 4b demonstration for these waters is Kitsap County’s Pollution Identification and Correction (PIC) program. The PIC program monitors, identifies and controls non-point sources of pollution, focusing on failing septics and non-point source animal wastes. BMPs used by the PIC program to improve water quality include county rules and regulations to properly operate and maintain on-site septic systems in the watersheds. The county is actively engaged in on-site system education, dye testing of suspect systems, and enforcement of the county rules and regulations governing on-site sewage systems. In addition, the Kitsap Conservation District (a non-regulatory agency) assists small farm owners and owners of livestock to implement BMPs for animal waste management and farm pollution control. When a regulatory approach is needed, however, the county enforces its regulations for handling and disposal of annual manure and pet waste. In 2003, the PIC program was recognized with a Local Hero Award by Washington’s governor for its efforts to preserve, protect, and sustain Puget Sound. Ecology expects that the county’s PIC program will result in attainment of the fecal coliform water quality standard for these waters by 2012. This paper presents Ecology’s demonstration for assigning these waters to Category 4b according to USEPA’s Category 4b guidance, lessons learned in developing the restoration strategy, and potential challenges for maintaining these waters in Category 4b for future 303(d) reporting cycles.

Onsite Sewage System Regulation Along the Great Lakes and the US EPA “Homeowner Awareness” Model

According to the United States Environmental Protection Agency (US EPA), a significant percentage of residential onsite sewage systems (OSSs) are failing at any given time. The US EPA has therefore issued a set of recommended guidelines for OSS regulatory programs aimed at reducing overall failure rates. We conducted a survey of OSS regulatory program administrators with jurisdictions bordering a Great Lake. Our goal was to determine their programs' capacities to meet the US EPA's recommendations. We found that although some local programs meet the US EPA's recommendations, most do not. In this article, we present our findings and conclusions for one of the US EPA's models, the baseline "Homeowner Awareness" model. Most areas do not have recommended requirements that systems be inspected when properties transfer between owners. A majority do not track changes in ownership within the computerized databases they use to record information about systems. Although most provide at least "one-time" information to homeowners regarding proper OSS maintenance, most do not contact them periodically with reminders of needed maintenance. We include recommendations for resolving some of the issues that our research identified.

Buffer distances for on-site sewage systems in Sydney's drinking water catchments

Pathogens and nutrients released from on-site sewage systems represent a risk to surface and ground water quality, particularly where there are sensitive receiving waters such as in drinking water catchments. Buffer zones between on-site systems and waterways are one barrier used to protect water quality. The increased time and distance they provide increases the opportunities for the effluent purification functions of the soil to occur. A risk management model is proposed to assess the efficacy of the buffer zones in Sydney's drinking water catchments. The model is the basis for the development of performance based setback distances for on-site systems from waterways, and incorporates stochastic analysis of pathogen and nutrient transport in the environment and consideration of the effluent quality variability from on-site systems. Catchment-scale integration of contaminant transport is employed to facilitate a risk assessment of on-site systems. The risk management model also allows for the impact of on-site system management and maintenance on catchment water quality to be assessed through scenario building and feedback mechanisms.

Landscape context of rural residential development in southeastern Wisconsin (USA)

Private on-site sewage systems serve residential development in rural landscapes throughout the United States. In the State of Wisconsin, three major types of private sewage systems facilitate residential development on sites that span gradients in slope, soil permeability, depth to bedrock, and depth to water-table. Conventionalsoil-absorption sewage treatment systems are constructed on sites with minimal physiographic constraints; more highly engineered alternative sewage treatment systems are installed on sites with moderate to severe constraints; holding tanks provide no on-site sewage treatment and are employed on sites with the most severe physiographic limitations. An environmental impact statement (EIS), prepared in 1979 on the proposed widespread use of alternative private sewage systems, suggested that alternative systems might facilitate in-fill development on poor sites near existing cities and lead to compact, higher density development patterns. The research reported in this paper tested the validity of this EIS scenario by comparing development patterns associated with a sample of conventional systems, alternative systems, and holding tanks installed during the 1980s in Ozaukee County, Wisconsin. Land use data, soils data, and other site attribute data were assembled and analyzed in a vector geographic information system (GIS). Because each type of private sewage system has a unique set of siting criteria, the three sets of sampled systems are located in significantly different physiographic regions within the County. Collectively, installations of all three systems facilitated scattered residential development throughout the rural landscape. This development consists of relatively small residential patches dispersed within an agricultural matrix. Wastewater management technology, if not constrained by public policies or other socioeconomic factors, can be an important anthropogenic factor influencing both the process and pattern of landscape change.

Private Sewage System Impacts in Wisconsin Implications for Planning and Policy

Abstract Rural and suburban development has been and will continue to depend heavily on the use of on-site private sewage systems. The exodus to rural settings combined with changing technologies for sewage disposal that reduce site limitations to development have raised a broad set of land use, infrastructure, and environmental concerns. In a study of development in Wisconsin, we found that the type of private on-site sewage system technology makes little or no difference in the extent of sprawl, conversion of agricultural and forested land, and the provision of public infrastructure. However, these new technologies make the use of traditional health-oriented land use regulatory policy increasingly ineffective for managing land use and environmental concerns.