Treatment Of Liquid Effluents Research Articles

High Aluminum content in the aquifer of Camaçari industrial pole, state of Bahia, Brazil: Correlation with natural and anthropogenic environmental factors using multivariable analysis

<p class="MsoNormal">This work used multivariable analysis to correlate groundwater high aluminum content in the area of the Liquid Effluent Treatment Center—CETREL of the Camaçari Industrial Pole, with natural environmental factors: geology, hydrogeology, precipitation, soil and vegetation; and anthropic: equipments of treatment and disposal of industrial waste from CETREL. This company made available data from 99 monitoring wells, period 2006–2016, with aluminum content above (0.2mg/L) the limit established by the Ministry of Health Ordinance Nº 888, 5 April 2021. Previous studies have indicated that there is no correlation of aluminum in groundwater of the Camaçari Industrial Pole with other metallic contaminants; also, that aluminum in the studied region is disseminated in the geological matrix, clayey soils, and poor and leached Cerrado soils. The Kruskal-Wallis test indicated significant correlation of high aluminum content with the treatment/disposal areas, geology, soil and vegetation; and no correlation with precipitation and hydrogeology. The four environmental factors indicating the highest average aluminum content (±C<sub>95%</sub>), in descending order, are: Clayey Soils, Organic Sludge Farm I, Marizal Formation, and Herbaceous-Subshrub Vegetation. The multivariable analysis indicated that, the most influential factors on the high aluminum content in groundwater of the CETREL region, are all ultimately associated with the leaching of aluminum present in the solid matrix. As CETREL processes are not correlated with aluminum residues, the results were an important information for the company environmental managers.</p>

High Aluminum content in the aquifer of Camaçari industrial pole, state of Bahia, Brazil: Correlation with natural and anthropogenic environmental factors using multivariable analysis

<p class="MsoNormal">This work used multivariable analysis to correlate groundwater high aluminum content in the area of the Liquid Effluent Treatment Center—CETREL of the Camaçari Industrial Pole, with natural environmental factors: geology, hydrogeology, precipitation, soil and vegetation; and anthropic: equipments of treatment and disposal of industrial waste from CETREL. This company made available data from 99 monitoring wells, period 2006–2016, with aluminum content above (0.2mg/L) the limit established by the Ministry of Health Ordinance Nº 888, 5 April 2021. Previous studies have indicated that there is no correlation of aluminum in groundwater of the Camaçari Industrial Pole with other metallic contaminants; also, that aluminum in the studied region is disseminated in the geological matrix, clayey soils, and poor and leached Cerrado soils. The Kruskal-Wallis test indicated significant correlation of high aluminum content with the treatment/disposal areas, geology, soil and vegetation; and no correlation with precipitation and hydrogeology. The four environmental factors indicating the highest average aluminum content (±C<sub>95%</sub>), in descending order, are: Clayey Soils, Organic Sludge Farm I, Marizal Formation, and Herbaceous-Subshrub Vegetation. The multivariable analysis indicated that, the most influential factors on the high aluminum content in groundwater of the CETREL region, are all ultimately associated with the leaching of aluminum present in the solid matrix. As CETREL processes are not correlated with aluminum residues, the results were an important information for the company environmental managers.</p>

Hazard Identification and Risk Analysis of Liquid Effluent Treatment Plant Apply in Chemical Process Industry

The chemical process industry is one of the categories of highly polluting industries and generates strong wastewater of high COD along with hazardous waste which requires effective treatment and disposal/reuse of effluents. In this review, the various sources of wastewaters in the chemical industry are identified and the best available technologies to remove them are critically evaluated. The aim of the present research work was to determine the behavior of various parameters of the chemical wastewater. During the entire study evaluate, monitor, and check various environmental parameters whether they are complying with a given standard or not given by regulatory authority at chemical Industry,. The India based industry produced bulk drugs, fatty acids, fatty alcohol, food additives, personal care products, and others. The monitoring data of the effluent treatment plant will give information on the pollution control by the company and the management of waste. Overall analysis showed that there is no significant difference in pH, BOD, COD, and ammoniacal Nitrogen. The use of conventional treatment methods along with membrane reactors and advanced post-treatment methods resulting in a Coagulation wastewater treatment technology appears to be the best

TECNOLOGÍAS DEL BENEFICIADO DE CAFÉ Y TRATAMIENTO DE EFLUENTES LÍQUIDOS

<p><strong>Background.</strong> The coffee processing process generates polluting solid and liquid waste. It is possible to reduce its effects through treatments that allow its use. <strong>Objective.</strong> To analyze the alternatives for the management of the effluents and residues generated in the coffee processing process to reduce its effects and to show treatments that have had positive results. <strong>Methodology.</strong> To obtain the information, specialized search engines were used in databases such as: RESEARCHGATE, GOOGLE SCHOLAR, CIRAD, CATIE, IICA, ELSEVIER, SCIENCIE DIRECT, REDALYC, SCOPUS. An exploration and analysis of 100 documents related to the following topics was carried out: 1) history of the use of effluent treatment systems in coffee processing, 2) types of treatments for the management of liquid and solid waste, 3) operation of these technologies, capacity, place where the research was carried out, variables measured, as well as the capacity of these systems. The search period was planned from 1980 to 2023. The history of the beginning of the systems for the treatment of waste generated in coffee processing was also investigated. The key words used for the search were: wet processing, wastewater, solid and liquid waste, coffee by-products, treatment systems, chemical oxygen demand, biological oxygen demand, total solids, turbidity, anaerobic treatments, and aerobic treatments. Approximately 100 documents were reviewed for the writing of the paper. <strong>Main findings.</strong> Research has been reported since 1980. Colombia and Mexico have focused on the development of machinery to mechanize processing operations to reduce water use, as well as anaerobic treatment systems, biodigesters and wetlands. <strong>Implications.</strong> It is necessary to know the main methods of wastewater treatment in the coffee processing process to determine the most suitable in coffee growing regions. <strong>Conclusions.</strong> Anaerobic biodigestion technology is the most used for the treatment of liquid effluents and with the best results. For the solid effluent, different alternatives are used for substrate such as the extraction of substances for industry, composting and biomaterials, among others.</p>

Study on two-step ozone treatment of liquid effluents from livestock farms

Wastewater ozonation, for epidemic animal diseases, is an effective method. The disadvantage of this method is relatively high percentage of unreacted ozone (10-40%). This paper proposes a combined method of mixing ozone with liquid effluents: first - barbotage, and at the second stage - injection or mechanical emulsification. It was found that the two-stage treatment increases the mixing efficiency (respectively disinfection) to 88 - 90 %.

Photocatalytic treatment of real liquid effluent from hydrothermal carbonization of agricultural waste using metal doped TiO2/UV system

This study investigated treatment of real liquid effluent generated from hydrothermal carbonization (HTC) of macadamia nut shell by employing transition metals Cu, Ni, and Fe doped titanium dioxide (TiO2) photocatalysts. The anatase TiO2 based photocatalysts were prepared via sol-gel method, and calcined at 400 °C. The modification with metal dopants was performed via ultrasonic assisted incipient wetness impregnation method. The prepared photocatalysts were characterized using XRD, UV-Vis DRS, SEM-EDX, and N2 physisorption. The influence of metal dopants, types of TiO2 support, and initial pH of the wastewater on the photocatalytic degradation performance of total organic carbon (TOC) and chemical oxygen demand (COD) in the wastewater were investigated. The results revealed that Fe doped TiO2 exhibited the highest photocatalytic activity followed by Cu and Ni, respectively. Among all, Fe doped anatase TiO2 were the most promising catalyst as it performed the highest removal of 75.1% for TOC and 94.1% for COD after 1 h irradiation at pH 4, achieving the lowest TOC and COD concentration of 405.62 mg/L and 91.26 mg/L, respectively. The findings suggested that photocatalytic degradation of HTC liquid effluent could be a potential treatment before releasing the wastewater to the environment.

Hydroponic rhizofiltration of dairy wastewater by Coleus Scutellarioides &Portulaca Oleracea

Rhizofiltration through floating hydroponic process (FHP) is a cost effective and prospective technique for the treatment of liquid effluents. Coleus scutellarioides and Portulaca oleracea are effective macrophyte for phytoaccumulation because of their morphological and physiological properties. A limited study has been performed with macrophyte in treating dairy wastewater. An initiative has been taken with a table scale experimental study to evolve a bio-raft based Portulaca oleracea and Coleus scutellarioides for treatment of dairy effluent with non-aerated and aerated on raw dairy effluent. First time in research the Coleus scutellarioides and Portulaca oleracea have been grown hydroponically in combination with aeration. Amidst the treatment system, aerated Portulaca oleracea floating hydroponic process shows maximum removal efficiency in phytoaccumulation of raw dairy wastewater. The study outcomes exhibited a remarkable reduction in TSS (79.43 %), TDS (64.36 %), BOD (82.36 %), and COD (81.86 %) from aerated system. Study found that the nutrient contents such as total phosphorous (75.55 %), phosphate (74.24 %) and total nitrogen (74.67 %) are also accumulated by Portulaca oleracea efficiently. Nutrients accumulation attributed to the growth of Coleus scutellarioides and Portulaca oleracea. The study presents a low cost promising future for fostering a sustainable technology for treatment of dairy effluent.

Uso de residuos de café como biosorbente para la remoción de metales pesados en aguas residuales

El presente artículo presenta una revisión de los diferentes residuos del beneficio y consumo de café, usados como material adsorbente en la biosorción de metales pesados de soluciones acuosas. Se esboza en primera instancia particularidades de la biosorción, como los mecanismos de captura de los contaminantes, tipos de materiales adsorbentes, entre ellos los provenientes del café, como las variables que controlan el proceso. En una segunda instancia se plasman investigaciones en relación a la biosorción, en las que se desarrollaron cinéticas químicas para evaluar velocidades de remoción de los metales pesados, e isotermas para determinar tasas o capacidades de adsorción con los residuos de café modificados térmica o químicamente. Se puede señalar que muchos autores han encontrado ventajas competitivas frente al uso de residuos café como la pulpa, borra, mucílago, entre otros, en comparación con adsorbentes convencionales, debido a su propiedades fisicoquímicas los convierten en unos excelentes intercambiadores iónicos , son de alta abundancia debido a la vocación agrícola del país y al alto consumo del café a nivel nacional e internacional, además de su bajo costo y facilidad de manejo y tratamiento, concluyéndose entonces que dichos materiales presentan un futuro promisorio en el tratamiento de efluentes líquidos.

Carbon footprint of the Novosibirsk region Waste sector

To achieve carbon neutrality in Russia by 2060, it is necessary to regulate the volume of greenhouse gases at the regional level. Among all regions of Russia, the balance of greenhouse gases by sectors of the economy is calculated only for the Sakhalin region. The study of this article aims to assess the level of greenhouse gas emissions from the Waste sector in Novosibirsk region, taking into account territorial and sectoral characteristics. During the study, the authors used the methodology of the Intergovernmental Panel on Climate Change and the methodological recommendations of the Ministry of Natural Resources and Environment of Russia № 15p, through which the authors evaluated methane (CH4) and nitrogen oxide (N2O) emissions from solid waste disposal and from the treatment of liquid waste and effluents. Greenhouse gas emissions in 2020 were 1.57 mln. t CO2 equivalent, including 1.09 mln. t CO2-equivalent from solid waste disposal and 0.48 mln. t CO2 equivalent from liquid waste and sewage treatment. The main contributor to the growth of greenhouse gas emissions was emissions from solid municipal waste disposal, increasing by 0.06 million tons of CO2-equivalent over the past four years. Analysis of the current state and calculation has shown that the Novosibirsk Region has a low level of infrastructure development for separate waste collection, capacities of waste-sorting plants, as well as equipment of the centralized sewage system and quality of waste and effluent treatment. Therefore, it is necessary to introduce resource-saving and low-waste technology, the formation of a closed-cycle economy, the implementation of the transition to the multi-container separate collection of waste. It is advisable to disseminate technologies for collection of landfill gas and its use as fuel, the direction of organic waste for the production of commercial compost, biogas or feed and feed additives, as well as the development of technologies for obtaining biochar from organic waste and its further use in agriculture.

Production of Plant Proteases and New Biotechnological Applications: An Updated Review.

An updated review of emerging plant proteases with potential biotechnological application is presented. Plant proteases show comparable or even greater performance than animal or microbial proteases for by‐product valorization through hydrolysis for, for example, cheese whey, bird feathers, collagen, keratinous materials, gelatin, fish protein, and soy protein. Active biopeptides can be obtained as high added value products, which have shown numerous beneficial effects on human health. Plant proteases can also be used for wastewater treatment. The production of new plant proteases is encouraged for the following advantages: low cost of isolation using simple procedures, remarkable stability over a wide range of operating conditions (temperature, pH, salinity, and organic solvents), substantial affinity to a broad variety of substrates, and possibility of immobilization. Vegetable proteases have enormous application potential for the valorization of industrial waste and its conversion into products with high added value through low‐cost processes.

Sustainable management of textile solid waste materials: The progress and prospects

Textile industries produce large quantities of liquid and solid waste materials with toxic components that can pollute land and water resources. The treatment of liquid effluents is ongoing while management of solid wastes and sludge is neglected for their incineration and landfilling. The management approaches are not sustainable since they extend the pollution and lead to global warming and climate variation. This minireview explores the types of solid wastes produced during textile processing from manufacture to post-consumption. The study also reviews the dominant approaches of managing such wastes using empirical evidence with the aim of suggesting sustainable approaches to manage the wastes. It was found that landfilling and incineration approaches predominantly used to manage textile solid wastes result to more environmental harm and therefore, reuse, recycling biological and radiological degradation of such wastes was recommended for sustainability. The sustainable methods were found to reduce greenhouse gas emissions, reduce consumption of new fabric and encourage eco-friendly production of new materials from the textile wastes. The success of the methods is however limited due to the refractory nature of some textile waste components, slow activity and efficacy and hence more advances in their research and technology are suggested to validate the sustainability claim in the technologies.

Adsorption of Crystal Violet on Rice Husk Activated Carbon

The need to develop effective technology for the treatment of liquid effluent of dye-intensive industries such as textile, rubber, paint, and printing is synonymous with the need to save the life-threatening risks posed by these carcinogenic and mutagenic pollutants on human and aquatic lives. Isotherms of adsorption of crystal violet (CV) on activated carbon (AC) synthesized from rice husk are presented herewith to elucidate the mechanism of the adsorption process of crystal violet dye contaminated water on rice husk activated carbon. AC was synthesized from rice husk via a phosphoric acid activating agent at low temperatures. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D-R) isotherm studies were employed. The mean square values for Langmuir, Freundlich, Temkin and D-R models were 0.98, 0.91, 0.94, and 0.63, respectively. Analysis of the isotherms of the adsorption of crystal violet sorbate on the synthesized rice husk sorbent suggested that the adsorption process proceeded via a homogeneous monolayer mechanism. Langmuir isotherm gave the best fit of the adsorption process. Langmuir isotherm constant was –1.40 l/mg, and the equilibrium adsorption capacity was 13.53 mg/g.

OBTAINING THE SILICON-CONTAINING TITANIUM PHOSPHATE UNDER HETEROGENEOUS SYNTHESIS CONDITIONS

The authors investigated the synthesis of composite materials produced by not simply mixing the components mechanically. The materials are chemically derived on the basis that the combined action of the beneficial properties of such compositions significantly outweighs the action of each component due to synergistic effects. For this purpose, a titanosilicate precursor, TiO2∙nSiO2 (ТSP), synthesized from an accessible technogenic waste containing the mineral titanite (CaSiTiO5) was used. Researches were carried out in the heterogeneous system TiO2∙SiO2-H3PO4-H2O. And the innovative method was developed for obtaining silicon-containing titanophosphate of the composition TiOHPO4∙2H2O or TiO(H2PO4)2·2H2O, depending on the structural features of TSP, as well as on the synthesis conditions - phosphoric acid concentration and temperature. The influence of structural characteristics of titanosilicate precipitate on its chemical activity in heterogeneous synthesis of silicon-containing titanophosphate was studied. The synthesised mesaporous material is a powder with a particle size of 5-15 µm. The correlation between the phase composition of the synthesised compositions and the surface properties of their particles is shown. The sorption capacity of the obtained titanophosphates in the static mode was determined. In particular, the more titanophosphate phase is in the composition of the composition, the higher are the values of Ssp and Vpore particles and therefore their sorption capacity is higher. When comparing the sorption properties of synthesised and conventional sorbents, ion exchange resins and titanium phosphates, used for purification of liquid effluents from Sr2+, Cs+, Co2+ cations, comparable indicators were obtained. The results have shown that the use of silicon-containing titanium phosphate for the treatment of liquid effluents containing non-ferrous metal cations as well as radionuclides may be promising.

Advanced Oxidative Techniques for the Treatment of Aqueous Liquid Effluents from Biomass Thermochemical Conversion Processes: A Review

Advanced Oxidative Techniques for the Treatment of Aqueous Liquid Effluents from Biomass Thermochemical Conversion Processes: A Review

Valorization of potato peel residues to produce a bioflocculant to be used in the treatment of liquid effluents

The present study aims primarily to investigate the flocculation capacity of a novel potato peel-based bioflocculant in wastewater treatment. The analysis of wastewater revealed high COD and BOD5 contents that could respectively reach the values 529.08 mg O2/l and 317.03 mg O2/l. In addition, the effect of experimental parameters such as the pH, coagulant/flocculant dosage, and contact time, was studied using the coagulation-flocculation treatment technique. The experiments were carried out with a lab-scale jar-test apparatus where aluminum chloride (AlCl3) was used as a coagulant agent. It should be noted that the optimal dose of AlCl3 was equal to 0.6 g at 10 mn, with turbidity reduction of 99.01%. Moreover, the flocculation tests showed higher turbidity removal (98%), for a flocculant dosage of 0.2g. The results obtained in this study indicated that using the natural potato peel-based flocculant, in the presence of a coagulant, provides an effective and environmentally friendly coagulation option for wastewater treatment.

Copper recovery from sludges generated in the electrolyte treatment plant of a pyrometallurgical complex

Electrolytic sludge is generated in the last stage of the electrolyte decontamination treatment plant in the manufacture of cathodic copper (> 99.99 % Cu). Currently, this sludge is recycled back to the process due to the high concentration of copper, although its recirculation involves a serious problem of arsenic accumulation in the industrial process. This negatively affects the quality of commercial copper. Therefore, the main focus of this study was the recovery of copper contained in the electrolyte sludge as copper (II) sulfate pentahydrate (CuSO4∙5H2O) for its return to the industrial process and/or commercialization. The remaining waste, which contains mainly As and other toxic chemical species, were eliminated in a controlled repository. To this end, an exhaustive characterization of the electrolytic sludge was performed to determine its chemical composition, mineral phases, and particle size. The main results indicated that the sludge was composed of very fine particles (~ 99 % < 100 μm), containing mostly Cu (~ 54 %) (Cu3As, Cu2O, Cu and CuSO4∙xH2O), As (~ 10 % as Cu3As) and S (~ 7 % as CuSO4∙xH2O). More than 90 % of the Cu contained in the sludge was recovered as very pure copper sulfate (≥ 99.5 %) by an evaporative crystallization process. In addition, around 70 % of the As was removed in the process as a solid (> 99 % in As2O3). The rest of pollutants remained in the final solution, which ultimately will be treated in the liquid effluent treatment plant. Therefore, valorization of the electrolytic sludge was achieved by copper recovery as CuSO4∙5H2O using evaporative crystallization; this process was an effective way for both recovering Cu and removing the As contained in the electrolytic sludge generated in the electrolyte treatment plant.

Application of Artificial Neural Networks in the Tertiary Treatment of Liquid Effluent with the Microalgae Chlorella vulgaris

AbstractModeling of biotechnological processes is difficult due to their nonlinear characteristics. Therefore, an artificial neural network was developed as a viable option for the prediction of the main variables of the tertiary treatment with Chlorella vulgaris. The network was designed with a hyperbolic tangent activation function and trained using a set of experimental and simulated data. The Levenberg‐Marquardt algorithm was used to train the network; four input neurons (luminosity, ammonium ion, phosphate, and initial biomass concentrations) and two output neurons (ammonium ion and phosphate concentrations) were fixed. The network architecture with one hidden layer [4,7,2] was chosen because it presented the lowest mean square error of the test combined with high R2, indicating that the network provides a good model for use in real applications.

Photocatalytic Concrete Blocks Nanomodified with Zinc Oxide for Paving: Mechanical Performance and Microstructural Characteristics

Abstract Concrete block pavement is considered an ideal substrate for the application of photocatalyst materials. In the paving area, titanium dioxide (TiO2) has been the most widely used semiconductor because of its properties. However, zinc oxide (ZnO) has been recently used as an alternative material to TiO2 in heterogeneous photocatalysis, being applied mainly for the treatment of liquid effluents. In this perspective, the aim of this study was to evaluate the capacity of concrete blocks nanomodified with ZnO in the degradation of nitrogen oxides (NOx) as well as the impact of the nanomaterial on the mechanical properties and microstructural characteristics of concretes. For this purpose, concretes were produced with ZnO incorporation of 3 %, 6 %, and 9 %, being submitted to photocatalytic tests, simple compressive strength, flexural strength, and dynamic Young’s modulus, as well as mercury intrusion porosimetry tests and image evaluations using scanning electron microscopy. Together, evaluation of the influence of nano-ZnO on cement paste hydration reactions was carried out. It could be concluded that the addition of ZnO to concrete provides photooxidative capacity to the material; however, it impairs the mechanical performance and the development of the cementitious matrix microstructure.

Assessment of Concept Feasibility of Combined Electrolysis and Catalytic Exchange in Decontamination of Low Deuterium – Tritiated Heavy Water

A CANDU type fission reactor maintains large amounts of heavy water inventory with desired isotopic purity for use in the moderator and coolant circulation loops. But substantial amounts of water escape out of reactor system pressure boundaries and fills into the containment building volume due to normal, off-normal, maintenance and emergency activities in the power station. The heavy water escape poses a radiological hazard owing to the tritium activity and thus needs to be processed in heavy water inventory management units and the nuclear power station effluent treatment facility. These escapes are collected using vapour/liquid recovery systems of power station and processed either in vacuum distillation based upgrading columns or treated directly in liquid effluent treatment units and discharged into environment. Whenever the escapes recovered are small in quantities and low in deuterium isotopic purity, chemical exchange based Combined Electrolysis and Catalytic Exchange process is a more viable option for decontamination over conventional distillation. This paper assesses the concept feasibility of using CECE process as an effective volume reduction method for decontamination of low deuterium-tritiated heavy water. The study proposes a scheme for decontamination considering a base case analysis in a typical CANDU station. It is theoretically proved that in comparison to the dilution methods followed in liquid effluent treatment units of power station, CECE process not only results in the recovery of valuable heavy water, but also in the reduction of diluent requirements by several orders of magnitude. Moreover, similar low radioactivity water effluents are expected during the operation of upcoming fusion reactors like ITER, DEMO facilities, etc. CECE based decontamination system shall be considered as an efficient effluent processing technology for nuclear material accounting and recovery of fuel isotopes in ITER, DEMO facilities also.

Pathogen flows from on-site sanitation systems in low-income urban neighborhoods, Dhaka: A quantitative environmental assessment.

Despite wide usage of on-site sanitation, there is limited field-based evidence on the removal or release of pathogens from septic tanks and other primary treatment systems, such as anaerobic baffled reactors (ABR). In two low-income areas in Dhaka, we conducted a cross-sectional study to explore pathogen loads discharged from commonly used on-site sanitation-systems and their transport in nearby drains and waterways. We collected samples of drain water, drain sediment, canal water, and floodwater from April-October 2019. Sludge, supernatant, and effluent samples were also collected from septic tanks and ABRs. We investigated the presence and concentration of selected enteric pathogens (Shigella, Vibrio cholerae (V. cholerae), Salmonella Typhi (S. Typhi), Norovirus Genogroup-II (NoV-GII), and Giardia) and presence of Cryptosporidium in these samples using quantitative polymerase chain reaction (qPCR).The equivalent genome copies (EGC) of individual pathogens were estimated in each sample by interpolation of the mean Ct value to the corresponding standard curve and the dilution factor for each sample type. Absolute quantification was expressed as log10 EGC per 100mL for the water samples and log10 EGC per gram for the sediment samples. Among all samples tested (N=151), 89% were contaminated with Shigella, 68% with V. cholerae and NoV-GII, 32% with Giardia, 17% with S. Typhi and 6% with Cryptosporidium. A wide range of concentration of pathogens [range: mean log10 concentration of Giardia=0.74 EGC/100mL in drain ultrafiltration samples to mean log10 concentration of NoV-GII and Giardia=7.11 EGC/100mL in ABR sludge] was found in all environmental samples. The highest pathogen concentrations were detected in open drains [range: mean log10 concentration=2.50-4.94 EGC/100mL], septic tank effluent [range: mean log10 concentration=3.32-4.65 EGC/100mL], and ABR effluent [range: mean log10 concentration=2.72-5.13 EGC/100mL]. High concentrations of pathogens (particularly NoV-GII, V.cholerae and Shigella) were frequently detected in environmental samples from two low-income urban neighbourhoods of Dhaka city. The numerous environmental exposure pathways for children and adults make these findings of public health concern. These results should prompt rethinking of how to achieve safe sanitation solutions that protect public health in dense low-income areas. In particular, improved management and maintenance regimes, further treatment of liquid effluent from primary treatment processes, and appropriate application of onsite, decentralised and offsite sanitation systems given the local context.