Agricultural Reuse Research Articles

Demonstration scale treatment of drainage canal water in the Nile Delta through a combination of facultative lagoons and hybrid constructed wetlands

Drainage canal water (DCW), a mixture of Nile water, drainage water and municipal wastewater, is largely used for irrigation in the Nile Delta. Facultative lagoons (FL) and constructed wetlands (CWs) represent interesting options for DCW treatment before its agricultural re-use, but very few studies investigated their implementation in Egypt. This work aimed at developing at demonstration scale (250 m3 d-1) a FL+CW treatment train capable to turn DCW into an effluent reusable in agriculture. Three types of hybrid CWs were tested in parallel for 530 days. The combination of FL with a cascade hybrid CW, operated at a 200 L d-1 m-2 surface loading rate, led to medium-to-high removal efficiencies (suspended solids 90%, total nitrogen 84%, phosphate 80%, COD 67%, faecal coliforms 2.2 Log) and surface removal rates (COD 47.5 t y-1 ha-1, total nitrogen 10.9 t y-1 ha-1, faecal coliforms 1.5 1011 MPN y-1 ha-1). The effluent, compliant with class C of EU 2020/741 regulation, is potentially reusable to irrigate numerous Egyptian crops. The results show that the combination of FLs with cascade hybrid CWs has a great potential for the treatment of DCW and low-strength municipal wastewater, with near-zero energy consumption, null consumption of chemicals and a land requirement varying between 1.1% and 1.5% of the agricultural land irrigated with the treated DCW.

Optimizing the final rest period of sludge treatment wetlands: Assessment of biosolids quality

Wastewater Treatment Plants (WWTPs) generate a substantial amount of sludge as a residue of the wastewater treatment process. The management of this sludge requires the adoption of cost-effective and environmentally friendly techniques. Sludge Treatment Wetlands (STW) have emerged as an effective means to manage and treat sludge, resulting in the production of biosolids suitable for agricultural purposes. This study aimed to ascertain the optimal operation in terms of final rest period for STWs in the Mediterranean region to boost the production of biosolids for agricultural applications. Two WWTPs in Spain were monitored for a period of 9 months, during which several physic-chemical parameters were monitored to determine the optimal final rest period. The findings revealed that, when sludge feeding period was stopped in summer, a final rest period of 6 months was sufficient to reach biosolids suitable for agricultural re-use. These biosolids displayed a content of 53% total solids (TS), a mineralization rate of 40% volatile solids (VS/TS), a stabilization degree (SD) of 40%, and a high nutrient content. Moreover, the presence of heavy metals, pathogens, antimicrobial resistance genes (ARGs), antibiotics, and pesticides was generally low. Overall, this study demonstrates that, in the Mediterranean Region, 6 months of rest period starting in summer are appropriate for sludge treatment wetlands to effectively generate biosolids with suitable characteristics to be safely re-used as a bio-based fertilizer.

Highly Efficient Recovery of Phosphate from Water Using Cerium Carbonate Hydroxide-Decorated Magnetic Biochar: A Slow-Release Phosphate Fertilizer for Agricultural Reuse

Highly Efficient Recovery of Phosphate from Water Using Cerium Carbonate Hydroxide-Decorated Magnetic Biochar: A Slow-Release Phosphate Fertilizer for Agricultural Reuse

Investigation of the agricultural reuse potential of urban wastewater and other resources derived by using membrane bioreactor technology within the circular economy framework

The European Union, as delineated in Regulation (EU) 2020/741, sets forth minimum criteria for the reuse of wastewater. Directive 86/278/CEE sets the regulations for the reuse of sewage sludge in agriculture. This study aimed to investigate the treated water derived from a pilot plant situated in Granada, Spain, that utilizes membrane bioreactor technology to process real urban wastewater with the quality standards necessary for agricultural reuse. Additionally, the study evaluated the utilization potential of other resources generated during wastewater treatment, including biogas and biostabilized sludge. The pilot plant incorporated a membrane bioreactor featuring four ultrafiltration membranes operating continuously alongside a sludge treatment line operating in batch mode. The pilot plant operated during four cycles, each with distinct hydraulic retention times (6 h and 12 h) and variable mixed liquor-suspended solids concentrations (ranging from 2688 mg L−1 to 7542 mg L−1). During these cycles, the plant was doped with increasing concentrations of emerging contamination compounds (diclofenac, ibuprofen, and erythromycin) to test their effect on the resources derived from the treatment. Subsequently, a tertiary treatment involving an advanced oxidation process was applied to the different water lines, which left the wastewater treatment plant for a period of 30 min and utilized varying concentrations of oxidant. The results indicate that the effluent obtained meets the required quality standards for agricultural use. Therefore, there is potential to use this waste as a resource, which is in line with the principles of the circular economy. Furthermore, the other resources generated during the treatment process, such as the biogas produced during the digestion process and the biostabilized sludge, have the potential to be used as resources according to the circular economy indicators.

Bioavailability of Endocrine Substances in Aquatic Ecosystems, Emerging Contaminants (ECs) and Impact on Agricultural Water Reuse

Bioavailability of Endocrine Substances in Aquatic Ecosystems, Emerging Contaminants (ECs) and Impact on Agricultural Water Reuse

Performance evaluation of a wastewater treatment plant from a dairy in the state of Minas Gerais, Brazil: a case study.

Wastewater generated in dairies has a strong polluting potential and must be treated for disposal into water bodies or reuse. The objective of this work was to analyze the efficiency of removing pollutants through the processes used by a wastewater treatment plant (WWTP) of a dairy located in the state of Minas Gerais, Brazil. For this purpose, the results of the characterization analyses referring to raw and treated wastewater were interpreted. The results showed that the sequence of processes used in the WWTP (water/oil separation, dissolved air flotation, followed by biodegradation in an upflow anaerobic filter) is efficient in removing on average 99.1% of COD and 98.7% of BOD5. For treated wastewater, data on pH and concentration of total suspended solids, total ammoniacal nitrogen, surfactants, settleable solids, and oils and greases also met the standards for disposal into water bodies. For reuse in agriculture, treated wastewater can be used for irrigation, but it is recommended to additionally evaluate the Escherichia coli parameter. When evaluating the existence of linear correlation between COD and BOD5 data, it was possible to find only a moderate correlation (R2 equal to 0.7) for treated wastewater.

Evaluation of environmental geochemical signatures due to RO rejects on arid agricultural farms and tangible solutions

The impact of reverse osmosis (RO) rejects in the groundwater presents a significant challenge in arid regions. This study collected groundwater samples, product water, and reverse osmosis brine (ROB) from evaporation ponds and analyzed them for major ions and trace elements. Test boreholes were drilled near the ROB site along the flow direction, and borehole sediment samples were collected. The samples were predominantly gravelly sand, and the depth to water level fluctuated around 30 m below ground level (bgl), with minerals mainly consisting of calcite, gypsum, and Quartz. Data loggers reflected a rise in water level (<22 m bgl) corresponding to higher electrical conductivity (>16 mS/Cm) during the cropping period in many locations, confirming the impact of ROB in groundwater. The results were further supported by enriched signatures of δ18O (∼ +1.5‰) and δ2H (∼ +15‰). The saturation index of the minerals reflected that carbonate minerals (Calcite > Dolomite) were saturated in the ROB relative to the groundwater. The vertical variation of mineral assemblages in the boreholes indicated gypsum precipitation in the capillary zone along with calcite and dolomite. The assemblage varies as the groundwater moves from the disposal site. The speciation of different compounds along the groundwater path indicated higher carbonate and sulfate species (CaCO3 > CaHCO3> CaSO4 > NaSO4 > MgSO4) near the disposal site, with variations along the flow direction. Considering the significant variation in temperature in the region (5 to 50 ℃), the water sample composition was modeled using PHREEQC, suggesting that the increase in temperature led to supersaturation of Epsomite and Gypsum compositions. The ROB was theoretically mixed with groundwater and product water in different proportions, and an optimum composition (10:90) for safe disposal was derived and tested fit for reuse in agriculture.

Evaluation of Treated Wastewater from Constructed Wetlands for Reuse in Agriculture

Evaluation of Treated Wastewater from Constructed Wetlands for Reuse in Agriculture

Generalized Richards model of slow sand filtration to remove lead pollutant from polluted waters: study of velocity effect

In Morocco, numerous regions face water scarcity. To address water shortages in the arid Marrakech region, agricultural reuse of wastewater can be a viable solution, provided that accessible and cost-effective methods, such as slow sand filtration, are employed to reduce pollutant levels. In the vicinity of the Mine Draa Lasfar, wastewater discharged into the Tensift River has led to significant contamination by metallic trace elements, including lead (Pb). This contamination spreads from the water to the soil, plant cover, and living organisms, with severe Pb contamination observed in children, leading to serious neurological diseases. Addressing this critical issue, our study explores the application of slow sand filtration for water treatment. This method is reliable and environmentally friendly, particularly effective at lower water velocities, ensuring optimal contaminant removal. We introduced the Generalized Richards model, a versatile mathematical tool, which outperformed the standard logistic model by providing a more accurate fit to our experimental data. In conclusion, slow sand filtration, when implemented in areas like Mine Draa Lasfar, offers a promising solution for mitigating metallic trace elements contamination in water sources, with the Generalized Richards model enhancing our understanding and optimization of the filtration process.

Long-term agricultural reuse of treated wastewater and sewage sludge: developing a Time to Critical Content Index for metal species

This study evaluates the sustainability of spreading wastewater or sewage sludge on agricultural land, balancing benefits with contamination risks. Conventional ecological risk indices often fail to address the long-term accumulation of metals in soils. We investigate the feasibility of spreading based on current knowledge of potentially contaminating metals and their behavior in soil. We analyzed the speciation of metals (Ag, Cd, Co, Cr, Cu, Ni, Pb, Ti, Zn) through sequential extraction in sludge, treated wastewater, and soils after 14 years of application of sewage sludge and treated wastewater issued from an Algerian wastewater treatment plant. We introduce a Time to Critical Content Index (TCCI) that calculates the time required to reach critical levels of potentially mobile metals, considering total metal content and speciation. The TCCI takes into account product knowledge, soil characteristics, metal behavior, ecological/toxicological thresholds, and regulations. Applied to our case study, the TCCI indicates that spreading sewage sludge can continue despite metal contents exceeding regulatory ceiling values. The index serves as a precautionary measure, adaptable to evolving knowledge, providing a comprehensive framework for sustainable agricultural practices.Graphical

Recovery of plant nutrients from human excreta and domestic wastewater for reuse in agriculture: a systematic map and evidence platform

BackgroundAchieving a more circular and efficient use of nutrients found in human excreta and domestic (municipal) wastewater is an integral part of mitigating aquatic nutrient pollution and nutrient insecurity. A synthesis of research trends readily available to various stakeholders is much needed. This systematic map collates and summarizes scientific research on technologies that facilitate the recovery and reuse of plant nutrients and organic matter found in human excreta and domestic wastewater. We present evidence in a way that can be navigated easily. We hope this work will help with the uptake and upscaling of new and innovative circular solutions for the recovery and reuse of nutrients.MethodsThe systematic map consists of an extension of two previous related syntheses. Searches were performed in Scopus and Web of Science in English. Records were screened on title and abstract, including consistency checking. Coding and meta-data extraction included bibliographic information, as well as recovery pathways. The evidence from the systematic map is embedded in an online evidence platform that, in an interactive manner, allows stakeholders to visualize and explore the systematic map findings, including knowledge gaps and clusters.ResultsThe evidence base includes a total of 10 950 articles describing 11 489 recovery pathways. Most of the evidence base is about recovery technologies (41.9%) and the reuse of recovered products in agriculture (53.4%). A small proportion of the evidence base focuses on the characteristics of recovered products (4.0%) and user acceptance and perceptions of nutrient recovery and reuse (0.7%).ConclusionsMost studies we mapped focused on nutrient recovery from ‘conventional’ systems, that is, from centralized sewer and wastewater treatment systems that produce biosolids and a treated effluent. While we also found substantial research on nutrient recovery from source-separated urine, and to some extent also on nutrient recovery from source-separated excreta (notably blackwater), the body of research on nutrient recovery from source-separated feces was relatively small. Another knowledge gap is the relative lack of research on the recovery of potassium. More research is also needed on user acceptance of different recovery technologies and recovered products.

The Potential of Elephantorrhiza goetzei Seed Extract as a Coagulant for Household Drinking Water Treatment

ABSTRACTPoor access to adequate, clean, and safe water is one of the greatest world problems people encounter. There has been considerable attention in recent times toward the use of natural coagulants for water treatment. This study seeks to promote this by investigating the potential of Elephantorrhiza goetzei (E. goetzei) seed extract as natural coagulants for water treatment. This included the determination of key ingredients responsible for the coagulation process and optimal dosages for the removal of turbidity, fluoride, manganese, and iron. The residual content of organic matter in the treated water and the quality of sludge produced were also investigated. The methodology consisted of a proximate analysis procedure to investigate the active ingredient(s) responsible for coagulation and standard jar tests. Standard methods were used for the analyses. Coagulant dosages ranging from 0 to 300 mg/L at a rapid mixing speed of 120 rpm for 1 min, a slow mixing speed of 30 rpm for 15 min, and a settling time of 15 min were used for the jar test. The analysis of variance (ANOVA) using IBM SPSS Version 20 was conducted, and regression models were developed to determine the effect of coagulant dosage on turbidity, pH, total dissolved solids, fluoride, iron, manganese, chemical oxygen demand (COD), nitrogen, and phosphorus. The results obtained from the proximate analysis of E. goetzei seed extract show that values of 5.25%, 21.40%, 8.23%, 32.99%, 2.20%, and 29.93% were obtained for moisture, crude protein, crude fiber, fat, ash, and carbohydrate content, respectively. Moreover, seed extract of E. goetzei achieved removal efficiencies up to 94.8%, 50.1%, 90.0%, and 53.9% for turbidity, fluoride, iron, and manganese in water, respectively. The coagulant has the potential to achieve the desired World Health Organization (WHO) drinking water standards for turbidity, fluoride, iron, and manganese. The COD increased from 55.3 to 419.3 mg/L as the coagulant dosage increased from 0 to 100 mg/L. This could cause an unwanted rise in microbial activities, affecting the microbiological quality of the treated water. The total nitrogen and phosphorus concentrations obtained in the sludge at 100 mg/L were 0.343 and 0.194 µg/kg, respectively, and this compromises its attractiveness for agricultural reuse purposes.

Vermifiltration as a green solution to promote digestate reuse in agriculture in small-scale farms

Digestates from low-tech digesters need to be post-treated to ensure their safe agricultural reuse. This study evaluated, for the first time, vermifiltration as a post-treatment for the digestate from a low-tech digester implemented in a small-scale farm, treating cattle manure and cheese whey under psychrophilic conditions. Vermifiltration performance was monitored in terms of solids, organic matter, nutrients, and pathogens removal efficiency. In addition, the growth of earthworms (Eisenia foetida) and their role in the process was evaluated. Finally, the vermicompost and the effluent of the vermifilter were characterized in order to assess their potential reuse in agriculture.Vermifilters showed high removal efficiency of chemical oxygen demand (55–90%), total solids (60–80%), ammonium nitrogen (83–97%), and phosphate-P (28–49%). Earthworms effectively grew and reproduced on digestate (i.e. earthworms number increased by 183%), enhancing the vermifiltration performance, while reducing clogging and odour-related issues. Both the vermicompost and effluent produced complied with legislation limits established for soil improvers and wastewater for fertigation, respectively. Indeed, there was an absence of pathogens and non-detectable heavy metals concentrations. Vermifiltration may be thus considered a suitable post-treatment option for the digestate from low-tech digesters, allowing for its safe agricultural reuse and boosting the circular bioeconomy in small-scale farms.

Performance of vertical and horizontal treatment wetlands planted with ornamental plants in Central Chile: comparative analysis of initial operation stage for effluent reuse in agriculture.

This study comparatively evaluated effluent reuse from two TWs-a horizontal subsurface flow (HF) and a vertical subsurface flow (VF)-used for rural wastewater treatment in Central Chile during the initial operation stage. The two TWs were planted with Zantedeschia aethiopica and were operated for 10months at a pilot scale. The water quality of the influent and effluents was measured and compared with reuse regulations. The results showed similarities in the behavior of the effluents from the two TWs, presenting differences only in the chemical oxygen demand (COD) and different forms of nitrogen, suggesting the necessity of complementary treatment stages or modifications to the operation. The effluents from the HF better fulfilled the reuse standards for irrigation, as the VF faced problems associated with its size. However, a complementary disinfection system is necessary to improve pathogen removal in the effluents coming from the two TWs, especially to be reused as irrigation water for crops. Finally, this work showed the potential for applying subsurface TWs for wastewater treatment in rural areas and reusing their effluents as irrigation water, practice that can contribute to reducing the pressure on water resources in Chile, and that can be used as an example for other countries facing similar problems.

Urban wastewater disinfection by FeCl3-activated biochar/peroxymonosulfate system: Escherichia coli inactivation and microplastics interference

Biochar coupled with peroxymonosulfate (PMS) to produce sulfate radicals and its application to urban wastewater disinfection has been rarely investigated and no information is available about microplastics (MPs) interference on the disinfection process. In this study, FeCl3-activated biochar (Fe-BC) was coupled to PMS to evaluate the inactivation of Escherichia coli (E. coli) in real secondary treated urban wastewater. Surface morphology of Fe-BC sample, characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), showed a rough texture with uniform distribution of iron particles over the entire surface area. E. coli inactivation improved (∼3.8 log units, detection limit = 1 CFU/100 mL) as Fe-BC concentration was decreased (from 1.0 g/L to 0.5 g/L), at a constant PMS dose (300 mg/L). Besides, removal efficiency of E. coli was negatively affected by the presence of small (30–50 μm) polyethylene MPs (PE MPs) (200 mg/L), which could be attributed to the adsorption of MPs on Fe-BC surface, according to SEM images of post-treated Fe-BC. The low disinfection efficiency of Fe-BC/PMS system in presence MPs could be due to blocking of Fe-BC sites for PMS activation and/or radicals scavenging during treatment. These results allowed to unveil the mechanisms of MPs interference on E. coli inactivation by Fe-BC/PMS, as well as the potential of this process to make the effluent in compliance with the stringent limit for agricultural reuse.

Mechanisms of Alleviating Gypsum Scaling by Antiscalants during Membrane Desalination: Implications on Agricultural Drainage Water Reuse

Mechanisms of Alleviating Gypsum Scaling by Antiscalants during Membrane Desalination: Implications on Agricultural Drainage Water Reuse

Integrated assessment of decentralized wastewater treatment plants in semi-arid region in Bolivia

ABSTRACT This study comprehensively evaluates four decentralized wastewater treatment plants intended for agricultural reuse in a semi-arid low-moderate temperature region. It considers environmental, technical, economic, and social perspectives. Anaerobic baffled reactors with hybrid gravel filters (ABR + HGF + VGF) proved the most efficient, with moderate requirements in space, O&amp;M, and energy, albeit the highest treatment cost. Up-flow sludge blanket reactor with activated sludge (UASB + AS) demonstrated high efficiency and compactness, with moderate treatment costs. However, it incurred high energy demands, complex O&amp;M, and more sludge generation. UASB with horizontal gravel filter (UASB + HGF) was among the most land-intensive systems, with moderate costs and O&amp;M requirements, and low energy consumption. However, it fell short of meeting certain environmental criteria. ABR with stabilization ponds (ABR + PONDS) emerged as the most economical, with low energy consumption, but was also among the most land-intensive and failed to achieve adequate effluent quality. Socially, all WWTPs were well accepted for agricultural reuse benefits. In terms of odor perception, UASB + AS and ABR + HGF + VGF exhibit the lowest impact. The Most Appropriate Treatment Technology Index (MATTI) ranked ABR + HGF + VGF and UASB + AS as adequate technologies, while UASB + HGF and ABR + PONDS were poorly adequate. The study recommends a four-dimensional assessment for selecting the most suitable technology, considering the specific context.

Application of Low-Pressure Nanofiltration Membranes NF90 and NTR-729HF for Treating Diverse Wastewater Streams for Irrigation Use

The application of low-pressure nanofiltration (NF) was investigated for three different applications: water reuse from acid mine drainage (AMD), surface water containing natural organic matter (NOM) and agricultural reuse of microfiltered biologically treated sewage effluent (MF-BTSE). AMD contains many valuable rare earth elements (REEs) and copper (Cu) that can be recovered with fresh water. The NF90 membrane was investigated for recovery of fresh water from synthetic AMD. A steady permeate flux of 15.5 ± 0.2 L/m2h was achieved for pretreated AMD with over 98% solute rejection. NF90 achieved a high dissolved organic carbon (DOC) rejection of 95% from surface water containing NOM where 80% of the organic fraction was hydrophilic, mainly humics. The NF process maintained a high permeate flux of 52 LMH at 4 bars. The MF-BTSE was treated by NTR-729HF for agricultural reuse. NTR-729HF membranes were capable of rejecting DOC and inorganics such as sulfates and divalent ions (SO42−, Ca2+ and Mg2+) from MF-BTSE, with less than 20% rejection of monovalent (Na+ and Cl−) ions. The sodium adsorption ratio (SAR) was significantly reduced from 39 to 14 after treatment through NTR-729HF at 4 bar. The resulting water was found to be suitable to irrigate salt-sensitive crops.

Combination of ultrafiltration, activated carbon and disinfection as tertiary treatment of urban wastewater for reuse in agriculture

In the present study, three ceramic ultrafiltration (UF) membranes UF1 (20 nm), UF2 (50 nm) and UF3 (100 nm) were optimized using the Box-Behnken design (BBD) of response surface methodology (RSM) to determine the most adaptable membrane for reuse. The effectiveness of membranes was based on the retention capacity of chemical oxygen demand (COD), biochemical oxygen demand at 5 days (BOD5) and total suspended solids (TSS) as a function of transmembrane pressure (TMP), circulation velocity (CV) and volume concentration factor (VCF). In addition, the study investigated membrane fouling based on the variation in permeate flux under different operational conditions. Among the tested membranes, UF1 demonstrated superior retention efficiency compared to UF2 and UF3. Using granular activated carbon (GAC) and powdered activated carbon (PAC) with UF1 significantly improved water quality. Moreover, the combination of UF1 separately with GAC and PAC reduced amoxicillin residues by 60 % and 69 %, respectively. Furthermore, the UF1 membrane alone showed significant removal of bacterial loads, exceeding 90 % removal of total coliforms, fecal coliforms and Escherichia coli, as well as complete (100 %) elimination of helminth eggs. The treatment process ended with disinfection by sodium hypochlorite (NaOCl), providing total (100 %) elimination of all remaining bacteria in the water.

Development of a Constructed Wetland for Greywater Treatment for Reuse in Arid Regions: Case Study in Rural Burkina Faso

This study implemented and assessed, over a period of four weeks, a full-scale constructed wetland designed to collect and treat the greywater for a rural household located in an arid environment typical of Africa’s Sahel region. The system was constructed from local materials and consisted of a shower room, a receiving basin, a pre-treatment filter, and a subsurface horizontal flow wetland planted with Chrysopogon zizanioides. Results showed the overall removal of organic matter was greater than 90%, and orthophosphate and ammonium were reduced by 73% and 60%, respectively, allowing for the treated water to retain some embedded nutrients. The removal efficiency of fecal bacteria varied from 3.41 (enterococci) to 4.19 (fecal coliforms) log10 units which meets World Health Organization Guidelines for restricted irrigation. Our assessment of the full-scale household constructed wetland technology adds to the relatively low number of constructed wetland studies conducted outside a laboratory setting. Furthermore, it supports efforts to promote safe reuse of an underutilized resource at the rural household level in Sub-Saharan Africa and other arid regions in the developing world, supporting prospects for using treated greywater for agricultural reuse in regions that experience water scarcity, climate variability, and land degradation.