Wastewater treatment using integrated anaerobic baffled reactor and Bio-rack wetland planted with Phragmites sp. and Typha sp

Elucidating the Potential of Vertical Flow-Constructed Wetlands Vegetated with Different Wetland Plant Species for the Remediation of Chromium-Contaminated Water

Water scarcity is one of the key global challenges affecting food safety, food security, and human health. Constructed wetlands (CWs) provide a sustainable tool to remediate wastewater. Here we explored the potential of vertical flow-CWs (VF-CWs) vegetated with ten indigenous wetland plant species to treat chromium (Cr)-contaminated water. The wetland plants were vegetated to develop VF-CWs to treat Cr-contaminated water in a batch mode. Results revealed that the Cr removal potential of VF-CWs vegetated with different wetland plants ranged from 47% to 92% at low (15 mg L−1) Cr levels and 36% to 92% at high (30 mg L−1) Cr levels, with the maximum (92%) Cr removal exhibited by VF-CWs vegetated with Leptochloa fusca. Hexavalent Cr (Cr(VI)) was reduced to trivalent Cr (Cr(III)) in treated water (96–99 %) of all VF-CWs. All the wetland plants accumulated Cr in the shoot (1.9–34 mg kg−1 dry weight (DW)), although Cr content was higher in the roots (74–698 mg kg−1 DW) than in the shoots. Brachiaria mutica showed the highest Cr accumulation in the roots and shoots (698 and 45 mg kg−1 DW, respectively), followed by Leptochloa fusca. The high Cr level significantly (p < 0.05) decreased the stress tolerance index (STI) percentage of the plant species. Our data provide strong evidence to support the application of VF-CWs vegetated with different indigenous wetland plants as a sustainable Cr-contaminated water treatment technology such as tannery wastewater.

Field-scale decentralized domestic wastewater treatment system: Effect of dynamic loading conditions on the removal of organic carbon and nitrogen

The field-scale decentralized wastewater treatment system (DWTS) was developed with an anaerobic baffled reactor (ABR) and a newly configured hybrid constructed wetland (HCW) vegetated with Typha angustifolia and Canna indica to treat 42 kLd of domestic wastewater. Biorack baffled constructed wetland (BBCW) and baffled vertical flow constructed wetland (BVFCW) were used in the first and second stage of HCW respectively. DWTS was assessed for its efficiency to remove COD, BOD and TKN under high (varying flow and varying COD) and moderate (constant flow and varying COD) dynamic loading conditions. The tracer study and pertinent computation showed the good performance of DWTS in its hydraulic efficiency. COD of raw wastewater was the treatment-limiting step in ABR. BBCW sustained larger fluctuations in loading rates [hydraulic (0.43-10.29 m³/m2.d) and organic (0.08-2.30 kgCOD/m2.d)]. The draining (unsaturated) conditions enhanced COD and BOD removal in BVFCW. DWTS was found to be efficient for the average removal of COD (70-90%) and TKN (40-65%). HCW contributed 50-60% and 70-80% to COD and TKN removal respectively. The quantification of impacts on treatment efficiency and sustainability of DWTS was demonstrated at field-scale under high and moderate dynamic conditions.

Field-scale baffled and biorack hybrid constructed wetland: effect of fluctuating loading rates and recirculation for domestic wastewater treatment

The conventionally used constructed wetlands require modification/s to minimize clogging problems and space requirement. In this study, a field-scale baffled and biorack hybrid constructed wetland (BBHCW) was developed as a part of 42 KLD decentralized wastewater treatment (DWT) system at Walchand College of Engineering, Sangli (M.S.), India for domestic wastewater. Brickbats were used as support medium in the baffled portion and corrugated sheets in biorack. Mixed vegetation of Typha angustifolia and Canna indica was used in both baffled and biorack portions. BBHCW was operated under the dynamic conditions of flow (0.60-9.89 m³/m² day) and strength (0.12-2.12 kg COD/m² day) for 8 months. The performance was assessed for the removal of organic carbon and nitrogen with and without recirculation of treated effluent. Tracer studies showed that the hydraulic efficiency was satisfactory. COD, BOD₃, and TKN removal is possible to an extent of 26.30 ± 1.36, 29.08 ± 2.43, and 19.39 ± 2.27%, respectively, under dynamic conditions. Recirculation enhances the removal efficiency of COD by 5.00-10.00%. However, TKN removal was not significant with or without recirculation. Morphological study showed that vegetation growth was well supported in BBHCW. The discarded corrugated sheets in BR and brickbats in BSFW are the most appropriate low-cost options. The clogging problem is reduced significantly. BBHCW is sturdy enough to absorb shock loading and space requirement can be reduced by judicious choice of HLR and OLR. BBHCW is an alternative to conventionally used sub-surface constructed wetland as a part of DWT. Novelty statementDevelopment of newly configured baffled and biorack hybrid dual-species constructed wetland (BBHCW) for field scale application.Use of discarded brickbat and cement sheets as a new support medium and bioracks.Performance assessment of field-scale BBHCW for the removal of organic carbon (expressed as COD and BOD₃), and nitrogen (expressed as TKN) from domestic wastewater under highly dynamic conditions induced by fluctuating hydraulic loading rate (0.60-9.89 m³/m² day) and organic loading rate (0.12-2.12 kg COD/m² day).

The Use of Constructed Wetland for Mitigating Nitrogen and Phosphorus from Agricultural Runoff: A Review

The loss of nitrogen and phosphate fertilizers in agricultural runoff is a global environmental problem, attracting worldwide attention. In the last decades, the constructed wetland has been increasingly used for mitigating the loss of nitrogen and phosphate from agricultural runoff, while the substrate, plants, and wetland structure design remain far from clearly understood. In this paper, the optimum substrates and plant species were identified by reviewing their treatment capacity from the related studies. Specifically, the top three suitable substrates are gravel, zeolite, and slag. In terms of the plant species, emergent plants are the most widely used in the constructed wetlands. Eleocharis dulcis, Typha orientalis, and Scirpus validus are the top three optimum emergent plant species. Submerged plants (Hydrilla verticillata, Ceratophyllum demersum, and Vallisneria natans), free-floating plants (Eichhornia crassipes and Lemna minor), and floating-leaved plants (Nymphaea tetragona and Trapa bispinosa) are also promoted. Moreover, the site selection methods for constructed wetland were put forward. Because the existing research results have not reached an agreement on the controversial issue, more studies are still needed to draw a clear conclusion of effective structure design of constructed wetlands. This review has provided some recommendations for substrate, plant species, and site selections for the constructed wetlands to reduce nutrients from agricultural runoff.

Post treatment of anaerobically treated brewery effluent using pilot scale horizontal subsurface flow constructed wetland system

The anaerobic process is considered to be a sustainable technology for the treatment of wastewaters rich in organic matter mainly due to its lower energy consumption and production of value-added products such as biogas and organic fertilizer. However, it cannot be seen as providing 'complete' environmental solution as its treated effluents would typically not meet the desired discharge limits in terms of residual carbon, nutrients and other pollutants. This has given impetus to subsequent post treatment in order to meet the environmental standards and protect the receiving water bodies and environment. The aim of this study was to evaluate the post-treatment potential of a pilot scale two-stage horizontal subsurface flow constructed wetland (HSSFCW) system planted with Cyperus alternifolius and Typha latifolia, respectively, for enhanced removal of residual carbon and nutrient from an up-flow anaerobic sludge blanket (UASB) reactor treated brewery effluent. A pilot scale two-stage HSSFCW was integrated with the UASB reactor, and its performance efficiency was assessed for the removal of total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN), ammonium-nitrogen (NH4-N), total phosphorous (TP), and orthophosphate (PO43-). Macrophytes aboveground biomass and nutrient accumulation potential were also determined following standard methods. The results from this study showed that Cyperus alternifolius planted CW cell removed 68.5% TSS, 74.2% COD, 55.7% TN, 68.6% NH4-N, 41.1% TP and 48.1% PO43-. Moreover, further polishing with Typha latifolia planted CW cell enhanced the removal efficiencies to 89% TSS, 92% COD, 83.6% TN, 92.9% NH4-N, 74.4% TP, and 79.5% PO43-. Strong linearity and Pearson correlation was found between macrophyte biomass and nutrient accumulation in each CW cell (Cyperus alternifolius: R2 = 0.91, r = 0.97 for TN; R2 = 0.92, r = 0.96 for TP; and Typha latifolia: R2 = 0.96, r = 0.98 for TN and TP), and showed substantial nutrient reduction with cumulative nutrient accumulation of 1290 gTNm-2 and 708.7 gTPm-2 in the complete system. The performance of the pilot CW system as a tertiary treatment for brewery wastewater showed that the effluent meets the permissible discharge standards throughout the year excluding phosphorous.

Unveiling the Potential of Novel Macrophytes for the Treatment of Tannery Effluent in Vertical Flow Pilot Constructed Wetlands

The phytoremediation potential of macrophytic species has made them an inevitable component of constructed wetlands (CWs) for the treatment of industrial effluents. The macrophytes must have tolerance for the harsh conditions imposed by effluents for an effective establishment of the CW system. In this context, the basic purpose of this work was to investigate the efficacy of five indigenous emergent macrophytes (Brachiaria mutica, Canna indica, Cyperus laevigatus, Leptochloa fusca, and Typha domingensis) for the remediation of tannery effluent in vertical subsurface flow CWs. The ability of each macrophytic species to tolerate pollution load and to remove pollutants from the effluent was assessed. The effect of tannery effluent on the survival and growth of macrophytes was also studied. The treated tannery effluent samples were analyzed for electrical conductivity (EC), pH, biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), chlorides (Cl−), sulphates (SO42−), oil and grease, and Cr levels. All of the studied macrophytes significantly decreased the pollution load of tannery effluent, and the higher nutrient content of effluent stimulated their growth without any signs of negative health effects. Leptochloa fusca and T. domingensis performed better in removing pollutants and showed higher growth rates and biomass than other tested macrophytes and can be considered preferred species for use in CWs treating tannery effluent. Brachiaria mutica showed morphologically better results than C. indica and C. laevigatus.

Effectiveness of wastewater treatment systems in removing microbial agents: a systematic review

Background

Due to unrestricted entry of wastewater into the environment and the transportation of microbial contaminants to humans and organisms, environmental protection requires the use of appropriate purification systems with high removal efficiency for microbial agents are needed. The purpose of this study was to determine the efficacy of current wastewater treatment systems in removing microbes and their contaminants.

Methods

A systematic review was conducted for all articles published in 5 Iranian environmental health journals in 11 years. The data were collected according to the inclusion and exclusion criteria and by searching the relevant keywords in the articles published during the years (2008–2018), with emphasis on the efficacy of wastewater treatment systems in removing microbial agents. Qualitative data were collected using a preferred reporting items for systematic reviews and meta-analyzes (PRISMA) standard checklist. After confirming the quality of the articles, information such as the name of the first author and the year of publication of the research, the type of study, the number of samples, the type of purification, the type of microbial agents and the rate of removal of microbial agents were entered into the checklist. Also the removal rates of the microbial agents mentioned in the studies were compared with united states environmental protection agency (US-EPA) standards.

Results

In this study, 1468 articles retrieved from 118 issues of 5 environmental health journals were reviewed. After reviewing the quality of the articles in accordance with the research objectives, 14 articles were included in the study that were published between 2010 and 2018. In most studies, two main indicators Total coliforms and Fecal coliforms in wastewater were investigated. Removing fungi and viral contamination from wastewater was not found in any of the 14 studies. Different systems (activated sludge, stabilization ponds, wetlands, and low and medium pressure UV disinfection systems were used to remove microbial agents in these studies. Most articles used active sludge systems to remove Total coliforms and Fecal coliforms, which in some cases were not within the US-EPA standard. The removal of Cysts and Parasitic eggs was only reporte from stabilization pond systems (SPS) where removal efficiency was found in accordance with US-EPA standards.

Conclusions

Different types of activated sludge systems have higher efficacy to remove microbial agents and are more effective than other mentioned systems in removing the main indicators of sewage contamination including Total coliforms and Fecal coliforms. However, inappropriate operation, maintenance and inadequate handling of activated sludge can also reduce its efficiency and reduce the removal of microbial agents, which was reported in some studies. Therefore, it is recommended to conduct research on how to improve the operation, maintenance, and proper management of activated sludge systems to transfer knowledge to users of sludge systems and prevent further health issues related to microbial agents.

Disinfection of anaerobic/aerobic sanitary effluent using ozone: Formaldehyde formation

The scarcity of natural resources supports the perspective of reusing treated effluents, mainly in agriculture, where the reduction in the demand of drinking water and the provision of alternative sources for nutrients are important. However, the process of disinfection, essential to the protection of human health, generates deleterious by-products to both humans and the environment. This research aimed to evaluate the use of ozone as a disinfectant for wastewater treated by anaerobic/aerobic baffled reactor for later agricultural reuse. Disinfection tests were conducted by applying ozone, in batch, with applied dosages of 5, 8, and 10 mg O₃ /L and contact time of 7 min. All the tests led to formaldehyde formation, therefore within the standard suggested by the World Health Organization. For the indicators total coliforms and Escherichia coli, the ozone was considered effective, satisfying the criteria for agricultural reuse according to the World Health Organization of a dosage of 8 mg O₃ /L. PRACTITIONER POINTS: Proposal of decentralized system (anaerobic/aerobic baffled reactor + ozone disinfection) for effluent treatment for agricultural reuse. Formation of formaldehyde dependent on applied ozone dose. Demand of ozone consumed preferentially for the formation of by-products, with low removal of COD. High formaldehyde formation (high ozone demand) can impair the inactivation of pathogens. System promotes effluent that meets the standards established by the World Health Organization (WHO) for agricultural reuse.

Performance evaluation of a decentralized wastewater treatment system in India

A Decentralized Wastewater Treatment System (DEWATS) provides an economically feasible and efficient wastewater treatment solution especially in developing countries. It has an enormous potential for developing a sustainable environmental sanitation system. In this study, the treatment efficiency of eight DEWATS plants was evaluated in the state of Maharashtra, India, for their performance in terms of selected physico-chemical parameters of the wastewater. Although the efficiency of some of the plants was lower than that reported in literature, the effluent quality of all the plants was within the permissible discharge limits of the Central Pollution Control Board for all the parameters. Comprehensive assessment of Plant I was carried in terms of its technical and socio-economic aspects. Moreover, LCA tool has been utilized to evaluate the environmental impacts of the operation stage of DEWATS. The midpoint, CML 2001 (April 2015) methodology was adopted, in which 11 impact categories were considered. From the life cycle impact assessment and interpretation, the main impacts are identified as releases of COD, P-PO₄^3-, and N-NH₄⁺ to water bodies and disposal of sludge. Due to negligible energy consumption, the operation stage was found to be less damaging to the environment. It was concluded that DEWATS can be a good alternative for treating wastewater with negligible energy and chemical consumption.

Constructed wetlands as sustainable ecotechnologies in decentralization practices: a review

Recently, a range of novel and cost-effective engineered wetland technologies for decentralization practices of domestic wastewater treatment have been developed with ecological process modification, the use of functionalized plants, and advanced biofilm formation. However, selecting the one that can be more appreciated for on-site sanitation is still uncertain. This paper reviews the role of plants, media materials, microorganisms, and oxygen transfer in domestic wastewater purification through constructed wetlands (CWs). The effectiveness of traditional and recently developed CWs and the necessity of an induced biofilm attachment surface (BAS) in these systems for the treatment of domestic sewage are presented. This review also elucidates the idea of CWs for domestic wastewater characteristics highly stressed by total dissolved solids and the adaptive strategies in mitigating the cold climate impacts on their efficiencies. Further research needed to enhance the stability and sustainability of CWs is highlighted. By a more advanced investigation, BAS CWs can be specified as an ideal treatment process in decentralization.

Influence of urban activity in modifying water parameters, concentration and uptake of heavy metals in Typha latifolia L. into a river that crosses an industrial city

BACKGROUND

Heavy metals like Cu, Cd, Pb, Ni, Co and Cr can naturally be found almost all over this planet in various amounts. Urban activities such as heavy metal industry, traffic and waste can rapidly increase the metal concentrations in a fresh water ecosystem.

METHODS

This study was done in natural conditions to capture as many aspects in heavy metals pollution and bioremediation of Nicolina River, Romania considered a stream model which is under anthropogenic pressure. Water, sediment and leaves samples of Typha latifolia L. were collected during October 2013 and analyzed in order to assess certain heavy metals (Cu, Cd, Pb, Ni, Co and Cr) from each sampling site using GF-HR-CS-AAS with platform. Heavy metals in significant concentrations in cattail samples were correlated with the water parameters to show the possibility to use the cattail leaves as indicators in heavy metals pollution with potential in bioremediation because they can be easily harvested in autumn and this species is spread worldwide.

RESULTS

The levels of metals concentrations in leaves were: Cu > Ni > Cr > Pb > Co knowing that copper is an essential element for plants. The sampling time was important to draw the river diagnosis for heavy metal pollution. The samples were collected, from river, after more than 60 days without rain same as a "human patient" prepared for blood test. Cobalt was considered the metal marker because it was an element with the lowest level of usage in the city. Compared with it only lead, cadmium and copper were used intensively in the industrial activities.

CONCLUSIONS

T. latifolia L. can be use as an indicator for the health of the studied stream and it was noticed that the heavy metals were not accumulated, although the metal uptake was influenced by sediments and water parameters. The alkalinity of the studied river acts as an inhibitor in the bioremediation process of cattail for cadmium and copper. Lead was uptake by leaves and the water parameters influenced it but it wasn't concentrated enough in leaves to propose this species in lead bioremediation process for Nicolina River.