Bioaccumulation of potentially toxic elements in leafy and tuberous vegetables: a comparison based on meta-analysis studies with a cumulative health risk assessment.

Seventy seven research papers published from 1986 to 2018 were observed. These papers investigated PTEs (Pb, Cd, Cu, As, Fe, Zn, Ni, and total Cr) in leafy (mint, spinach, coriander, and lettuce) and tuberous (potato, carrot, radish, and onion) vegetables irrigated by wastewater. The studies observed in our paper were conducted in 19 countries. The PTEs concentrations were compared among studies and the human health risk was observed. According to the obtained meta-analysis results, PTEs concentrations (mg/kg) in vegetables were found in the following order Zn (34.216)> Cu (22.581)> Ni (14.056)> Pb (10.173)> Cr (8.308)> Fe(8.130)> As(1.881)> Cd (1.763). Hazard index for children was higher than that for adults and for both groups, the calculated HQ was higher than 1, which indicates that there is a health risk for the consumers. This study provides a comprehensive analysis that demonstrates the urgent necessity for treating PTE pollution in agricultural areas worldwide.

The concentration of potentially toxic elements (PTEs) in apple fruit: a global systematic review, meta-analysis, and health risk assessment.

The presence of potentially toxic elements (PTEs) in crops can directly/indirectly affect consumers' health. The contamination of apple as one of the most consumed fruits with PTEs such as lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), and nickel (Ni) leads to carcinogenic risk (CR) and non-carcinogenic risk (n-CR). In this regard, a systematic review, meta-analysis, and health risk assessment regarding the concentration of the PTEs in apples was conducted using international databases such as Scopus and PubMed. According to the results, the rank order of PTEs in apple fruits was Pb (427.45 µg/kg-wet weight) > Ni (228.74 µg/kg-wet weight) > Cr (212.43 µg/kg-wet weight) > As (123.93 µg/kg-wet weight) > Cd (15.28 µg/kg-wet weight). n-CR was higher than 1 for the USA, Serbia for adults, and Poland for children. CR for adults in Serbia, Spain, Greece, China, Bangladesh, and Pakistan and children in Serbia, Spain, Greece, China, and Bangladesh were not acceptable (CR > 1.00E - 06 value). In this regard, the pooled PTEs of apples can cause CR and n-CR issues. Therefore, constant monitoring and reduction of pesticide application are strongly recommended for controlling PTEs in apple fruits.

Evaluation of a novel integrated membrane biological aerated filter for water reclamation: A practical experience.

The use of treated wastewater in addition to solving the problem of water shortage, can increase soil fertility and reduce the use of chemical fertilizers. We aim to provide a high-quality effluent to feed membrane system, reduce treatment costs and enhance the efficiency of wastewater recycling. All experiments were conducted on a novel integrated membrane biological aerated filter (IMBAF) consisting of a down flow cylindrical biological aerated filter (BAF) filled by silica and a novel sand-coated polystyrene granules (SCP), followed by ultrafiltration (UF) and reverse osmosis (RO) membranes. IMBAF reactor, with 73.6 L volume, was operated for 270 days (in three 90-day stages) with different conditions of returning backwash water. Accordingly, BAF generated high quality water for feeding UF membrane with 94.2%, 68%, 54.4%, 91.2%, and 99.95% of turbidity, 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), oil and grease (O&G), fecal coliform (FC) removal, respectively. At the end of stage 3, 99.88% of influent was recycled by UF and only 0.12% was disposed of as sludge. The BAF and UF module efficiently promote the quality of water entering RO system. After 75 days of continuous operation, the increase in trans-membrane pressure (TMP) and also decrease in RO membrane permeability were about 14% and 9.4%, respectively, indicating low clogging of the membrane. The use of BAF structure designed in this study increases the wastewater recycling rate, decreases membrane clogging and thereby reduces the costs of concentrate disposal and chemical cleaning.