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Background: Ammonia has hazardous health effects on humans. To begin with, inhalation of ammonia can be harmful to the respiratory system. The main aim of this study is to determine the concentrations of ammonia in water and evaluate its effects on human health. Methods: In this study, 20 drinking water samples were collected from different locations in Khartoum State, Sudan. Results: The concentration of ammonia (NH3 - N) ranged between 0.01 and 1.96 mg/L. The concentration of NH3 - N reported higher than World Health Organization (WHO) standard (0.2 mg/L) in 55% of the collected samples. A questionnaire was distributed to 124 participants from different origins to measure their level of awareness about the effect of ammonia on health. Conclusions: According to the results of the questionnaire and chemical analysis, raising awareness about ammonia is needed. Furthermore, periodical testing and monitoring of drinking water is also necessary to do treatment for polluted water with ammonia. [ABSTRACT FROM AUTHOR]

Healthcare facility wastewater considerably increases the levels of micropollutants in municipal wastewater. Considering this, the presence of contaminants of emerging concern in the environment has been highlighted as a global environmental problem. Electrochemical advanced oxidation (EAO) generate strong oxidants such as HO•, H2O2, and O3 - which can remove organic pollutants in water including pharmaceutical. This review presents the latest research findings concerning the mechanisms, influencing factors, and innovative approaches for treating wastewater generated by healthcare institutions. Electrochemical oxidation has proven a promising wastewater treatment technology, especially, for pharmaceutical-contaminated wastewater. EAO is widely regarded as a pioneering technique in the field of wastewater treatment because of its strong performance in the mineralization treatment for pharmaceuticals as well as the detoxification treatment of extremely biologically harmful organics. The use of EAO technology is of utmost importance in augmenting the efficiency of electrochemical systems in the decomposition of organic substances. Furthermore, it lays the groundwork for implementing these systems to treat wastewater derived from medical facilities and hospitals. Nevertheless, it is noteworthy that most experimental studies have focused on single-component wastewater that has been artificially prepared in laboratory settings. Wastewater from healthcare institutions often exhibits a complex and diverse composition, influenced by various factors. [ABSTRACT FROM AUTHOR]

In this study, four coagulants were used to investigate their performances for the treatment of raw landfill leachate. Two inorganic coagulants, namely, ferric sulfate, Fe2 (SO4 )3 and zinc sulfate, ZnSO4 were compared to two types of palm date seeds, that is, khlas and sukkari as natural coagulants. Type of coagulant, dosage, pH and rapid mixing speed were designated as input variables, that is, operating conditions. In order to determine and compare the leachate treatment performances of the four coagulants, four responses were selected for this research, namely, chemical oxygen demand (COD), color, ammoniacal nitrogen (NH3 –N) or simply ammonia and total suspended solids (TSS). A response surface model (RSM) was developed for each selected response to find the optimum operating conditions for the input variable and for each coagulant that result in maximum removals. 72 experiments under different operating conditions were performed of which 18 runs were conducted for each type of coagulant wherein 100 mL of raw landfill leachate was the sample volume used for each run. The optimum operating conditions were found in the models and experimentally validated. The optimum dosage of ferric sulfate, zinc sulfate and khlas was found to be 6 mL. However, a lower dosage of 4.32 mL was found to be the optimum for sukkari. The optimal pH for ferric sulfate and sukkari was 5, whilst a pH of 9 was obtained for khlas and zinc sulfate. Finally, the optimum rapid mixing speeds for khlas and sukkari were rounded off to 195 and 200 rpm, respectively. Meanwhile, higher optimal rapid mixing speeds of 240 and 250 rpm were rounded out for ferric sulfate and zinc sulfate, correspondingly. Hence, the optimal reductions of COD, color, ammonia and TSS by (ferric sulfate–zinc sulfate) were rounded off to 55%–53%, 89%–73%, 15%–17% and 91%–89%, respectively. On the other hand, the optimum removals obtained by the natural coagulants (khlas–sukkari) were as the following: 12%–15% COD, 53%–56% color, 12%–14% ammonia and 78%–67% TSS. As regards the maximum removals of COD, color, ammonia and TSS by (ferric sulfate–zinc sulfate), they were found and rounded off to 60%–60%, 89%–84%, 18%–21% and 95%–96%, respectively. Contrariwise, the maximum reductions obtained by the natural coagulants (khlas–sukkari) were as the following: 16%–24% COD, 70%–74% color, 17%–17% ammonia and 91%–82% TSS. Thereupon, the natural coagulants showed effective removals, notably in terms of color, ammonia and TSS that could adequately replace the inorganic coagulants. A big margin of improvement in the removal of COD and other pollutants by khlas and sukkari could possibly be achieved in the upcoming studies by extensively investigating the preparation techniques of the natural coagulants. [ABSTRACT FROM AUTHOR]

Different health management strategies may need to be implemented in different regions to cope with diseases. The current work aims to evaluate the relationship between air quality parameters and the number of new COVID-19 cases in two different geographical locations, namely Western Anatolia and Western Black Sea in Turkey. Principal component analysis (PCA) and regression model were utilized to describe the effect of environmental parameters (air quality and meteorological parameters) on the number of new COVID-19 cases. A big difference in the mean values for all air quality parameters has appeared between the two areas. Two regression models were developed and showed a significant relationship between the number of new cases and the selected environmental parameters. The results showed that wind speed, SO2, CO, NOX, and O3 are not influential variable and does not affect the number of new cases of COVID-19 in the Western Black Sea area, while only wind speed, SO2, CO, NOX, and O3 are influential parameters on the number of new cases in Western Anatolia. Although the environmental parameters behave differently in each region, these results revealed that the relationship between the air quality parameters and the number of new cases is significant. [ABSTRACT FROM AUTHOR]

Recovery of wastewater is essential for better management of water resources and can aid in reducing regional or seasonal water shortages. When algae were used to clean wastewater, amazing benefits were guaranteed, such as a decrease in the formation of dangerous solid sludge and the creation of valuable algal biomass through recycling of the nutrients in the wastewater. The trace elements nitrogen, phosphorus, and others that microalgae need for cell development are frequently present in contaminated wastewater. Hence, microalgal bioremediation is used in this study as an effective technique for the simultaneous treatment of COD, NH3-N, and orthophosphate from domestic wastewater and biomass production. Different concentrations of wastewaters were used. The maximum removals attained were: 84% of COD on the fifth day using the lowest mixing ratio of 50%, 95% of ammoniacal nitrogen, and 97% of phosphorus. The highest biomass production was achieved at day 12, except for the mixing ratio of 80% where the growth rate increased until day 14 at 400 mg/L. [ABSTRACT FROM AUTHOR]

This study examines the use of date stone powder-based plant natural coagulant in the treatment of iron and steel industrial effluent. Coagulation process was conducted using different dosage from date stone powdered (0.2–10 g/L) and different pH values (5–10) using orbital shaker at 200 rpm. The treatment efficiency was evaluated by examine the removal for chemical oxygen demand (COD), total suspended solids (TSS), ammonia-nitrogen (NH3 –N), manganese (Mn), iron (Fe), zinc (Zn), aluminum (Al), and nickel (Ni). The maximal removal for COD, TSS, NH3 –N, Mn, Fe, Zn, Al, and Ni were 59.4%, 99%, 92.1%, 87.1%, 97.7%, 94.8%, 65.8%, and 80.3%, respectively. Date stone powder has enormous promise as a plant-based natural coagulant for industrial effluent wastewater treatment and might be used to treat effluent from the iron and steel industries. [ABSTRACT FROM AUTHOR]

Various chemical coagulants have previously been used for wastewater treatment with substantial efficacy in eliminating heavy metals and other criteria. However, their economic effectiveness and the remnant of harmful chemical precipitates that pose hazards to human health and the environment. As a result, utilizing plant-based natural coagulants is seen as an alternative non-toxic, biodegradable, and ecologically beneficial strategy. This study aims to investigate the performance of pinecone seed powder as a natural coagulant in iron and steel factory wastewater treatment, as well as to optimize the operating parameters to determine the feasibility of employing pinecone seed powder in wastewater treatment. Using 0.6 g/200 mL pinecone as a controlling factor, pH, and settling time, the response surface methodology, a statistical experimental design was utilized to increase the chemical oxygen demand (COD), ammoniacal nitrogen (NH3–N), and heavy metals removal efficiency. COD, NH3–N, Fe, Mn, Ai, Cu, and Ni removal efficiencies at pH 8 were 76%, 44%, 88%, 93%, 87%, 50%, and 92%, respectively. Except for Fe (0.0170), Mn (0.0021), and Cu (0.001), the quadratic models for the parameters specified were determined to be significant with a low probability. [ABSTRACT FROM AUTHOR]

Algae have the potential to be used as a feedstock for the synthesis of valuable compounds and biofuels. In addition, algal waste can be further transformed into biofuel, biogas, and biochar using different thermochemical processes such as microwave pyrolysis, pyrolysis, torrefaction, and hydrothermal conversion. Due to its high specific surface area, rapid electron transport, and graphitic carbon structure, algal biochar carbonized at high temperatures has shown outstanding performance for applications as CO2 adsorbents, supercapacitors, and persulfate activation. Due to the combination of various functional groups and porous structures, the algae biomass pyrolysis at a moderate temperature produced high-quality biochar that shows high performance in terms of pollutant removal, while low-temperature pyrolysis produces coal fuel from algae via torrefaction. Over time, there have been exponentially more petroleum-based polymers created that have harmful impacts on both humans and the environment. As a result, researchers are becoming more interested in algae-based biopolymers as a potential alternative strategy for establishing a sustainable circular economy globally. The advantages of microalgal biopolymer over other feedstocks are its capacity to compost, which provides greenhouse gas credits, its quick growth ability with flexibility in a variety of settings, and its ability to minimize greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

The use of olive seed powder as a plant-based natural coagulant in treating iron and steel factory wastewater was studied. The concentrations of chemical oxygen demand (COD), total suspended solids (TSS), ammonia-nitrogen (NH3 –N), manganese (Mn), iron (Fe), zinc (Zn), aluminum (Al), and nickel (Ni) in effluent wastewater were investigated. Coagulation experiments on the effects of iron and steel factory wastewater, pH, and olive seed powder dosage on coagulation efficacy were conducted using an orbital shaker and a flocculation device. The maximum removal percentages of COD, TSS, NH3 –N, Mn, Fe, Zn, Al, and Ni by olive seeds powder were 86.3%, 99%, 72.4%, 80.9%, 91.5%, 92.6%, 73.7%, and 84.3% for effluent at natural pH 8 using a 5 g/L dosage, respectively. The Fourier-transform infrared spectroscopy study showed the presence of several functional groups involved in the coagulation process. It is possible to argue that olive seed powder has enormous potential as a plant-based natural coagulant for wastewater treatment and that it might be used to treat wastewater from iron and steel factories. [ABSTRACT FROM AUTHOR]

Solar energy has recently become a viable option for desalinating seawater, primarily in arid regions. However, increasing the productivity of solar still by integrating experimental base and modelling methods is still subject to prediction errors; therefore, the main objective of this research is to postulate and test boosting algorithms for predicting the efficiency and productivity of the system. Five boosting regressors were deployed and evaluated: categorical boosting, adaptive boosting, extreme gradient boosting, gradient boosting machine, and gradient boosting machine (LightGBM). The proposed regressors are implemented based on the system’s actual recorded dataset (consisting of 720 observations). The dataset consists of input variables, which are the wind speed (V), cloud cover, humidity, ambient temperature (T), solar radiation (SR), (Tio), (Tw), (Tv), and (Tt). Also, the output variable is represented by the productivity of the system. The dataset was separated into training (70%) and testing (30%) sets. In order to decrease regressors errors, hyperparameter optimization was employed. GradientBoosting approach provided the best prediction, with 95% R2 accuracy and 39.57 root mean square error (RMSE) error. The LightGBM technique achieved 94% R2 accuracy and 40.07 RMSE error in the testing dataset. The results reveal that GradientBoosting outperforms the cascaded forward neural network in predicting system productivity (CFNN). [ABSTRACT FROM AUTHOR]

Microplastic is an emerging pollutant causing trouble worldwide due to its extensive distribution and potential hazards to the ecological system. Some fundamental questions about microplastics, such as their presence, source, and possible hazards, remain unanswered. These issues develop because of a lack of systematic and comprehensive microplastic analysis. As a result, we thoroughly evaluated current knowledge on microplastics, including detection, characterization, occurrence, source, and potential harm. Microplastics are found in seawater, soil, wetlands, and air matrices worldwide based on findings. Visual classification, which can be enhanced by combining it with additional tools, is one of the most used methods for identifying microplastics. As soon as is practicable, microplastics analytical methods ought to be standardized. New techniques for analyzing nano-plastics are urgently needed in the meantime. Numerous studies have shown that microplastics’ impacts on people and soil are significantly influenced by their size, shape, and surface physicochemical characteristics. Finally, this study suggests areas for future research based on the knowledge gaps in the area of microplastics. [ABSTRACT FROM AUTHOR]

This study aims to investigate the performance plant-based natural coagulant from rosehip seed powder in the treatment of iron and steel factory wastewater. The concentrations of COD, total suspended solids (TSS), ammonia-nitrogen (NH3–N), manganese (Mn), iron (Fe), zinc (Zn), aluminum (Al), and nickel (Ni) in effluent wastewater were examined. Coagulation investigations were carried out using an orbital shaker and a flocculation apparatus to investigate the effects of iron and steel factory effluent, pH, and rosehip seeds powder dosage on coagulation efficacy. The rosehip powder removes a large amount of COD, TSS, NH3–N, Mn, Fe, Zn, Al, and Ni from effluent at pH 8 with percentages of 86.1%, 99%, 79%, 86%, 91.7%, 90.6%, 73.7%, and 100%, respectively, at 1 g/L. The effects of pH ranges ranging from (5–10) reveal that the wastewater sample’s natural pH (8) demonstrates the maximum practicable removal effectiveness. FTIR analysis revealed the presence of numerous functional groups involved in the coagulation process. One may argue that rosehip seed powder holds great potential as a natural plant-based coagulant for water treatment and could be used to treat effluent from iron and steel factories. [ABSTRACT FROM AUTHOR]

Utilization of pinecone powder as a plant-based natural coagulant for the treatment of iron and steel factory effluent was examined. The concentrations of chemical oxygen demand (COD), total suspended solids (TSS), ammonia-nitrogen (NH3 –N), manganese (Mn), iron (Fe), zinc (Zn), aluminum (Al), and nickel (Ni) in effluent wastewater were investigated. Results showed that the maximal removal of COD, TSS, NH3 –N, Mn, Fe, Zn, Al, and Ni using pinecone powder were 83.3%, 99%, 83.9%, 86.8%, 93.7%, 89.7%, 73.7%, and 86.7%, respectively for effluent at natural pH 8 using a dosage of 3 g/L. The Fourier-transform infrared spectroscopy result showed the existence of various functional groups involved in the coagulation process. Overall, this study shows that pinecone powder has enormous promise as a natural coagulant for water treatment and it could be utilized to treat effluent from iron and steel plants. [ABSTRACT FROM AUTHOR]

Nanoscale zero-valent iron (nZVI) has been extensively investigated for the remediation of soil, wastewater, and groundwater contaminated with heavy metals. This paper presents a collective review of nZVI synthesis, nZVI interaction mechanisms with heavy metals, factors affecting nZVI reactivity, recent applications of nZVI for heavy metals removal, and the environmental concerns of nZVI application for soil microorganisms and plants. Modified nZVI, spatially biochar supported nZVI (BC@nZVI) and sulfidation nanoscale zero-valent iron (S-nZVI) showed high heavy metals removal efficiency and more stable performance compared to nZVI alone. The removal of heavy metals by nZVI is as a synergistic process where adsorption, oxidation/reduction and precipitation occur simultaneously or in series. pH and organic matter are the main factors that significantly affect nZVI reactivity. Toxic effects of nZVI are observed for the soil microorganisms as the direct contact may cause a decrease in cell viability and membrane damage. A low concentration of nZVI promotes the growth of plant whereas high concentration decreases root length. It is observed that, further research is needed to enhance nZVI recovery techniques, evaluate the effectiveness of novel modified nZVI and their effects on the environment, and the full-scale application of nZVI. [ABSTRACT FROM AUTHOR]

Landfill remains as the most common municipal waste disposal method in the world. However, the production of leachate associate with landfill persists as a major drawback, which bring harmful effect to the environment. Persulfate oxidation is recently used for stabilized leachate treatment. Persulfate alone is still limited for leachate oxidation and an activation method is required to improve its performance. Accordingly, this study aims to investigate and compare the performance of persulfate subjected to thermal activation in treating stabilized leachate. Different experimental operational factors were considered and evaluated such as, S2 O8 2–/chemical oxygen demand (COD) ratio, temperature, and reaction time. Experiments were designed and optimized by using response surface methodology, and results were analysed by using analysis of variance. The removal efficiencies for COD and colour using inactivation persulfate were reported only at 14% and 29%, respectively. However, the efficiencies were improved to 93.39% and 94.00% for COD and colour after thermal activation of persulfate under an optimum condition of 10 S2 O8 2–/COD ratio, 80°C and 120 min. The maximum efficiency was achieved at the treatment cost of RM0.66 per litre of leachate. [ABSTRACT FROM AUTHOR]

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In this study, selected physicochemical and heavy metal concentrations were identified and analyzed in leachate samples. The leachate samples were collected at four different stages namely; raw equalization pond (EqP), dissolved air floatation combined with coagulation (DAF1/coagulation), sequencing batch reactor (SBR), and dissolved air floatation combined with coagulation (DAF2/coagulation). For each stage, 19 parameters were tested covering 12 physiochemical parameters including pH, dissolved oxygen (DO), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), color, ammonical nitrogen (NH3–N), total suspended solids (TSS), total dissolved solids (TDS), electrical conductivity (EC), total concentrations of sodium (Na), magnesium (Mg), and calcium (Ca) as well as the total concentrations of seven heavy metals involving iron (Fe), copper (Cu), cadmium (Cd), lead (Pb), manganese (Mn), nickel (Ni), and zinc (Zn). Identifying the characteristics of the four leachate samples from each stage was aided with three different statistical methods consisting of descriptive, factor, and cluster analyses. The results of factor analysis showed that 95.34% of the total variation in the selected parameters was explained by two factors and identified as the responsible factors. Cluster analysis exhibited that the four ponds entirely have different properties (EqP, DAF1, SBR, and DAF2). This study helps to evaluate and comprehend the behavior of the designated parameters and better understand their relationships with one another for more efficient, practical, and productive landfill leachate treatment and management. [ABSTRACT FROM AUTHOR]

One of the main precursors of air pollution and acid rains is the presence of the recalcitrant thiophenic compounds, for example dibenzothiophene (DBT) and its derivatives in transportation fuels. In an attempt to achieve the worldwide regulations of ultra-low sulfur transportation fuels without affecting its hydrocarbon skeleton, a biphasic medium containing 100 mg/L DBT dissolved in n-hexadecane (1/4 oil/water v/v) used for enrichment and isolation of selective biodesulfurizing bacterium from an oil-polluted sediment sample collected from Egyptian Red Sea shoreline. The isolated bacterium is facultative anaerobe, motile, spore-former, and mesophile. It is genetically identified as Paenibacillus glucanolyticus strain HN4 (NCBI Gene Bank Accession No. MT645230). HN4 desulfurized DBT as a model of the recalcitrant thiophenic compounds without affecting its hydrocarbon skeleton via the 4S-pathway producing 2-hydroxybiphenyl (2-HBP) as a dead end product. HN4 substantiated to be a hydrocarbon tolerant, biosurfactants(s) producer, and endorsed unique enzymatic system capable of desulfurizing broad range of thiophenic compounds and expressed an efficient desulfurization activity against the recalcitrant alkylated DBTs. As far our knowledge, it is the first reported BDS study using P. glucanolyticus. Statistical optimization based on One-Factor-At-A-Time (OFAT) technique and response surface methodology (RSM) applied for elucidation of mathematical model correlations describing and optimizing the effect of different physicochemical parameters on batch biphasic BDS process. That illustrated an approximate increase in BDS efficiency by 1.34 fold and recorded 94% sulfur removal in biphasic batch process at optimum operation conditions of 120 h, 0.14 wt% S-content model oil (DBT dissolved in n-hexadecane), 33.5 °C, pH7 and 1/1 oil/water phase ratio, and 147 rpm. Resting cells of HN4 in a biphasic reactor (1/1 v/v) decreased the sulfur content of a refractory thiophenic model oil (thiophene, benzothiophene, DBT, and alkylated DBT dissolved in n-hexadecane) from 0.14 to 0.027 wt%, and petro-diesel from 0.2 to 0.04 wt%, within 120 h, keeping the calorific value of the treated fuel intact. Consequently, that novel strain could be recommended as a promising candidate for BDS as complementary to hydrodesulfurization process in oil refinery. [ABSTRACT FROM AUTHOR]

The performance of seven oxidation treatments on stabilized landfill leachate namely; O3, Fenton, Fenton followed by O3, persulfate, persulfate followed by O3, simultaneous O3/Fenton, and simultaneous O3/persulfate were evaluated and compared. The study aims to assess the variation between all the seven oxidation treatments with regards to COD and color removal. The analysis of variance (ANOVA) and Tukey's test showed that there were significant differences between the performances of the treatments. The O3 treatment removed the lowest COD and color while the simultaneous O3/Fenton, Fenton followed by O3, simultaneous O3/persulfate and persulfate followed by O3 removed the highest. Hence, these treatments are recommended to remove organics from stabilized landfill leachate. [ABSTRACT FROM AUTHOR]

Nowadays, fresh drinking water has become increasingly scarce, especially in arid and semi-arid areas. Usually, the water found in these areas is seawater or brackish water and contains harmful contaminants, which directly affect human health, and therefore cannot be used for drinking purposes. Since arid and semi-arid areas are blessed with abundant solar radiation, small solar still units can be used to desalinate seawater and produce cheap drinking water. In this study, the capacity of an inclined copper-stepped solar still to produce fresh drinking water from seawater using solar energy was experimentally tested. This study aims to evaluate the distilled water quality produced by the solar desalination system. The system effectively eliminated all physicochemical parameters such as total suspended solids (TSS), pH, total dissolved solids (TDS), turbidity, salinity, conductivity, and atomic elements (Ca2+, Cl−, Mg2+, Na+, SO4 2−, and K+). Biological analyses were also conducted in this study including the analysis of ammoniacal nitrogen (NH3–N), biological oxygen demand (BOD), and chemical oxygen demand (COD). Each parameter was found to have values that are within the safe limits set by the Malaysian NDWQS and WHO. [ABSTRACT FROM AUTHOR]

Landfills are one of the main point sources of groundwater pollution. This research mainly aims to assess the risk of nitrate transport from the unlined landfill to subsurface layers and groundwater using experimental results and the SESOIL model. Samples from 12 groundwater wells downstream of the landfill were collected and analyzed in 2008, 21 years after the landfill construction. The average concentration in the wells was 54 mg/L, slightly higher than the World Health Organization ( 50 mg/L) standards. SESOIL model was used to predict the concentration at the bottom of the unsaturated zone. Results indicated that the current mean concentration at the bottom of the unsaturated zone is 75 mg/L. the model predicted that the level of NO3 will increased up to 325 mg/L within 30 years. Accordingly, the concentration in groundwater wells near the landfill area is expected to gradually increase with time. Although the current risk associated with the level might not be harm to adults, however, it might pose severe risks to both adults and infants in the near future due to leaching. Urgent mitigation measures such as final cell cover (cap), lining system and vertical expansion should be considered at the landfill to protect the public health in the area. [ABSTRACT FROM AUTHOR]

The major drawback of the wide applicability of biodiesel is its price compared to the conventional petro-diesel. The feedstock and the applied catalyst in the transesterification reaction are the main contributor for the overall cost of the biodiesel production. Thus, this study summarizes the optimization of a batch transesterification reaction of used domestic waste oil (UDWO) with methanol using CaO, which can be easily prepared from different cheap and readily available natural sources. Quadratic model equations were elucidated describing the effect of methanol:oil molar ratio, CaO concentration wt.%, reaction temperature °C, reaction time h, and mixing rate rpm on biodiesel yield and conversion percentage. The optimum operating conditions were found to be competitive with those of the high-cost immobilized enzyme Novozym435. An overall acceptable agreement was achieved between the produced biodiesel, its blends with petro-diesel and the available commercial petro-diesel, and the international fuel standards. A precise and reliable logarithmic mathematical model was predicted correlating the production of pure high-quality biodiesel yield with the conversion percentage which were measured based on the fatty acid methylester content and decrease in viscosity, respectively. [ABSTRACT FROM AUTHOR]

In this study, response surface methodology based on face center composite – 1/2 factorial fraction design (FCCD) of experiments was employed to optimize the batch transesterification process of waste cooking oil as one of the most abundant and readily available domestic wastes with methanol using immobilizedCandida antarcticalipase (Novozym435) to maximize the production of high-purity biodiesel. Statistically significant second-order quadratic model equations (p< 0.0001) were elucidated through multiple regression analysis to describe the interrelationships between response of interest (biodiesel yield wt% and % conversion, i.e. the transesterification efficiency) and five independent variables (methanol:oil molar ratio, enzyme concentration wt%, reaction temperature °C, reaction time h, and mixing rate rpm). The statistical significance of the effect of these variables (factors) and their interactions on the transesterification efficiency was evaluated and the validity of the predicted models was confirmed. The optimum operating conditions were found to be: 3.63:1 M:O, 8.94 wt% Novozym435, 45.23°C, 2.76 h, and 535.84 rpm. This produced 97 wt% biodiesel yield with % conversion of ≈ 91.79%. An overall acceptable agreement was achieved between the produced biodiesel fuel properties at the aforementioned optimal operating conditions and the Egyptian petrodiesel and international biodiesel standards. [ABSTRACT FROM AUTHOR]

The aim of the current study is to evaluate the effectiveness of combined persulphate with hydrogen peroxide (S2O82-/H2O2) oxidation as a post-treatment of biologically treated palm oil mill effluent (POME) for the first time in the literature. The removal efficiencies of chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N), and suspended solids (SS) were 36.8%, 47.6%, and 90.6%, respectively, by S2O82- oxidation alone under certain operation conditions (i.e., S2O82- = 0.82 g, pH 11, and contact time 20 min). Nevertheless, the combined process (S2O82-/H2O2) achieved 75.8% and 87.1% removals of NH3-N and SS, respectively, under 2.45/1.63 g/g H2O2/S2O82-, pH 11, and 20 min oxidation. Moreover, 56.9% of COD was removed at pH 8.4. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the performance of combined solar photo-catalyst of titanium oxide/zinc oxide (TiO2/ZnO) with aeration processes to treat petroleum wastewater. Central composite design with response surface methodology was used to evaluate the relationships between operating variables for TiO2 dosage, ZnO dosage, air flow, pH, and reaction time to identify the optimum operating conditions. Quadratic models for chemical oxygen demand (COD) and total organic carbon (TOC) removals prove to be significant with low probabilities (<0.0001). The obtained optimum conditions included a reaction time of 170 min, TiO2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), and pH 6.8 COD and TOC removal rates of 99% and 74%, respectively. The TOC and COD removal rates correspond well with the predicted models. The maximum removal rate for TOC and COD was 99.3% and 76%, respectively at optimum operational conditions of TiO2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), reaction time (170 min) and pH (6.8). The new treatment process achieved higher degradation efficiencies for TOC and COD and reduced the treatment time comparing with other related processes. [ABSTRACT FROM AUTHOR]

This work illustrates a comparative study on the applicability of the natural calcium oxide (CaO) prepared from waste eggshells and chemical CaO as basic heterogeneous catalyst in the transesterification of waste cooking oil (WCO) with methanol for production of biodiesel. Response surface methodology (RSM) based on D-optimal design of experiments was employed to study the significance and interactive effect of methanol-to-oil (M:O) molar ratio, catalyst concentration, reaction time, and mixing rate on biodiesel yield. Second-order quadratic model equations were obtained describing the interrelationships between dependent and independent variables to maximize the response variable (biodiesel yield) and the validity of the predicted models were confirmed. The activity of the produced natural biocatalyst was comparable to that of chemical CaO, producing high yield of biodiesel ≈91 and 98% at 8.57:1 M:O, 3.99 catalyst wt%, 31 min reaction time, and 398.88 rpm mixing rate at 60°C, respectively. Fuel properties of the produced biodiesel were measured and compared with those of Egyptian petro-diesel and international biodiesel standards. The overall biodiesel characteristics either prepared using natural or chemical CaO were comparable and acceptable, encouraging the application of CaO prepared from waste eggshells for production of biodiesel as an efficient, environmentally friendly, sustainable, and low cost heterogeneous catalyst. [ABSTRACT FROM PUBLISHER]

As the ponding system used to treat palm oil mill effluent (POME) frequently fails to satisfy the discharge standard in Malaysia, the present study aimed to resolve this problem using an optimized electrocoagulation process. Thus, a central composite design (CCD) module in response surface methodology was employed to optimize the interactions of process variables, namely current density, contact time and initial pH targeted on maximum removal of chemical oxygen demand (COD), colour and turbidity with satisfactory pH of discharge POME. The batch study was initially designed by CCD and statistical models of responses were subsequently derived to indicate the significant terms of interactive process variables. All models were verified by analysis of variance showing model significances with Prob >F< 0.01. The optimum performance was obtained at the current density of 56 mA/cm2, contact time of 65 min and initial pH of 4.5, rendering complete removal of colour and turbidity with COD removal of 75.4%. The pH of post-treated POME of 7.6 was achieved, which is suitable for direct discharge. These predicted outputs were subsequently confirmed by insignificant standard deviation readings between predicted and actual values. This optimum condition also permitted the simultaneous removal of NH3-N, and various metal ions, signifying the superiority of the electrocoagulation process optimized by CCD. [ABSTRACT FROM AUTHOR]

Production water collected from the “Nafoora” oil water pit, located near the Gallo Oasis, Libya, was used for the screening of obligate hydrocarbonoclastic bacteria that can degrade crude oil. Bacterial strain NAF1 was isolated and characterized after enrichment on crude oil at pH 7 and 30 °C. Solid Waste Dates (SWD) and Corn Steep Liquor (CSL) were usedas to enhance biodegradation of crude oil. Strain NAF1 was able to utilize a number of aliphatic and aromatic hydrocarbons. During growth on natural products, high emulsifying activity in the presence of cells was also observed, which indicated the production of biosurfactant by strain NAF1. The new isolated strain NAF1 produced a yellow-green pigment. The bacterial strain showed removal efficiency of 91 and 97 % of crude oil in 28 days when cultivated with >0.5 % (w/v) of pretreated CSL and SWD, respectively. Alignment of the 16S rRNA gene sequences of NAF1 with sequences obtained by Basic local Alignment search tool (BLAST) search revealed 98 % similarity to P. aeruginosa PAO1. Therefore, the crude oil-metabolizing bacterium could secrete surfactants using agro-industrial products as substrates, which further enhanced hydrocarbon degradation. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the performance of employing H2O2 reagent in persulfate activation to treat stabilized landfill leachate. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as persulfate and H2O2 dosages, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following two responses proved to be significant with very low probabilities (<0.0001): chemical oxygen demand (COD) and NH3-N removal. The obtained optimum conditions included a reaction time of 116 min, 4.97 g S2O8 2-, 7.29 g H2O2 dosage and pH 11. The experimental results were corresponding well with predicted models (COD and NH3-N removal rates of 81% and 83%, respectively). The results obtained in the stabilized leachate treatment were compared with those from other treatment processes, such as persulfate only and H2 only, to evaluate its effectiveness. The combined method (i.e., /S2 only, to evaluate its effectiveness. The combined method (i.e., /S2O8 2-/H2O2) achieved higher removal efficiencies for COD and NH3-N compared with other studied applications. [ABSTRACT FROM AUTHOR]

In this work, factorial design analysis based on central composite design of experiments was employed to study the effect of process parameters for biosorption of Reactive Red-84 dye onto bioethanol fermentation spent waste biomass ofSaccharomyces cerevisiae. Factorial experiments with five factors: mixing rate rpm, incubation period h, process temperature °C, initial dye concentration mg/L and biosorbent dosage wt% (w/v) at three levels were conducted. A highly statistically significant quadratic model at 95% confidence level (p < 0.0001,R20.9120 and0.8519) was developed to charcterize the influence of the different considered variables on biosorption efficiency. Response surface methodology was employed to optimize the process, recording maximum biosorption % of ≈62% (51.67 mg/g) at 90 rpm, 13 h, 15°C, 100 mg/L and 0.6%, respectively. Approximately 95% of adsorbed dye was desorbed by elution with NaOH solution of pH 9 and the regenerated biosorbent was employed for four successive cycles. TiO2nanoparticles 6–15 nm were prepared and used for photo-catalytic degradation of desorbed dye solution. The proposed integrating biosorption and photo-catalytic degradation process results in no secondary pollution in the form of any concentrated wastes, which is an important environmental aspect. [ABSTRACT FROM PUBLISHER]

Pichia veronae strain HSC-22 (accession number KP012558) showed a good tolerance to relatively high temperature, ethanol and sugar concentrations. Response surface optimization based on central composite design of experiments predicted the optimal values of the influencing parameters that affect the production of bioethanol from sugarcane molasses to be as follows: initial pH 5, 25% (w : v) initial molasses concentration, 35°C, 116 rpm, and 60 h. Under these optimum operating conditions the maximum bioethanol production on a batch fermenter scale was recorded as 32.32 g/L with 44% bioethanol yield. [ABSTRACT FROM AUTHOR]

Backsround: Leachate pollution is one of the main problems in landfilling, and researchers have yet to find an effective solution to this problem. The technology that can be used may differ based on the type of leachate produced. The most problematic parameters in leachate are chemical oxygen demand (COD), ammonia, and color. Material and Methods: The performance of ozone/Fenton in advanced oxidation process (AOPs) in treating stabilized leachate was investigated. The optimal dosages of Fenton reagent (0.05 mol L-1 (1,700 mg/L) H2O2 and 0.05 mol L-1 (2,800 mg/L) Fe2+) were determined through preliminary experiments and added to the leachate sample into the ozone reactor. The input ozone concentration in a 2 L leachate sample was 80 g/m3 NTP ± 0.5% under 1 bar pressure. The initial COD varied between 250 and 2360 mg/L, color varied between 470 Pt. Co. to 4530 Pt. Co., and NH3-N varied between 150 mg/l to 1170 mg/L. Results: the maximum removal efficiency was 87% for COD, 100% for color, and 22% for NH3-N at lowest leachate concentration. The lowest amount of consumed ozone (1.28 KgO3/ Kg COD) corresponded to the initial concentration of COD (2000 mg/L) with 60% removal of COD during 1 h ozonation. The biodegradability (BOD5/COD) improved from 0.09 in raw leachate to 0.27 at 500 mg/L initial COD. Conclusion: The current study revealed that the use of ozone/Fenton (O3/H2O2/Fe2+) in AOPs is more efficient in removing COD and color in low concentrations of semi-aerobic stabilized leachate and in improving biodegradability. [ABSTRACT FROM AUTHOR]

This study investigated the effects of O3 and O3/S2O82− in the advanced oxidation process (AOPs) on the biodegradable and soluble characteristics of semiaerobic stabilized solid waste leachate. The biodegradability (BOD5/COD) ratio improved from 0.034 to 0.05 and 0.29 following O3 and O3/ S2O82−, respectively. Fractions of biodegradable COD(bi) (24%), nonbiodegradable COD(ubi) (76%), soluble COD(s) (59%), biodegradable soluble COD(bsi) (38%), nonbiodegradable soluble COD(ubsi) (62%), and particulate COD (PCOD) (41%) in stabilized leachate were also investigated. The fraction of COD (bi) increased to 28 and 39% after applying O3 and O3/ S2O82− in AOPs, respectively. COD(S) increased to 65 after O3 and to 72% after O3/AOPs, whereas COD (bsi) increased to 38 and 55% after O3 and O3/AOPs, respectively. The removal efficiency of total COD was obtained at 15 after O3 alone and improved to 72% following ozone-based AOPs, whereas PCOD reduced from 41 to 35 after O3 and 28% after ozone-based AOPs. Ozone/Prsulfate is an efficient method for degradation of stabilized leachate, enhanced biodegradability and improved biodegradable and soluble characteristics of stabilized leachate. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 184-191, 2014 [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the performance of employing Fenton's reagent in the advanced oxidation of ozone to treat stabilized landfill leachate in an ozone reactor. A central composite design (CCD) with response surface methodology (RSM) was applied to evaluate the relationships between operating variables, such as ozone and Fenton dosage, pH, and reaction time, to identify the optimum operating conditions. Quadratic models for the following four responses proved to be significant with very low probabilities (<0.0001): chemical oxygen demand (COD), color, NH3–N, and ozone consumption (OC). The obtained optimum conditions included a reaction time of 90 min, 30 g/m3ozone, 0.01 mol/LH2O2,0.02 mol/L Fe2+, and pH 5. COD, color, and NH3–N removal rates of 79%, 100%, and 20%, respectively, and 0.18 kg O3/kg COD OC were obtained. The predictions correspond well with experimental results (COD, color, and NH3–N removal rates of 78%, 98.5%, and 19%, respectively, and 0.29 kg O3/kg COD OC). This method reduces the treatment time and improves the treatment efficiency relative to a previously published method that used Fenton's reagent prior to ozonation. [ABSTRACT FROM AUTHOR]

In this study, tannin-based natural coagulant was used to treat stabilized landfill leachate. Tannin modified with amino group was utilized for the treatment process. Central composite design (CCD) was used to investigate and optimize the effect of tannin dosage and pH on four responses. The treatment efficiency was evaluated based on the removal of four selected (responses) parameters; namely, chemical oxygen demand (COD), color, NH3–N and total suspended solids (TSS). The optimum removal efficiency for COD, TSS, NH3–N and color was obtained using a tannin dosage of 0.73 g at a pH of 6. Moreover, the removal efficiency for selected heavy metals from leachate; namely, iron (Fe2+), zinc (Zn2+), copper (Cu2+), chromium (Cr2+), cadmium (Cd2+), lead (Pb2+), arsenic (As3+), and cobalt (Co2+) was also investigated. The results for removal efficiency for COD, TSS, NH3–N, and color were 53.50%, 60.26%, and 91.39%, respectively. The removal of selected heavy metals from leachate for Fe2+, Zn2+, Cu2+, Cr2+, Cd2+, Pb2+, As3+ and cobalt Co2+ were 89.76%, 94.61%, 94.15%, 89.94%, 17.26%, 93.78%, 86.43% and 84.19%, respectively. The results demonstrate that tannin-based natural coagulant could effectively remove organic compounds and heavy metals from stabilized landfill leachate. [ABSTRACT FROM AUTHOR]