Ammonia emission during composting results in anthropogenic odor nuisance and reduces the agronomic value of the compost due to the loss of nitrogen. Adjusting the operating parameters during composting is an emerging in situ odor control technique that is cheap and highly efficient. The effects of in situ NH₃ emission control were investigated in this study by simultaneously adjusting key operating parameters (such as C/N ratio, aeration rate, and moisture content) during the composting processes (C1–C9). Results showed that the average NH₃ emission concentrations for different treatments were in the order of C1 > C4 > C2 > C5 > C3 > C6 > C7 > C8 > C9. The total content of NH₃ emission (21.02 g/kg) in C9 (C/N ratio = 35, aeration rate = 15 L/min, and moisture content = 60%) was much lower than that (65.95 g/kg) in C1 (C/N ratio = 15, aeration rate = 5 L/min, and moisture content = 60%). The nitrogen loss ratio was 27.36% for C1, while 16.15% for C9. The microbial diversity and abundance in C9 and C1 were compared using high-throughput sequencing. The relationship between NH₃ emission, operating parameters, and the related functional microbial communities was also investigated. Results revealed that Nitrosospira, Nitrosomonas, Nitrobacter, Pseudomonas, Methanosaeta, Rhodobacter, Paracoccus, and Sphingobacterium were negatively related to NH₃ emission. According to the above results, the optimal values for different operating parameters for the in situ NH₃ control during kitchen waste composting were, respectively, moisture content of 70%, C/N ratio of 35, and aeration rate of 15 L/min, with the order of effectiveness from high to low being aeration rate > C/N > moisture. This information could be used as a valuable reference for the in situ NH₃ emission control during kitchen waste composting.

Biodiesel production from microalgae has been researched extensively and attempted to commercialize on a large scale, but there are major hurdles in the production process like harvesting and low lipid content, which should be studied to enhance the process and make it economical. Present study aimed to improve the lipid productivity of Chlorella minutissima and Chlorella pyrenoidosa by modifying the carbon and nitrogen content of the medium. Both organisms were grown in BG11 medium for the first 6 days and thereafter grown in a modified BG11 medium completely deprived of nitrogen for 2 to 10 days. Nitrogen deprivation increased the lipid productivity of Chlorella minutissima to 20% and that of Chlorella pyrenoidosa to 17.6% by day 6. This was further coupled with carbon addition in the form of citric acid (5 g/L), sodium acetate (5 g/L), sodium carbonate (5 g/L), and sodium potassium tartarate (5 g/L), which increased the total lipid productivity of Chlorella minutissima up to 24% and that of Chlorella pyrenoidosa up to 23%. The highest lipid productivity of up to 24% for Chlorella minutissima and up to 23% for Chlorella pyrenoidosa was observed with nitrogen deprivation coupled with sodium acetate. Acidic transesterification revealed the presence of fatty acid methyl esters, majority of which consisted of hexadecanoic acid methyl ester and octadecanoic acid methyl ester. Maximum of 3% fatty acid methyl esters for Chlorella minutissima and 4% for Chlorella pyrenoidosa were obtained under nitrogen deprivation and sodium acetate as a carbon source. Thus, nitrogen deprivation coupled with sodium acetate as an increased carbon source in BG11 medium helps to increase the lipid productivity of Chlorella minutissima and Chlorella pyrenoidosa, and produces long-chain fatty acid methyl esters of C17 and C19 along with C21, C25, and C29.

In the textile industry, the amount of dye unfixed in fabrics is discarded with wastewaters. Effluents of this nature can be treated efficiently by adsorption on activated bone char, but the reuse of adsorbent is necessary for the technique to be economically feasible. Therefore, the objective of this work was to study the process of desorption of BF-5G blue dye from a bone char fixed-bed column. Solutions of sodium chloride, acetic acid and ethyl alcohol were tested as regenerating agents. Due to the hydrophobicity effect of organic solvent molecules, the highest desorption capacity was observed for ethyl alcohol solution, and the fixed bed was reused after six cycles of adsorption. The other solutions did not promote significant desorption. The results showed that adsorption of the dye involved irreversible interactions between adsorbate molecules and bone char. However, the use of acetic acid solution resulted in the neutralisation of some of the adsorbent surface charges, allowing the fixed bed to operate for a longer time in the second cycle than in the first.

Biosorption potential of oxidised coconut coir (OCC) for removal of Cd(II) was evaluated by multi-column arrangement by connecting three columns in series. Effect of flow rate at 5, 10 and 15 mL/min was studied at 30 mg/L initial Cd(II) concentration. The dynamic capacity of the system was found to be 321, 206 and 83 mg/L for 5, 10 and 15 mL/min flow rates, respectively, by applying the bed depth service time model. Biosorbent usage rates for single-column and multi-column systems were compared. Better utilisation of biosorbent was observed when the columns are connected in series at similar operating parameters. A simple acid-base regeneration procedure was found to be effective in desorbing/regenerating the cadmium bound biosorbent. Adsorption efficiency was found to decrease from 76.3% for the first cycle to 72.2% and 70.6% in the second and third cycles, respectively. Regeneration efficiencies were more than 94% up to 3 cycles. The study highlights the effectiveness of the multi-column system in biosorption against the conventional single-column system.

Pollution caused by heavy metals is a prime concern due to its impact on human health, animals, and ecosystems. Cr(VI), generated in a range of different industries as a liquid effluent, is one of the most frequent contaminants. In the work presented herein, the adsorption efficiency of three species of native yeasts from Ecuador (Kazachstania yasuniensis, Kodamaea transpacifica, and Saturnispora quitensis) for Cr(VI) removal from simulated wastewater was assessed, taking Saccharomyces cerevisiae as a reference. After disruption of the flocs of yeast with a cationic surfactant, adsorption capacity, kinetics, and biosorption isotherms were studied. K. transpacifica isolate was found to feature the highest efficiency among the four yeasts tested, as a result of its advantageous combination of surface charge, individual cell size (4.04 μm), and surface area (1588.27 m²/L). The performance of S. quitensis was only slightly lower. The remarkable biosorption capacities of these two isolates (476.19 and 416.67 mg of Cr(VI)/g of yeast, respectively) evidence the potential of non-conventional yeast species as sorption microbial particles for polluted water remediation.

Phosphorus (P) is a significant limiting nutrient which is essential for all forms of lives. However, phosphate rock reserves are depleting rapidly due to population growth. At the same time, several countries have imposed legislative regulations on P-release into surface waters due to eutrophication. Nutrient recovery from wastewater can facilitate a sustainable, cost-effective and environment-friendly source of phosphorus. Although P-recovery as struvite from wastewater has been widely studied for a long time, there still exists a lot of challenges for widespread full-scale implementation. This paper presents a comprehensive analysis of the current state of the technologies for phosphorus recovery in the form of struvite. Fluidized bed reactors (FBRs) are widely used compared to continuously stirred reactors for P-recovery as struvite because of different solid and liquid retention time. Commercially available technologies were reported to accomplish about 80% P-removal efficiencies with a reasonable P-recovery for the most of the cases. The struvite production rate of various technologies varies from 0.89 to 13.7 kg/kg influent P. Nevertheless, these technologies are associated with several shortcomings such as high operational costs, high energy consumption, and large footprint. Increasing efforts focusing on the development of sustainable and commercially feasible technologies are expected in this sector as P-recovery is considered to be the future of wastewater engineering.

Oxidative degradation and mineralization of the antifungal drug Nystatin (NYS) was investigated using photochemical advanced oxidation processes UV-C irradiation (280–100 nm), H₂O₂ photolysis (UV/H₂O₂), and photo-Fenton (UV/H₂O₂/Fe³⁺). The effect of operating parameters such as [H₂O₂], [Fe³⁺], and [NYS] initial concentrations on degradation efficiency and mineralization ability of different processes was comparatively examined in order to optimize the processes. Photo-Fenton was found to be the most efficient process attaining complete degradation of 0.02 mM (19.2 mg L⁻¹) NYS at 2 min and a quasi-complete mineralization (97%) of its solution at 5 h treatment while UV/H₂O₂ and UV-C systems require significantly more time for complete degradation and lower mineralization degrees. The degradation and mineralization kinetics were affected by H₂O₂ and Fe³⁺ initial concentration, the optimum dosages being 4 mM and 0.4 mM, respectively. Consumption of H₂O₂ during photo-Fenton treatment is very fast during the first 30 min leading to the appearance of two stages in the mineralization. The evolution of toxicity of treated solutions was assessed and confirmed the effectiveness of photo-Fenton process for the detoxification of NYS solution at the end of treatment. Application to real wastewater from pharmaceutical industry containing the target molecule NYS showed the effectiveness of photo-Fenton process since it achieved 92% TOC removal rate at 6-h treatment time.

Secondary aluminum smelting industry, as an important source of polychlorinated naphthalene (PCN) in environment, has been concerned in recent years. To figure out the emission characteristics of PCNs and the potential influence on surrounding environment, two typical secondary aluminum smelting plants were selected and PCNs were determined in flue gas, fly ash, aluminum slag, soil, and air samples collected at and around the plants by GC-MS coupled with DFS. PCN emission factors from the flue gas of the two plants (mean 0.006 ng toxic equivalents/t) were found obviously decreased compared with similar smelting process detected in 2010. The stage of feeding material was still the major PCNs discharge period during the whole smelting process. The total PCN concentrations in air were found to be ranked as following: workshops (290–1917 pg/m³), the area near the workshops (62.3–697 pg/m³), and the surrounding areas (29.9–164 pg/m³, mean 64.5 pg/m³). Similar high concentrations of PCNs were found in soil from by the workshop door (983 ng/g dry weight). Soil-air exchange calculations indicated that mono-CN to tetra-CN would volatilize but hepta-CN and octa-CN would be deposited to the soil. Exposure of plant workers and local inhabitants to PCNs through inhalation was found to be acceptable but higher (especially for workers in the workshops) than living areas. The workshop and the nearby area are potential PCNs polluted areas and should be paid attention during the practical operation.

Generally, fungi have the ability to secrete large amounts of secondary metabolites which have the ability to reduce metal ions to metallic nanoparticles. In this report, silver nanoparticles (AgNPs) were synthesized by using an endophytic fungus isolated from the medicinal plant, Catharanthus roseus (Linn.). The endophytic fungus was identified as Botryosphaeria rhodina based on the ITS sequencing. The synthesized AgNPs were characterized by adopting various high-throughput techniques, scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDAX), high-resolution transmission electron microscopy (HR-TEM) and UV–Visible spectrophotometer. In vitro anticancer efficacy of AgNPs was tested on A-549 cells. The synthesized AgNPs were effective in scavenging free radicals and induced hallmarks of apoptosis including nuclear and DNA fragmentation in lung (A549) cancer cell lines under in vitro conditions. The results suggested that the natural biomolecules in the endophytic fungi incorporated into the nanoparticles could be responsible for the synergetic cytotoxic activity against cancer cells. The AgNPs were found to have cytotoxicity IC₅₀ of 40 μg/mL against A549 cells. To the best our knowledge, this is the first report demonstrating that AgNPs from Botryosphaeria rhodina could be able to induce apoptosis in various types of cancer cells as a novel strategy for cancer treatment.

Groundwaters are normally consumed without previous treatment and therefore the monitoring of contaminants in order to guarantee its safety is necessary. Thus, we aimed to evaluate the groundwater contamination by metals and emerging contaminants, seeking to understand the relationship between their presence in the groundwater and the use and land cover profile of Itaporã and Caarapó. In addition, the contaminant concentrations observed were compared with maximum permitted values (MPV) and/or with calculated water quality criteria (WQC) for human consumption to investigate possible human health risks due to the groundwater intake. We collected one groundwater sample from each of the 12 wells located in Itaporã and 11 wells located in Caarapó. The metals were analyzed using ICP-OES and the emerging contaminants using LC-MS/MS. At least 1 of the 9 metals analyzed was found in each of the samples. In 12 samples, the metal concentrations verified exceeded the MPV or calculated WQC. A risk to human health has been observed for metals Co, Mn, Cr, and Ni. The emerging contaminant concentrations found in some samples were low (ng/L) and probably did not pose health risks, but their presence in the groundwater showed the impact of agriculture and the inadequate disposal of domestic sewage in the wells of both cities.