Effects of nanostructured zeolite and aflatoxin B1 in growth performance, immune parameters and pathological conditions of rainbow trout Oncorhynchus mykiss.

The reduction of Aflatoxin B1 (AF) in juvenile rainbow trout (Oncorhynchus mykiss) diet was analyzed after supplementing Nanostructured Zeolite (NZ) in a 56-day experiment. Two hundred and seventy juveniles with an average weight of 23 ± 3.7 g were placed in 6 different groups of C (control as a basal diet), NZ0.5 (basal diet + 0.5% NZ), NZ1 (basal diet + 1% NZ), AF5 (basal diet + 5 mg AFB1), AF5 NZ0.5 (basal diet + 5 mg AFB1 + 0.5% NZ), AF5 NZ1 (basal diet + 5 mg AFB1 + 1% NZ) with three replications and were fed four times a day based on their satiation. No significant differences were observed in terms of growth performance among the experimental groups (P > 0.05). However, hepatosomatic index in fish fed by AF5 NZ0.5 was reduced compared with NZ0.5 group (P < 0.05). The carcass moisture content showed a higher amount in treatment AF5 NZ0.5 compared to the control group (P < 0.05). There was a decrease in fat content in treatment AF5 compared to that of the control group (P < 0.05). Serum total protein, albumin and globulin levels in fish fed with aflatoxin were lower than in fish fed the diet without AF for all levels of NZ (P < 0.05); however, the interaction between AF and NZ was not significant (P > 0.05). Concentrations of C3, C4 and immunoglobulin M together with serum lysozyme activity showed no significant differences among all treatments (P > 0.05). No considerable histopathological lesions were observed in liver, kidney and spleen for all treatments. Based on the results, NZ showed some effects on physiological functions in juvenile rainbow trout fed by 0.5% dietary NZ which could improve performance in this species.

Solid waste production and its management in dental clinics in Gorgan, northern Iran.

BACKGROUND: Waste produced in dental clinics has been the topic of investigations for many years. These waste materials have important health impacts and are hazardous to humans and the environment. OBJECTIVE: To investigating solid waste production and its management in dental clinics in Gorgan, northern Iran. METHODS: In this cross-sectional study, 45 of 143 public dental practices and 5 of 25 private dental practices were selected and studied. From each clinic, 3 samples were taken and analyzed at the end of successive working days (Tuesday and Wednesday). Samples were manually sorted into 50 components. The measured components were then classified on the basis of their characteristics, hazard potentials, and WHO classification. RESULTS: The total annual amount of dental waste produced in public and private dental practices in Gorgan was 12 015.1 and 3135.0 kg, respectively. Production percentages of infectious, domestic, chemical and pharmaceutical, and toxic waste in public dental practices were 38.4%, 33.7%, 6.6%, and 0.6%, respectively. The percentages for private practices were 8.7%, 10.6%, 1.1%, and 0.1%, respectively. CONCLUSION: Dental waste management in Gorgan is inadequate; dental waste is not properly segregated, collected, and disposed, as demanded by the WHO. Employees in dentist offices must be trained in correct handling of waste products and the associated risks.

Modeling of nonylphenol degradation by photo-nanocatalytic process via multivariate approach.

Modeling of photocatalytic degradation of nonylphenol (NP), an endocrine disrupter and toxic compound, has been investigated in synthetic aqueous solutions containing ZnO nanoparticles as semiconductor using multivariate approach. In this regard, a full factorial experimental design was performed in order to study the main variables affecting the degradation process as well as their most significant interactions. Initial NP concentrations ([NP](0)) of 0.454-9.08 µM, were treated with UV-vis/ZnO using different pH and nanocatalyst loading rates. Effect of experimental parameters on the NP degradation rate constant was established by the response surface plots. The degradation rate constant decreased with an increase in the initial concentration of NP, while it increased with ZnO loading until a concentration of 0.5 g L(-1). The rate constant increases with increase in pH up to 10, after which a significant decrease is observed. The results showed that most influential factors on NP degradation constant are the [NP](0), pH of reaction media, and ZnO loading rate, and the most significant interaction is [NP]-pH. Finally, two mathematical models have been proposed to estimate NP degradation rate constant (k) on the basis of the significant variables and interactions. Predicted results of models showed good agreement with the experimental data (R(2) = 0.83 and 0.93).

Bioassay of methyl tertiary-butyl ether (MTBE) toxicity on rainbow trout fish.

Methyl tertiary-butyl ether (MTBE) has been widely used as a gasoline additive. Water resource contamination due to spillage and accidental leakage of gasoline during fuel transportation may cause an important threat to aquatic life. In this work, the bioassay of MTBE toxicity on rainbow trout was performed. MTBE solutions of 250, 500, 750, 1000, and 1250 mg L(-1) were prepared in five aquariums and aerated for 96 h. LC50 values of each experiment were measured according to probit analysis. A mathematical relationship between time exposure and LC50 of MTBE for rainbow trout was developed. The relative toxicity of MTBE to rainbow trout and to other organisms was also reviewed. It was shown that the toxicity of MTBE does not change significantly in the time exposure between 24 and 72 h varying from 878 to 831 mg L(-1), respectively. After 72 h of rainbow trout exposure to MTBE, LC50 value gradually decreased and reached 773 mg L(-1) in 96 h of contact time. In conclusion, the result of this work showed that the toxicity of MTBE to rainbow trout was relatively low.

The treatment of wastewater containing crude oil with aerated submerged fixed-film reactor.

An aerated submerged fixed-film (ASFF) bioreactor was developed to treat an artificial wastewater based on crude oil. Bee-Cell 2000 was used as support media having porosity of 87% and a specific surface area of 650 m2 m(-3). The system was able to achieve 70.87-93.12% removal efficiencies of Chemical Oxygen Demand (COD) in the organic loading rate range of 1.310 to 15.797 g COD m(-2) day(-1). Data gained exhibited that the effluent COD concentration ranged between 68.68 and 292.60 mg L(-1) at organic loadings experienced. Therefore, an ASFF process showed that it was feasible to treat high oily wastewater in order to meet the discharge standards.

Behavior of an aerated submerged fixed-film reactor (ASFFR) under simultaneous organic and ammonium loading.

The performance of an aerated submerged fixed-film reactor (ASFFR) under simultaneous organic and ammonium loading and its effect on nitrification was studied. Organic loadings varied in the range of 1.93 to 5.29 g chemical oxygen demand (COD) m-2 d-1 and NH4-N loadings were in the range of 116 to 318 mg NH4-N m-2 d-1. Increments of loading rates were obtained both by increasing the flow rate and increasing the influent substrate in individual pilot runs. Results showed that with organic loading rates up to 3.97 g COD m-2 d-1, complete nitrification was achievable. Although high organic loading such as 5.29 g COD m-2 d-1 could cause nitrification to stop, shifting to lower organic loadings made nitrification start and set rapidly to its previous steady-state concentrations. Comparison of results showed that in the ASFFR, nitrification would be severely affected by an organic loading rate of 5.29 g COD m-2 d-1 by increasing either the flow or the influent substrate. It should be noted that the average value of dissolved oxygen was 3.4 mg L-1 with an air supply of 15 L min-1, and there was no indication of oxygen limitation. The results of this study show the flexibility of ASFFRs under changing organic loads. Furthermore, for achieving complete nitrification and optimum application of these reactors for protecting receiving water from the environmental hazards of ammonium, the maximum organic loading that would present complete nitrification should be considered.