Sanitary Wastewater Treatment Research Articles

Singular Spectrum Analysis of Pathogenic Microorganisms in a Sanitary Wastewater Treatment System

Singular Spectrum Analysis of Pathogenic Microorganisms in a Sanitary Wastewater Treatment System

The influence of light intensities and micropollutants on the removal of total coliforms and E. coli from wastewater in a flat-panel photobioreactor

The presence of micropollutants and pathogens in sanitary wastewater and surface water is a growing concern that impacts public health, environmental balance and the maintenance of water supply services. To improve sanitary wastewater treatment, it is necessary to develop and improve sustainable technologies. Among the available options, microalgae-based systems stand out for their efficiency and generation of value-added byproducts. To study the impact of luminosity and the presence of micropollutants (13 selected) on the removal of E. coli and total coliforms from real anaerobically treated wastewater, a pilot flat-panel photobioreactor (50 L) was operated in batch mode in a tropical climate region. This is the first study to evaluate whether micropollutants interfere with coliform groups, considering a microalgae-based system and an experiment in a tropical climate region. E. coli had better removal (from 104 to 101 CFU 100 mL−1) than did total coliforms (from 104 to 103 CFU 100 mL−1). The removal of E. coli was more strongly linked to luminosity and temperature, while the removal of total coliforms was influenced by the presence of the selected micropollutants.

Wastewater quality index (WWQI) as an indicator for the assessment of sanitary effluents from the oil and gas industries for reliable and sustainable water reuse

With the development of numerous industries, the increasing use of water resources and the discharge of pollutants into the environment, particularly industrial wastewater, has become extremely important. The purpose of this study was the assessment of sanitary wastewater treatment plants attributed to the oil and gas industries as reliable and sustainable water resources based on the wastewater quality index (WWQI). The findings revealed that the facilities under investigation effectively process and discharge their effluents following the Environmental Protection Organization's standards. Springtime has the maximum removal in wastewater treatment plants (WWTPs), with typical removal values of COD and BOD5 of 96.1% and 97.1%, while pH in the effluent of these WWTPs was 7.22, and DO in the range of 1–6.3 mg/L throughout this period. In addition, fecal coli removal efficiencies were 98.6%, respectively. Finally, the wastewater treatment system in the four refineries investigated has resulted in a considerable decrease in microbiological and organic pollutants in conformity with environmental regulations permitting wastewater reuse for irrigation and agriculture, as well as discharge into adsorption wells. However these treatment plants perform poorly in terms of cumulative and WWQI models (13.86–16.05), it is clear from the results and discussion of this research that the results of the treated wastewater from the under-investigation plants comply with the Environmental Protection Organization of Iran's standards required for discharge to surface water or reuse in agricultural land irrigation. Still, the treatment system should be constantly audited and improved to reach a higher rank according to the WWQI.

Electro-Fenton systems for “on-site” sanitary wastewater treatment: Towards an off-grid technology for developing countries

Nowadays, 2.3 billion people in the world (almost a third of the planet´s population) live in communities that lack a sewer system and the financial resources for its installation. In this work, two electrochemical reactors based on the Fenton reaction were evaluated as a tertiary treatment for real sanitary wastewater which was obtained from a pre-treatment using biological processes. The evaluated systems were solar-powered, modular, off-grid operated and tested for open use. The processes consist on treating real sanitary wastewater with an anaerobic biodigester followed by a biological anoxic-aerobic stage and finally using the electrochemical reactors. The solid waste is stabilized using a solar heater and the outcoming aqueous effluent has an average organic matter concentration measured as chemical oxygen demand of 30.6 ± 10.1 mgO2 L−1, biological chemical demand of < 10 mgO2 L−1, total organic carbon of 14.8 ± 3.6 mgC L−1, total suspended solids of < 7.96 mg L−1 and total nitrogen of 36.2 ± 12.1 mgN L−1. The treated water falls below the limits established by the Mexican regulations on concentration of organic matter, total suspended solids, helminth eggs (HE) (< 1 HE L−1) and is close to the limit concentration for fecal coliforms. The goal of this study was to verify the functionality of the prototypes under realistic conditions so that these findings can contribute to the development of a technology for on-site sanitary wastewater treatment systems.

Determinação das variáveis operacionais de um sistema ecológico para tratar águas residuais sanitárias no semiárido

There is a growing importance of the theme of water reuse in the context of sustainable constructions. Currently, the increase in demand and the decrease in the supply of quality water is one of the problems that have been affecting, mainly, large urban populations. In this context, there is a need to encourage practices, programs and policies that help in water conservation. The reuse of water is a strategic activity, in addition to being an important tool in the integrated management of water resources. Given the above, regarding the reuse of water, there is the possibility of using sanitary wastewater for irrigation purposes. The present work had as general objective the development of the project of an ecological system for the treatment and agricultural use of sanitary wastewater on the campus of the Federal Rural University of the Semi-Árido (UFERSA), in Mossoró/RN, to mitigate possible environmental impacts caused by dispose of this effluent. For this, an ecological system for the treatment and agricultural use of sanitary wastewater was carried out, endowed with the survey of information necessary for the preparation of the executive project, where it was possible to estimate that in this facility approximately 61 people generate about 3.05 m³ d-1 of treated sanitary wastewater; and also calculate the dimensions of the treatment system; consisting of a septic tank with two chambers, a flooded system built with elephant grass extracting plant and a solar reactor; as well as preparing the calculation and descriptive memorials and the assembly of the systems executive project.

Advanced treatment of effluent extended aeration process using biological aerated filter (BAF) with natural media: modification in media, design and backwashing process

Biological aerated filters (BAFs) have high filtration efficiency due to their tolerance of hydraulic and organic shocks are suitable for the treatment of complex and sanitary wastewater. In this study, for the first time, natural media of date kernel from Bam city was used as the BAF reactor media, with a meshing sand filter separated by a standard metal grid from the natural filter section used at the end of the reactor. This can be considered an innovation in the media and filtration. Aeration in the related reactor with 160 cm height was performed bilaterally as up-flow and continuously by nozzles throughout the reactor media. In this work, the actual effluent of the hospital wastewater treatment plant was employed as the inflow wastewater to the reactor, and its organic and inorganic parameters were measured before and after the treatment by the BAF reactor. The backwashing process was also studied in three ways: bottom backwashing (TB), top backwashing (BB), and top and bottom backwashing (TBBS), to determine the amount of water consumed and to achieve the desired result. According to the results obtained in this study, the removal efficiencies of inorganic and microbial contaminants, amoxicillin and azithromycin were obtained as follows: BOD5: 98.48%, COD: 92.42%, {text{NO}}_{3}^{ - }: 99.4%, P: 93.3%, Coliforms: 97%, Color: 42.8%, Turbidity: 95%, Sulphate: 30%, TSS: 98.9%, Amoxicillin: 20% and azithromycin: 13%. In the backwashing process, the amount of water consumed in these three TB, BB, and TBBS methods were obtained 300, 164, and 118 L, respectively, So, TBBS method was selected as the optimal method. Based on the results obtained in this study, it is concluded that the BAF process with natural date kernel has a high efficiency in removing organic and inorganic contaminants from hospital wastewater, also the concentration of most of the effluent parameters was less or in accordance with EPA standard.

Toxicity Study of the Sanitary Wastewater Treatment Plant Sludge Aiming Its Reuse in Agriculture

Toxicity Study of the Sanitary Wastewater Treatment Plant Sludge Aiming Its Reuse in Agriculture

Proficient Sanitary Wastewater Treatment in Laboratory and Field-Scale Microbial Fuel Cell with Anti-Biofouling Cu0.5Mn0.5Fe2O4 as Cathode Catalyst

For successful field-scale application of microbial fuel cell (MFC), the power recovery from field-scale MFC needs to be improved considerably with simultaneous reduction in its fabrication cost. These problems can be addressed by applying low-cost and efficient cathode catalyst in MFCs. In this regard, Cu0.5Mn0.5Fe2O4 (CuMnFe) was synthesized and applied as cathode catalyst in lab and field-scale MFCs with capacity of 150 ml and 25 l, respectively. Lab-scale MFC having CuMnFe as cathode catalyst demonstrated power density of 176.0 ± 8.2 mW m−2, which was competitive with MFC having Pt as cathode catalyst (183.0 ± 12.6 mW m−2) and it was about seven times higher than control MFC (25.5 ± 4.5 mW m−2) having no catalyst. Application of CuMnFe as cathode catalyst in field-scale MFC produced power density of 7.74 mW m−2, which was three-times higher than the power produced by the field-scale MFC operated without any cathode catalyst (2.58 mW m−2). The cathode catalyst CuMnFe also demonstrated excellent anti-biofouling properties, which in turn improved the power production of field-scale MFC. Therefore, low-cost CuMnFe can be anticipated as an efficacious cathode catalyst for application in MFCs that would produce long term stable higher power, while offering simultaneous treatment to wastewater.

Evaluating the performance of a sequencing batch reactor for sanitary wastewater treatment using artificial neural network

AbstractIn this work, the performance of a sequencing batch reactor (SBR) was studied for treating sanitary wastewater of Yazd power plant, Iran. For this purpose, at the first, a pilot system was designed, installed, and started up. Then the effects of retention time, pH, temperature, influent chemical oxygen demand (COD) concentration, and air flow rate were investigated on the effluent concentration of COD. In SBR reactor used in the Yazd power plant, the microalga was not used for the wastewater treatment. In this case, the COD effluent output was, at the best conditions, approximately 92 mg/L. In the studied SBR system, we used the Chlorella vulgaris microalgae and microorganisms, simultaneously. In this case, the COD level reached 34 mg/L. An artificial neural network (ANN) was developed by applying Levenberg‐Marquardt training algorithm to predict the effluent concentration of COD. The optimum conditions were obtained at pH = 8, temperature of 30°C, influent COD concentration of 600 mg/L, and air flow rate of 50 L/min. ANN predicted results were in good agreement with the experimental data with a validation coefficient of determination (R2) and validation mean square error of 0.962 and 0.0015, respectively.

The use of Horizontal Flow Constructed Wetland for Treatment of Sanitary Wastewater in Iraq

Constructed wetland is engineering systems used for wastewater treatment, whose objective is to reuse water, under the controlled condition, the mechanisms of treatment that occur in natural environments, through the development and get better the process that includes the porous media, plants, and gathering microbial. This paper explains horizontal flow in constructed wetland treatment, the horizontal flow is moving through the gravel media bed and vegetation which permits the wastewater flow through roots and has contact with the biofilm created in the subsurface wetland. To estimate the quality of treated water, some physical, chemical and biological parameters were measured. Treated wastewater from fieldwork showed removal efficiency was increased with time and showed the average removal after detention time of 3, 4, and 6 days, respectively, (47.7 %, 53.2 %, 77.5%) removal of COD, (45.1%, 52.8%, 64.4%) removal of TN, (55.4%, 58.8%, 72.2%) removal of NH4, also average removal of Nitrate was (19.41%) after 3 days. The results showed that the system was effective in removing target pollutants.

Black water treatment by an upflow anaerobic sludge blanket (UASB) reactor: a pilot study.

Decentralized sanitary wastewater treatment has become a viable and sustainable alternative, especially for developing countries and small communities. Besides, effluents may present variations in chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total nitrogen values. This study describes the feasibility of using a pilot upflow anaerobic sludge blanket (UASB) reactor to treat wastewater with different organic loads (COD), using black water (BW) and sanitary wastewater, in addition to its potential for preserving nutrients for later recovery and/or reuse. The UASB reactor was operated continuously for 95 weeks, with a hydraulic retention time of 3 days. In Phase 1, the reactor treated simulated BW and achieved 77% CODtotal removal. In Phase 2, treating only sanitary wastewater, the CODtotal removal efficiency was 60%. Phase 3 treated simulated BW again, and CODtotal removal efficiency was somewhat higher than in Phase 1, reaching 81%. In Phase 3, the removal of pathogens was also evaluated: the efficiency was 1.96 log for Escherichia coli and 2.13 log for total coliforms. The UASB reactor was able to withstand large variations in the organic loading rate (0.09-1.49 kg COD m-3 d-1), in continuous operation mode, maintaining a stable organic matter removal.

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.

Combined use of biogas from sanitary landfill and wastewater treatment plants for distributed energy generation in Brazil

Biogas is a fuel which has a high potential energy and it is produced from the anaerobic degradation of organic material. It can be used for many applications such as heat and electrical generation and fueling vehicles. Given that anaerobic reactors and landfills are the main forms for treating domestic solid waste in Brazil, this current article presents a five scenario analysis on the energy potential and economic viability of the combined use of biogas produced in these structures for generating electricity in the city of Itajubá, Brazil. From the energy point of view, the best case scenario is the combined use of biogas from sanitary landfill and sewage treatment station. This scenario resulted in an installed power of 685 kW, with an annual energy production capable of supplying approximately 10% of the city’s energy. Concerning the economic aspect, the best option is the use of biogas from sanitary landfill in an isolated manner, due to the shorter distance of the transport of the gas, in comparison with other scenarios. The results demonstrate the potential and possibility of economic viability for the use of biogas in urban structures for these microregions in Brazil, indicating that the development of biogas use in small cities can be accomplished within the resolutions of distributed microgeneration. Such potential tends to increase as basic sanitation grows throughout the country.

An environmental-friendly study on sanitary wastewater treatment for small community

An environmental-friendly study on sanitary wastewater treatment for small community

Long-term performance of an integrated constructed wetland for advanced treatment of mixed wastewater

The aim of this study was to investigate long-term performance of a full-scale integrated constructed wetland (CW) system for advanced treatment of sanitary and industrial mixed wastewater. The system consisted of a vertical subsurface flow (VSF) CW, a free water surface (FWS) CW, and a horizontal subsurface flow (HSF) CW in series. Results from six-year operation showed that the system resulted in average removal efficiencies of 70%, 70%, 34%, 52%, 45%, 74%, 21%, 43%, and 98% for COD, NH4-N, NO3-N, TN, TP, TSS, F−, Ni, and E. coli, respectively. Especially, NH4-N was effectively removed by the VSF CW. With relatively high hydraulic loading rates (18.0–43.6cmd−1) and short hydraulic retention times (1.04–2.51 d), the removal efficiencies of the system were quite stable for most of the water quality parameters, while the removal efficiency of TN increased from 49% to 60% during the six years. The removal efficiencies of the system were generally stable with the change of seasons. This study demonstrates that the VSF+FWS+HSF CW system can be a valuable approach for advanced wastewater treatment to meet the more stringent discharge requirement.

Assessing environmental impacts of constructed wetland effluents for vegetable crop irrigation

ABSTRACTThe objective of this study was to monitor and assess environmental impacts of reclaimed wastewater (RW), used for irrigation of vegetable crops, on soil, crop quality and irrigation equipment. During 2013, effluents of a horizontal sub-surface flow constructed treatment wetland (TW) system, used for tertiary treatment of sanitary wastewater from a small rural municipality located in Eastern Sicily (Italy), were reused by micro-irrigation techniques to irrigate vegetable crops. Monitoring programs, based on in situ and laboratory analyses were performed for assessing possible adverse effects on water-soil-plant systems caused by reclaimed wastewater reuse. In particular, experimental results evidenced that Escherichia coli content found in RW would not present a risk for rotavirus infection following WHO (2006) standards. Irrigated soil was characterized by a certain persistence of microbial contamination and among the studied vegetable crops, lettuce responds better, than zucchini and eggplants, to the irrigation with low quality water, evidencing a bettering of nutraceutical properties and production parameters.

Characteristics, treatments, and management for disposal of sanitary wastewater in South Pars Gas processing plants

Improper or inadequate treatment, handling, and disposal of sanitary wastewater can have far reaching impacts on the environment. These impacts are the reasons for management and regulation of South Pars Gas processing plants. Foaming, high suspended solids, high biodegradable material and low pH are the main causes of pollution problems in the sanitary wastewater treatment (activated sludge process) of a gas processing plant. Recent inspection of the sanitary treatment package showed that significant foaming has occurred in inlet Sump and aeration Tank of the unit as well as increasing BOD (biochemical oxygen demand) of effluent stream. The object of the present investigation is (a) to focus on the performance assessment of activated sludge process and potential reasons of pollution that have been gained from observations and laboratory results in South Pars Gas processing plant (b) to discuss the effects of these reasons on the specification of effluent wastewater, (c) to analyze operational management and modification of current activated sludge system and (d) from the results suggest some techniques for pollution control in the plant.

The application of a solar still in domestic and industrial wastewater treatment

A study on the treatment of sanitary and industrial wastewater by solar still was conducted in Malaysia by UKM (Universiti Kebangsaan Malaysia) University during November and December 2011 and January 2012. The experiment was performed by feeding three types of wastewater into a solar still. The pilot-scale solar still consisted of a stepped type solar still with an effective area of 0.8m2. The characteristics of the raw wastewaters indicated that the chemical oxygen demand (COD) was high at 425mg/L for sanitary wastewater and 2650mg/L for diluted industrial wastewater and that the maximum turbidity was between 150 and 820 NTU (Nephelometric Turbidity Units) for both types of wastewater. The results showed that the condensate COD was between 2 and 86mg/L for the different types of feed. The COD removal efficiency of the still was greater than 86.83±3.45%. It was shown that the condensate quality in terms of total dissolved solids (TDSs), total suspended solids (TSSs), COD and turbidity matched the quality of high-grade water and it is suitable to discharge to surface water. The method was also successful in removing bacteria. Heterotrophic bacteria counts were enumerated to determine the inactivation percentage of HPC (Heterotrophic plate counts). A reduction greater than 86.75±10.88% for HPC was achieved.

Efficiency of Mesocosm-Scale Constructed Wetland Systems for Treatment of Sanitary Wastewater Under Tropical Conditions

Subsurface-flow constructed wetlands technology (SSFW) has been used successfully for treating sanitary wastewater throughout North America and Europe. However, treatment wetland technologies have not been used extensively in the tropics. To advance tropical studies, a pilot-scale SSFW was constructed on the campus of the University of the Atlantic in Barranquilla, Colombia. The systems performance was monitored from January to July of 2009. The treatment system consisted of a 760-L septic tank followed by three mesocsom-scale subsurface-flow constructed wetlands in parallel arrangement. Clarified wastewater was batch loaded to each unit at a rate of 53 L/m2/day to affect a hydraulic retention time of approximately 3 days. One of the treatment units served as a non-planted control (gravel only), while the other two treatment units were planted with either Eriochloa aristata or Eleocharis mutata. The objective of this study was to evaluate the comparative efficacy of the treatment units (planted vs. unplanted), with respect to their abilities to augment treatment of septic tank effluent (sanitary wastewater). Monitored parameters included plant biomass, oxidation–reduction potential, chemical oxygen demand (COD), temperature, dissolved oxygen, pH, ammonia–nitrogen (NH 4 + –N) nitrate– and nitrite–nitrogen (NO3–N, NO2–N), phosphates (PO 4 − ), and coliform bacteria. Total biomass (dry matter) was 2.84 and 0.87 Kg/m2 for E. aristata and E. mutata, respectively. Redox potential in the plant rizospheres averaged −172 mV (±164.1) in E. aristata, 29 mV (±251.1) in E. mutata, and 32 mV (±210.5) in the unplanted control. COD removal was superior in planted vs. non-planted systems (>75% vs. 47%). Ammonia and total phosphorus removal averaged 69% and 85%, respectively, in planted systems versus 31% and 59% in the unplanted system. Removal of total and fecal coliforms averaged 96%. Results of this pilot study revealed that SSFW technology in the tropics can provide significant removal of organic matter, nutrients, and bacteria from clarified sanitary wastewater.

Effect of impeller type and agitation on the performance of pilot scale ASBR and AnSBBR applied to sanitary wastewater treatment

The objective of this work was to assess the effect of agitation rate and impeller type in two mechanically stirred sequencing batch reactors: one containing granulated biomass (denominated ASBR) and the other immobilized biomass on polyurethane foam (denominated AnSBBR). Each configuration, with total volume of 1 m(3), treated 0.65 m(3) sanitary wastewater at ambient temperature in 8-h cycles. Three impeller types were assessed for each reactor configuration: flat-blade turbine impeller, 45 degrees -inclined-blade turbine impeller and helix impeller, as well as two agitation rates: 40 and 80 rpm, resulting in a combination of six experimental conditions. In addition, the ASBR was also operated at 20 rpm with a flat-blade turbine impeller and the AnSBBR was operated with a draft tube and helix impeller at 80 and 120 rpm. To quantify how impeller type and agitation rate relate to substrate consumption rate, results obtained during monitoring at the end of the cycle, as well as the time profiles during a cycle were analyzed. Increasing agitation rate from 40 rpm to 80 rpm in the AnSBBR improved substrate consumption rate whereas in the ASBR this increase destabilized the system, likely due to granule rupture caused by the higher agitation. The AnSBBR showed highest solids and substrate removal, highest kinetic constant and highest alkalinity production when using a helix impeller, 80 rpm, and no draft tube. The best condition for the ASBR was achieved with a flat-blade turbine impeller at 20 rpm. The presence of the draft tube in the AnSBBR did not show significant improvement in reactor efficiency. Furthermore, power consumption studies in these pilot scale reactors showed that power transfer required to improve mass transfer might be technically and economically feasible.