Use of nitrate, sulphate, and iron (III) as electron acceptors to improve the anaerobic degradation of linear alkylbenzene sulfonate: effects on removal potential and microbiota diversification.

Linear alkylbenzene sulfonate (LAS) is a synthetic anionic surfactant that is found in certain amounts in wastewaters and even in water bodies, despite its known biodegradability. This study aimed to assess the influence of nitrate, sulphate, and iron (III) on LAS anaerobic degradation and biomass microbial diversity. Batch reactors were inoculated with anaerobic biomass, nutrients, LAS (20 mg L-1), one of the three electron acceptors, and ethanol (40 mg L-1) as a co-substrate. The control treatments, with and without co-substrate, showed limited LAS biodegradation efficiencies of 10 ± 2% and 0%, respectively. However, when nitrate and iron (III) were present without co-substrate, biodegradation efficiencies of 53 ± 4% and 75 ± 3% were achieved, respectively, which were the highest levels observed. Clostridium spp. was prominent in all treatments, while Alkaliphilus spp. and Bacillus spp. thrived in the presence of iron, which had the most significant effect on LAS biodegradation. Those microorganisms were identified as crucial in affecting the LAS anaerobic degradation. The experiments revealed that the presence of electron acceptors fostered the development of a more specialised microbiota, especially those involved in the LAS biodegradation. A mutual interaction between the processes of degradation and adsorption was also shown.

Use of life cycle assessment as a tool to evaluate the environmental impacts of textile effluents: a systematic review.

The textile industry is known for its large consumption of water, energy, and chemical products, making it one of the most environmentally impactful activities. To measure these environmental impacts, life cycle analysis (LCA) is a powerful tool that considers the entire process, from the extraction of raw materials to the finalization of textile products. In this context, this work aimed to present a systematic study on the use of the LCA methodology in the environmental assessment of effluents from the textile industry. The survey for data was carried out using the Scopus and Web of Science databases, and the PRISMA method was utilized for organizing and selecting of articles. During the meta-analysis phase bibliometric and specific data were extracted from selected publications. For the bibliometric analysis, a quali-quantitative approach was adopted, and the VOSviewer software was employed. The review encompasses a total of 29 articles, which were published between 1996 and 2023.The majority of the reviewed articles have shown the use of the LCA as a supportive tool for optimization focusing on sustainability, comparing the environmental, economic, and technical aspects through different approaches. The findings revel that China has the highest number of authors among the selected articles, while researchers from France and Italy had the highest number of international collaborations. The ReCiPe and CML methods were the most frequently used for evaluating life cycle inventories, with global warming, terrestrial acidification, ecotoxicity, and ozone depletion being the main impact categories. The use of activated carbon in textile effluents treatment has shown to be promising since it is environmentally friendly.

Effect of filtration rates on the performance and head loss development in granular filters during the post-treatment of anaerobic reactor effluent.

This study investigated the performance of a granular filtration system (GFS) composed of a rock filter (RF), a rapid sand filter (RSF), and an activated carbon filter (ACF), applied to the post-treatment of an anaerobic reactor effluent. Four filtration rates (FR) were applied to the GFS (in m3·m-2·d-1): 100-60-60, 100-90-90, 200-120-120, and 200-160-160, for RF-RSF-ACF, respectively. A clarified final effluent with low turbidity (~ 10 NTU), solids (~ 6.5 mg TSS.L-1), and organic matter content (~ 40 mg COD.L-1) was obtained when the GFS worked with FR up to 100-90-90 m3·m-2·d-1. For higher FR, the effluent quality was a little poorer. Principal component analysis showed when the RSF operated at 120 or 160 m3·m-2·d-1, it presented an effluent with higher turbidity which did not affect negatively the ACF performance. The hydraulic load limits in the RSF were reached in periods of 45, 30, and 24.5 h for the FR of 60, 120, and 160 m3·m-2·d-1, respectively, and head loss analysis depicted a more distributed solid retention through the sand depth with the lower FR. Thus, the results revealed that the RF-RSF-ACS system is a promising alternative for effluent polishing of anaerobic reactor, especially when the FR is set at 90 m3·m-2·d-1 or even higher.

Effect of reclaimed water and dehydrated sludge on the morpho-physiology and yield of sorghum.

The effect on the morpho-physiological parameters and yield of sorghum cultivated in a greenhouse with reclaimed water (RW) and (dehydrated sludge (DS) obtained in a sewage treatment plant, was evaluated. Six treatments (T), with five repetitions each, were carried out in entirely randomized blocks. Water (W) was used in T1 (W) (control), T2 (W + NPK), and T3 (W + DS); RW was used in T4 (RW), T5 (RW + P), and T6 (RW + DS). The results showed that irrigation with only RW (T4), or W + DS (T3) was very suitable for the cultivation since an adequate nutritional supply was provided. The positive effects on the morpho-physiological parameters, plant height, stem diameter and stem length (in cm), were: T3 - 148.8, 1.50, and 103, respectively; T4 - 154, 1.70, and 107, respectively; and on the grain production in weight of 1000 seeds (g), and productivity in grains per plant: T3 - 6.97 and 1453, respectively; T4 - 6.81 and 1636, respectively. Both treatments showed for most of the parameters, no significant differences compared with those of T2 or T5 with supplementary fertilizers. A high production of metabolites (mg g-1) like free amino acids was also shown: T3 - 6.45; T4 - 8.43 and proline: T3 - 1.86; T4 - 1.77, known to be a good indication of a plant natural defence against stress conditions, and in soluble protein: T3 - 11.20; T4 - 13.51. Therefore, since the production of such grains with RW or DS can be environmentally and economically beneficial, their use is recommended for small and medium farmers in semiarid regions.

Effect of individual or combined physical and chemical factors on the anaerobic biodegradation of linear alkylbenzene sulphonate.

The effect of six important factors on the anaerobic biodegradation of linear alkylbenzene sulphonate (LAS) was evaluated using a response surface methodology. The factors were: (i) co-substrate concentration (CC), (ii) contact time between LAS and microorganisms, (iii) temperature, (iv) hardness, (v) pH, and (vi) LAS source. The results showed that individually or combined, CC with chemical oxygen demand (COD) ≤50 mg L-1 was the factor that mostly favoured LAS biodegradation; whereas at COD >50 mg L-1, adsorption to sludge and solubilisation in the aqueous medium were favoured. Two-factor interactions promoted the highest percentages of biodegradation (45-52%), adsorption (43-45%), and solubilisation (18-25%). The three-factor interactions resulted in small percentage increases of up to 11%, 5%, and 13% for biodegradation, adsorption, and solubilisation, respectively, compared to those of two-factor interactions. The interactions of four, five, and six factors resulted in a non-significant effect on LAS biodegradation, adsorption, and solubilisation, with percentages close to those quantified for the two- and three-factor interactions. Concentrations of up to 30 mg LAS L-1 did not significantly affect the COD removal efficiency (74-88%) from the medium. These values are commonly obtained in full-scale anaerobic systems used to treat domestic sewage.

Formation and stability of aerobic granular sludge in a sequential batch reactor for the simultaneous removal of organic matter and nutrients from low-strength domestic wastewater.

Simultaneous removal of organic matter, nitrogen, and phosphorus, via simultaneous nitrification and denitrification (SND) and enhanced biological phosphorus removal processes, was evaluated in a pilot-scale sequential batch reactor. The focus was on granule's morphology, stability, microbiological composition, and reactor performance while treating diluted domestic wastewater with total chemical oxygen demand (CODt) of ≈ 200 mg.L-1. The applied organic loading rate was 0.9 ± 0.3 kg CODt.m-3.d-1 in the experiment. Aerobic granular sludge developed gradually. After 87-day operation, granules (diameter ≥ 0.2 mm) were ≥ 50 % of the biomass, and after 168 days, complete granulation was obtained (≥ 80 % of biomass). In the third period (days 168-247, complete granulation), mixed liquor biomass reached a volatile suspended solids (VSS) concentration of 1.2 ± 0.3 g VSS.L-1, with the granules remaining stable until the experimental end. In this period, low effluent concentrations of COD, nitrogen (NH4+-N, NO2--N and NO3--N) and phosphate (PO43-P) were obtained (mg.L-1): 36 ± 11; 4 ± 5; 3 ± 3, 4 ± 5; and 0.9 ± 0.4, respectively. COD, NH4+-N, and PO43--P removal efficiencies (%) were 80 ± 11; 83 ± 20; and 55 ± 24, respectively. Heterotrophic nitrification and SND were observed, resulting in a process efficiency of 31 % even with dissolved oxygen applied to saturation. The phosphate removal was mainly attributed to denitrifying phosphorus accumulating organisms. Pseudomonas, the dominant genus found, acted in nitrogen and phosphorus removal. Pseudoxanthomonas also assisted in phosphorus removal. Bacterial communities in the flocs (≈ 20 % of biomass) during the last period were similar to those in the granules; therefore, they constituted the basis for granule formation, directly contributed to the simultaneous good removal of organic matter and nutrients.

Biological treatment of real textile wastewater containing sulphate, salinity, and surfactant through an anaerobic-aerobic system.

Real textile wastewater containing high salinity (up to 12.6 g·kg-1) and surfactant (up to 5.9 mg·L-1 of linear alkylbenzene sulfonate - LAS) was submitted to biological treatment for colour (up to 652 mg Pt-Co·L-1) and sulphate (up to 1,568.6 mg SO4-2·L-1) removal. The influence of ethanol and molasses supplementation was firstly evaluated in anaerobic batch reactors for the removal of dyes and sulphate. Subsequently, aiming to remove aromatic amines (dye degradation by-products), an anaerobic-aerobic continuous system supplemented with molasses was applied. Supplementation had no influence on colour removal (maximum efficiencies around 70%), while it improved sulphate reduction (23% without supplementation against 87% with supplementation), and conferred robustness to the reactors, which recovered quickly after higher salinity impact. The aerobic reactor removed aromatic amines when the level of surfactants was lower than 1.0 mg LAS·L-1, but the performance of the system was hindered when the concentration was increased to 5.9 mg LAS·L-1. Findings suggest that the supplementation of an easily biodegradable organic matter might be a strategy to overcome wastewater fluctuation in composition.

Start-up strategies to develop aerobic granular sludge and photogranules in sequential batch reactors.

In this study, start-up strategies to develop conventional aerobic granular sludge (AGS) and algal aerobic granular sludge (AAGS) (photogranules), were investigated. The granulation experiment was conducted in four sequencing batch reactors (SBR), of which two were conventional SBRs (RC1, RC2) used as control, and two were photo-SBRs (R1, R2). R1 and RC1 were operated with a 40-min feeding during the reactors´ anaerobic cycle period, whereas R2 and RC2 with a 60-min feeding. All the reactors were operated in two phases with a C:N = 4:1 in Phase I and 8:1 in Phase II. In Phase I, AGS in RC1 and RC2 was formed 15 days before the AAGS development in R1 and R2. However, the AAGS generally presented better stability and higher diameter. On the other hand, AGS presented greater abundance of extracellular polymeric substances producing organisms, such as Xanthomonadacea and Rhodocyclaceae. Chemical oxygen demand (COD) and NH4+-N removal efficiencies were similar in all the four reactors of approximately 70% and 60%, respectively. In this phase, despite the good biomass structure, the reactors were not able to completely oxidize the high influent concentration of NH4+-N (100 mg.L-1) and COD (400 mg.L-1). This can be associated to the short time of the aerobic phase and low biomass content. In Phase II in all the reactors, a good increase in COD and NH4+-N removal efficiencies to values above 95% and 93%, respectively, was achieved under a higher C:N ratio of 8 with lower influent concentration of NH4+-N (50 mg.L-1). The 60-min anaerobic feeding period in R2 and RC2 resulted in greater removal efficiency of nitrogen, confirming that small variation on cycle periods can affect the biomass composition; the biomass presented more compact granules and larger diameters under 60 min-feeding when compared with those obtained with 40 min-feeding in Phase I.

Modelagem matemática para sistema de tratamento de esgoto doméstico com remoção simultânea de matéria orgânica e nitrogênio / Mathematical modeling for domestic sewage treatment system with simultaneous removal of organic matter and nitrogen

RESUMO Neste trabalho, avaliou-se o uso do modelo matemático ASM3 para um sistema piloto de reator compartimentado anaeróbio/anóxico e aeróbio tipo MBBR, utilizado para a remoção simultânea de matéria orgânica e nitrogênio em esgoto doméstico. A simulação computacional foi implementada pelo software ASIM. Selecionou-se um conjunto padrão de parâmetros para o modelo, com uma combinação dos valores calibrados e dados da literatura. Com a modelagem computacional foi possível incluir as características operacionais próprias do sistema de tratamento e, embora o modelo não tenha tido sua capacidade de previsão dos parâmetros validada, foi possível verificar a aplicabilidade do ASM3 para as fases operacionais definidas neste estudo.

ABSTRACT In this work, the use of the ASM3 mathematical model for a pilot system of anaerobic/anoxic and aerobic MBBR compartmentalized reactor, for the simultaneous removal of organic matter and nitrogen in domestic sewage, was evaluated. The simulation was implemented by the ASIM software. A standard set of parameters was selected for the model, with a combination of calibrated values and literature data. With the computational modeling, it was possible to include the operational characteristics of the treatment system and, although the model capacity to predict the parameters could not be validated. Nevertheless, it was possible to verify the applicability of the ASM3 model for the operational phases defined in this study.

Iron(II) monosulfide (FeS) minerals reductively transform the insensitive munitions compounds 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO).

As military applications of the insensitive munitions compounds (IMCs) 2,4-dinitroanisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO) increase, there is a growing need to understand their environmental fate and to develop remediation strategies to mitigate their impacts. Iron (II) monosulfide (FeS) minerals are abundant in freshwater and marine sediments, marshes, and hydrothermal environments. This study shows that FeS solids can reduce DNAN and NTO to their corresponding amines under anoxic ambient conditions. The reactions between IMCs and the FeS minerals were surface-mediated since they did not occur when only dissolved Fe2+(aq) and S2-(aq) were present. Mackinawite, a tetragonal FeS with a layered structure, reduced DNAN mainly to 2-methoxy-5-nitroaniline (MENA), which in turn was partially reduced to 2-4-diaminoanisole (DAAN). The layered structure of mackinawite provided intercalation sites likely responsible for partial adsorption of MENA and DAAN. Mackinawite entirely reduced NTO to 3-amino-1,2,4-triazol-5-one (ATO). The reduction of IMCs showed concurrent oxidation of mackinawite to goethite and elemental sulfur. A commercial FeS product, composed mainly of pyrrhotite and troilite, reduced DNAN to DAAN and NTO to ATO. At pH 6.5, DNAN and NTO transformation rates were 667 and 912 µmol h-1 m-2, respectively, on the mackinawite surface and 417 and 1344 µmol h-1 m-2, respectively, on the commercial FeS surface. This is the first report of the reduction of a nitro-heterocyclic compound (NTO) by FeS minerals. The evidence indicates that DNAN and NTO can be rapidly transformed to their succeeding amines in anoxic subsurface environments and aquatic sediments rich in FeS minerals.

Selecting the best electron donor and operational temperature for the rapid biotransformation of the insensitive munitions compound 2,4-dinitroanisole (DNAN) by anaerobic sludge.

2,4-Dinitroanisole (DNAN) is a toxic compound increasingly used by the military that can be released into the environment on the soil of training fields and in the wastewater of manufacturing plants. DNAN's nitro groups are anaerobically reduced to amino groups by microorganisms when electron donors are available. Using anaerobic sludge as the inoculum, we tested different electron donors for DNAN bioreduction at 20 and 30 °C: acetate, ethanol, pyruvate, hydrogen, and hydrogen + pyruvate. Biotic controls without external electron donors and abiotic controls with heat-killed sludge were also assayed. No DNAN conversion was observed in the abiotic controls. In all biotic treatments, DNAN was reduced to 2-methoxy-5-nitroaniline (MENA), which was further reduced to 2,4-diaminoanisole (DAAN). Ethanol or acetate did not increase DNAN reduction rate compared to the endogenous control. The electron donors that caused the fastest DNAN reductions were (rates at 30 °C): H2 and pyruvate combined (311.28 ± 10.02 µM·d-1·gSSV-1), followed by H2 only (207.19 ± 5.95 µM·d-1·gSSV-1), and pyruvate only (36.35 ± 2.95 µM·d-1·gSSV-1). Raising the temperature to 30 °C improved DNAN reduction rates when pyruvate, H2, or H2 + pyruvate were used as electrons donors. Our results can be applied to optimize the anaerobic treatment of DNAN-containing wastewater.

Bioremediation of polycyclic aromatic hydrocarbons in contaminated mangroves: Understanding the historical and key parameter profiles.

Sensitive biomes, such as coastal ecosystems, have become increasingly susceptible to environmental impacts caused by oil logistics and storing, which, although more efficient nowadays, still cause spills. Thus, bioremediation techniques attract attention owing to their low impact on the environment. Among petroleum-based compounds, polycyclic aromatic hydrocarbons (PAHs) are known for their potential impact and persistence in the environment. Therefore, PAH bioremediation is notably a technique capable of reducing these polluting compounds in the environment. However, there is a lack of understanding of microbial growth process conditions, leading to a less efficient choice of bioremediation methods. This article provides a review of the bioremediation processes in mangroves contaminated with oils and PAHs and an overview of some physicochemical and biological factors. Special attention was given to the lack of approach regarding experiments that have been conducted in situ and that considered the predominance of the anaerobic condition of mangroves.

Covalent binding with model quinone compounds unveils the environmental fate of the insensitive munitions reduced product 2,4-diaminoanisole (DAAN) under anoxic conditions.

2,4-Dinitroanisole (DNAN) is an insensitive munitions compound expected to replace 2,4,6-trinitrotoluene (TNT). The product of DNAN's reduction in the environment is 2,4-diaminoanisole (DAAN), a toxic and carcinogenic aromatic amine. DAAN is known to become irreversibly incorporated into soil natural organic matter (NOM) after DNAN's reduction. Herein, we investigate the reactions between DAAN and NOM under anoxic conditions, using 1,4-benzoquinone (BQ) and methoxybenzoquinone (MBQ) as model humic moieties of NOM. A new method stopped the fast reactions between DAAN and quinones, capturing the fleeting intermediates. We observed that DAAN incorporation into NOM (represented by BQ and MBQ models) is quinone-dependent and occurs via Michael addition, imine (Schiff-base) formation, and azo bond formation. After dimers are formed, incorporation reactions continue, resulting in trimers and tetramers. After 20 days, 56.4% of dissolved organic carbon from a mixture of DAAN (1 mM) and MBQ (3 mM) had precipitated, indicating an extensive polymerization, with DAAN becoming incorporated into high-molecular-weight humic-like compounds. The present work suggests a new approach for DNAN environmental remediation, in which DNAN anaerobic transformation can be coupled to the formation of non-extractable bound DAAN residues in soil organic matter. This process does not require aerobic conditions nor a specific catalyst.

Bacteria Make a Living Breathing the Nitroheterocyclic Insensitive Munitions Compound 3-Nitro-1,2,4-triazol-5-one (NTO).

The nitroheterocyclic 3-nitro-1,2,4-triazol-5-one (NTO) is an ingredient of insensitive explosives increasingly used by the military, becoming an emergent environmental pollutant. Cometabolic biotransformation of NTO occurs in mixed microbial cultures in soils and sludges with excess electron-donating substrates. Herein, we present the unusual energy-yielding metabolic process of NTO respiration, in which the NTO reduction to 3-amino-1,2,4-triazol-5-one (ATO) is linked to the anoxic acetate oxidation to CO2 by a culture enriched from municipal anaerobic digester sludge. Cell growth was observed simultaneously with NTO reduction, whereas the culture was unable to grow in the presence of acetate only. Extremely low concentrations (0.06 mg L-1) of the uncoupler carbonyl cyanide m-chlorophenyl hydrazone inhibited NTO reduction, indicating that the process was linked to respiration. The ultimate evidence of NTO respiration was adenosine triphosphate production due to simultaneous exposure to NTO and acetate. Metagenome sequencing revealed that the main microorganisms (and relative abundances) were Geobacter anodireducens (89.3%) and Thauera sp. (5.5%). This study is the first description of a nitroheterocyclic compound being reduced by anaerobic respiration, shedding light on creative microbial processes that enable bacteria to make a living reducing NTO.

The key role of oxygen in the bioremoval of 2,4-diaminoanisole (DAAN), the biotransformation product of the insensitive munitions compound 2,4-dinitroanisole (DNAN), over other electron acceptors.

Insensitive munitions compounds, such as 2,4-dinitroanisole (DNAN), are replacing conventional explosives. DNAN is anaerobically reduced to 2,4-diaminoanisole (DAAN), a toxic aromatic amine. However, the removal of DAAN under different redox conditions is yet to be elucidated. Herein, we analyzed DAAN consumption in biotic and abiotic microcosms when exposed to different redox conditions (without added electron acceptor, without added electron acceptor but with pyruvate as a co-substrate, with sulfate, with nitrate, and with oxygen), using an anaerobic sludge as inoculum. We observed that DAAN autoxidation, an abiotic reaction, was significant in microaerobic environments. DAAN also reacted abiotically with heat-killed sludge up to a saturation limit of 67.4 µmol DAAN (g VSS heat-killed sludge)-1. Oxygen caused the fastest removal of DAAN in live sludge among the conditions tested. Treatments without added electron acceptors (with or without pyruvate) presented similar DAAN removal performances, although slower than the treatment with oxygen. Sulfate did not exhibit any effect on DAAN removal compared to the treatment without added electron acceptors. Nitrate, however, inhibited the process. An enrichment culture from the microcosms exposed to oxygen could be developed using DAAN as the sole substrate in microaerobic conditions. The enrichment profoundly changed the microbial community. Unclassified microorganisms accounted for 85% of the relative abundance in the enrichment culture, suggesting that DAAN microaerobic removal might have involved organisms that were not yet described. Our results suggest that DAAN microaerobic treatment can be coupled to DNAN anaerobic reduction in sludge, improving the treatment of DNAN-containing wastewaters.

Cultivo de melancia no semiárido irrigado com diferentes lâminas de esgoto doméstico tratado / Watermelon cultivation in the semi-arid irrigated with different heights of treated domestic sewage

RESUMO O objetivo deste trabalho foi avaliar a viabilidade agronômica do uso de esgoto doméstico tratado em reator anaeróbio para o cultivo de melancia tipo Crimson Sweet. Em estudo de campo no Sertão Pernambucano, avaliou-se a aplicação de quatro lâminas de irrigação por meio do sistema de gotejamento. Foram avaliadas as lâminas de 50, 75, 100 e 125% baseadas nos resultados da evapotranspiração e nas exigências do sistema de irrigação adotado. A caracterização do efluente tratado indicou conformidade com as recomendações para a aplicação agrícola, entretanto a concentração de sólidos suspensos (114 mg.L-1) demandou maior frequência de limpeza dos gotejadores. Foram observados um aumento da capacidade de troca catiônica e uma redução do pH do solo em todos os tratamentos. O tratamento com lâmina a 125% resultou em frutos de maiores tamanho (20,78 cm) e peso (7,12 kg.un-1), bem como de produtividade média (61,1 t.ha-1). Estes valores são superiores às médias nacional e do Estado de Pernambuco, demonstrando a viabilidade agronômica do reúso nas condições testadas.

ABSTRACT The aim of this paper was to assess the agronomic viability of using anaerobically treated domestic sewage in cultivation of Crimson Sweet watermelon. In a field experiment conducted in the semi-arid region of Pernambuco state, Brazil, four treatments (T) were used to assess the effects of irrigation using dripping system on fruits and soil. Four heights of 50% (T1), 75% (T2), 100% (T3) and 125% (T4), based on the calculated evapotranspiration and irrigation needs, were applied. The treated effluent characteristics indicated compliance with the recommendations for agricultural application, but the concentration of suspended solids (114 mg.L-1) demanded frequent cleansing of the dripper blockages. We observed an increase in the cation exchange capacity and a decrease of the soil pH in all the treatments. The best results were obtained with the treatment T4 (height of 125%), which showed watermelons of bigger size (20.78 cm), as well as the highest productivity (61.1 t.ha-1) and fruit weight (7.12 kg.un-1). These values are higher than those of the country and Pernambuco state, demonstrating the agronomic feasibility of reuse under the studied conditions.

A PVC-pipe device as a sanitary barrier for improving rainwater quality for drinking purposes in the Brazilian semiarid region.

We evaluate the behavior of a device designed to automatically divert and store the first flush of harvested rainwater in cisterns. The first phase (PI) was conducted with artificial precipitation in an experimental installation seeking to identify how many millimeters of rainwater should be diverted to preserve the rainwater quality. In the second phase (PII), we designed a PVC-pipe device to store the first millimeter of rainwater, and tested it in field (a rural area in Brazil) during two real rainfall events. In the third phase (PIII), the device and a hand pump were assayed for two years using eight cisterns in a rural area where people drink the rainwater. PI results indicated that the most significant pollution of the rainwater is flushed with the first millimeter of rain, and diversion promoted the removal of 98% and 100% of the total coliforms and Escherichia coli, respectively. The bacteriological behavior was maintained in the subsequent phases. The device was able to preserve the quality of the rainwater most of the time, satisfying drinking requirements for the parameters of turbidity and color. The satisfactory performance of the device was confirmed in the field, behaving as a sanitary barrier for rainwater quality protection.

The effect of methanogenesis inhibition, inoculum and substrate concentration on hydrogen and carboxylic acids production from cassava wastewater.

Manipueira is a carbohydrate-rich agro-industrial waste from cassava processing. It is considered well suitable for biotechnological processes, such as hydrogen and carboxylic acids production, due to the high content of easily degradable organic matter. However, the proper methanogenesis inhibition method, inoculum type, and organic loads are factors still limiting the processes. The objective in this work was to evaluate the effects of such factors on byproducts production in anaerobic reactors. Batch experiments were conducted with 2.3-L flasks during two operational phases. In the first phase (P1), inhibition of methanogens in the sludge was evaluated using acetylene (1% v/v of headspace) and heat treatment (120 °C, 1 atm for 30 min). In the second phase (P2), three inoculum types obtained from common anaerobic sludges (bovine rumen and sludges from municipal and textile industrial wastewater treatment plants) were individually assayed. P2 aimed to identify the best inoculum, based on hydrogen production ability, which was tested for three initial concentrations of manipueira in terms of chemical oxygen demand (COD) (10, 20 and 40 g O2/L). Results of P1 indicated that either acetylene or heat treatment efficiently inhibited methanogenesis, with no methane production. However, the maximum H2 production potential by applying heat treatment (~ 563 mL) was more than twice compared with that by acetylene treatment (~ 257 mL); and butyrate was the main carboxylic acid by-product (~ 3 g/L). In P2 experiments after sludge heat treatment, the highest hydrogen yield (1.66 ± 0.07 mol H2/mol glucose) and caproic acid production (~ 2 g/L) were observed at 20 g O2/L of manipueira COD, when bovine rumen was the inoculum. The primary metabolic degradation products in all P2 experiments were ethanol, acetic, butyric, propionic and caproic acids. The finding of caproic acid detection indicated that the applied conditions in manipueira anaerobic degradation favored carbon chain elongation over methanogenesis.

Multi-criteria analysis for municipal solid waste management in a Brazilian metropolitan area.

The decision-making process involved in municipal solid waste management (MSWM) must consider more than just financial aspects, which makes it a difficult task in developing countries. The Recife Metropolitan Region (RMR) in the Northeast of Brazil faces a MSWM problem that has been ongoing since the 1970s, with no common solution. In order to direct short-term solutions, three MSWM alternatives were outlined for the RMR, considering the current and future situations, the time and cost involved and social/environmental criteria. A multi-criteria approach, based on the Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE), was proposed to rank these alternatives. The alternative that included two private landfill sites and seven transfer, sorting and composting stations was confirmed as the most suitable and stable option for short-term MSWM, considering the two scenarios for the criteria weights. Sensitivity analysis was also performed to support the robustness of the results. The implementation of separate collections would minimize the amount of waste buried, while maximizing the useful life of landfill sites and increasing the timeframe of the alternative. Overall, the multi-criteria analysis was helpful and accurate during the alternative selection process, considering the similarities and restrictions of each option, which can lead to difficulties during the decision-making process.