On-site Systems Research Articles

Microfluidic paper-based analytical device with a preconcentration system for the measurement of anionic surfactants using an optode detector.

The paper discusses the development of a low-cost, simple, and sensitive on-site measurement system for anionic surfactants (AS), specifically sodium alkylbenzene sulfonate (LAS), using a microfluidic paper-based analytical device (μPAD) with an optode as a detector. The need arises due to the discharge of AS-containing wastewater into natural environments, posing risks to aquatic organisms. Traditional methods for AS measurement have drawbacks like the use of harmful solvents, time-consuming procedures, and the need for expensive equipment, prompting the exploration of alternative approaches. The μPAD incorporates a sample solution preconcentration system using filter paper modified with chitosan. The optode, a chemical sensor detecting analytes optically, is employed for AS detection. When a large volume of AS is added to a positively charged modified filter paper with chitosan, the AS is adsorbed and concentrated on the filter paper. The concentrated AS is eluted with a small volume of alkaline solution, and the eluted AS is detected by the optode in the μPAD. The μPAD with preconcentration provides improved sensitivity and a broader range of detection compared to the method without preconcentration. In the present μPAD method, linear alkylbenzenesulfonate (LAS) in the concentration range of 0.1 to 10 μmol dm-3 was measured. The developed μPAD offers advantages such as portability, cost-effectiveness, and negligible interference from coexisting substances in environmental water samples. The μPAD method was applied for the determination of LAS in tap water and river water.

Analysis of fecal pollution load factor from septic tanks of residential area (study case: Bandung City, Indonesia)

According to the Ministry of Environment and Forestry, 2017, domestic waste is the most significant contributor to pollution sources in the Citarum watershed (62.16%) and Bandung City (94.15%). To overcome the problem, planning for infrastructure development and improvement of the domestic sewage treatment system is necessary. One of the essential characteristic parameters, which is the subject of this study, is the pollutant load factor parameter in the city of Bandung. Compared to sewage pipelines, the domination of domestic wastewater treatment in Bandung is the On-site Sanitation System (OSS) (38.47%), and the most widely used type of OSS is a septic tank. For this reason, thirty fecal sludge samples were taken from two fecal disposal points in Bandung City, and the concentrations of TSS, COD, BOD, and Ammonia were then analyzed. Based on the results of the study, the range of fecal sludge pollutant load factor for TSS in Bandung City is 57.28 g / person/day – 1,064 g / person/day with an average value of 546.39 g / person/day, the range for total COD is 30.06 g / person/day – 294.99 g /person/day with an average of 294.99 g / person/day, the total BOD range is 14.05 g /person/day – 504.97 g / person/day with an average of 175.5 g / person/day, and ammonia range 1.61 g/person/day – 3.11 g/person/day with an average of 2.62 g/person/day. Based on fecal sludge data, the result can be considered a recommendation to re-determine the main domestic wastewater pollution indicator generation. The new suggestions can be used to design an adequate domestic wastewater treatment system, especially in Bandung. The pollutant load factors can also be used to estimate the pollution loading of wastewater generated by present and future populations. It is important in urban growth planning.

Impact of On-Site Sanitation and Siting of Boreholes on Ground Water Quality in Choma Urban: A Case of New Kalundu and Humba Residential Areas.

Groundwater is a climate–resilient source of freshwater for most sub–Sahara African countries and plays a vital role in sustaining improved access to safe water in pursuit of United Nations Sustainable Development Goal 6 – water and sanitation for all by 2030. However, the potential for on-site sanitation to cause major contamination to groundwater has been known for many years, prompting authorities to advise minimum safe distances between boreholes (water sources) and soakaway. This study evaluated the effects of on-site sanitation and borehole placement on the quality of groundwater in residential areas. The study employed an embedded mixed methodology with a descriptive cross-sectional approach. 138 household heads were involved in the study and 15 water samples were collected for microbiological analysis. Data from households was collected using structured questionnaires while upholding all ethical issues. The study found that 85% of households used on-site sanitation systems as their primary means of waste treatment and disposal, while the remaining 15% used other methods like pit latrines. Due to the utility company’s unstable and unreliable supply of water, residents turned to alternative sources of drinking water, such as drilling boreholes and hand-dug wells within and around compounds, using soakaway systems for waste disposal close to the drinking water source. The chi-square tests revealed that the position of the soakaway, as well as the distance between the water sources and the soakaway, have an influence on water quality. The study concluded that establishment of water sources near any pollution source (soakaway) has a negative impact on the quality of groundwater resources. We recommended that local authorities should not permit construction at any plot less than 30 x 30 meters in its dimensions to have both borehole and on-site sanitation system but rather one of the two.

A syndromic diagnostic assay on a macrochannel-to-digital microfluidic platform for automatic identification of multiple respiratory pathogens.

The worldwide COVID-19 pandemic has changed people's lives and the diagnostic landscape. The nucleic acid amplification test (NAT) as the gold standard for SARS-CoV-2 detection has been applied in containing its transmission. However, there remains a lack of an affordable on-site detection system at resource-limited areas. In this study, a low cost "sample-in-answer-out" system incorporating nucleic acid extraction, purification, and amplification was developed on a single macrochannel-to-digital microfluidic chip. The macrochannel fluidic subsystem worked as a world-to-chip interface receiving 500-1000 μL raw samples, which then underwent bead-based extraction and purification processes before being delivered to DMF. Electrodes actuate an eluent dispensed to eight independent droplets for reverse transcription quantitative polymerase chain reaction (RT-qPCR). By reading with 4 florescence channels, the system can accommodate a maximum of 32 detection targets. To evaluate the proposed platform, a comprehensive assessment was conducted on the microfluidic chip as well as its functional components (i.e., extraction and amplification). The platform demonstrated a superior performance. In particular, using clinical specimens, the chip targeting SARS-CoV-2 and Flu A/B exhibited 100% agreement with off-chip diagnoses. Furthermore, the fabrication of chips is ready for scaled-up manufacturing and they are cost-effective for disposable use since they are assembled using a printed circuit board (PCB) and prefabricated blocks. Overall, the macrochannel-to-digital microfluidic platform coincides with the requirements of point-of-care testing (POCT) because of its advantages: low-cost, ease of use, comparable sensitivity and specificity, and availability for mass production.

An on-site inspection system for explosives in a container using dust collection through a vent cover and ion mobility spectrometric detection.

Rapid and accurate cargo-inspection systems are required for shipping containers, because illegal and hazardous items, such as explosives and drugs, can be easily concealed in large containers. Dust in a container is suspended in the air and deposited in vent covers. The vapor and particulate matter of explosives can be adsorbed onto the dust. In this study, a model vent cover system was developed for a container and explosive-adsorbed dust specimens were modeled using organic [cotton fabric (CF) and sawdust (SD)] and inorganic substances [clay (CL) and silica (SL)]. The dust was placed in the inner part of the vent cover and collected through the vent holes, and the explosive components present in the dust were rapidly analyzed using ion mobility spectrometry (IMS). Three explosives, namely 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), and pentaerythritol tetranitrate (PETN), were investigated along with two different collection filters, namely poly(tetrafluoroethylene) (PTFE) and lens cleansing paper (LCP). The dust collection rate decreased when the dust was located away from the vent holes. The order of the dust collection rate was SD > CF > SL > CL. The limit of detection (LOD) of TNT was considerably lower than those of RDX and PETN. The LODs of the explosives when using the LCP collection filter were lower than those when using the PTFE filter. The LOD order was CF < SD < CL < SL for the PTFE collection filter and CL < SL < CF < SD for the LCP filter. The technique developed in this study can be employed as a rapid and accurate cargo inspection system for shipping containers.

Inactivation of Escherichia coli in domestic wastewater by modified septic tank treatment

The Sustainable Development Goals (SDGs) targets for the improvement of drinking water, sanitation, and hygiene (WASH) makes the development of wastewater infrastructure in many countries is increasing. In Indonesia, the development of sewer connections remained limited nationally, most households still rely on on-site sanitation systems that mainly use septic tanks technology. Septic tank as watertight containment itself cannot provide the treatment to comply with the effluent standard of domestic wastewater, while a lot of application of septic tank do not follow by suggested technology for further treatment. That makes the need of septic tank improvement as modified septic tank (MST) system. One of parameters removed by MST better is microbial content. This research aims to identify Escherichia coli inactivation in MST, how the process along the treatment impact E. coli concentration and identification the effectiveness of trichloroisocyanuric acid (TCCA) tablet application as disinfectant in E. coli inactivation, and concurrently safe to environment. This research was conducted in laboratory using MST reactor set-up consists of pre-sedimentation chamber, fixed bed anoxic chamber, and MBBR chamber to treat synthetic wastewater. The synthetic wastewater, composed by C6H12O6, NH4Cl, KH2PO4 and E. coli culture is used. With influent E. coli concentration was 108-109, it was reduced to 108 in pre sedimentation chamber, 106-107 in fixed bed anoxic chamber, 105-106 in MBBR chamber and final effluent, all in MPN/100 ml unit. E. coli was inactivated 99.84% along MST process but with relative high concentration to be discharged. Application of TCCA tablet 90% active chlorine with contact time 15 minutes is adequate to inactivate E. coli completely but generates high concentration of chlorine residual.

On-site Septic Systems: The Sustainable Removal of Excess Nutrients

On-site Septic Systems: The Sustainable Removal of Excess Nutrients

Simplified capture, extraction, and amplification of cellular DNA from water samples.

DNA analysis in water samples is attracting attention in various fields. However, conventional methods for DNA analysis require a work-intensive and time-consuming sample pre-treatment. In this study, a simplified pre-treatment method for analyzing DNA in water samples was evaluated. The process consists of filtration, DNA extraction, and amplification, which can be achieved within a short time. In the filtration process, two types of filters, firstly a tissue paper (Kimwipe) and then a glass filter (GF/F), were used in sequence. The first large pore size filter enabled a reduction in filtration time by removing large particulate matter impurities present in river water matrix. Cells spiked into 1 L of river water were recovered at more than 90% within approximately 5min filtration time. Also, DNA was extracted from the captured cells directly on the surface of the filter in only 5min. Thus, DNA collection and extraction from a water sample can be completed within about 10min. Furthermore, PCR amplification was performed directly from DNA-attached filter sections, which greatly reduced the number of required pre-treatment steps. Finally, we succeeded in establishing a simple and fast on-site pre-treatment system by using a hand-driven syringe filtration method. This pre-treatment system is expected to offer the possibility for the future establishment of a rapid and easy DNA analysis method applicable to various types of water samples.

Comparison of the PFAS and physical-chemical parameter fluctuations between an ash landfill and a MSW landfill

Studies of per- and polyfluoroalkyl substances (PFAS) fluctuations at landfills have focused on municipal solid waste (MSW) leachate. Few studies exist that evaluate fluctuations (defined by the coefficient of variation, CV) in MSW incinerator ash (MSWA) landfill leachate and that evaluate PFAS fluctuations in stormwater, groundwater, and treated liquids on-site. In this study, aqueous landfill samples (leachate, treated leachate, stormwater, gas condensate, ambient groundwater, and effluent from a groundwater remediation system) were collected from a MSW and an MSWA landfill geographically located within close proximity (less than 40 km). The objective of this study was to compare the leachate compositions between these two landfill types and to evaluate temporal variations. Results indicated that the CV of total detected PFAS concentrations in leachate was higher for the MSW landfill (CV = 43 %) compared to the MSWA landfill (CV = 16 %). The total detected PFAS concentration in MSW leachate samples (mean: 9641 ng/L) was higher than in MSWA leachate samples (mean: 2621 ng/L) (p < 0.05). Within a landfill, PFAS concentrations were correlated (rs > 0.6, p < 0.05) with alkalinity, total organic carbon (TOC), and ammonia. Results from the on-site leachate treatment system at the MSW landfill indicated reductions in COD, TOC, and ammonia; however, the ∑26PFAS concentration increased 3 % after the treatment. Overall, results demonstrated that differences between landfill types and fluctuations in PFAS within landfills should be considered when designing landfill leachate collection and treatment systems to remove PFAS. The comparative analysis in this study can provide insights into optimizing leachate management for MSW and MSWA landfills.

Penentuan Jenis dan Wilayah Prioritas Pelayanan Sistem Pengelolaan Air Limbah Domestik di Kecamatan Rancasari Kota Bandung

Rancasari Subdistrict is located in Bandung City, comprises four urban villages, encompassing 0,19 km2 with six blocks of light slum areas. Slum areas are areas that tend to have more vulnerable environmental conditions due to the minimal availability of environmental infrastructure, one of which is sanitation facilities. Based on this, Rancasari subdistrict needs to determine the type of domestic wastewater management system service and priority service areas. Determination of the service type of domestic wastewater management system is determined based on Attachment 1 of Regulation of the Minister of Public Works and Public Housing Number 4 of 2017, while priority areas are determined based on Bandung City Regional Regulation Number 5 of 2022, Regional Regulations Bandung City Number 10 of 2015, and the area of slum settlements in each village. Rancasari Subdistrict is suitable for on-site system, while the main priority area is Manjahlega Village, then Mekarjaya, Derwati, and Cipamokolan. It is necessary to develop domestic wastewater management system facilities in the main priority area in the form of development of existing communal septic tanks and communal wastewater treatment facility, as well as the closure of piped domestic wastewater disposal facility leading to the Cidurian River to stop open defecation.

Identification of fecal contamination sources of groundwater in rural areas of Vhembe District Municipality, Limpopo Province, South Africa.

Groundwater is a valuable source of drinking water worldwide, recognized as an improved drinking water source. However, on-site sanitation systems may put groundwater at risk of fecal contamination. In the present study, two approaches were used to ascertain the sources of fecal contamination in groundwater used by communities of the Vhembe District Municipality. Overall, 87.5% of boreholes (n = 70) in the wet and 72.5% in the dry season were contaminated with Escherichia coli, and septic tank (n = 18) wastewaters displayed up to 104 cfu/mL E.coli. Host-specific Bacteroidales quantitative polymerase chain reaction (qPCR) assays established the presence of human (BacHum and HF183) and animal (Cytb, BacCan, and Pig-2Bac) genetic markers in groundwater from 15.7% of boreholes (wet) and 10% of boreholes (dry). No strong associations were founded between culturable E.coli counts and the presence/absence of marker genes for all the markers except for Cytb marker, which showed a weak significant correlation (r = 0.217; p = <0.01) between E.coli and the Cytb marker under dry seasonal conditions. Human markers and Cytb were present in the household septic tank wastewater samples. Significant differences in marker genes distribution in wastewater were observed using the Chi-squared test: HF183 (p = <0.001) and BacHum (p = <0.001). Overall, no association was recorded between markers in groundwater and in wastewater for 18 households' septic tanks. A combined culturable E.coli and host-specific Bacteroidales qPCR assays remain an appropriate approach for the identification of fecal contamination of groundwater. PRACTITIONER POINTS: Households primarily used private boreholes for drinking water, as a primary source. Most households used on-site sanitation systems, including ventilated improved pit latrines and flush toilets connected to septic tanks. Escherichia coli was detected in groundwater, and the sources of fecal contamination were humans and animals (pigs, dogs, and chickens). The presence of human and animal markers in groundwater suggests that humans and animals are liable for fecal contamination. Fecal contamination in drinking water sources poses a significant concern due to pathogenic microorganisms posing potential human health risks.

Strategies for Low CO2-emission Schools in Norway

Regional and national strategies targeting climate change are a driver for reducing greenhouse gas emissions. Municipalities play an important role towards a sustainable society and in restructuring needed to reach the 2030 European Climate targets. They often require that new buildings shall be zero emission and that the building’s carbon footprint shall be reduced compared to a reference building, starting with public buildings. To reach low or zero emission buildings, the production of renewable energy must equal or outweigh the CO2-emissions associated with the building. The energy consumption of the building should be decreased before designing on-site renewable energy generation systems. This is ensured by following a holistic energy design approach: energy conservation, reducing electrical energy, efficient energy management and producing renewable energy. Although Norway has had a focus on low and zero emission buildings, there is a limited number of low CO2-emission schools. These are designed and constructed by various actors. Therefore, the practical experience and knowledge in the industry is scattered and still in development. This paper aims to summarize practical strategies for low CO2-emission schools in Norway. Several case studies were analyzed to identify common traits and interviews were conducted to identify opportunities, challenges and strategies.

P-Alert earthquake early warning system: case study of the 2022 Chishang earthquake at Taitung, Taiwan

A series of earthquakes that struck Taiwan's southern Longitudinal Valley on September 17 and 18, 2022 severely damaged several buildings in Taitung and Hualien. The Chishang earthquake, which had a magnitude of ML 6.8 and a large foreshock with a magnitude of ML 6.6 the day before, was the mainshock in this sequence. The strongest intensity reported in the epicentral region during this earthquake sequence, which was 6 + , is the highest ever recorded since the Central Weather Bureau (CWB, renamed as the Central Weather Administration since September 15, 2023) revised its seismic intensity scale. National Taiwan University (NTU) has operated a low-cost earthquake early warning (EEW) system known as the P-Alert for a decade. In this study, we demonstrate the performance of the P-Alert network during the 2022 Chishang earthquake and the largest foreshock. The P-Alert network plotted shake maps during these earthquakes that displayed various values within 5 min. The high shaking areas on these maps were in good agreement with observed damages during this earthquake, providing valuable insights into rupture directivity, a crucial component of earthquake engineering. Individual P-Alert stations acted as on-site EEW systems and provided a lead time of 3–10 s within the blind zone of CWB. For the ML 6.8 mainshock, there was a lead time of at least 5 s, even up to 10 s, demonstrating their effectiveness in the blind zone. The P-Alert regional EEW system provided the first report about 9 s and 7 s after the mainshock and the largest foreshock occurrence, respectively, with estimated magnitudes of 5.74 and 5.67. The CWB system estimated magnitudes of 6.72 and 6.16 in the first report, respectively, about 7 s and 9 s after the earthquake occurrence. The timeliness of the two systems were not significantly different. Despite the effectiveness of the P-Alert network, data loss due to connection interruptions prompted us to develop a new compact data logger for improved data availability.

Machine Learning Applied to Acoustic Insulation Analysis in Residential Buildings - Part 2: Vertical partitions

The use of Machine Learning (ML) tools has grown a lot in several areas, including in the civil construction space. Part one of this study tried to use ML to estimate results for sound insulation of floor systems and had concluded that ML is not applicable to those situations. Part two tried some adjustments to the ML script and used an on-site vertical partition system test database as input with ML tools used to estimate new results based on the input data. The conclusion of this new study is that the tool is now more applicable to floor systems but it is not the best form to predict the results, given the complexity of sound propagation between rooms, which is not considered in the statistical analysis of the machine.

Development of a multiplex recombinase polymerase amplification coupled with lateral flow dipsticks for the simultaneous rapid detection of Salmonella spp., Salmonella Typhimurium and Salmonella Enteritidis

Abstract Objectives Salmonella spp. is a world-leading foodborne pathogen and its rapid detection is essential for ensuring food safety. Conventional methods require expensive instruments, considerable operational skills and cannot provide fast mobile on-site systems to detect Salmonella in food. Materials and Methods A visual method was established based on multiple recombinase polymerase amplification (RPA) coupled with lateral flow dipsticks (LFD) for the simultaneous detection of Salmonella spp., Salmonella Enteritidis and Salmonella Typhimurium in vitro and food. Results The optimal volume and temperature for the multiplex RPA-LFD method were determined to be 25 μL and 38 °C, respectively. The reaction process was completed within 25 min and the results were observed visually. The limits of detection (LODs) were 2.8×102, 5.9×102, and 7.6×102 CFU/mL for Salmonella spp., S. Enteritidis and S. Typhimurium, respectively. Meanwhile, the results of the established method showed no cross-reactivity between the Salmonella cells and other common foodborne bacteria, which was highly specific for Salmonella. More importantly, the developed method exhibited good performance in artificially contaminated chicken samples with the LODs of 2.8×103, 5.9×103, and 7.6×103 CFU/mL for Salmonella spp., S. Enteritidis, and S. Typhimurium, respectively. Finally, the application of the multiple RPA-LFD methods in retailed food samples displayed that this method was effective and practical for the detection of Salmonella spp. in food. Conclusion The developed multiplex RPA-LFD method provides a new sensitive and rapid alternative for the specific detection of Salmonella spp. and its important serovars in food.

A computational-fluid-dynamics study on scaling up a single flat membrane reactor for on-site hydrogen production

The accessibility of hydrogen stations has been problematic for remote areas, although the demand for fuel-cell electric vehicles has risen. We propose a 50-Nm3/h on-site hydrogen production system using the accessible liquid-fuel infrastructure. The system integrates a pressurized steam reformer and a catalytic membrane reactor to produce high-purity hydrogen. This study focuses on scaling up our membrane reactor for enhanced hydrogen permeation while maintaining acceptable similarity and performance to make the system compact and effective. We compare three scale-up methods, which keep the inlet Reynolds number, gas hour space velocity, and Damköhler-Peclet number constant, respectively. After selecting the third case for its best similarity, we increase the scale to eight and conclude that any scale beyond four is not ideal for our specific membrane reactor. By increasing the scale to four, we reduce the number of reactors for the 50 Nm3/h target by 91% while achieving a hydrogen recovery of 91%. Future studies can refer to the scale-up process that maintains the reactor similarity and high performance in this work for choosing an appropriate scale for membrane reactors.

Determination and implementation of an onsite management system for motor-vehicle wash effluents: A field-scale commercial application toward sector sustainability

The global upsurge of vehicle wash enterprises is allied to the production of large wastewater volumes. This effluent contains organic and inorganic compounds which can cause environmental pollution. Upscaling the laboratory-scale systems for motor-vehicle wash wastewater (MVWW) treatment to field-scale commercial application is essential for enabling the circular economy framework, meeting the United Nations' 2030 Agenda. In this study, 98 research publications on MVWW treatment technologies were scrutinized for bibliometric-meta analysis. After, a practical treatment option was identified and designed for implementation in a Ugandan motor-vehicle wash station and a comprehensive economic evaluation was performed. A continental outlook on MVWW quality showed that its major pollutants include oil-greasy compounds, surfactants, and suspended solids. Results showed that a hybrid system consisting of coagulation/flocculation/sedimentation and sand/gravel filtration was identified as the most practical treatment method for implementation in motor-vehicle washing stations. The final effluent of the field-scale integrated treatment system contained turbidity = 2 ± 0.0 NTU, chemical oxygen demand (COD) = 18.9 ± 0.6 mg/L, surfactants = 3.2 ± 0.3 mg/L, supporting onsite recyclability in motor-vehicle washing activities. The integrated system demonstrated a profitability scenario with a benefit-cost ratio (B/C) > 1 and a payback period of 2.7 years. Implementing the hybrid system for onsite MVWW treatment could fulfil targets of sustainable development goals related to; water conservation, water recycling and reuse, and environmental protection.

Towards a generic solution to onsite wastewater treatment

Decentralized wastewater treatment, specifically onsite treatment, is fundamental to recent wastewater management paradigms. However, onsite solutions often produce inadequate effluent quality for reuse and are ineffective in removing organic micropollutants (OMPs). This study suggests a multistep onsite system for treating wastewater in varying conditions. The system comprises biological treatment in a recirculating vertical-flow bioreactor (RVFB) followed by ozonation and ultrafiltration. The system was constructed on a farm in the Israeli Negev desert and tested year-round for its effluent quality and removal of two model OMPs. Additionally, laboratory-scale experiments were conducted to understand the field data. The system has demonstrated stable performance over varying climate conditions and wastewater qualities during one year of operation. The RVFB reduced the total suspended solid (TSS) concentration by up to 96 %, the dissolved organic carbon by up to 88 %, and the biodegradable OMP, Ibuprofen, by approximately 82 %. Ozonation had limited impact on effluent quality, most likely due to low ozone concentrations, but interestingly efficiently reduced Carbamazepine, a recalcitrant OMP, by around 87 %. Additionally, the laboratory experiments using the farm's wastewater demonstrated the ozone's potential efficiency in improving effluent quality. The final membrane filtration treatment step fully removed the residual TSS and E. coli, achieving effluent quality that meets the standards for wastewater reuse. The membrane exhibited stable performance over one month without chemical cleaning, probably due to the pre-ozonation step. Overall, this study highlights the potential of the suggested system to effectively treat diverse wastewater types and produce high-quality effluent suitable for reuse.

Fecal sludge characterization, treatment, and resource recovery options: a state-of-the-art review on fecal sludge management.

A rise in population and urbanization demanded that a robust fecal sludge management (FSM) value chain be used to restructure the sanitation system throughout the world securely. A significant global need exists to adopt efficient and sustainable FSM. On-site sanitation systems (OSS) produce fecal sludge (FS). FS is produced when excreta and blackwater are combined and stored or treated, either alone or in combination with greywater. FS can be semisolid or slurry and raw or partially digested. Critical examination of FS characteristics, i.e., biochemical oxygen demand (BOD), chemical oxygen demand (COD), total solids (TS), and pathogen count, varies from 600-56,836mg/l, 6656 to 201,200mg/l, 830-123,000mg/l, and 105 to 109 E. coli/l of FS respectively. Helminth eggs range from 2500-25,000/l of FS. Public health and the environment are negatively impacted by septic tank overflows and the careless discharge of FS into open spaces affecting groundwater quality, water bodies, irrigation fields, open drains, places outside villages, etc. Thus, deciding on a proper treatment technology for FS before discharging it into open land or reusing FS is essential to create a pollution-free environment. This paper highlights the practices adopted for FSM under its different processes, such as collecting, characterization, treating, and reusing of on-site FS and bibliometric analysis on documents on fecal sludge. A thorough analysis has been carried out by reviewing all important literature available globally.

Real-time prediction of distance and PGA from P-wave features using Gradient Boosting Regressor for on-site earthquake early warning applications

SUMMARY On-site earthquake early warning (EEW) systems represent an important way to reduce seismic hazard. Since these systems are fast in providing an alert and reliable in the prediction of the ground motion intensity at targets, they are particularly suitable in the areas where the seismogenic zones are close to cities and infrastructures, such as Central Italy. In this work, we use Gradient Boosting Regressor (GBR) to predict peak ground acceleration (PGA), and hypocentral distance (D) starting from P-wave features. We use two data sets of waveforms from two seismic sequences in Central Italy: L'Aquila sequence (2009) and the Amatrice–Norcia–Visso sequence (2016–2017), for a total of about 80 000 three-component waveforms. We compute 60 different features related to the physics of the earthquake using three different time windows (1 s, 2 s and 3 s). We validate and train our models using the 2016–2017 data sets (the bigger one) and we test it on the 2009 data set. We study the performances of GBR predicting D and PGA in terms of prediction scores, finding that the models can well predict both targets even using 1 s window, and that, as expected, the results improve using longer time windows. Moreover, we perform a residual analysis on the test set finding that the PGA can be predicted without any bias, while the D prediction presents a correlation with the moment magnitude. In the end, we propose a prototype for a probabilistic on-site EEW system based on the prediction of D and PGA. The proposed system is a threshold-based approach and it releases an alert on four possible levels, from 0 (far and small event) to 3 (close and strong event). The system computes the probability related to each alert level. We test two different set of thresholds: the Felt Alert and the Damage Alert. Furthermore, we consider the lead time (LT) of the PGA to distinguish between useful alerts (positive LT) and Missed Alerts (MA). In the end, we analyse the performance of such a system considering four possible scenarios: Successful Alert (SA), Missed Alert (MA), Overestimated Alert (OA) and Underestimated Alert (UA). We find that the system obtains SA rate about 80 per cent at 1 s, and that it decreases to about 65 per cent due to the increase in MA. This result shows how the proposed system is already reliable at 1 s, which would be a huge advantage for seismic prone regions as Central Italy, an area characterized by moderate-to-large earthquakes (Mw &amp;lt; 7).