Decentralized Treatment Systems Research Articles

Adopting sea water reverse osmosis desalination technologies for sustainable development: lessons learnt from Algiers Science and Technology for membranes 2023 workshop

The city of Algiers hosted the workshop on Science and Technology for Membranes from 30th May to 1st June 2023—STM 2023, held in Algeria. The main topics focused on Reverse Osmosis (RO) desalination technologies, decentralized autonomous systems, wastewater recycling for circularity, and the effects of green membrane processes on socio-economic growth. This review examines the influence of global trends and instabilities (i.e., climate change, disrupted supply chain platforms, natural disasters) on the steady supply of freshwater. The implementation of RO desalination solutions and their sustainability are assessed based on resiliency factors, which is helpful to screen water treatment alternatives based on technological benefits, ecological safety and environmental protection. Key takeaways from this study call for rolling out local membrane production capabilities, promoting the benefits of autonomous decentralized treatment systems, prioritizing innovative solutions to reduce greenhouse gas emissions, and for developing RO-specific equipment recycling infrastructures. Implementing these new tactics can lead to mitigate water scarcity and enable a sustainable deployment of desalination membrane technologies in Algeria and its region.

Demonstration and performance analysis of on-beach public toilet with a decentralised modified French vertical flow constructed wetland and ex situ electrochlorination integrated treatment system

Abstract This study demonstrated an on-beach public toilet equipped with a sustainable decentralised treatment system in Goa, India. The number of toilet users, freshwater demand, and wastewater (WW) generated per day were documented. The treatment system consisted of a modified French-type vertical flow constructed wetland (MVFCW) and electrochlorinator. The first and second stage MVFCW were an unsaturated and saturated type, respectively. The onsite beach bore well water with a chloride concentration of 8464 ± 415.18 mg/L was electrolysed for 1 h at 40.49 Am−2. Then MVFCW effluent was disinfected by dosing 2412.50 + 278.61 mg/L of chlorine (Cl2) generated at a disinfectant dilution ratio of 1:300 (Cl2:WW). The average daily toilet users, freshwater usage, and WW generated were 96 ± 17.02, 1381.38 ± 380.35 L, and 1407.98 ± 611.8 L, respectively. The integrated treatment system treated 1,400 L/day. The integrated treatment system achieved an average percentage removal of 93.38 ± 0.38% chemical oxygen demand, 79.18 ± 1.55% NO3−, 98.45 ± 0.22% total ammoniacal nitrogen, 93.13 ± 1.19% PO4−3, 87.28 ± 0.2% total suspended solids, 83.09 ± 1.16% total organic carbon, 80.22 ± 0.87% total carbon, 80.05 ± 0.12% inorganic carbon, and 100% coliform. The power consumption cost was 0.17 INR m−3.

Sustainability of a Low-Cost Decentralized Treatment System for Wastewater Reuse: Resident Perception-Based Evaluation for Arid Regions

Small communities and most rural settlements in the Kingdom of Saudi Arabia (KSA) store domestic wastewater in residential septic tanks and transport it to the nearest centralized wastewater treatment plant. Without a sanitary sewerage system, the residents encounter various socioeconomic and environmental challenges related to sewage collection vehicles, the production of objectionable gases, and leaking septic tanks. The present study developed a resident perception-based methodology to appraise the sustainability of a low-cost ceramic filter bioreactor-type decentralized wastewater treatment system (DWWTS) for a small community of 1300 residents (160 households) in Qassim (KSA). In addition to six demographic factors, nine indicators assessed residents’ perceptions about existing and proposed wastewater management systems. A hierarchical-based system of sub-indices evaluated the three dimensions of sustainability using four environmental, nine social, and three economic indicators. The indicators translated into dichotomous questions posed to 34 respondents in the study area. The statistical analysis assessed the association of responses with the willingness to accept (WTA) the proposed DWWTS. A subjective rating scheme translated the responses into performance scores, and a fuzzy-based method aggregated the scores into sub- and top-level indices. The top of the hierarchy showed a close agreement between the resident’s perception and DWWTS’ sustainability. The study found that residents’ knowledge about environment and resource conservation resulted in a moderately high willingness to reuse treated effluent and WTA the decentralized system. The study also showed that the economic viability of a DWWTS remained at a moderate performance level due to a low monthly waste disposal cost. The study’s findings present a high potential for sustainable community-maintained DWWTS initially supported by the government. The proposed approach facilitates decision-makers working in ministries concerning water resources, environmental protection, and agricultural production in evaluating the sustainability of DWWTS for small communities in arid regions.

Study on Effectiveness of Intervention of a Vertical Flow Constructed Wetland in between Septic Tank and Soak Pit for the Treatment of Septic Tank Effluent

Septage comprises the solid and liquid constituents of any primary treatment system, including a Septic Tank. In this study, the wastewater collected from a septic tank is passed through a partially converted anaerobic filter, and a vertical flow constructed wetland (VFCW) before being sent to a soak pit. The main objective of this case study was to check the effectiveness of incorporating a VFCW between a septic tank and a soak pit to bring down the consequences created due to effluent seepage from soak pits to the groundwater. Conventionally, the effluent gets directly passed to soak pits after primary onsite treatment in the septic tank. The soak pit walls made of porous materials allow the gradual seepage of final effluent into the ground, polluting the groundwater reserves. We analyzed the septic tank effluent from 60 households wherein the effluent was let off into the soak pits. The various parameters analyzed with their averages were 393.83 ± 293.41 mg.L-1 for COD, 151.48 ± 94.37 mg.L-1 for BOD, 30.81 ± 13.05 mg.L-1 for NO3-, 23.35 ± 13.54 mg.L-1 for PO43-, 7.35 ± 0.31 for pH, 184.05 ± 163.20 mg.L-1 for TSS, 3.05 x 107± 2.04 x 108 CFU.100mL-1 for TC. Therefore, it is certain that the final effluent being sent into soak pits after primary treatment does not meet the Central Pollution Control Board (CPCB) discharge standards. In this case study, we were able to obtain final effluent values after VFCW treatment as 55.72 mg.L-1 for COD, 12.12 mg.L-1 for BOD, 10.2 mg.L-1 for NO3-, 3.74 mg.L-1 for PO43-, 7.41 for pH, 8.37 mg.L-1 for TSS, 379.27 mg.L-1 for TS and 51.9 CFU.100mL-1 for TC. With this case study, we were able to resolve this impediment by bringing down the values of all the parameters considered while analyzing under the limits of discharge standards set by CPCB. The removal efficiency of COD, BOD, NO3-, PO43-, pH, TSS, and TC after wetland was found to be 89.46%, 88.051, 63.484, 44.37%, 3.41%, 98.47%, 97.71%, 97.19% respectively. The study has proven that with the introduction of another decentralized treatment system between a septic tank and soak pit, it is safe to dispose of the effluent into soak pits, thereby reducing the chances of groundwater pollution considerably.

Evaluation of a Modular Filter Concept to Reduce Microplastics and Other Solids from Urban Stormwater Runoff

This paper describes an innovative Decentralized Technical Sustainable Drainage System (SuDS) concept, which is based on technical devices, such as sieves, sedimentation barriers, floating barriers and a magnetic module, which addresses, mainly, the fine matter. The SuDS is designed as a retrofit system so that no costly and time-consuming conversion measures are necessary. Due to the possibility of free configurability of individual modules in the three levels, road, gully and drain, a novel solution approach is presented, which is not available on the market, for a reduction in solids in general and microplastics in particular. The retention performance of selected modules and their combinations is demonstrated by means of bench tests according to the test procedure of the German Institute for Construction Engineering (DIBt) for the evaluation of decentralized treatment systems. Four different rain intensities, from light to medium up to heavy rain, are charged to the filter modules. Collected and fractionated road-deposited sediment (RDS) was selected as the test substance (10 kg). Additional tests with tyre powder, PE pellets, cigarette butts and candy wrappers helped to make clear the filter process of the particulate matter. The retention performance was determined by the mass balance between the defined dosage and at the outlet. For this purpose, the total volume flow of the effluent was passed over a stainless-steel sieve with a diameter of 600 mm and a mesh size of 20 µm. For the test substance, RDS retention rates up to 97% were measured. Very fine matter, particularly, was technically challenging to obtain; <63 µm up to 66% could be retained by the filter modules. Modules in the road space, such as porous asphalt or additional retention spaces, in the area of the curb as well as direct infiltration in the road drainage shaft are theoretically described and discussed. The outlook also addresses the potential of an intelligent network to reduce the input of pollution from urban stormwater runoff.

Preliminary evaluation of the decontaminating potential of a manganese oxide supported on mordenite

The treatment and in situ reuse of greywater could greatly contribute to reduce the water demand at the municipal level, thereby achieving social, economic, and environmental benefits. Decentralized treatment systems use chemical, physical and biological methods to decontaminate water, which then allows its reuse in garden irrigation, filling toilets or cleaning without primary contact with the inhabitants of the home, among other uses. In several of these systems (such as submerged wetlands or biofilters), filter materials are used. For example, zeolites and manganese oxides (MnOx) are reported in the literature as excellent candidates for use in water treatment due to their adsorption properties and, in the case of the latter, to its oxidation potential. In this work, a coating with a manganese oxide was carried out through a precipitation reaction on mordenite-type zeolitic material, to be used as a filter material in decentralized greywater treatment systems. The synthetized composite material was analyzed by the methylene blue adsorption test and the experimental data was adjusted to the Langmuir Isotherm model. The value of the specific surface area of the MnOx-coated mordenite-type zeolite was also estimated. With this analysis, it was possible to obtain preliminary results about the capacity of this material to decontaminate household greywater, which needs to be confirmed by further research.

Neighborhood-Scale Urban Water Reclamation with Integrated Resource Recovery for Establishing Nexus City in Munich, Germany: Pipe Dream or Reality?

With the rapid expansion of cities due to population growth and urbanization, conventional centralized wastewater collection and treatment systems are slowly becoming a burden; expensive maintenance is required for aging plants and piping infrastructure, the cost of expanding the capacity to cover demand from population growth, and new regulations for tighter control over certain pollutants such as micropollutants. As an alternative to this system, this study discusses the feasibility of decentralized treatment systems at the neighborhood scale. Taking a Water-Energy-Food (WEF) Nexus approach, such systems can support water and energy conservation, recovery of water, energy, and nutrients as well as generation of energy from wastewater, be customized to individual water and energy requirements, and eliminate the need for lengthy pipe networks. The method employed in this study is comparing the economic feasibility of the status quo to a proposed decentralized solution. The study finds that the costs of implementing a hypothetical decentralized water reclamation with an integrated resource recovery system using an anaerobic membrane bioreactor (AnMBR) in a downtown high-density neighborhood of the city of Munich, Germany, can theoretically be recuperated within two years. This alternative system may cost 60% of what it costs to run the centralized system. By linking the AnMBR to a biogas digestor and using systematically harvested organic waste as a co-substrate, the decentralized system can generate enough energy to run itself and even feed some energy to the grid. This study is highly hypothetical, yet generating evidence such as this can support a systemic socio-technical transition towards a more circular economy with optimal resource recovery.

A novel concentrated solar membrane-distillation for water purification in a building integrated design

Solar-assisted Vacuum Membrane-Distillation provides a lower-energy alternative to water treatment, particularly desalination in dry areas. While horizontally integrated (roof-top) decentralized treatment systems exist, vertically integrated (balcony) water treatment systems remain unexplored. This study improves upon a previous solar-VMD system with a compound parabolic collector and integrate it onto the vertical faces of a building. The novel VMD system generates a flux of >8 L water per square meter of membrane area per hour when operating at a temperature above 65 °C and with a 15 kPa vacuum pressure during peak solar conditions (>800 W/m2). This system's performance was identical under clean-water and desalination operating modes, reinforcing the use-case of urban desalination. Furthermore, a numerical model was developed and validated to be utilized for parametric study. Finally, an economic analysis has shown that the system has a levelized cost of water of 21.5 USD/m3, with the cogeneration of heat via hot water (i.e., a levelized cost of heat of 0.015 USD/kWh) off-setting costs. Assuming a use-case of rural implementation whereby water transport costs dominate, the payback period of the design is around 2 years. Ultimately, this demonstrates a viable decentralized water treatment/hot-water system that can alleviate water scarcity in arid areas.

Efficacy Assessment of Decentralized Wastewater Treatment Systems in treating Faecal Sludge within Dar es Salaam City

Dar es Salaam Water and Sewerage Authority (DAWASA) considers DEWATS as effective system for faecal sludge management especially from unplanned settlements. No study has been done in Tanzania to assess the treatment efficiency, adoptability and sustainability of the systems. That being the case, this study aimed at assessing the treatment efficiency of the Decentralized Treatment Systems installed within the city. Kigamboni and Mburahati DEWATS were selected as case study areas for the study whereby, quantitative method was used for data collection. The collected results showed that most of the physical parameters were within the allowable range specified by Tanzanian Standards for municipal wastewater discharge (TZS 860:2006). Nitrate and Phosphate levels were within the allowable range at both treatment plants. The BOD5 and COD for Kigamboni DEWATS were four times higher than the maximum allowable safe limit for each. Both Kigamboni and Mburahati DEWATS failed to lower the coliform levels of faecal sludge to meet the maximum allowable discharge standard (10,000 cfu/100 ml) by having the effluent quality of 115,000 cfu/ 100 ml and 22,875,000 cfu/100 ml respectively. Addition of dosing chamber between the gravel filter and polishing dosed at 6mg/l of chlorine remediated the state.

Inconvenient truth: unsafely managed fecal sludge after achieving MDG for decades in Thailand

Abstract In most low- and middle-income countries, due to financial constraints and improper management practices, the expansion of conventional centralized systems to enhance wastewater management services is not practical. Despite the fact that the majority of the world population has met the Millennium Development Goals 7c (MDG7c) targets, more than 2.5 billion are still using unimproved sanitation facilities and affecting the safety of drinking water and public health. Because of this problem, a novel approach on ‘Non-Sewered Sanitation’ with decentralized treatment systems is being recognized as a promising alternative to accomplish the Sustainable Development Goal No. 6 (SDG6) targets on ‘Safe Water and Sanitation’ and bringing health benefits to the people. This study aimed to investigate the current status of access to improved sanitation facilities in relation to the MDG7c and SDG6 in Thailand and comparing with other countries, including the effects of unsafely managed fecal sludge (FS) on the prevalence of diarrhea and liver fluke infections. The prevailing constraints and weaknesses were identified, and effective sanitation management measures to accomplish SDG6 targets were recommended. Based on data collected from 20 cities located in the north and northeastern regions of Thailand during the period of 2015–2020, the sanitation facilities data on conventional centralized systems and FS management facilities that affect the prevalence of diarrhea and liver infections were analyzed and interpreted using statistical and response surface methodology techniques. The findings showed that most of the surveyed cities have achieved the MDG7c targets, but 70% of the FS generated from on-site sanitation systems are still unsafely managed, caused by limited expansion of sewage systems for wastewater collection and conveyance (with inadequate operation and maintenance) as well as the financial constraints, especially in areas outside of urban neighborhoods. The effective sanitation management practices to accomplish the SDG6 targets were proposed such as increasing the capacity of sanitation facilities to be 55,000 m3/day/30,000 households, designing appropriate FS collection program and treatment technology, and providing more awareness programs for safe sanitation management and health risk protection.

Development of a semi-quantitative approach for the assessment of microbial health risk associated with wastewater reuse: A case study at the household level

This study proposes a modified methodology for semi-quantitative microbial risk assessment (SQMRA) based on the risk matrix presented in the World Health Organization (WHO) Sanitation Safety Planning manual adding the variable ranking for probability of infection in the estimations of risk scores, which composes the risk matrix. The approach is applied to cases where quantitative microbial risk assessment (QMRA) studies are hindered by the lack of information regarding pathogens in the (waste)water, collected as a set of primary data. The methodology is fully described and its application is demonstrated by comparing the microbial risk to which individuals are exposed within a residence in different scenarios of direct or indirect exposure to wastewater. Three current scenarios and one proposed scenario, with four sub-scenarios, focused on the use of a decentralized treatment system and greywater reuse in a single-family residence. Scenarios were selected for application of the SQMRA to elucidate if solutions considering source separation and reuse would bring more health-related risks, or attenuate the existing ones related to the conventional onsite wastewater treatment and soil disposal. None of the studied alternatives achieved risk score above 160 (very high). Considering the average score of each alternative by exposed group, the current scenarios, representing low-cost, informal solutions, posed the highest risks for children. All proposed reuse types reduced the risks from high to medium (score 43.9) for children and from medium to low (score 22.2) for adults. The adapted approach was demonstrated to be a useful tool, aiding the decision-making process and clarifying uncertainties raised when source separation and household reuse are proposed.

Phosphorus Recovery from Wastewater: Bioavailability of P Bound to Calcareous Material for Maize (Zea Mays L.) Growth

(1) Phosphorus (P) is an essential plant nutrient, and P deficiency negatively affects plant growth and development. Furthermore, P is a finite and nonrenewable resource, and there is an urgent need to recover P from some of the important waste streams in society. Newly engineered calcareous materials (sol–gel coated cat litter (CATSAN®)) can bind P from wastewater in decentralized treatment systems and potentially enable P recycling into agricultural production by direct addition of the P saturated material. (2) The effects of the addition of two P-enriched calcareous materials as fertilizers for maize (Zea mays L.) growth were investigated in a mesocosm experiment. We compared fertilization with the P-enriched materials at rates of 6, 12, 25, 50, 100 kg P ha−1 yr−1 with fertilization with commercial NPK fertilizer. (3) The P fertilization by the P-enriched materials had a significant positive effect on plant height, biomass, maximum light-saturated photosynthetic rate, respiration rate, and total P content in biomass. However, plants fertilized by the commercial NPK fertilizer performed significantly better in the majority of measured parameters at identical fertilization rates. (4) The bioavailability of the P bound to the calcareous material was very low. However, the studied material has the potential to be used as part of a decentralized treatment solution to remove and subsequently recover and recycle P from wastewater.

Assessment of water reuse potential of wastewater treatment systems used in Mumbai, India

Ever growing population of Mumbai has put additional pressure on existing infrastructure in terms of huge demand for portable water as well as treatment of city’s waste water. Study aimed at review of city’s wastewater in order to understand the reality of treatment quality of wastewater, it’s reusability in terms of offsetting growing water demands of domestic, industrial and agricultural fields in and around the city. Literature review and case study method was used in order to get primary as well as secondary data for achieving data regarding overall functioning and water balance of the city. Because of lot of irregularities, current wastewater management systems are asking for paradigm shift from current centralized wastewater treatment systems to decentralized wastewater treatment systems. Conventional treatment systems treat wastewater as a ‘waste’ yet there is some reuse potential. Concept of collecting water and wastewater separately for better treatment, increased reuse potential, savings upon energy and better nutrient recovery can be used in order to move towards more ecologically and economically sound waste water management systems. To demonstrate this idea documentary and discourse analysis is used. The paper starts by providing general overview about water scarcity and security in India and then proceeds to provide comparative analysis between centralized and decentralized treatment systems used in the city in order to identify it’s water reuse potential. Second, legislative and policy framework used in the city for wastewater treatment and management which is then followed by outline of the current situation and reflections on system dynamics in City. Third, the paper ends with a discussion on practical implications, policy options and conclusion. The presented study gives conceptual model based on Net Zero concept which can be helpful in making of sustainable future cities.

Performance of a novel vertical flow constructed wetland for greywater treatment in rural areas in Jordan

ABSTRACT Jordan is facing severe challenges in terms of water scarcity and wastewater management. Thus, there is a growing need for adopting innovative approaches to overcome these challenges. Within the framework of this study, a pilot project was implemented to treat household greywater in rural areas in Jordan with a purpose of reuse for irrigation. The project consists of designing and developing four vertical flow constructed wetland (VFCW) systems located in different sites and integrating them in a decentralized treatment system. The project work aims particularly to present a model of an innovative, compact and effective modified VFCW system. The performance of the systems was assessed by analyzing the quality of the influent and effluent streams through testing 19 water quality parameters. The results revealed that the design was adequate and efficient in treating greywater as exemplified by removal efficiencies of 90%, 90% and 92% for BOD, COD and TSS respectively. Moreover, the other physico-chemical parameters (T-N, T-P, N-NO3-, Turbidity, Ca, Mg, SO4-, and heavy metals) measured in the effluent streams complied all with the Jordanian standards for unrestricted irrigation. Therefore, the outcomes of the current study can be invested to support the use of constructed wetlands in Jordan as a sustainable technology to improve the wastewater management practices and reinforce the decentralized wastewater treatment approach in rural areas.

Phosphorous recovery from septic tank liquor: Optimal conditions and effect of tapered velocity gradient

The growing recognition of the potential of recovery of products from, and recycling of, wastewater is matched by a growing interest in decentralized treatment systems. Sanitation-focused policies and interventions, undertaken by many developing countries, are dominated by septic tanks for septage management. As reserves of phosphate rock continue being depleted, recovery of phosphorus (P) from the waste stream is one of the practical strategies to deal with that depletion. Partial anaerobic digestion of septic tank liquor converts organic P to soluble orthophosphate form, allowing it to be recovered. Factors that influence such recovery, namely pH, the molar ratio of magnesium (Mg) to P, velocity gradient, and mixing duration were tested and optimized for recovering P as struvite. Interactions between the above factors and their possible influence on the efficiency of P recovery were also examined. Under optimal conditions, more than 90% of P could be recovered. The maximum size of struvite crystals was 201 μm. Among the factors that influenced P recovery, pH and the Mg/P ratio affected recovery efficiency whereas the velocity gradient and mixing duration affected the size of struvite crystals. Tapering the velocity gradient not only increased the crystal size significantly, from 280 μm to 371.9 μm, but also reduced energy requirement by 62%. The study showed that new reactors designs can be based on the concept of tapered velocity gradient to improve the properties of struvite crystals.

Designing the Next Generation of Fe0-Based Filters for Decentralized Safe Drinking Water Treatment: A Conceptual Framework

The ambitious United Nations Sustainable Development Goal for 2030 to “leave no one behind” concerning safe drinking water calls for the development of universally applicable and affordable decentralized treatment systems to provide safe drinking water. Published results suggest that well-designed biological sand filters (BSFs) amended with metallic iron (Fe0-BSFs) have the potential to achieve this goal. Fe0-BSFs quantitatively remove pathogens and a myriad of chemical pollutants. The available data were achieved under various operating conditions. A comparison of independent research results is almost impossible, especially because the used Fe0 materials are not characterized for their intrinsic reactivity. This communication summarizes the state-of-the-art knowledge on designing Fe0-BSFs for households and small communities. The results show that significant research progress has been made on Fe0-BSFs. However, well-designed laboratory and field experiments are required to improve the available knowledge in order to develop the next generation of adaptable and scalable designs of Fe0-BSFs in only two years. Tools to alleviate the permeability loss, the preferential flow, and the use of exhausted filters are presented.

Performance evaluation of a down-flow hanging sponge (DHS) reactor as a decentralized domestic wastewater treatment system in tropical regions

In this study, a pilot-scale down-flow hanging sponge (DHS) reactor was operated in the community plant of Bangkok for the treatment of domestic wastewater (COD 285 mg/L, BOD 105 mg/L) collected by separate sewer to evaluate the reactor’s feasibility as a decentralized treatment system. The DHS reactor was operated for 600 days at ambient temperatures of 25–30 °C, both with constant flow conditions and with fluctuating flow conditions that simulated wastewater discharge patterns of the community. The results indicate that under constant flow at an HRT of 5 h, the volumetric loading rates of 0.36 kgBOD/m3-sponge/day and 0.16 kgN/m3-sponge/day were the optimum operational conditions of the DHS reactor in order to satisfy the effluent discharge standards. The DHS achieved removal rates of 89, 95, 91 and 90% for COD, BOD, TSS and NH4-N. Under the fluctuating flow condition, improvement of denitrification was confirmed at volumetric loading rates of 0.50 kgBOD/m3-sponge/day and 0.18 kgN/m3-sponge/day. The fluctuating flow of wastewater positively affects retained sludge activities in terms of homogenizing sludge concentration and stimulating oxygen uptake rates. These results suggest that the DHS reactor can be applied as a decentralized treatment system for domestic wastewater with fluctuating flow rates in tropical regions.

PROPOSTA DE UM SISTEMA DE TRATAMENTO DESCENTRALIZADO A PARTIR DA CARACTERIZAÇÃO DAS ÁGUAS RESIDUÁRIAS DA FAZENDA EXPERIMENTAL DA UNINCOR, TRÊS CORAÇÕES – MG

As águas residuárias são oriundas das atividades domésticas e/ou institucionais e apresentam características em função dos usos à qual a água foi submetida. Este trabalho teve como objetivo caracterizar quantitativamente e qualitativamente as águas residuárias da Fazenda Experimental da UninCor, em Três Corações/MG e propor um sistema de tratamento decentralizado. Assim, realizaram-se visitas “in loco” para observar as atividades diárias desenvolvidas pelos usuários e sua frequência visando identificar quantitativamente as águas residuárias, conforme NBR 7229/1993, a vazão em L.dia-1. Das atividades observadas, tem-se águas residuárias proveniente do uso de vasos sanitários, lavatórios, cozinha, máquina de lavar, limpeza em geral e do centro cirúrgico do hospital veterinário, que apresentam um elevado teor de carga orgânica em função da grande quantidade de sangue e do alto teor de gorduras. A amostra para caracterização qualitativa das águas residuárias foi coletada e analisada em laboratório conforme os procedimentos estabelecidos no Standart of methods” (APHA, 2005). As variáveis avaliadas foram matéria orgânica (DBO5 e DQO), pH, turbidez, condutividade elétrica, cloretos e amônia. Foi quantificada uma vazão de 1.500 L/dia de efluentes da Fazenda Experimental da UninCor. Sendo que, para o tratamento desses efluentes e, de acordo com os resultados para caracterização qualitativa a relação DQO/DBO apresentou valor de 1,77, viabilizando-se a proposição de um tratamento biológico para estas águas residuárias. Conclui-se após a caracterização quantitativa e qualitativa que o tratamento das águas residuárias da Fazenda UninCor será por um sistema descentralizado, por de meio de tanque séptico seguido de wetlands.

Household-based biodigesters promote reduction of enteric virus and bacteria in vulnerable and poverty rural area

The present study evaluated the river water quality improvement by implementation of household-based biodigesters in vulnerability and poverty rural area, in Minas Gerais State-Brazil. For that, 78 household-based biodigesters were installed for domestic wastewater treatment. Wastewater was collected before and after treatment and the physicochemical parameters and pathogens removal (human adenovirus (HAdV), hepatitis A (HAV) virus, Salmonella sp. and Escherichia coli) were evaluated; Additionally, river water was sampled before and after the household-based biodigesters implementation, to verify the contamination reduction and the positive impact of domestic wastewater treatment on waterborne pathogen reduction, considering HAdV, HAV, Salmonella sp. and E. coli quantification. The applicability in real-scale of decentralized treatment systems using household-based biodigesters promoted reduction of 90, 99, 99.99 and 99.999% from HAV, Salmonella sp., E. coli and HAdV from domestic wastewater, respectively; The river water quality improvement before the wastewater treatment application was highlight in the present study, considering that the reduction of waterborne pathogens in this water in 90, 99.99 and 99.999% of E. coli, HAV and HAdV, respectively (Salmonella sp. was not detected in river water). In general, this is an important study for encouraging the decentralized sanitation in vulnerable and poverty area, as well in rural sites, considering the positive impact of this implementation on public health.

Algae turf scrubber and vertical constructed wetlands combined system for decentralized secondary wastewater treatment.

Water shortage is a current problem faced by many regions. The deterioration of water bodies driven by the directly discard of untreated wastewater worsens the water shortage and implies in more costly treatments to meet local standards for water quality. In rural areas, the problem is even worse, once conventional centralized treatment plants do not encompass them. Decentralized treatment systems must present low-cost, local availability, standards-meeting efficiency, and simplified operation. The present study examines the combined use of algae turf scrubber and down-flow vertical constructed wetlands for a University's sanitary wastewater treatment. After a hydraulic detention time of 21days, the unit was able to reach 49%, 48%, 98%, 82%, 99.2%, 70.1%, 44%, 83%, 72%, 86%, 69%, 95%, and 99.9% for conductivity, total soluble solids, turbidity, apparent color, N-NH3, total nitrogen, P-soluble, total carbon, chemical oxygen demand, inorganic carbon, TOC, Escherichia coli, and total coliforms. In accord to the Brazilian standard ABNT 13969/97, the treated effluent is eligible for reuse in floor and sidewalks washing, garden irrigation, and landscaping purposes.