Sequential anaerobic-aerobic digestion has been demonstrated as a promising alternative for enhanced sludge stabilization. In this paper, a feasibility study of the sequential digestion applied to real waste activated sludge (WAS) and mixed sludge is presented. Process performance is evaluated in terms of total solid (TS) and volatile solid (VS) removal, biogas production, and dewaterability trend in the anaerobic and double-stage digested sludge. In the proposed digestion lay out, the aerobic stage was operated with intermittent aeration to reduce the nitrogen load recycled to the wastewater treatment plant (WWTP). Experimental results showed a very good performance of the sequential digestion process for both waste and mixed sludge, even if, given its better digestibility, higher efficiencies are observed for mixed sludge. VS removal efficiencies in the anaerobic stage were 48 and 50 % for waste and mixed sludge, respectively, while a significant additional improvement of the VS removal of 25 % for WAS and 45 % for mixed sludge has been obtained in the aerobic stage. The post-aerobic stage, operated with intermittent aeration, was also efficient in nitrogen removal, providing a significant decrease of the nitrogen content in the supernatant: nitrification efficiencies of 90 and 97 % and denitrification efficiencies of 62 and 70 % have been obtained for secondary and mixed sludges, respectively. A positive effect due to the aerobic stage was also observed on the sludge dewaterability in both cases. Biogas production, expressed as Nm³/(kgVSdₑₛₜᵣₒyₑd), was 0.54 for waste and 0.82 for mixed sludge and is in the range of values reported in the literature in spite of the low anaerobic sludge retention time of 15 days.

To determine an optimal species pool for periphytic microfauna colonization surveys, a multivariate approach was used to identify the influential species from a raw dataset of periphytic microfauna. Samples were collected at two depths of 1 and 3 m in coastal waters of the Yellow Sea using a glass slide method. From the full 77-species dataset, a 23-species subset with sufficient information of the whole community was identified. The small subset maintained sufficient information of colonization pattern of entire raw communities (correlation coefficient >0.95). The colonization curves based the small subset well fitted the MacArthur-Wilson and logistic model equations in both species composition and individual abundance, respectively. Compared to the functional parameters based on the full dataset, the colonization rates (G) were significantly high and the time reaching 90 % equilibrium species number (T₉₀) significantly low (P < 0.05), while the growth rates (r) and the time reaching 50 % maximum abundance (T₅₀) showed no significant changes (P > 0.05) at both depths, respectively. The species richness, diversity, and evenness represented significantly closed linear relationships between the subset and the full dataset. The results suggest that the small subset might be used as a robust optimal species pool for colonization-based bioassessment surveys and allows developing a time-efficient protocol for marine monitoring programs using of periphytic microfauna.

This study aimed to assess the antibiogram of Aeromonas strains recovered from cattle faeces and the potential pathogenic status of the isolates. The antibiogram of the Aeromonas isolates demonstrated total resistance to clindamycin oxacillin, trimethoprim, novobiocin and ticarcillin. However, Aeromonas strains were sensitive to cefotaxime, oxytetracycline and tobramycin. The Aeromonas strains from Lovedale and Fort Cox farms were found to possess some virulence genes. The percentage distribution was aer 71.4 %, ast 35.7 %, fla 60.7 %, lip 35.7 % and hlyA 25 % for Lovedale farm and aer 63.1 %, alt 10.5 %, ast 55.2 %, fla 78.9 %, lip 21 % and hlyA 35.9 % for Fort Cox farm. Class 1 integron was present in 27 % of Aeromonas isolates; the bla TEM gene was present in 34.8 %, while the blaP1 class A β-lactamase gene was detected in 12.1 % of the isolates. Approximately 86 % of the isolates formed a biofilm on microtitre plates. The presence of multiple antibiotic resistance and virulence genes in Aeromonas isolates from cattle faeces reveals the pathogenic and infectious importance of these isolates and is of great significance to public health. The possession of a biofilm-forming capability by such isolates may lead to difficulty during the management of infection related to Aeromonas species.

The characteristics of volatile organic compounds (VOCs) emitted from several consumer and commercial products (body wash, dishwashing detergent, air freshener, windshield washer fluid, lubricant, hair spray, and insecticide) were studied and compared. The spray products were found to emit the highest amount of VOCs (~96 wt%). In contrast, the body wash products showed the lowest VOC contents (~1.6 wt%). In the spray products, 21.6–96.4 % of the VOCs were propane, iso-butane, and n-butane, which are the components of liquefied petroleum gas. Monoterpene (C₁₀H₁₆) was the dominant component of the VOCs in the non-spray products (e.g., body wash, 53–88 %). In particular, methanol was present with the highest amount of VOCs in windshield washer fluid products. In terms of the number of carbon, the windshield washer fluids, lubricants, insecticides, and hair sprays comprised >95 % of the VOCs in the range C₂–C₅. The VOCs in the range C₆–C₁₀ were predominantly found in the body wash products. The dishwashing detergents and air fresheners contained diverse VOCs from C₂ to C₁₁. Besides comprising hazardous VOCs, VOCs from consumer products were also ozone precursors. The ozone formation potential of the consumer and commercial spray products was estimated to be higher than those of liquid and gel materials. In particular, the hair sprays showed the highest ozone formation potential.

Despite decades of intensive research, lead (Pb) toxicity still remains one of the most frequently investigated subjects in environmental health. Whole blood lead (BPb) is usually used to evaluate Pb exposure for both screening and clinical diagnosis. However, it is generally recognized that BPb is not a sensitive biomarker for Pb exposure in hematological studies. Considering hematocrit (HCT) variation in different situations, HCT-adjusted BPb or erythrocyte Pb (EPb) may be more relevant when evaluating the hematotoxicity of blood Pb. Data collected from 855 preschool children, 3–7 years of age, allowed us to examine the relationship between EPb and hemoglobin (Hb) levels. Multivariate linear regression was performed to determine the significance of EPb as predictor of Hb after covariate adjustment; then, mean differences of Hb levels between quartiles of EPb and BPb (1st quartile as reference) were determined using ANOVA followed by Student’s t test. The dose-response curve between EPb and HCT was plotted using locally weighted scatterplot smoothing (LOWESS) method. A doubling of EPb was associated with a 2.44 g/L decrease in Hb level. Compared to the 1st quartile group of EPb, the 3rd and 4th quartile groups showed significant decreases in Hb levels (3.01 and 3.97 g/L, respectively). Compared to the 1st quartile group of BPb, the 2nd quartile group showed a decrease in Hb levels (0.63 g/L), while the 3rd and 4th quartile groups showed increases in Hb levels (0.78 and 1.45 g/L, respectively). Increased EPb levels are significantly associated with decreased Hb levels in preschool children. HCT must be taken into consideration in investigating the hematological effects of Pb. Compared to BPb, EPb or HCT-adjusted BPb appear as a more effective biomarker to interpret the hematotoxicity of lead. Furthermore, blood erythrocytes are not only a repository of Pb but also a primary target of its toxicity.

High concentrations of uranium(VI) in the Witwatersrand Basin, South Africa from mining leachate is a serious environmental concern. Treatment systems are often ineffective. Therefore, optimization of a bioremediation system that facilitates the bioreduction of U(VI) based on biostimulation of indigenous bacterial communities can be a viable alternative. Tolerance of the indigenous bacteria to high concentrations of U and the amount of citric acid required for U removal was optimized. Two bioreactor studies which showed effective U(VI) removal more than 99 % from low (0.0037 mg L⁻¹) and high (10 mg L⁻¹) concentrations of U to below the limit allowed by South African National Standards for drinking water (0.0015 mg L⁻¹). The second bioreactor was able to successfully adapt even with increasing levels of U(VI) feed water up to 10 mg L⁻¹, provided that enough electron donor was available. Molecular biology analyses identified Desulfovibrio sp. and Geobacter sp. among known species, which are known to reduce U(VI). The mineralogical analysis determined that part of the uranium precipitated intracellularly, which meant that the remaining U(VI) was precipitated as U(IV) oxides and TEM-EDS also confirmed this analysis. This was predicted with the geochemical model from the chemical data, which demonstrated that the treated drainage was supersaturated with respect to uraninite > U₄O₉ > U₃O₈ > UO₂₍ₐₘ₎. Therefore, the tolerance of the indigenous bacterial community could be optimized to remediate up to 10 mg L⁻¹, and the system can thus be upscaled and employed for remediation of U(VI) impacted sites.

A combined chemical and biological analysis of samples from a major obsolete pesticide and persistent organic pollutant (POP) dumpsite in Northern Tajikistan was carried out. The chemical analytical screening focused on a range of prioritized compounds and compounds known to be present locally. Since chemical analytics does not allow measurements of hazards in complex mixtures, we tested the use of a novel effect-based approach using a panel of quantitative high-throughput CALUX reporter assays measuring distinct biological effects relevant in hazard assessment. Assays were included for assessing effects related to estrogen, androgen, and progestin signaling, aryl hydrocarbon receptor-mediated signaling, AP1 signaling, genotoxicity, oxidative stress, chemical hypoxia, and ER stress. With this panel of assays, we first quantified the biological activities of the individual chemicals measured in chemical analytics. Next, we calculated the expected sum activity by these chemicals in the samples of the pesticide dump site and compared the results with the measured CALUX bioactivity of the total extracts of these samples. The results showed that particularly endocrine disruption-related effects were common among the samples. This was consistent with the toxicological profiles of the individual chemicals that dominated these samples. However, large discrepancies between chemical and biological analysis were found in a sample from a burn place present in this site, with biological activities that could not be explained by chemical analysis. This is likely to be caused by toxic combustion products or by spills of compounds that were not targeted in the chemical analysis.

The concentrations of metals/metalloids in blood plasma collected from 111 healthy residents (51 female, 60 male) in Hong Kong (obtained from the Hong Kong Red Cross Blood Transfusion Service, from March to April 2008) were quantified by means of a double-focusing sector field inductively coupled plasma optical emission spectrometer (ICP-OES). Results showed that concentrations of these toxic metals such as Hg, Cd, and Pb in Hong Kong residents were not serious when compared with other countries. Males accumulated significantly higher (p < 0.05 or 0.01) Fe (female 0.92 mg/L; male 1.28), Sn (0.44 μg/L; 0.60), Cr (0.77; 0.90), Hg (1.01; 1.73), and Pb (23.4; 31.6) than females. Smokers accumulated significantly higher (p < 0.05) Cd (smoker 0.27 μg/L; nonsmoker 0.17) and Pb (32.8; 17.6) than nonsmokers. Positive correlations were found between concentrations of As, Cd, Pb, and Hg, with respect to seafood diet habit, body mass index (BMI), and age. More intensive studies involving more samples are needed before a more definite conclusion can be drawn, especially on the causal relationships between concentrations of metals/metalloids with dietary preference and lifestyle of the general public.

In this study, the leaching of 14 substituted phenylurea herbicides (PUHs) through disturbed soil columns packed with three different soils was investigated in order to determine their potential for groundwater pollution. Simultaneously, a series of experiments were conducted to demonstrate the effect of four different organic wastes (composted sheep manure (CSM), composted pine bark (CPB), spent coffee grounds (SCG) and coir (CR)) on their mobility. All herbicides, except difenoxuron, showed medium/high leachability through the unamended soils. In general, addition of agro-industrial and composted organic wastes at a rate of 10 % (w/w) increased the adsorption of PUHs and decreased their mobility in the soil, reducing their leaching. In all cases, the groundwater ubiquity score (GUS) index was calculated for each herbicide on the basis of its persistence (as t½) and mobility (as KOC). The results obtained point to the interest in the use of agro-industrial and composted organic wastes in reducing the risk of groundwater pollution by pesticide drainage.

Enzyme activity and microbial population in soils have important roles in keeping soil fertility. ZJ0273 is a novel pyrimidynyloxybenzoic-based herbicide, which was recently developed in China. The effect of ZJ0273 on soil enzyme activity and microbial population in two different soils was investigated in this study for the first time. The protease activity was significantly inhibited by ZJ0273 and this inhibiting effect gradually weakened after 60-day incubation. The results also showed that ZJ0273 had different stimulating effects on the activities of dehydrogenase, urease, and catalase. Dehydrogenase was consistently stimulated by all the applied concentrations of ZJ0273. The stimulating effect on urease weakened after 60-day incubation. Catalase activity was subject to variations during the period of the experiments. The results of microbial population showed that the number of bacteria and actinomycetes increased in ZJ0273-treated soil compared with the control after 20 days of incubation, while fungal number decreased after only 10 days of incubation in soils. DT50 (half-life value) and k (degradation rate constant) of ZJ0273 in S1 (marine-fluvigenic yellow loamy soil) and S2 (Huangshi soil) were found 69.31 and 49.50 days and 0.010 and 0.014 day⁻¹, respectively.