Ammoniacal leaching and recovery of copper from alloyed low-grade e-waste

The paper concerns a hydrometallurgical method for selective recovery of copper from low-grade electric and electronic wastes. The following consecutive stages were proposed: smelting of the scraps to produce Cu–Zn–Ag alloy, leaching of the alloy in ammoniacal solution, and selective copper electrowinning. Cu–Zn–Ag alloy was a polymetallic and five-phase system. It was leached in chloride, carbonate, sulfate and thiosulfate solutions. This resulted in the separation of the metals, wherein metallic tin and silver as well as lead salts remained in the slimes, while copper and zinc were transferred to the electrolyte. Copper was selectively recovered from the ammoniacal solutions by the electrolysis, leaving zinc ions in the electrolyte. The best conditions of the alloy treatment were obtained in the ammonia–carbonate system, where the final product was copper of high purity (99.9 %) at the current efficiency of 60 %. Thiosulfate solution was not applicable for the leaching of the copper alloy due to secondary reactions of the formation of copper(I) thiosulfate complexes and precipitation of copper(I) sulfide, both inhibiting dissolution of the metallic material.     

Spent sulfuric acid plant catalyst: valuable resource of vanadium or risky residue? Process comparison for environmental implications

Environmental Science and Pollution Research - The enormous amount of spent catalysts generated worldwide may pose a risk to the environment because of their high load of metals, including...     

Effect of humate on biological treatment of wastewater containing heavy metals

This paper presents results of investigations on the influence of humic substances (humate, HS) on the biological treatment of wastewater containing heavy metals (Cr, Cu, Fe, Mn, Ni, and Zn). Respirometric studies indicated that the investigated system complied with the Haldane model for inhibitory wastes. Chemical analyses showed that, while the soluble COD removal was high (82%), only 7% of ammonia was oxidized to nitrate. An addition of HS (500 mg L⁻¹) mitigated the inhibitory effect of the wastewater on the returned activated sludge. The system with HS complied with the Monod model for non-inhibitory wastes, and the removal of ammonia and metals was 99% and over 90%, respectively. It is suggested that an application of HS could be beneficial for treatment plants receiving wastewater streams containing heavy metals.     

The conceptual model of an eco-industrial park based upon ecological relationships

The necessity to follow the rules of sustainable development in the everyday industrial practice has led to the formulation of the concept of an industrial ecosystem mimicking the natural ecosystem. Following this analogy, the conceptual model of an eco-industrial park, which is an organised form of the industrial ecosystem, was presented in this paper. The model comprises of (1) the structure of the ecosystem, (2) the classification of the enterprises as producers, consumers and decomposers, (3) mass and energy flows and (4) types of interactions. The classification of the enterprises introduced here as well as the analysis of mass and energy flows indicates that the diversity of the enterprises in eco-industrial parks is desired. Furthermore, the minimal condition to create the symbiotic relationships between the enterprises is established, claiming that at least one industrial producer or decomposer must be involved in the eco-industrial park. The application of this model will facilitate the design and development of eco-industrial parks and enable the identification of symbiotic relationships between the entities of such a park and other types of industrial ecosystems. In order to show the applicability of the proposed model and its potential for the practical implementation two case studies are presented.     

Discrete and time-integrated sampling for chromium load calculations in a watershed with an impoundment reservoir at an exceptionally low water level

Instantaneous (discrete) and time-integrated (composed) samples were collected during a 19-week period in a watershed impacted by discontinuous discharges from local tanneries (Carpathians Mountains, Poland). Existence of the impoundment reservoir in this watershed allowed investigation of its role in chromium transport. In collected samples, dissolved and particulate chromium concentrations were measured to apportion both loads. This study has demonstrated that the impoundment reservoir retains not only particulate but also a dissolved form of chromium and its efficiency reaches 74–94 %. Sampling results proved that chromium contamination in the investigated river is variable and discontinuous. Discrete sampling can lead to an underestimation of chromium contamination level (up to 78 %), especially when illegal/unexpected discharges occur in the watershed. A discrete sampling regime also produces less reliable data for contaminant budget calculations, especially in sites where strong variability of contamination is anticipated, while at the output from reservoirs, the load can be reasonably estimated using this mode of sampling.     

Long-Term Monitoring of Scots Pine Litter Decomposition Rates Throughout Sweden Indicates Formation of a More Recalcitrant Litter in the South

Decomposition studies were carried out at sites throughout Sweden, including the four Integrated Monitoring sites. Scots pine needle litterbag weight loss measurements over 3 or 5 years were determined at 26 sites and repeated up to 27 times, depending on the site. Humus layer respiration rates were determined for 20 sites in 1987–1989 and repeated in 2007–2008. Partial Least Squares (PLS) regression was used to elucidate the relative importance of climatic and soil factors. Annual needle weight losses decreased only slowly (20–10%) over 3–5 years for all northern (>60°N) sites but decreased sharply from 30 to 10% in the third year in southern (<60°N) sites. Respiration rates of southern sites were less (40% on average) than those of northern sites. Humus layer N was positively correlated to needle weight loss during the first and the second years, but negatively correlated in the third year and to respiration rates. The results indicated that litter formed in southern Sweden became more recalcitrant in later stages of decomposition compared to litter produced in northern Sweden.     

Lead accumulation and elimination in tissues of Prussian carp, Carassius gibelio (Bloch, 1782), after long-term dietary exposure, and depuration periods

We studied the bioaccumulation of lead in selected tissues of Prussian carp Carassius gibelio (Bloch, 1782) during 12 and 24 months exposure to different doses of this metal in feed and the elimination of lead from tissues during the following 12-month depuration period. Lead concentration was determined using atomic absorption spectrometry method. The highest lead concentrations were observed at 2.0?±?0.54 to 7.4?±?1.1 mg?kg^?1 in the kidney, 3.0?±?0.13 to 5.2?±?0.17 mg?kg^?1 in the bone, and 4.5 (±0.4)?mg?kg^?1 in the hepatopancreas of fish from groups exposed to lead dietary concentration from 8 to 49 mg?kg^?1 for 24 months. The rate of accumulation were generally the highest at the beginning of exposure as evidenced by the highest monthly increments of bioaccumulation observed after 3 months of contamination for muscles, hepatopancreatic gland, intestine, and gills. Also analysis of the monthly increments of lead bioaccumulation in bone tissue and the highly significant coefficients of correlation indicate that the dynamics of accumulation are clearly dependent on dose of exposure. Depuration of accumulated lead from the organs depended mainly on tissue and duration of elimination period. Very rapid depuration was observed in soft tissues such as the intestine or muscles. Very low elimination was observed for scales and bones where until the end of the experiment highly significant lead concentration differences were observed in all groups in relation to the control group. Chronic dietary exposure in the range of 8–49 mg Pb?kg^?1 resulted in no significant effects on the growth and survival of Prussian carp females.     

Assessment of boscalid and pyraclostrobin disappearance and behavior following application of effective microorganisms on apples

ABSTRACT

The aim of this study is to assess the disappearance of boscalid (IUPAC name: 2-chloro-N-[2-(4-chlorophenyl)phenyl]pyridine-3-carboxamide) and pyraclostrobin (IUPAC name: methyl N-[2-[[1-(4-chlorophenyl)pyrazol-3-yl]oxymethyl]phenyl]-N-methoxycarbamate) residues in apple fruit, and to verify whether an organic fertilizer enriched with strains of antagonistic microorganisms can reduce pesticide residue levels. Field trials were conducted in a commercial orchard on apples of the Gloster variety, during 21 days after the treatment with Bellis 38 WG and the subsequent application of Zumba Plant formulation containing Bacillus spp., Trichoderma spp. and Glomus spp. In control samples, the decrease rate of boscalid and pyraclostrobin residue levels followed an exponential function, described by formulae R_t = 0.2824e^?0.071t and R_t = 0.1176e^?0.060t, with the coefficient of determination of r² = 0.8692 and r² = 0.9268, respectively. These levels dropped to half (t_1/2) of their initial values after 9.8 and 11.5 days, respectively. The treatment with Zumba Plant resulted in a reduction in boscalid and pyraclostrobin residue levels by 52% and 41%, respectively. The results of this study are of importance for horticulture sciences and for producers of apples using plant protection products (PPPs).