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•Agro-industrial treated wastewater was reused for tomato and broccoli irrigation.•The main physico-chemical properties of wastewater met the Italian standards for irrigation ...reuse.•Quantity and quality of crops were not affected by wastewater.•No impact of wastewater on chemical properties of irrigated soil was observed.•Low level of fecal indicator was found in plants, tomato fruits and broccoli heads.
In many countries of the Mediterranean region, characterized by frequent drought periods, agricultural production often occurs under water deficiency or conditions that cause the depletion of the existing water resources. In these areas, the reuse of reclaimed wastewater for crop irrigation could contribute to mitigate/decrease water shortage, support the agriculture sector and protect groundwater resources. In 1.5-year field experiments in Southern Italy (Apulia Region), the effects of irrigation with treated agro-industrial wastewater on soil properties, crops yield and qualitative traits of crop products, including their microbiological safety, were assessed. Groundwater (GW), secondary treated wastewater (SW) and tertiary treated wastewater (TW) from an innovative “on-demand” UV disinfection system were used to irrigate tomato and broccoli, cultivated in succession. The three irrigation water sources and the corresponding irrigated soils, plants and crop products were analyzed for the main physico-chemical characteristics, quali-quantitative parameters and fecal indicators. SW and TW showed higher values of the main physico-chemical parameters than GW. SW irrigated soil resulted in a significant increase of NH4-N, Na+, SAR, EC (below the threshold value beyond which a soil is defined as saline) during the first tomato crop cycle, and of pH during the broccoli growing season. Irrigation with treated wastewater did not significantly affect the marketable yield nor the qualitative traits of tomato and broccoli crops, except for the Na+ and NO3− content (below the threshold levels defined by the European guidelines for vegetables). High levels of E. coli (above the Italian limit for reuse), Fecal coliforms and Fecal enterococci (up to 104 CFU 100ml−1) were observed in the SW and, when chlorination was not done, in the TW. Nevertheless, E. coli was not isolated from any sample of soil, plant and crop product, probably due to its rapid die-off. Moreover, low concentrations of Fecal coliforms and Total heterotrophic count were found in plant and crop product. The drip irrigation system used, which avoided the close contact between water and plant, may have contributed to this. Under the conditions applied in this study, the reuse of treated agro-industrial wastewater for irrigation can be considered an effective way to cope with agricultural water shortage in the Mediterranean area.
Bacterial consortia have a primary role in the biological degradations occurring in activated sludge for wastewater treatment, for their capacities to metabolize the polluting matter. Therefore, the ...knowledge of the main metabolic pathways for the degradation of pollutants becomes critical for a correct design and operation of wastewater treatment plants. The metabolic activity of the different bacterial groups in activated sludge is commonly investigated through respirometry. Furthermore, in the last years, the development of “omic” approaches has offered more opportunities to integrate or substitute the conventional microbiological assays and to deeply understand the taxonomy and dynamics of complex microbial consortia. In the present work, an experimental membrane bioreactor (MBR) was set up and operated for the treatment of municipal wastewater, and the effects of a sudden decrease of the organic supply on the activated sludge were investigated. Both respirometric and metaproteomic approaches revealed a resistance of autotrophic bacteria to the substrate stress, and particularly of nitrifying bacteria. Furthermore, metaproteomics allowed the identification of the taxonomy of the microbial consortium based on its protein expression, unveiling the prevalence of Sorangium and Nitrosomonas genera both before and after the organic load decrease. Moreover, it confirmed the results obtained through respirometry and revealed a general expression of proteins involved in metabolism and transport of nitrogen, or belonging to nitrifying species like Nitrosomonas europeae, Nitrosomonas sp. AL212, or Nitrospira defluvii.
Climate change and a growing population around the Mediterranean Rim are increasing the need for water and, consequently, the pressure on resources in terms of both quantity and quality. High-quality ...water should be primarily reserved to drinking water while reclaimed water is an alternative for other usages. A review of situations in Tunisia, Jordan, France, and Italy involving the use of reclaimed water highlights the disparity in national regulations governing this alternative water resource and in its management. On the first hand, the use of recycled water for irrigation can have an adverse impact on public health and the environment, depending on treatment and irrigation practices. On the other hand, it may also represent a new source of water: wastewater should no longer be considered as waste but, rather, as a new resource to be handled in a circular economy-type loop. Current scientific knowledge in agronomic and environmental sciences, as well as in the economic and social sciences, can be integrated and used to lower the associated risk through the effective management of irrigation using recycled water and to address the following questions: (i) How can the time-varying nutrient needs of crops be managed to operate safe environmental reuse within an adapted risk assessment framework? (ii) What socio-economic models can render this integrated approach sustainable? (iii) What treatment systems and irrigation technology can be used to support these ideas and with what information? (iv) What changes in the regulations are needed?
A self-forming dynamic membrane bioreactor (SFD MBR) is a cost-effective alternative to conventional MBR, in which the synthetic membrane is replaced by a “cake layer,” an accumulation of the ...biological suspension over a surface of inert, low-cost support originated by filtration itself. Under optimized conditions, the cake layer is easy to remove and quick to form again, resulting a “dynamic membrane.” The permeate of the SFD MBR has chemo-physical characteristics comparable to those of conventional ultrafiltration-based MBR. In this paper, two nylon meshes with pore sizes of 20 and 50 µm, respectively, were tested in a bench-scale SFD MBR in which an air mass load (AML) was periodically supplied tangentially to the filtration surface to maintain filtration effectiveness. The SFD MBR equipped with 20 µm nylon mesh coupled with 5 min of AML every 4 h showed the best performance, ensuring both a permeate with turbidity values always below 3 NTU and revealing no increases in transmembrane pressure (TMP) with manual maintenance needs. A benchmark test with the only difference of a suction break (relaxation) instead of AML was conducted under identical operating conditions for validation with an already known maintenance strategy. This latter test produced a permeate of very good quality, but it needed frequent TMP increases and consequent manual cleanings, showing that a periodic AML coupled with the use of a 20 µm mesh can be an optimal strategy for long-term operation of SFD MBR.
In biological wastewater treatments, microbial populations of the so-called activated sludge work together in the abatement of pollutants. In this work, the metabolic behavior of the biomass of a ...lab-scale plant treating industrial pharmaceutical wastewater was investigated through a metaproteomic approach. The complete treatment process included a membrane biological reactor (MBR) coupled with an advanced oxidation process (AOP) for partial breakdown of non-biodegradable molecules. Proteins from biomass samples collected pre- and post-AOP application were investigated by two-dimensional gel electrophoresis (2DE), mass spectrometry (MS), and finally identified by database search. Results showed that most proteins remained constant between pre- and post-AOP. Methanol dehydrogenase (MDH) belonging to Hyphomicrobium zavarzinii appeared as the most constantly expressed protein in the studied consortium. Other identified proteins belonging to Hyphomicrobium spp. revealed a predominant methylotrophic metabolism, and H. zavarzinii appeared as a key actor in the studied microbial community.
•Sludge cake acts as key actor of filtration in SFD-MBR for wastewater treatment.•IFAS integration decreased the excess sludge and enhanced denitrification.•The presence of carriers increased the ...frequency of mesh clogging.•Both SFD-MBRs showed performance comparable to MBR in same operating conditions.
Two lab-scale Self Forming Dynamic Membrane BioReactors (SFD-MBR), equipped with 50 µm nylon meshes were set up and operated for the treatment of real municipal wastewater. Plastic carriers were added in one of the two bioreactors to generate a combination of the Integrated Fixed-film Activated Sludge (IFAS) and the SFD-MBR technologies. Overall, the two systems performed very well, achieving excellent effluent quality under steady state conditions and showing good resilience to extreme organic loading conditions. Continuous air scouring and periodical mesh cleaning by jet rinsing with tap water were effective in maintaining stable and high productivity (membrane flux around 67 L m2 h−1) over a period of 140 days. The application of the IFAS process resulted in lower production of excess sludge and improved denitrification. On the other hand, under the tested conditions the combined IFAS-SFD-MBR showed a higher tendency to mesh clogging with respect to the SFD-MBR.
Reuse of treated wastewater for crop irrigation can contribute to mitigate water stress, especially in Mediterranean countries. The use of reclaimed municipal wastewater for this purpose was ...demonstrated by numerous studies and full-scale installations. On the other hand, reuse of industrial effluents in irrigation is uncommon and the knowledge in this field is limited. This work aims at assessing the suitability of agro-industrial effluent reuse for irrigation. In the case study presented, a full-scale tertiary treatment based on membrane ultrafiltration and UV disinfection was tested at an agro-industrial site in Apulia (Italy). The wastewater treatment plant processed the stream produced at a vegetable canning factory, and the treated effluents were used for field scale irrigation tests. The variability of wastewater quality and its effects on treatment process performances and reclaimed water quality were investigated. An economic evaluation of the full scale tertiary treatment was also performed. The results showed that the adopted technologies effectively removed suspended solids and the faecal indicator Escherichia coli below the local standards for reuse in irrigation. Furthermore, the use of treated agro-industrial wastewater had no inhibitory effects on the growth of tomato and broccoli, neither resulted in any faecal contamination of crops. In general, the present study shows that reuse of treated wastewater for irrigation is a suitable practice to close the water cycle in the agro-industrial sector. This is very important in areas where the sustainability of agriculture and transformation activities depends on the water available for irrigation. This practice also avoids the discharge of pollutants into water bodies, reducing the environmental impacts of agro-industrial productions.
•Irrigation with treated agro-industrial wastewater is a suitable practice.•Treated wastewater had no inhibitory effects on the growth of tomato and broccoli.•There were no negative effects on soil salinity and microbial safety of crops.•Closing the water cycle in the agro-industry allowed the irrigation of 13 ha.•Segregation and separate treatment of heavily polluted fractions may be considered.
•A SFD MBR operated at 93Lm−2h−1 effectively treated real municipal wastewater.•Continuous mesh air scouring was a key factor for ensuring effective operation.•The effluent produced with 20 and 50μm ...mesh had similar quality features.•The 20μm mesh had much higher cleaning requirements than the 50μm mesh.
The Membrane BioReactor (MBR) is a well-established filtration-based technology for wastewater treatment. Despite the high quality of the effluent produced, one of the main drawbacks of the MBR is membrane fouling. In this context, a possible evolution towards systems having potentially lower installation and operating costs is the Self Forming Dynamic Membrane BioReactor (SFD MBR). Key of this technology is the self-formation of a biological filtering layer on a support of inert material. In this work, a lab-scale aerobic SFD MBR equipped with a nylon mesh was operated at approximately 95Lm−2h−1. Two mesh pore sizes (20 and 50μm) and three air scouring flow rates (150, 250, and 500mLairmin−1) were tested at steady state. Under all the tested conditions, the SFD MBR effectively treated real municipal wastewater. The quality of the produced effluent increased for lower mesh size and lower air scouring intensity.
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•The SFD MBR is a reliable technology for municipal wastewater treatment.•High flux (60–70 L m−2 h−1) and low effluent turbidity (1–4 NTU) can be achieved.•Better performance was ...observed at higher SRT.•More stable F/M ratios resulted in higher effluent quality.•Biological process stability is a key aspect to enhance the overall performance.
A lab-scale Self-Forming Dynamic Membrane BioReactor (SFD MBR) equipped with a nylon mesh was operated for the treatment of real municipal wastewater under a volumetric loading rate of 0.9–1.1 gCOD L−1 d−1 and a flux of 61–68 L m−2 h−1. During an experimental period of more than 600 d, three runs were performed with different solids retention times (SRT of 15, 30, and 50 d). At the steady state, the system had always good biological and filtration performances, but the mesh clogging tendency and the solid removal observed varied with the SRT. Lower filtration performance, both in terms of permeate quality and productivity, was observed under unstable conditions for the biological processes, such as start-up and variations of the food-to-microorganism ratio. Higher SRT resulted in more stable biological process at the steady state, which positively affected the filtration performance even in front of organic load variations.
Reuse of treated wastewater for crop irrigation has been widely adopted to mitigate the effects of water scarcity on agricultural yields and to help preserving the integrity of aquatic ecosystems. ...This paper presents the outcomes of one-year monitoring of a full-scale agro-industrial wastewater treatment plant designed for water reuse, with a multistage tertiary treatment based on sand filtration, membrane ultrafiltration, storage and on-demand UV disinfection. We aimed to test flow cytometry as a monitoring tool to provide on-site indications on tertiary treatment performances and on the quality of treated wastewater along the treatment scheme. Membrane ultrafiltration retained prokaryotic cells and E. coli (>3 log). During storage of treated effluents, a significant decay of E. coli was observed together with the growth of prokaryotic and eukaryotic cells, and the UV disinfection was effective only against fecal indicators. The microbial quality of the treated effluent was comparable to the control groundwater locally used for irrigation. On-site rapid assessments by flow cytometry allowed unveiling crucial aspects affecting the microbiological quality of ultrafiltration permeate and treated effluent immediately after sampling, including plant operating performances and microbial removal patterns across the treatment train.
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•Microbial quality assessments unveiled cell removal and plant operating conditions.•Ultrafiltration was the major process affecting the water microbial load.•Cell growth in membrane permeates and adaptation to storage affected water quality.•UV-treated wastewater was as suitable for irrigation as the local groundwater.•Flow cytometry complemented conventional approaches to monitor water reuse systems.
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