Heavy metal accumulation and genotoxic effect of long-term wastewater irrigated peri-urban agricultural soils in semiarid climate.

Water scarcity is becoming an alarming issue in the Mediterranean countries. Therefore, using the treated wastewater in the irrigation is considered as a valuable option. However, uncontrolled and long-term irrigation by wastewater leads to human health and environmental damages, mainly related to some specific pollutants. The assessment of the availability and toxicity of the heavy metals after long term irrigation, under semi-arid climate, is not yet well documented. In this study, physicochemical properties, genotoxicity (Vicia faba micronucleus test), total and available (CaCl2-extractable) concentrations of Cr, Pb, Cu, Zn, Co and Cd in eight soils of peri-urban farms irrigated with wastewater were examined to evaluate their accumulation. The results indicated that long-term irrigation with wastewater induced significant increase of electrical conductivity, organic matter, calcium carbonate equivalent and nutrient availability. Total and available concentration of heavy metals were significantly higher (P < 0.05) in irrigated soils by wastewater. The total concentrations of Zn, Pb, Cu, Cr, Cd and Co in irrigated soils by wastewater at 0-40 cm depth were 85.69, 43.94, 34.86, 14.62, 9.94 and 7.17 mg kg-1, respectively. Furthermore, the increase of the available metal fraction in irrigated soils by wastewater at 0-40 cm depth followed the following order: Co (1270.1%) > Cd (914.5%) > Cu (881.5%) > Cr (471.2%) > Pb (230.8%) > Zn (223.8%). The micronucleus assay indicated significant increase of micronucleus frequencies (41.25‰, 35.48‰, 21.66‰, 16.23‰ and 13.62‰ respectively for P1, P2, P3, P4 and P7) which were higher than the negative control (0‰) and the irrigated soil by fresh water (3.29‰). The micronucleus induction was significantly correlated with the high available fraction of Cd, Co and Zn at P1, P2 and P7. The genotoxicity can be a powerful test to assess the ecological effects associated with the interactions of heavy metals with other pollutants.

Application of different chemometric assisted models for spectrophotometric quantitative analysis of velpatasvir and sofosbuvir.

Four chemometric assisted spectrophotometric models were developed for the quantitative analysis of velpatasvir and sofosbuvir, in their newly FDA approved pharmaceutical dosage form. Due to the existed overlap of the scanned absorption spectra between velpatasvir and sofosbuvir, this resulted in degree of difficulty of the possibility of the conventional spectrophotometric methods to quantify and analyze the cited drugs simultaneously. Classical least squares, principal component regression, partial least squares and genetic algorithm partial least squares were designed and compared for the quantitative analysis of velpatasvir and sofosbuvir in their binary mixture. Experimental design for different concentrations of the studied drugs was done based on the spectral sensitivity of velpatasvir and sofosbuvir and the confirmed ratio of the two drugs in the commercial pharmaceutical dosage form. Optimization of the described models was adopted with the aid of five-levels, two factors experimental design. Successfully quantitative assay of the drugs in Epclusa® tablets was done by the proposed models. Statistically comparative analysis for the obtained models results with another published capillary electrophoresis quantitative analytical method was performed. It is noteworthy mentioning that there was no significant difference between the proposed models and the published method with respect to the accepted statistical parameters.

Helminth eggs inactivation efficiency by sludge co-composting under arid climates.

Primary sludge (PS) from the wastewater treatment plants is constituted of organic matter and other nutrients that could be reused as soil fertilizers. However, primary sludge amendment is hampered due to the presence of pathogens that could be responsible for several infections in various ways depending on the prevalence of the human sources. This study investigates helminth eggs (HE) removal and inactivation efficiency by co-composting. So, PS was mixed with date palm waste as a bulking material at a 1:1 volume ratio. The C/N ratio decreased from 25:1 to 12:1 and temperatures above 50ºC were observed since 33 days. The initial concentration of HE eggs in the PS is 135.9 per 10 g DR. Microscopic examination of the PS, according to the Bailenger method, showed the presence of nematodes and Cestodes represented by: Ascaris lombricoïde, Ancylostomes duodenale, Trichuris trichiura, Capilaria spp, Hymenolepis nana, Taenia saginata, and Ascaris lombricoïde. After 60 days of co-composting, the charge of parasites was reduced to 18 eggs per 10 g per DR. The viability of ascaris eggs was examined using a light microscope and the percentage of the embryonated eggs was determined. No viable eggs were observed in the final compost. The result corroborates the WHO guidelines for the application of the composted sewage sludge safely for agriculture purposes.

Assessment of the genotoxicity of antibiotics and chromium in primary sludge and compost using Vicia faba micronucleus test.

The objective of this study was to investigate chemical, biological and eco-toxicological parameters of a compost produced through the co-composting of dewatered primary sludge (DPS) and date palm waste to evaluate in which extent it can exploited as a bio-fertilizer. DPS and date palm waste were co-composted in aerobic conditions for 210 days. Physico-chemical parameters were evaluated during composting (total organic carbon, total nitrogen, pH, available forms of phosphorus). Furthermore, heavy metals (Cd, Cu, Cr, Pb, Ni, Zn) and antibiotics (fluoroquinolones, macrolides and tetracyclines) content were analyzed in the DPS. To evaluate the genotoxicity of substrates, Vicia faba micronucleus test was carried out. Single and combined toxicities of a mixture of antibiotics (ciprofloxacin, enroflxacin, nalidixic acid, roxithromycin and sulfapyridin) and chromium (Cr2 (SO4)3 and K2Cr2O7) were examined. Although the final compost product showed a significant decrease of the genotoxicity, almost 50% of the micronucleus frequency still remained, which could be explained by the persistence of several recalcitrant compounds such as chromium and some antibiotics. Overall, the presence of antibiotics and chromium showed that some specific combination of contaminants represent an ecological risk for soil health and ecosystems even at environmentally negligible concentrations.

Fate of antibiotics present in a primary sludge of WWTP during their co-composting with palm wastes.

Antibiotics persistence in the primary sludge can contribute to the emergence of these molecules in the environment and limit the agricultural recycling of sludge without any preliminary treatment. Composting is a widely used process for recycling sludges and then can contribute to the antibiotics removal. However, little interest is actually given to the evaluation of the persistence of some antibiotics families after the sludge co-composting and more particularly to the final compost valorization. In this work, antibiotics concentrations of ßeta-lactams, Macrolides, Lincosamide, Tetracyclines, Sulfonamides and Fluoroquinolones were checked in the primary sludge of the wastewater treatment plants (WWTP) of Marrakesh (Morocco) before its co-composting. The results showed a final high amount of the fluoroquinolones family (4.21 and 2.92 µg/kg DM for Ciprofloxacin and Ofloxacin respectively) compared to the other studied families. To assess the fate of antibiotics, the primary sludge and palm waste were windrowed and composted during 120 days. The final compost showed a high level of organic matter decomposition (52%) and a C/N ratio of 12 which insure the compost quality. The assessment of antibiotics concentrations during co-composting showed that clarithromycin is more degraded particularly during the stabilization stage (43%), the degradation of lincomycin and tetracyclines is more significant during the maturation stage (36 and 75% respectively). Ampicillin and trimethoprim were degraded all along the process of co-composting (46 and 35% respectively). By the way, the persistence of the fluoroquinolones family was observed. This persistence could be a limiting key factor for the composted sludge valorization. So, more knowledge is needed to understand fluoroquinolones behavior and, then, to optimize their composting conditions.

Human and veterinary antibiotics during composting of sludge or manure: Global perspectives on persistence, degradation, and resistance genes.

Wastewater treatment plant effluent, sludge and manure are the main sources of contamination by antibiotics in the whole environment compartments (soil, sediment, surface and underground water). One of the major consequences of the antibiotics discharge into the environment could be the prevalence of a bacterial resistance to antibiotic. In this review, four groups of antibiotics (Tetracyclines, Fluoroquinolones, Macrolides and Sulfonamides) were focused for the background on their wide spread occurrence in sludge and manure and for their effects on several target and non-target species. The antibiotics concentrations range between 1 and 136,000 µg kg-1 of dry matter in sludge and manure, representing a potential risk for the human health and the environment. Composting of sludge or manure is a well-known and used organic matter stabilization technology, which could be effective in reducing the antibiotics levels as well as the antibiotic resistance genes. During sludge or manure composting, the antibiotics removals range between 17-100%. The deduced calculated half-lives range between 1-105 days for most of the studied antibiotics. Nevertheless, these removals are often based on the measurement of concentration without considering the matter removal (lack of matter balance) and very few studies are emphasized on the removal mechanisms (biotic/abiotic, bound residues formation) and the potential presence of more or less hazardous transformation products. The results from the few studies on the fate of the antibiotic resistance genes during sludge or manure composting are still inconsistent showing either decrease or increase of their concentration in the final product. Whether for antibiotic or antibiotic resistance genes, additional researches are needed, gathering chemical, microbiological and toxicological data to better understand the implied removal mechanisms (chemical, physical and biological), the interactions between both components and the environmental matrices (organic, inorganic bearing phases) and how composting process could be optimized to reduce the discharge of antibiotics and antibiotic resistance genes into the environment.

Efficiency of two sewage treatment systems (activated sludge and natural lagoons) for helminth egg removal in Morocco.

Morocco is a country known for its vulnerability of water resources because of its arid and semi-arid climate. Thus, recycled wastewater has been suggested for agricultural activities, but contamination of these wastewaters is a major concern. The current study aims to determine the occurrence of helminth eggs in urban wastewater and to evaluate the removal of these pathogens by two sewage treatment systems: activated sludge and natural lagoons. The samples of wastewater and sludge were collected from two wastewater treatment plants (WWTP) located in Marrakech and Chichaoua, Morocco. Parasitological identification, according to the Bailenger technique, showed the presence of Nematodes and Cestodes, which are pathogenic to humans and animals and are responsible for helminthiasis. The wastewater and sewage sludge samples from Marrakech carried Ascaris lumbricoïdes, Ancylostoma duodenale, Trichuris trichiura, Capillaria spp., Taenia spp. and Hymenolepis spp., while the samples from Chichaoua carried Ascaris lumbricoïdes, Ancylostoma duodenale, Trichuris trichiura and Capillaria spp. The overall removal efficiency of eggs in the treatment plants ranged from 100% in the WWTP of Marrakech using activate sludge to 94.97% in the WWTP of Chichaoua using natural lagoons. These results were discussed according to health risk and the cost-effectiveness of both wastewater treatment techniques.