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In this paper, we explore the applications of bacteriophages and the advantages of using these viruses to control undesirable organisms in wastewater treatment plants. Based on this, this paper reviewed the literature on the subject by performing a bibliometric and scientometric analysis of articles published in peer-reviewed journals through 2021. We obtained 806 publications, of which 40% were published in the last 5 years, demonstrating an increase in interest in the subject. These articles analyzed, bacteriophages in treatment plants were strongly linked to bacteria such as Escherichia coli and related to disinfection, inactivation, sewage, and wastewater, in addition, biocontrol studies have gained prominence in recent years, particularly due to the resistance of microorganisms to antibiotics. Studies have shown that bacteriophages have great potential for application in treatment systems to control unwanted processes and act as valuable economic and environmental tools to improve the efficiency of various treatment technologies. Although these viruses have already been studied in various applications to optimize treatment plant processes, technology transfer remains a challenge due to the limitations of the technique-such as physicochemical factors related to the environment-and the complexity of biological systems. The research focusing on application strategies in conjunction with molecular biology techniques can expand this study area, enabling the discovery of new bacteriophages.

The anaerobic ammonium oxidation (anammox) process has attracted significant attention as an economic, robustness, and sustainable method for the treatment of nitrogen (N)-rich wastewater. Anammox bacteria (AnAOB) coexist with other microorganisms, and particularly with ammonia-oxidizing bacteria (AOB) and/or heterotrophic bacteria (HB), in symbiosis in favor of the substrate requirement (ammonium and nitrite) of the AnAOB being supplied by these other organisms. The dynamics of these microbial communities have a significant effect on the N-removal performance, but the corresponding metabolic pathways are still not fully understood. These processes involve many common metabolites that may act as key factors to control the symbiotic interactions between these organisms, to maximize N-removal efficiency from wastewater. Therefore, this work overviews the current state of knowledge about the metabolism of these microorganisms including key enzymes and intermediate metabolites and summarizes already reported experiences based on the employment of certain metabolites for the improvement of N-removal using anammox-based processes. PRACTITIONER POINTS: Approaches knowledge about the biochemistry and metabolic pathways involved in anammox-based processes. Some molecular tools can be used to determine enzymatic activity, serving as an optimization in nitrogen removal processes. Enzymatic evaluation allied to the physical-chemical and biomolecular analysis of the nitrogen removal processes expands the application in different effluents.

Emerging contaminants (ECs) include endocrine-disrupting compounds, pharmaceuticals (lipid regulators, antibiotics, diuretics, non-steroid anti-inflammatory drugs, stimulant drugs, antiseptics, analgesic, beta blockers), detergents, disinfectants, and personal care products. The residues from these compounds have become a concerning because of their bioactive presence on environmental matrices, especially water bodies. The development of technologies, aiming the secure and efficient removal of these compounds from the environment or event to remove them before they achieve the environment, is necessary. In these context, the present review is about promising eco-friendly, low-cost and specially applied, including biological processes using microalgae, bacteria, enzymes produced by fungi, and adsorbent materials such as those recycled from other processes waste. The processes where revised considering the removal mechanism and the efficiency rate.

In this paper, we explore the applications of bacteriophages and the advantages of using these viruses to elucidate the possibility of applying them to control substrate competition organisms in anammox-based processes. The partial nitrification/anammox offers economic and structural advantages compared to conventional nitrogen removal processes. However, the appearance of substrate competing bacteria is typical, as is the case of nitrite-oxidizing bacteria (NOB), which tend to grow unrestrainedly in the system, converting all ammonia to nitrate, globally impacting the system once substrate availability is compromised. Thus, control measures to prevent this substrate competition are vital for process efficiency. We used a literature review depicting the main applications of bacteriophages in wastewater treatment plants. Initial studies demonstrated bacteriophages have great potential to be applied in anammox-based processes, such as partial nitrification/anammox (PN/A) acting to combat NOB, a valuable economic and environmental tool to improve the efficiency of nitrogen removal processes. Although these viruses have already been studied in various applications to optimize treatment plant processes, technology transfer remains a challenge due to the limitations of the technique and the complexity of biological systems. The research development focused on application strategies in conjunction with molecular biology techniques can expand this study area, enabling the discovery of bacteria and bacteriophages.

Improper disposal of animal waste is responsible for several environmental problems, causing eutrophication of lakes and rivers, nutrient overload in the soil, and the spread of pathogenic organisms. Despite the potential to cause adverse ecological damage, animal waste can be a valuable source of resources if incorporated into a circular concept. In this sense, new approaches focused on recovery and reuse as substitutes for traditional processes based on removing contaminants in animal manure have gained attention from the scientific community. Based on this, the present work reviewed the literature on the subject, performing a bibliometric and scientometric analysis of articles published in peer-reviewed journals between 1991 and 2021. Of the articles analyzed, the main issues addressed were nitrogen and phosphorus recovery, energy generation, high-value-added products, and water reuse. The energy use of livestock waste stands out since it is characterized as a consolidated solution, unlike other routes still being developed, presenting the economic barrier as the main limiting factor. Analyzing the trend of technological development through the S curve, it was possible to verify that the circular economy in the management of animal waste will enter the maturation phase as of 2036 and decline in 2056, which demonstrates opportunities for the sector's development, where animal waste can be an economic agent, promoting a cleaner and more viable product for a sustainable future.

Faced to the possibility of shortage of fossil fuels, researchers have focused their research for alternative production of biofuels. However, in order to guarantee an increase in the energy matrix, it is necessary to ensure that the process can be scaled up until it reaches the level of trade. In this sense, this study evaluated the production of second-generation ethanol using industrial sugarcane bagasse hydrolysate (non-detoxified) fermented by Wickerhamomyces sp. strain UFFS-CE-3.1.2, in bioreactor. For this, we carried out a fermentation without pH adjustment and another one with pH constantly controlled (7.00). The fermentation process conducted with adjusted pH favored the consumption of xylose and glucose and led to a production of 9.25 g L−1 of ethanol. The results indicate that the inhibitory effect of acetic acid can be reduced with the increase in pH, favoring the consumption of xylose levels by the yeast Wickerhamomyces sp. UFFS-CE-3.1.2. The production using a bioreactor brought similar results to those obtained in previous fermentation processes conducted in flasks, indicating the possibility of enlarging the system to commercial level. The mathematical model proposed led to an adequate fit when compared to experimental data.

Swine production chain generates residues with potential application in environmental processes. This study aimed at the use of swine hair as a potential biofilter for hexavalent chromium (Cr(VI)) removal from wastewater of tannery industry. The hair was pretreated using H2O2 in alkaline medium, and statistical analysis was carried out to evaluate the hair degradation, as well the Cr(VI) removal by the potential pretreated biofilter. The results showed 99% of Cr(VI) removal in 105 min of treatment in large pH range (1–10). Treated and untreated effluents were submitted to cytotoxicity study using vegetable and animal cells, demonstrating a significant reduction on toxicity to both cells. Therefore, swine hair demonstrated to be a promising residue for heavy metal removal on the perspective of an environmentally friendly technique.

Phosphorus (P) is essential for life and has a fundamental role in industry and the world food production system. The present work describes different technologies adopted for what is called the second-generation P recovery framework, that encompass the P obtained from residues and wastes. The second-generation P has a high potential to substitute the first-generation P comprising that originally mined from rock phosphates for agricultural production. Several physical, chemical, and biological processes are available for use in second-generation P recovery. They include both concentrating and recovery technologies: (1) chemical extraction using magnesium and calcium precipitating compounds yielding struvite, newberyite and calcium phosphates; (2) thermal treatments like combustion, hydrothermal carbonization, and pyrolysis; (3) nanofiltration and ion exchange methods; (4) electrochemical processes; and (5) biological processes such as composting, algae uptake, and phosphate accumulating microorganisms (PAOs). However, the best technology to use depends on the characteristic of the waste, the purpose of the process, the cost, and the availability of land. The exhaustion of deposits (economic problem) and the accumulation of P (environmental problem) are the main drivers to incentivize the P’s recovery from various wastes. Besides promoting the resource’s safety, the recovery of P introduces the residues as raw materials, closing the productive systems loop and reducing their environmental damage.

Oily wastewater is generated in large amounts by different industry segments, such as food and beverage, oil and gas, cosmetics, and metal processing. Its incorrect disposal causes soil and water contamination, generating environmental and public health problems. In this sense, the use of membranes able to remove the oil present in the wastewater has shown to be a promising technology that can treat a larger range of oily wastewaters than conventional systems without losing the high oil removals. Catalytic membrane processes can combine the separation and catalyzed degradation of the oil, minimizing fouling and increasing the membrane lifespan. Thus, this chapter aims to approach the main aspects of oily wastewater treatment by catalytic membranes, including enzymatic and advanced oxidation processes, as photocatalysis, electrocatalysis, and Fenton-like processes. The chapter is organized in six sections: introduction, oily wastewater, membranes for oily wastewater treatment, catalytic membranes, conclusions, and future trends.

A collection of kinetic models to explore the bacteria pathway inhibition by high-ammonia during deammonification process was fitted. The main goal was to determine the substrate concentration to operate the deammonification with efficiency, performance and low impact to ANAMMOX and ammonia-oxidizing bacteria (AOB) by substrate. A new mathematical model was created to describe the deammonification behavior, since the empirical theoretical models showed inconsistent parameters to describe the process. The proposed model showed significant prediction to the estimable parameters and according to it, until 550 mg NH3-N L−1 no inhibitions by ammonia and nitrite were observed. However, concentrations higher than this promote the decrease on specific bacterial activity and nitrite accumulation, since it was not quickly consumed by the bacteria. The proposed model can be applied to predict microorganism affinity and inhibition by substrate over a wide range of ammonia concentrations (

Different pretreatments were evaluated on corn stalk (Zea mays) applied as a lignocellulosic source in anaerobic co-digestion with swine manure, using sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) for biogas production purposes. Using H2SO4 we achieved a 75.1% removal of the hemicellulose fraction, in low acid concentrations (0.75% v.v−1). However, this technique inhibited the co-digestion process. Pretreatment with 12% of H2O2 (pH 11.5) increased the cellulose fraction by 73.4% and reduced the lignin content by 71.6%. This pretreatment is recommended for biogas production, as it increased the final volume of biogas by 22% and reduced the digestion time by one third. So, a promising alternative was obtained in order to facilitate the anaerobic digestion of the carbohydrates present in this biomass.

The application of the circular economy concept should utilize the cycles of nature to preserve materials, energy and nutrients for economic use. A full-scale pig farm plant was developed and validated, showing how it is possible to integrate a circular economy concept into a wastewater treatment system capable of recovering energy, nutrients and enabling water reuse. A low-cost swine wastewater treatment system consisting of several treatment modules such as solid-liquid separation, anaerobic digestion, biological nitrogen removal by nitrification/denitrification and physicochemical phosphorus removal and recovery was able to generate 1880.6 ± 1858.5 kWh d−1 of energy, remove 98.6% of nitrogen and 89.7% of phosphorus present in the swine manure. In addition, it was possible to produce enough fertilizer to fertilize 350 ha per year, considering phosphorus and potassium. In addition, the effluent after the chemical phosphorus removal can be safely used in farm cleaning processes or disposed of in water bodies. Thus, the proposed process has proven to be an environmentally superior swine waste management technology, with a positive impact on water quality and ensuring environmental sustainability in intensive swine production.

The performance of a deammonification reactor fed with increasing nitrogen loading rates (NLR) was evaluated. The digestate from a continuous stirred tank reactor (CSTR) treating sludge from a swine production unit was diluted to provide different ammonia concentrations. The biomass samples from the end of each experimental phase were analyzed for microorganism community evaluation. The results proved that deammonification system supported a NLR up to 3.27 ± 0.13 g N L−1 d−1 with nitrogen removal efficiency of 83%. The specific ammonia consumption rate (µNH3-N) did not decrease up to this NLR proving the stability of reactor performance. Anammox bacteria genus shifted along the experiment and at the end the predominant anammox bacteria found in the reactor was candidatus Brocadia. Finally, it was proved that a deammonification reactor for nitrogen removal from CSTR digestate could be easily controlled only by monitoring pH and dissolved oxygen.

We studied different pre-treatments of poultry litter aiming to add economic value to this residue. Strategies were applied to extract ammonium nitrogen with the aim of allowing its further use as fertilizer, and to promote the hydrolysis and solubilization of lignocellulosic components with the aim of facilitating its subsequent conversion to biogas. Ammonia extraction was performed by solubilization in water in a one-step process and by successive extraction steps (3 times 60 min). Successive extractions presented greater removal of total ammonia nitrogen than did one-step extraction, solubilizing about 36% of the ammonia in water. In parallel pre-treatment using ultrasound was performed to increase carbon bioavailability for anaerobic digestion. Using this tool, 24.7 g kg-1 of total organic carbon and 13.0 g kg-1 of total reducing sugars were solubilized, employing 10% dry mass sample amount, 100% amplitude ultrasound at frequency of 20 kHz amplitude and 2.5 min of treatment (energy input of 299 ± 7 kJ L-1; 3,822 ± 95 kJ kg-1). Anaerobic digestion of ultrassound pre-treated biomass was evaluated using a biological biogas production assay, and an increase of 10% of biogas production was obtained compared to untreated samples (147.9 and 163.0 mL g-1 for crude and pre-treated PL, respectively). The findings suggest that these are environmentally friendly and sustainable strategies to add economic value to poultry litter, reducing the environmental impacts of improper disposal.

Agro-industrial waste is essentially made up of oxygen-containing organic polymers. Unlike fossil fuels, organic waste biomass is highly oxygenated owing to the presence of carbohydrates. In decreasing order of predominance, carbon (C) is the main constituent (ranging from 30 to 60%) on a dry basis (db). Next is oxygen (O) (30–40%) by weight (db), hydrogen (H) (5–6%) (db) and finally nitrogen (N), sulfur (S) and chlorine (Cl) that are generally present in lower quantities (1%) (db). All these elements are organized in the form of sugars and other compounds (here I would like to add a few more) providing an attractive source for exploiting valuable resources in the energy and biorefinery sector.

In order for the conversion of lignocellulosic biomass to biofuels to be efficient, the use of pretreatments of the raw materials is fundamental to transform stable lignocellulosic structures, overcoming the recalcitrance of lignocelluloses, chemical composition, and digestibility in soluble sugars, thereby improving the subsequent process of fermentation. As seen in the previous sections, there are several types of pretreatments (biological, physical, chemical) as well as the possibility of combining these. Nevertheless, some of the approaches used may suffer from significant disadvantages in terms of economic production, industrial scales, and ecological impacts.

Among the proposals for the application of pretreated biomasses, those that make possible the realization of the circular economy appear as alternatives in several areas of biotechnology. Given this circular economy proposal, processes for this purpose can be adapted. When referring to pretreatment methods, some indicators should be considered, including energy cost, formation of inhibitors, sugar content (in some cases as production of ethanol), yield and its effects on the environment, and if necessary, existing methods can be adapted.

To meet the population’s demand for products and services, it is inevitable that industry will interact with the environment during the search for inputs and outputs in the production processes. With the globalization of the market, it is no longer efficient or sustainable for companies to employ linear economic models in which the fundamental idea is to extract raw material, transform it, and discard it at the end of its life cycle.

Pretreatment of residual biomass is one of the key elements in integrated conversion processes such as biorefineries. Biotechnology projects rely heavily on the efficient, technical, economic, and environmental feasibility of pretreatments. Pretreatment is a unitary operation that precedes a certain process, and it is not itself the ultimate goal of the activity. Nevertheless, the inclusion of this step increases the efficiency of subsequent processes by increasing accessibility to the primordial biomass structure, facilitating access to enzymes and reagents used in the development of high added-value products.

Organic carbon can affect the biological nitrogen removal process since the Anammox, heterotrophic and denitrifying bacteria have different affinities and feedback in relation to carbon/nitrogen ratio. Therefore, we reviewed the wastewater carbon concentration, its biodegradability and bioavailability to choose the appropriate nitrogen removal process between conventional (nitrification-denitrification) and Anammox-based process (i.e. integrated with the partial nitritation, nitritation, simultaneous partial nitrification and denitrification or partial-denitrification). This review will cover: (i) strategies to choose the best nitrogen removal route according to the wastewater characteristics in relation to the organic matter bioavailability and biodegradability; (ii) strategies to efficiently remove nitrogen and the remaining carbon from effluent in anammox-based process and its operating cost; (iii) an economic analysis to determine the operational costs of two-units Anammox-based process when compared with the commonly applied one-unit Anammox system (partial-nitritation-Anammox). On this review, a list of alternatives are summarized and explained for different nitrogen and biodegradable organic carbon concentrations, which are the main factors to determine the best treatment process, based on operational and economic terms. In summary, it depends on the wastewater carbon biodegradability, which implies in the wastewater treatment cost. Thus, to apply the conventional nitrification/denitrification process a CODb/N ratio higher than 3.5 is required to achieve full nitrogen removal efficiency. For an economic point of view, according to the analysis the minimum CODb/gN for successful nitrogen removal by nitrification/denitrification is 5.8 g. If ratios lower than 3.5 are applied, for successfully higher nitrogen removal rates and the economic feasibility of the treatment, Anammox-based routes can be applied to the wastewater treatment plant.

Sludge from the bottom of an anaerobic lagoon storage system contains nutrient residues, as well as inorganic and organic matter. These wastes have polluting impacts on swine farms, and beyond the management alternatives, few studies apply economic and sustainable biological methods to reduce their effects. In this study, denitrification was proposed as an alternative sludge treatment for settling tanks (ST), biodigesters, and stabilized lagoons. The sludge sources had different deposition times and bioavailable carbon concentrations. Accordingly, the effects of agitation and carbon and nitrate concentrations were evaluated. The best removal feasibility was presented with the ST sludge, corresponding to 25% (v v−1) of the background volume, achieving higher total organic carbon (1342 mg L−1 day−1) and nitrate (279 mg L−1 day−1) removal. Furthermore, sludge management by denitrification was affected by carbon bioavailability and proven to be cost-effective, with 125 days required for processing.

The objective of this study was to evaluate the ethanol production by Wickerhamomyces sp. using soybean straw and hull hydrolysates obtained by subcritical water hydrolysis and, afterward, the biogas production using the fermented hydrolysates. Ethanol was produced using the straw and hull hydrolysates diluted and supplement with glucose, reaching 5.57 ± 0.01 g/L and 6.11 ± 0.11 g/L, respectively. The fermentation in a bioreactor with changing the pH to 7.0 allowed achieving maximum ethanol production of 4.03 and 3.60 g/L for straw and hull hydrolysates at 24 h, respectively. The biogas productions obtained for the fermented hydrolysates of straw with and without changing the pH were 739 ± 37 and 652 ± 34 NmL/gVSad, respectively. The fermented hydrolysate of hull without changing the pH presented 620 ± 26 NmL/gVSad. The soybean residues produced biofuels, indicating these residues show potential as raw material for renewable energy production.

Anaerobic digestion is an environmentally friendly technology for the stabilization and recovery of biodegradable organic waste, both agroindustrial and urban. Hydrolysis is the first and one of the main steps of the anaerobic digestion process, as it determines the overall biodegradation rate of the substrates. Fibrous materials, for example, although rich in carbon, present sugars protected by lignocellulosic structures, which hinders their biodegradability. Lipid residues present a great energetic potential; however, they are hydrophobic, which hinders their hydrolysis. Residues that have coarse granulometry tend to exhibit long periods of biodegradation due to their small surface areas and difficult solubilization. In this regard, the present chapter will discuss the application of pretreatments of substrates for anaerobic biodigestion by physical, chemical, and biological methods. The aim is to facilitate the hydrolysis and increase the energy and nutritional use of the residues in shorter time intervals, increasing the yield and optimizing the biogas production chain.

In this study, we evaluated the concentration of lipases from Aspergillus niger using efficient and low-cost methods aiming at application in the treatment of waste cooking oils. The change in ionic strength of the medium by the addition of salt and precipitation with ethanol increased the specific activity from 2.90 to 28.50 U/mg, resulting in a purification factor of 9.82-fold. The use of acetone resulted in a specific activity of 33.63 U/mg, resulting in a purification factor of 11.60-fold. After that, the concentrated lipase was used in the hydrolysis of waste cooking oil and 753.07 and 421.60 µmol/mL of free fatty acids were obtained for the enzyme precipitated with ethanol and acetone, respectively. The hydrolysis of waste cooking oil catalyzed by homemade purified lipase in ultrasonic media can be considered a pretreatment of oil by converting a significant amount of triglycerides into free fatty acids.

This study aimed at evaluating the activity of peroxidases after ultrasound and microwave radiation exposure as an alternative to the wastewater treatment improvement. The results showed that after treatment with ultrasound using a power of 30% and a temperature of 55 °C was obtained an increase in relative activity, 129.5% in the enzyme from rice bran, 147.9% in the enzyme from soybean meal and 102.4% in the enzyme from horseradish. Using microwave radiation, the highest relative activity (107.4%) was observed for the peroxidase extracted from rice bran with 10 seconds of reaction time and a reaction temperature of about 50 °C. The data obtained in this study suggest that the ultrasonic bath and microwave are adequate for conducting reactions catalyzed by peroxidases because it was possible to increase their activity during the performed tests. Preliminary tests of enzyme application showed that the highest color removal occurred using 3 mL of the enzyme extract from rice bran and H2O2 concentrations of 40 mg L-1. This condition resulted in a color removal of about 40%.

O presente trabalho avaliou o processo de extracao de lipase produzida pelo fungo Aspergillus sp., identificado como um bom produtor da enzima. Para producao da lipase, foi utilizado o processo de fermentacao em estado solido tendo como substrato a torta de canola, subproduto agroindustrial resultante do processo de extracao do oleo de canola. Buscou-se avaliar a influencia da temperatura e do pH de extracao da enzima, para isso utilizou-se um delineamento experimental a fim de avaliar o processo de extracao. Os resultados obtidos mostraram que a temperatura mais adequada para a extracao das lipases e de 50oC e o pH, segundo analise estatistica nao apresentou efeito significativo, na faixa estudada.

O presente trabalho avaliou a producao de lipase utilizando o fungo Aspergillus sp., que foi identificado como um bom produtor da enzima. Foi utilizado como substrato no processo de fermentacao em estado solido, o subproduto da industria de processamento de canola, a torta de canola. Para este estudo foi elaborado um delineamento composto central 2² e entao verificou-se que a melhor condicao para a producao de lipase utilizando o fungo Aspergillus sp. tendo como substrato a torta de canola, foi de 60 % de umidade e, 2 % de ureia como fonte suplementar de nitrogenio.

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