The establishment of phytoextraction crops on highly contaminated soils can be limited by metal toxicity. A recent proposal has suggested establishing support crops during the critical initial phase by metal immobilization through soil amendments followed by subsequent mobilization using elemental sulphur to enhance phytoextraction efficiency. This ‘combined phytoremediation’ approach is tested for the first time in a pot experiment with a highly contaminated soil. During a 14-week period, relatively metal-tolerant maize was grown in a greenhouse under immobilization (before sulphur (S) application) and mobilization (after S application) conditions with soil containing Cd, Pb and Zn contaminants. Apart from the control (C) sample, the soil was amended with activated carbon (AC), lignite (Lig) or vermicompost (VC) all in two different doses (dose 1~45 g additive kg⁻¹ soil and dose 2~90 g additive kg⁻¹ soil). Elemental S was added as a mobilization agent in these samples after 9 weeks. Biomass production, nutrient and metal bioavailability in the soil were determined, along with their uptake by plants and the resulting remediation factors. Before S application, Cd and Zn mobility was reduced in all the AC, Lig and VC treatments, while Pb mobility was increased only in the Lig1 and VC1 treatments. Upon sulphur application, Fe, Mn, Cd, Pb and Zn mobility was not significantly affected in the C, AC and VC treatments, nor total Cd, Pb and Zn contents in maize shoots. Increased sulphate, Mn, Cd, Pb and Zn mobilities in soil together with related higher total S, Mn, Pb and Zn contents in shoots were observed in investigated treatments in the last sampling period. The highest biomass production and the lowest metal toxicity were seen in the VC treatments. These results were associated with effective metal immobilization and showed the trend of steady release of some nutrients. The highest remediation factors and total elemental content in maize shoots were recorded in the VC treatments. This increased phytoremediation efficiency by 400% for Cd and by 100% for Zn compared to the control. Considering the extreme metal load of the soil, it might be interesting to use highly metal-tolerant plants in future research. Future investigations could also explore the effect of carbonaceous additives on S oxidation, focusing on the specific microorganisms and redox reactions in the soil. In addition, the homogeneous distribution of the S rate in the soil should be considered, as well as longer observation times.

Inorganic fouling on the membrane surface is one of the major prevalent issues affecting the performance and cost of reverse osmosis system. Chemical dosage is a widely adopted method for the inhibition of inorganic scale on the membrane surface. In this study, CO₂ was used to control inorganic scale formation on surface of reverse osmosis (RO) membrane in wastewater reclamation. The pH of influent could be lowered by purging CO₂. It caused an increase in solubility of inorganic salts in water resulting in discharge of principle ions in concentrate stream. A pilot plant study was conducted with four different RO modules including control, with dosage of antiscalant, with purging CO₂ and with co-addition of antiscalant and CO₂. The effectiveness of CO₂ purging was assessed on the basis of operational analysis, in-line analysis and morphological results. Ryznar stability index was used to determine the scaling potential of system. The examined data indicated that CO₂ purging was successful to inhibit scale formation on the membrane surface. Moreover, CO₂ was found more eco-friendly than antiscalant, as no by-products were generated in concentrate stream.

Southeast Asia has undergone rapid developments in terms of urbanization, economic and population growth. The progress in sewerage treatment infrastructure has not kept pace with such developments. The inadequacy and inefficiency of sewerage systems has prompted the release of untreated sewage into the aquatic environment of Southeast Asia causing many waterborne illnesses since surface water is utilized for recreational, agricultural and aquaculture purposes and, above all, as a source of water intake in Southeast Asia. This paper will review the current data on molecular markers of sewage pollution including sterols and linear alkylbenzenes (LABs) in Southeast Asian aquatic environment to clarify the state of sewage pollution and the competence of sewage treatment plants (STPs) in this area. Despite the importance of sewage pollution research in the region, the number of studies using molecular markers to trace the sources of sewage pollution is limited. So far, indicators of sewage pollution have been investigated in aquatic environments of Indonesia, Vietnam, Malaysia, the Philippines, Thailand, Cambodia and Brunei among Southeast Asian countries. The concentrations and diagnostic ratios of faecal sterols and LABs show the release of untreated and primary treated urban waste into water bodies of these countries. Further studies are required to fill the data gaps in Southeast Asia and come to a better understanding of the trends of sewage pollution in this part of the world. Graphical abstract

The sewage sludge contains abundant organic substances as well as a complex variety of inorganic substances (such as heavy metals). The extraction of protein from sludge is a new treatment approach to promote the utilization of sludge as a resource. However, heavy metals in sludge are extracted together with organic matter during the extraction process. In this study, the amounts of protein and heavy metal in the supernatant extracted from sewage sludge were investigated, and the effects of different passivator (modified fly ash and modified sepiolite) on the speciation of different heavy metals in the sludge were examined. Both materials reduced the contents of protein and heavy metal in the supernatant. When the dosage of sepiolite was 0.10 g/g total suspended solids of sludge, the content of heavy metals was the lowest and the protein content had little change. It can be deduced by analysis of specific area that sepiolite can complex with heavy metal ions and the fly ash adsorb the metals by physical adsorption. The modified sepiolite can be seen as an ideal passivator due to higher protein content and less heavy metals in the supernatant, as well as more stable heavy metals in the sediments.

Sustainable organic biomedical waste management is a difficult challenge as this has become one of the serious hazardous wastes. Improper disposal of organic biomedical waste can lead to direct and indirect transmission of diseases. In the present research, the organic biomedical waste samples (32 g blood swabs, 12 g dressing swabs, and 6 g used cotton) were treated with Azadirachta indica (“Neem”) and Nicotiana tabacum (“Tobacco”) extracts at various concentrations and kept for 96-h degradation, followed by evaluation of physicochemical parameters. The physicochemical results of organic biomedical waste like pH of the experimental sets were within the optimum range and there was 63.33% of decrease of TDS, 86.15% and 95.30% reduction of BOD and COD, respectively was observed at the end of 96 h. The residues were mixed with 1000 g soil to confirm their role as a potential fertilizer. The physicochemical parameters of soil sample F₆ (neem+tobacco) show an excellent result among all. The phytochemical parameters of a plant were also enhanced as compared to control. The soil samples and the tomato plants were also not polluted by the heavy metals, they are within the limit given by WHO. The present study deals with the conversion of organic biomedical waste into potential fertilizer by using plant extracts which can purely be financially profitable to the farmer.

Polychlorinated dibenzo-p-dioxin (PCDDs), polychlorinated dibenzofurans (PCDF), and dioxin-like polychlorinated biphenyl (dl-PCB) are groups of toxic compounds released into the environment as unintentional by-products of combustion. They persist, bioaccumulate through the food chain, and cause adverse health effects. This review attempts to collate available information on the release of PCDD/Fs and dl-PCBs and other critical data relevant to their monitoring in Africa during the existence of the Stockholm Convention (SC). Much as the implementation of the SC may be lagging, literature showed that there has been encouraging efforts that have been made with respect to PCDDs/Fs and dl-PCBs monitoring in Africa. Results from a global monitoring study showed that PCDD/Fs released to air in Africa stood at 18–532 fg WHO₉₈ TEQ/M³ while dl-PCBs were 7–278 fg WHO₉₈ TEQ/m³. In human milk, the total concentration of PCDD/Fs, i.e., WHO 2005 TEQ LB has been reported to range from 0.5 ng/g fat to 12 ng/g fat. Fourteen laboratories in Africa participated in inter-laboratory assessments of persistent organic pollutants (POPs) with two specifically for PCDD/Fs analysis. This shows that some efforts are being made to boost capacity in Africa. Levels of PCDDs/Fs and dl-PCBs in clay consumed by pregnant women have been reported in Cameroon, Democratic Republic of Congo (DRC), Nigeria, Zimbabwe, Ĉote d’Ivoire, and Uganda with a maximum concentration of 103 pg TEQ/g. This finding was very significant since women are the most impacted through exposure to POPs, a fact that is acknowledged by the SC.

The analyzed sediments were taken from the man-made reservoirs (Velka Richnava, Rozgrund and Vindsachta) located in an area intensively mined for polymetallic ores since the end of the eleventh century (Banska Stiavnica region, Central Europe). The aims of this study were to determine the radioactivity of natural (²²⁶Ra, ²²⁸Th, ²¹⁰Pb) and artificial (¹³⁷Cs and ²⁴¹Am) radionuclides, compare the radionuclides’ distribution, and indicate the correlation of radioisotopes and their origin related to sediment properties. Two analytical techniques were used. ²²⁸Th, ²²⁶Ra, ²⁴¹Am, and ¹³⁷Cs were measured by means of gamma spectrometry and ²¹⁰Pb was determined by its daughter radionuclide ²¹⁰Po using alpha spectrometry. The results showed that the highest mean level of ²²⁶Ra (42.6 Bq·kg⁻¹), ²²⁸Th (49.7 Bq·kg⁻¹) and ²¹⁰Pb (75.2 Bq·kg⁻¹) was in the sediments collected from Rozgrund. The radioactivity of ¹³⁷Cs and ²⁴¹Am were present at a higher level in the layer related to Chernobyl (1986) accident and nuclear weapon test (1950/1960). The distribution of natural radionuclides was quite similar in all reservoirs. Chemometric analysis confirmed the radionuclides’ origin and correlation between the analyzed parameters.

The pyroligneous liquor is a product obtained during the production of charcoal, with well-known antimicrobial activity. In this work, we characterized the physical chemistry properties of a formulation composed of distilled pyroligneous liquor (DPL), obtained from Eucalyptus grandis, and chitosan. A good interaction between the polymer and the solvent was observed. Auto-supported films were prepared with these systems and characterized with respect to their structure and photo-protection properties, water vapor permeability, and resistance to water and to thermal degradation. They present a semi-crystalline structure and are hygroscopic, but are stable under immersion for up to 7 days. The swelling degree in water is 300% in weight and the permeability to water vapor was between 30 and 45 g m⁻¹ h⁻¹ (for films with 80 to 10 μm, respectively). The obtained films are able to efficiently block the incident UVB and UVC radiation; the molar absorptivity decreases exponentially with increasing wavelength and is stable up to 300 °C. These properties confer desirable properties to the films, obtained from these precursors of a renewable source, to be used as coatings.

The presence of chemicals in laboratories and research centers exposes the staff working at such indoor environment to health risks. In this piece of research, a study was performed on the indoor environment of the Center for Environmental Engineering Research at Sahand University of Technology (Tabriz, Iran). For this purpose, the parameters affecting the dispersion of volatile organic compounds (VOCs), including ventilation rate, room temperature, pollution emission time, venting location, air flow regime within the indoor environment, and the number of vents, were simulated via CFD modeling. The CFD modeling was performed three-dimensionally in unsteady state. In case of turbulent flow within the indoor environment, k–ε turbulence model was used to obtain air velocity profile. Experimental data was used to validate the model. Results of the present research showed that when the venting location is on the ceiling, pollution concentration of 25 ppm can be achieved at some low temperature under a particular set of conditions. However, when the venting location was on the walls close to the pollution source, concentrations as low as 5 ppm and lower were observed within the laboratory indoor environment.

Chlorine-containing organic waste (COWs) is a big threat for the waste incineration because of the dioxin generation and equipment corrosion. Recently, dechlorination and detoxification of COWs is emergent in order to lower the environmental risk and treatment costs. In this study, base-catalyzed decomposition processes with different hydroxides, hydrogen donors, and catalysts were conducted for pre-treatment of COWs to reduce organic chlorine content, with the TCB as a model compound and industrial rectification residues for verification. Results showed that maximum chlorine retention efficiency (CRE) of four alkalis followed the order of KOH > NaOH–KOH > NaOH > Mg(OH)₂, which were 98.3%, 93.4%, 97.2%, and 1.5%, respectively, and could be expressed as an apparent first-order reaction. The differences were resulted from the varying ionic potentials of the metal cations. Hydrogen donors (glycol, glycerol, paraffin oil, and PEG 200) acted as effective dechlorination regents follow the order of PEG > glycol > paraffin oil > glycerol. In addition, Fe, Ni, Cu, and activated carbon catalysts increased the CRE by 68.9% to 92.4%, 91.9%, 89.2%, and 73.3%, respectively. Residue analysis through X-ray diffraction and Fourier transform infrared spectroscopy revealed that KCl, sodium oxalate, and phenol were the main products and a plausible stepwise dechlorination pathway was proposed. The effectiveness of three optimized combinations including NaOH/PEG, KOH/PEG, and NaOH–KOH/PEG (with the Fe catalyst) was confirmed by using them for dechlorinating rectification residues, and they restrained 98.2%, 91.2%, and 94.6% of the chlorine, respectively. The organochlorine content decreased from 19.2 to 1.8% within 180 min, while inorganic chorine content increased from 1.5 to 18.9%, indicating the potential for COWs dechlorination.