Domestic Septic Tanks Research Articles

Nitrate Legacy in a Tropical and Complex Fractured Volcanic Aquifer System

AbstractNitrate legacy is affecting groundwater sources across the tropics. This study describes isotopic and ionic spatial trends across a tropical, fractured, volcanic multi‐aquifer system in central Costa Rica in relation to land use change over four decades. Springs and wells (from 800 to 2,400 m asl) were sampled for NO3− and Cl− concentrations, δ18Owater, δ15NNO3, and δ18ONO3. A Bayesian isotope mixing model was used to estimate potential source contributions to the nitrate legacy in groundwater. Land use change was evaluated using satellite imagery from 1979 to 2019. The lower nitrate concentrations (<1 mg/L NO3−N) were reported in headwater springs near protected forested areas, while greater concentrations (up to ∼63 mg/L) were reported in wells (mid‐ and low‐elevation sites in the unconfined unit) and low‐elevation springs. High‐elevation springs were characterized by low Cl− and moderate NO3−/Cl− ratios, indicating the potential influence of soil nitrogen (SN) inputs. Wells and low‐elevation springs exhibited greater NO3−/Cl− ratios and Cl− concentrations above 100 μmol/L. Bayesian calculations suggest a mixture of sewage (domestic septic tanks), SN (forested recharge areas), and chemical fertilizers (coffee plantations), as a direct result of abrupt land use change in the last 40 years. Our results confirm the incipient trend in increasing groundwater nitrogen and highlight the urgent need for a multi‐municipal plan to transition from domestic septic tanks to regional sewage treatment and sustainable agricultural practices to prevent future groundwater quality degradation effectively.

Experiencia de aplicación de microorganismos efectivos nativos (MEN) para el tratamiento de aguas residuales

Fecal contamination is one of the main freshwater quality problems worldwide. One of the proposed solutions for this problem is the treatment of the effluents at domestic orlocal level with microbial consortia such as effective microorganisms from native origin (MEN in Spanish). In this work we evaluated the ability of a MEN formulation produced in Uruguay to reduce fecal contamination in domestic effluents. To achieve this, experimentswere carried out at different scales, from in vitro to domestic septic tanks and in a section of the Malvín stream (in situ), combining liquid with solid MEN formulation and using fecal coliforms (FC) and particulate organic matter as performance indicators. Both at the laboratory level and in the septic tanks, CF decreased significantly after 8 weeks ofapplication. In the Malvín stream, a decrease in CF and a visual recovery of the water course were observed, with increased transparency and dissolved oxygen concentration. The results from this work suggest that MEN application to domestic wastewater represents a promising approach to reduce fecal contamination of freshwater andemphasize the need to change the manufacturing habits and management of septic tanks.

Hydrogeochemistry and groundwater quality assessment using the water quality index and heavy-metal pollution index in the alluvial plain of Atibaia river- Campinas/SP, Brazil

Alluvial aquifers are highly vulnerable to contamination, especially in areas with peri-urban occupation and on-site sanitation systems. Due to the importance of the quality of groundwater in those areas, this article aims to understand hydrochemical characteristics and to evaluate groundwater quality using the Water Quality Index (WQI) and Heavy-Metal Pollution Index (HPI). Seasonal sampling campaigns of 20 samples of groundwater in hand dug wells were done during wet and dry seasons. The main hydrochemical facies determined in the Piper Diagram allowed to classify the waters as Ca–HCO3, Ca–Na–HCO3 and Na–Ca–HCO3 during the wet season, and Ca–HCO3, Na–Ca–HCO3 and Na–Ca–Cl during dry season, suggesting shallow waters and short residence time. The groundwater in the study area is mostly controlled by the incongruous weathering of silicates and the process of ionic exchange, as well as the anthropogenic sources that act as secondary contributions. The saturation index results show a state of supersaturation (SI > 0) for the following minerals: goethite, kaolinite and illite, and subsaturation (SI < 0) for the minerals: calcite and dolomite. The groundwaters were subsaturated in most of the samples, and supersaturated in other samples related to the mineral phase Fe(OH)3. The significant correlations between NO3− and Cl− allowed to conclude that the study area is contaminated by domestic septic tanks, and that in the majority of the samplings natural iron rests above the limit for human consumption. WQI and HPI indicate that the majority of the samples showed excellent indexes and are adequate for consumption. However, in this study those indexes presented limitations, because they minimize some parameters that presents concentrations above the maximum value or evidences of contamination, as seen with Nitrate and Iron, respectively.

Re-engineering Domestic Septic Tanks into Biogas Tanks

This study is to design a novel septic tank, named Anaerobic Upflow Domestic Septic Tank (AUDST) to recover biogas asenergy and treat domestic sewage. The green technology proposes alternate options to existing Domestic Septic Tanks (DST),encourages anaerobically pre-treatment to reduce bacteria, pollutants, Total Suspended Solids (TSS), Chemical oxygen demand(COD) and Biological oxygen demand (BOD) before the effluent is discharged or is removed by cesspit trucks. Studies haveshown that DST in homes partially treat or just store sewage. Again, these DST have to be emptied from time to time becauseit lack features that will sustain anaerobic activity and usually the sludge is disposed of directly into the sea, water bodies andeven into open places such as “Lavender Hills” without any treatment or disinfection. These practices cause severe public healthand environmental problems. To tackle the challenge at household level, DST are redesigned to treat domestic sewage with lessmanagement, low operating cost, low secondary discharge of pollutants. The proposed new design concept is operated throughthree (3) units: such as desilting, anaerobic digestion and facultative filtration units. The anaerobic digestion stage is made upof baffle and anaerobic filter for accommodating sludge and providing a more intimate contact between anaerobic biomass andsewage which improves treatment performance. The anaerobic unit is fitted with locally woven baskets prefilled with packingmaterials. The aim is to strengthen the biological treatment process at this stage. The Facultative Filtration unit of the model isalso packed with filtering media such as gravels (3-6mm in diameter) that is low in cost, and has a high durability to produceeffluent with lower pollutants and suspended solids content to meet Ghana’s Environmental Protection Agency (EPA) standardsfor the discharge of domestic effluents.

Re-engineering Domestic Septic Tanks into Biogas Tanks

This study is to design a novel septic tank, named Anaerobic Upflow Domestic Septic Tank (AUDST) to recover biogas asenergy and treat domestic sewage. The green technology proposes alternate options to existing Domestic Septic Tanks (DST),encourages anaerobically pre-treatment to reduce bacteria, pollutants, Total Suspended Solids (TSS), Chemical oxygen demand(COD) and Biological oxygen demand (BOD) before the effluent is discharged or is removed by cesspit trucks. Studies haveshown that DST in homes partially treat or just store sewage. Again, these DST have to be emptied from time to time becauseit lack features that will sustain anaerobic activity and usually the sludge is disposed of directly into the sea, water bodies andeven into open places such as “Lavender Hills” without any treatment or disinfection. These practices cause severe public healthand environmental problems. To tackle the challenge at household level, DST are redesigned to treat domestic sewage with lessmanagement, low operating cost, low secondary discharge of pollutants. The proposed new design concept is operated throughthree (3) units: such as desilting, anaerobic digestion and facultative filtration units. The anaerobic digestion stage is made upof baffle and anaerobic filter for accommodating sludge and providing a more intimate contact between anaerobic biomass andsewage which improves treatment performance. The anaerobic unit is fitted with locally woven baskets prefilled with packingmaterials. The aim is to strengthen the biological treatment process at this stage. The Facultative Filtration unit of the model isalso packed with filtering media such as gravels (3-6mm in diameter) that is low in cost, and has a high durability to produceeffluent with lower pollutants and suspended solids content to meet Ghana’s Environmental Protection Agency (EPA) standardsfor the discharge of domestic effluents.

Hydrogeochemical characterization and groundwater quality assessment in the intensive agricultural zone of the Upper Cheliff plain, Algeria

The alluvial aquifer of Upper Cheliff (northern Algeria) is known for its intensive agricultural activities, which is based especially on groundwater exploitation. This aquifer is now facing a dual problem of quantity and quality, with a decrease in the groundwater levels and an increase in mineralization. Twenty monitoring samples were collected and analyzed for major ion during the dry season 2014. In the present study, we try to characterize the hydrogeochemical processes and to assess the impact of natural and anthropogenic conditions on groundwater mineralization. The analytical results of the dry season 2014 show a groundwater quality slightly alkaline (pH > 7) and indicate that the majority of samples have a values exceeding the limits of potability fixed by WHO in 2008, due to the various sources of anthropogenic pollution. The Piper diagram shows the dominance of groundwater types: Ca–Cl, the mixed facies (Cl–SO4–Ca–Mg), and Ca–HCO3: The mineralization process in this aquifer is mainly controlled by the lithology of the aquifer (exchange water–rock and weathering of calcareous crust dissolution in the unsaturated zone), by anthropogenic factors (discharges of untreated urban sewage, intensive use of fertilizers in agriculture and the use of domestic septic tanks by rural inhabitants) and also by geoclimatic conditions (semiarid climate). Suitability of groundwater shows more than 80% of samples have very poor quality for drinking and more than 20% of samples indicate a quality unsuitable for irrigation.

Ubiquitous Detection of Artificial Sweeteners and Iodinated X-ray Contrast Media in Aquatic Environmental and Wastewater Treatment Plant Samples from Vietnam, The Philippines, and Myanmar.

Water samples from Vietnam, The Philippines, and Myanmar were analyzed for artificial sweeteners (ASs) and iodinated X-ray contrast media (ICMs). High concentrations (low micrograms per liter) of ASs, including aspartame, saccharin, and sucralose, were found in wastewater treatment plant (WWTP) influents from Vietnam. Three ICMs, iohexol, iopamidol, and iopromide were detected in Vietnamese WWTP influents and effluents, suggesting that these ICMs are frequently used in Vietnam. ASs and ICMs were found in river water from downtown Hanoi at concentrations comparable to or lower than the concentrations in WWTP influents. The ASs and ICMs concentrations in WWTP influents and adjacent surface water significantly correlated (r (2)=0.99, p<0.001), suggesting that household wastewater is discharged directly into rivers in Vietnam. Acesulfame was frequently detected in northern Vietnamese groundwater, but the concentrations varied spatially by one order of magnitude even though the sampling points were very close together. This implies that poorly performing domestic septic tanks sporadically leak household wastewater into groundwater. High acesulfame, cyclamate, saccharin, and sucralose concentrations were found in surface water from Manila, The Philippines. The sucralose concentrations were one order of magnitude higher in the Manila samples than in the Vietnamese samples, indicating that more sucralose is used in The Philippines than in Vietnam. Acesulfame and cyclamate were found in surface water from Pathein (rural) and Yangon (urban) in Myanmar, but no ICMs were found in the samples. The ASs concentrations were two-three orders of magnitude lower in the samples from Myanmar than in the samples from Vietnam and The Philippines, suggesting that different amounts of ASs are used in these countries. We believe this is the first report of persistent ASs and ICMs having ubiquitous distributions in economically emerging South Asian countries.

Examination of a Miniaturized Funnel Trap for Aedes aegypti (Diptera: Culicidae) Larval Sampling

Funnel traps are often used to sample for the presence of Aedes aegypti (L.) (Diptera: Culicidae) larvae in subterranean aquatic habitats. These traps are generally > or = 15 cm in diameter, making them impractical for use in subterranean sites that have narrow (10-cm) access ports, such as those in standard-sized septic tanks. Recent research indicates septic tanks may be important habitats for Ae. aegypti in Puerto Rico and the Caribbean. To sample mosquito larval populations in these sites, a miniaturized funnel trap was necessary. This project describes the use of a smaller funnel trap for sampling larval populations. The effects of larval instar (third and fourth) and population density on trap efficacy also are examined. The trap detected larval presence 83% of the time at a larval density of 0.011 larvae per cm(2) and 100% of the time at densities > or = 0.022 larvae per cm(2). There was a significant trend of increasing percentage of recaptured larvae with higher larval population densities. Although the miniaturized funnel trap is less sensitive at detecting larval presence in low population densities, it may be useful for sampling aquatic environments with restricted access or shallow water, particularly in domestic septic tanks.

Mosquito species composition of the Dooars of West Bengal, India

The sub Himalayan Dooars belt of Jalpaiguri district in West Bengal is an endemic focal area for malaria. A survey of mosquitoes was conducted from four sites of the Central Dooars during 2006–07. The sampling sites were at Nagrakata, Binnaguri, Ballaguri, and Totopara. The different endophilic mosquito species recorded from hutments and tea garden dwellings were Anopheles minimus, An. varuna, An. maculatus, An. fluviatilis, An. vagus, An. culicifacies, An. hyrcanus, An. barbirostris, Culex quinquefasciatus, Cx. vishnui(group), Aedes aegypti, Ae. albopictus, Mansonia indiana, M. annulifera, Armigeres subalbatus and Toxorhynchites splendens. Per man-hour density (PMD) of all species were determined for the mosquitoes species. Besides a general rise in mosquito population, the predatory species, T. splendens was higher in rainy season than that of winter and summer. Anophlines comprised 55.17% of the total indoor resting collections and the different Anopheles species densities ranged from 3.79% to 12.24% of the total mosquito population. Malaria incidence in these areas is noted to be very high, particularly in Nagrakata and its surroundings. Total Culex density was 20.32% of the entire mosquito collection. Aedes and mansonia population were 7.55% and 4.98% respectively. Common mosquito growing areas were tea garden channels, streams, riverbeds, jungle pools, paddy fields, domestic muddy water passages and septic tanks. The information available in this study may help formulating an effective mosquito control strategy especially for Anopheles vectors in such endemic malarial zone of the Dooars.

A Combined Method: Precipitation and Capping, to Attenuate Eutrophication in Canadian Lakes

Abstract Eutrophication is a natural phenomenon, unfortunately amplified and accelerated by human activities. Phosphorus and nitrogen are the principal nutrients responsible for eutrophication. Their excess in the environment, of domestic and agricultural origins, represents an important toxicological risk for the users of water. These excessive nutrients cause algae overgrowth and excess oxygen consumption, which leads to anoxic waters, production of toxins (such as those produced by canobacteria), and the production of pollutant gases. Excess nutrients and dead biomass settles at the bottom of the lake together with other trace contaminants such as toxic metals that are trapped within bottom sediments. Seasonally, the sediments release nutrients and contaminants that need to be mitigated in order to prevent eutrophication and overall water contamination. In Quebec and in Canada several lakes suffer from this problem and solutions have been divided in preventive practices (better runoff controls, protection of shores, elimination of leaking domestic septic tanks) and rehabilitating practices (oxygenation of water, precipitation of nutrients, dredging of sediments or capping). This paper will present recent advances in the development of a combined rehabilitating technique: Precipitation of phosphorous and capping of contaminated sediments. The paper includes: a recent literature review; phosphorous precipitation experiments using alum under optimized parameters; capping design considerations and theory; as well as the results of an experimental simulation of capping using a composite liner calcite/sand.

Wastewater remediation using coal ash

Small-scale domestic septic tanks discharge excess nutrients such as phosphorus and nitrogen, as well as pathogens, which can degrade local water supplies. Unfortunately, traditional chemical and physical treatments are not practicable for single-home dwellings. This work reports on a potentially attractive solution to protect local water supplies by using a low-cost industrial waste, coal ash, for contaminant removal. Coal ash is produced as a consequence of electric power generation. The majority of the ash is disposed of in landfills and surface impoundments, or stored on- or off-site, producing large hills or leveling valleys. Only a small portion of the ash is ever utilized, mainly by cement industries and road construction. For example, in Canada less than 25% is used. Therefore, if useful applications can be found, an opportunity exists to make better use of this waste material. Bench-scale laboratory experiments and full-scale field tests show that coal ash has the capacity to remove phosphorus from domestic waste water. The experimental and field data demonstrate that phosphate levels and calcium levels can be correlated, although not in a simple manner. In addition, the ash in packed beds removed total suspended solid (TSS), biological oxygen demand (BOD), ammonia nitrogen (NH3—N), total Kjeldahl nitrogen (TKN), and E. coli. The removal of E. coli was close 100% in the cases studied.

Interrelation of wastewater and groundwater management in the city of Bijeljina in Bosnia

The city of Bijeljina lies on alluvial deposits of the river Drina, which provide groundwater storage of great capacity with good hydraulic properties. Groundwater is abstracted by wells which are located in a field close to the city, and used for public water supply. In the summer of 1993, large numbers of coliform bacteria were found repeatedly in two of the wells. A study was initiated with the main objective of providing a short-term solution to the problem, as well as some guidelines for the long-term groundwater management strategy. A regional groundwater flow model was developed, calibrated and verified. In situ tracer experiments were used to improve the reliability of particle tracking computations. The results were used to prove that the sources of pollution were domestic septic tanks upstream of the well field. The problem was temporarily solved by closure of five wells capturing polluted water and opening some new wells in the less affected zone. The particle tracking results show why this strategy works, but also show that it is only a temporary solution. As a long-term solution, a sewerage system and network of monitoring wells were proposed. The sewerage system has been constructed recently. The role of monitoring is to check if bacterial pollution has ceased following the construction of the sewerage system, as well as to detect other types of pollutants. Groundwater levels have been monitored for one year already, so the data for model re-calibration has been collected. The re-calibrated model can be used for more accurate delineation of protective zones, prediction of the risks related to other pollutants, analysis of the possibility to reactivate the closed wells, etc. As the major objective in long-term water resources management, it is proposed that an integrated approach should be adopted, with simultaneous management of water supply, wastewater and solid waste.

Borborids (Diptera: Sphaeroceridae) infesting Sewage Disposal Tanks, with Notes on the Life Cycle, Behaviour and Control ofLeptocera(Leptocera)caenosa(Rondani)

AbstractA unique problem involving borborid infestations in modern septic sewage-disposal tanks is described. Two species,Leptocera(Leptocera)caenosa(Rondani) andL. (Limosina)empirica(Hutton) are new to North America. A third, yet undetermined, is related toL. (Limosina)gracilipennisSpul.Adults emerging from tanks in new schools sometimes blackened lavatory windows. Domestic septic tanks were seldom infested and chemical tanks never infested. Factors responsible, prevention and control are discussed. The main pest species,L.caenosa, was cultured. At about 72°F. the egg stage lasted about 48 hrs. and the larval and pupal stages 7 or more days each. In a humid atmosphere males survived up to 32 days and females 79 days. Fertile eggs were laid as late as 47 days after mating, with a maximum of more than 1300 eggs per female. Observations, including olfactometer tests, indicated thatL.caenosashould not initiate a public health problem.