The combined treatment systems have become a potential alternative to treat highly polluted industrial wastewater to achieve high-quality treated effluents. The current review focuses on the treatment systems compromising electrocoagulation (EC) as a pretreatment step followed by a biological treatment step. The reasons for applying EC as a pretreatment process were mainly to (1) detoxify the wastewater by removing inhibitors of the biotreatment step or (2) to remove the major part of the COD or (3) the dissolved materials that could cause fouling to membrane bioreactors or (4) to increase the activity of the microorganisms. This combination represents a new and promising application characterized by higher performance and removal efficiency. The main published findings related to this application are presented and analyzed. Besides, the statistical models used to optimize the process variables and the kinetics of microorganism growth rate are discussed herein. Most of the previous investigations were conducted in a laboratory-scale level with biologically treated water as a feed to the EC process. Only a few works applied a hybrid system consisting of the biological step and the EC step. In all studies, improved performance and higher removal efficiencies of the combined process were achieved particularly when applying aluminum electrodes, providing more than 95% removal efficiency. Many researchers have reported that they had faced a significant problem in the operation of the electrocoagulation process associated with the reduction of electrodes’ efficiency caused by deposits of the coagulation complex. This problem needs to be effectively resolved.

Maternal exposure to high levels of persistent organic pollutants (POPs) and trace elements is an important concern for fetal growth. In our previous study, we showed the polychlorinated biphenyl (PCB) levels in maternal serum from the Chiba Study of Mother and Child Health (C-MACH) cohort and their relationships between PCB levels in cord serum with birth weight of newborn. Various reports on the relationship between chemical exposure and birth status have been published; however, studies that analyze the effects of both PCB and metal exposure together in one cohort are still limited. In this study, we aimed to determine the relationship of maternal serum levels of PCBs and toxic and essential trace elements [mercury (Hg), manganese (Mn), selenium (Se), and cadmium (Cd)], with birth weight and head circumference, in the C-MACH cohort. The median concentration of total PCBs in maternal serum around 32 gestational weeks (n = 62) was 360 pg g⁻¹ wet wt (41 ng g⁻¹ lipid wt). The levels of Hg, Mn, Se, and Cd in maternal serum were 0.89, 0.84, 100, and 0.024 ng g⁻¹, respectively. In this study, the Bayesian linear model determined the relationships of the birth weight and head circumference with combinations of PCB levels, toxic and essential trace elements, and questionnaire data. We found that PCB concentrations in maternal serum were weakly and negatively related to birth weight, whereas trace elements were not associated with birth weight. Serum PCB and Mn levels were negatively associated with head circumference, whereas other trace elements were not associated with head circumference. These results showed that maternal exposure to PCBs may be related to birth weight and head circumference, while maternal exposure to Mn is related to head circumference, even when adjusted based on the exposure levels of other contaminants, and maternal and fetal characteristics. Therefore, our findings indicate that maternal exposure to PCBs and Mn might be negatively related with birth weight and head circumference.

Food waste management (FWM) is considered to be an extremely important social issue besides an environmental one. Worldwide, it is estimated that 1.3 billion t/year of foods are disposed of in landfills (including edible and inedible foods). Moreover, FAO indicated that if food waste (FW) was a country, it could be the 3rd biggest CO₂ producer after China and the USA with more than 3.5–4.2 billion of t equivalence CO₂. Each citizen in the entire EU produces approximately 179 kg/year FW equal more or less with 600 €/year. This paper focuses on the concept of circular economy (CE) and how can we optimize and improve the production of biogas from UASB-R (upflow anaerobic sludge blanket reactor) using FW and natural minerals (clinoptilolite). The study was elaborated through laboratory scale experiments using different mixtures of FW, liquid waste from slaughterhouse (LWS), and natural clinoptilolite (Cli). The amount of biogas produced and the methane content of biogas were used as indicators in order to monitor and asses the performance of the anaerobic digester. The results of the present study were encouraging towards the use of FW in existing anaerobic treatment plants, suggesting selective collection at source of FW, diversion from landfills, and use as a secondary resource for energy recovery through a transition to a CE. The results indicate that the use of FW with zeolite duplicates the production of CH₄ within the same days of production compared with the control sample.

This study presents the characteristics of black carbon aerosol (BC) over a high-altitude site, Mahabaleshwar during the monsoon season. The mass concentration of BC exhibits a morning peak and a daytime build-up with a mean mass concentration of 303 ± 142 ng m⁻³. The simultaneous measurements of aerosol particle number concentration (PNC), cloud condensation nuclei concentration (CCN), and non-refractory particulate matter less than 1 μm size (NR-PM₁) were also made by using a Wide-Range Aerosol Spectrometer (WRAS), CCN counter and Aerosol Chemical Speciation Monitor (ACSM) respectively. The source apportionment using wavelength-dependent light absorption model reveals the dominance by wood burning sources during morning hours and traffic sources during remaining hours of the day. The diurnal variation of PNC follows the variability of BC mass concentration. However, CCN concentrations were high during the morning hours coinciding with the increased fractional contribution of organics. The k-means clustering coupled with fuzzy algorithm highlights the effect of different sources on aerosol size distribution. On the basis of size distribution curve, the 3 clusters were attributed to wood burning (mean diameter range: 50–100 nm), traffic (30–50 nm), and background aerosols (65–95 nm). The combined analysis of k-means clustering, fractional contribution of organics, and kappa variation suggests that higher CCN concentration during morning is mainly attributed to probable emission of the water-soluble organic/inorganic compounds from wood burning.

This paper presents the methodology and results of the national radon survey in Bulgaria and its spatial variability. The measurements were carried out in 2778 dwellings using CR-39 track detectors over two successive 9 and 3-month periods from April 2015 to March 2016. The arithmetic (AM) and geometric (GM) means of annual indoor radon concentration were 111 ± 105 Bq/m³ and 81 Bq/m³ (GSD = 2.15), respectively. The distribution of data has been accepted to be log-normal. Two hypotheses have been investigated in the paper. The first one was a spatial variation of indoor radon concentration and the second was spatiality of the factor that influences radon variation. The indoor radon concentrations in the 28 districts have been significantly different, which prove the first hypothesis. The influence of the factors, geology (geotectonic unit, type of rock, and faults distance of the measuring site), type of the region, and the presence of the basement in the building on radon spatial variation, was examined. The analyses have been shown that they significantly affect radon variations but with a relatively small contribution in comparison to the radon variation between district. Furthermore, the significance and contribution of the investigated factors were different in each district, which confirmed the second hypothesis for their spatiality.

This research focuses on the detailed experimental assessment of compression ignition (CI) engine behavior fuelled with Aegle marmelos (AM) seed cake pyrolysis oil blends. The study on effects of engine performance and emission a characteristic was designed using L₂₅ orthogonal array (OA). These multi-objectives were normalized through gray relational analysis (GRA). Likewise, the principal component analysis (PCA) was performed to assess the weighting values respective to every performance and emission characteristics. The variability induced by using the input process parameters was allocated using analysis of variance (ANOVA). Hence, GRA-coupled PCA were employed to determine the optimal combination of CI engine control factors. The greater combination of engine characteristics levels were selected with F₅ and W₅. The higher brake thermal efficiency (BTE) have been obtained for F20 fuel as 22.01% at peak engine load, which is 11.43% for diesel. At peak load condition, F20 fuel emits 14.99% lower HC and 18.52% lower CO as compared to diesel fuel. The improved engine performance and emission characters can be attained by setting the optimal engine parameter combination as F20 blend at full engine load condition. The validation experiments show an improved average engine performance of 67.36% and average lower emission of 64.99% with the composite desirability of 0.8458.

This study investigates the feasibility of recovery of phosphorus via struvite precipitation from a synthetic anaerobically treated distillery spent wash by optimizing the process using a chemical equilibrium model, namely Visual MINTEQ. Process parameters such as Mg²⁺, [Formula: see text], and [Formula: see text] ion concentrations and pH were used as inputs into the model. Increasing the molar ratio of [Formula: see text] from 0.8:1 to 1.6:1 at pH 9 led to an increase in phosphate recovery from 88.2 to 99.5%. The model and experimental results were in good agreement in terms of phosphate recovery, indicating that the Visual MINTEQ model can be used to pre-determine the process parameters for struvite synthesis. Increasing the concentration of calcium ion adversely affected the synthesis and purity of struvite, whereas the presence of melanoidins had no significant impact. This study demonstrates that phosphorus recovery through struvite precipitation is a sustainable approach to reclaim phosphorus from high-strength industrial wastewater.

This study was aiming to treat the chlorpyrifos (CPF), an organophosphate (OP) pesticide with microbial enzyme extract, and assess the toxicity effects of CPF before/after its treatment on the integrity of DNA (deoxyribonucleic acid) and the activities of enzymes AChE (acetylcholinestrase), GST (glutathione S-transferase), SOD (superoxide dismutase), CAT (catalase), and MDA (malondialdehyde) in different organs of rat. The untreated CPF in rat significantly increased the DNA damage and decreased the activities of all these enzymes. Among all the organs studied, the liver was the most affected organ. Further, CPF was treated with an OPH (organophosphate hydrolase) enzyme obtained from CPF degrading bacterial laboratory isolate Pseudomonas sp. (ChlD) to neutralize the toxicity of CPF. The crude intracellular enzyme extract degraded > 90% of added CPF and > 80% of its toxic intermediate 3,5,6-trichloropyridinol (TCP) which resulted in > 80% reduction of CPF toxicity in different organs of rat. Thus, this study not only illustrated the adverse effect of OPs on mammalian system but also suggested a highly efficient and eco-friendly way to remove the harmful pesticide from the environment and agricultural food products which may help to reduce the exposure of humans to such lethal toxicants.

The contents of 3 heavy metals (Al, Cd, and Pb) and 10 trace elements (B, Cr, Cu, Fe, Li, Mg, Ni, Sr, V, Zn) were determined by means of atomic emission spectrometry with inductively coupled plasma (ICP-OES) in 117 specimens of red mullet, Mullus surmuletus. The specimens were taken in two of the Canary Islands; two locations on the island of Tenerife: Candelaria on the northeast coast and Punta de Hidalgo on the north coast and Arguineguín, on the south coast of the island of Gran Canaria. No significant differences were found between the two sites in Tenerife regarding the metal content of the specimens studied, but differences were found between the specimens captured in Arguineguín and the two sites in Tenerife, the latter having higher concentrations of the analyzed metals.

Unapproved and illegal buildings have sprawled into the Northern Piedmont of the Qinling Mountains. The problem of illegal villas has aroused widespread public opinion and concern. The ecological environment of the Qinling Mountains has been seriously affected by the resurgence of illegal villas. This paper introduces the characteristics and distribution of illegal villas, analyzes the hazards caused by illegal villas, and describes control measures for illegal villas and land consolidation and ecological remediation in the Northern Piedmont of the Qinling Mountains. The results show that illegal planning and illegal development, as well as local governments’ irregularities, including control, governance, punishment, demolition, and compensation for illegal buildings in the expropriation of premises, have caused the problem of illegal construction of villas in the Northern Piedmont of the Qinling Mountains. Control measures for illegal villas are demolition, land consolidation, and ecological remediation. Policy implications for protection of Qinling Mountains are provided.