Industrial wastes generated from tanneries located in the southwestern part of Dhaka, pose serious threat to the environment. Surface accumulation of trivalent chromium reaching as high as 28,000 mg/kg have been encountered at 1 km distance from the waste lagoon. In contrast, maximum concentration of hexavalent chromium is about 1 mg/kg, and is very irregularly distributed all over the area. Although soil pH is alkaline in general, a sharp drop of pH down to 3.4 has been observed at some locations. Furthermore, high chloride (Cl) and lead (Pb) concentrations pose risk for city's groundwater quality, of which Pb is vulnerable for any chelate-assisted phytoremediation as it can enhance its mobility. Scanning electron microscope study showed chromium within the structure of clay minerals, mainly illite-smectite, and also as chlorite-chromian. Presence of lepidocrocite indicates a rather reactive phase which can undergo reductive dissolution and release Cr in the environment.

This study monitored nitrate levels in well water and analyzed their association with well attributes (physicochemical parameters of water, location, livestock farming conditions) in a nitrate-polluted, animal industry district in central Miyakonojo Basin, southern Kyushu, Japan, to characterize the nitrate status of groundwater in the district. Water quality varied considerably among the wells, with nitrate-N concentration and natural nitrogen-15 abundance in nitrate-N (δ¹⁵N-NO₃) ranging from 1.1-44.6 mg L⁻¹ and 4.2-17.8[per thousand], respectively. There was a significant positive correlation between nitrate-N concentration and δ¹⁵N-NO₃. Nitrate-N concentration was higher in wells located at higher elevations, having larger areas of livestock barns within a 100-m radius and with higher animal populations. Wells in pig farms showed a higher nitrate tendency than those in the other situations (cattle farm, poultry farm, non-livestock farm and non-farmer). The results show that the nitrate status of groundwater in the district has not been drastically changed since 1996, and the nitrate in the wells is of multiple origins (e.g. chemical fertilizer, animal wastes) with a tendency for higher contribution of animal wastes in more heavily polluted wells. The results also highlight a need for further regular monitoring of groundwater quality in the district particularly for wells; (1) located at higher elevations, (2) with a large area of livestock barns nearby, (3) in farms with a high animal population and/or (4) in pig farms.

In the present work, rapid test methods for field screening of soil for Cu, Ni, and Pb content are presented. They are based on commercially obtainable Microquant tests (Merck, Germany), which are originally developed for water analysis. The same type of color reaction was also used for the determination of heavy metals in soil extracts: Reagents to form colored metal complexes are cuprizone for Cu, dimethylglyoxime for Ni, and dithizone for Pb. The experimental conditions for the colorimetric determination of these metals in the soil extracts were studied and additionally modified. An aqua regia solution (HCl/HNO₃, 3:1) was used for the rapid extraction of metals from soil. To establish accuracy, results obtained with the proposed test methods were compared with those obtained with the standard laboratory method using microwave digestion and flame atomic absorption spectrometry (FAAS). Real soil samples containing metals at background levels generally yielded approximately 50% of the total content obtained with the standard FAAS method. High recovery values of spiked samples confirm that the colorimetric methods are unaffected by soil matrix effects.

In the present paper, electrocoagulation (EC) has been employed for the reduction of chemical oxygen demand (COD) reduction of a distillery wastewater (biodigester effluent) in a batch EC reactor using aluminum electrode. The individual and interactive effects of the four main independent parameters have been studied on the COD removal efficiency using a central composite experimental design. The parameters studied are current density (j): 44.65-223.25 A/m²; initial pH (pH ₀): 2-8; inter-electrode distance (g): 1-3 cm; and electrolysis time (t): 30-150 min. Pareto analysis of variance of the results showed a high coefficient of determination value (R ² = 0.9693) and satisfactory prediction for second-order regression model. Maximum COD removal efficiency of 52.23% was obtained with j = 120 A/m², pH ₀ = 6.0, g = 1 cm, and t = 150 min.

Nineteen soil samples (SE Spain) with very different chemical physical properties and developed over different parent materials were contaminated by adding increments of an acidic solution from oxidised pyrite tailings. The quantities of Cu, Zn, Cd and Pb precipitated by the soil samples were directly and significantly related to the pH-buffering capacity. However, when the contamination caused the pH to fall below 3.0 the soil tended to release a fraction of the element adsorbed, which increased as the pH decreased. The quantity of each precipitated element at which the action value for each element is reached, was also directly related to the pH-buffering capacity. Nevertheless, in carbonate-rich soils, the precipitated Cu and Zn maintained a relatively high level of bioavailability, while Cd reached a critical level with a content exceeding 25 mg kg⁻¹, regardless of the pH-buffering capacity.

The present research reproduces the chemical and microbiological reactions that occur naturally when a metal sulfide is discharged onto a natural soil, with special emphasis on iron cycle. The role of indigenous microbiota from an extremely acidic site on both weathering and attenuation processes related to the iron mobilization has been studied and the iron cycle has been reproduced at laboratory scale. In the first stage, the weathering phase, a residual sulfide mineral was bioleached using a mixed culture of iron-oxidizing bacteria isolated from the own substrate. The acid liquor obtained (pH 2), with a high metal concentration (160 mM in total iron), was filtered and neutralized. Solids obtained from the two sources (from the weathering process and after the neutralization stage) were characterized by X-ray and scanning electron microscope/energy dispersive X-ray spectroscopy, resulting ferric iron precipitates such as jarosites, goethites, and ferrihydrites with different crystalline properties. The contribution of ferric iron-reducing bacteria on the attenuation of high-content iron effluents was also studied. Mixed cultures of ferric iron-reducing bacteria, isolated from those acidic substrates, were active in reducing soluble ferric iron (60 mM in concentration), and a 66% of bioreduction was reached after 15 days. Dissimilatory ferric iron reduction has been achieved with adapted cultures at pH values from 7 to 4.

The paper summarizes results of chemical analyses of fog and rime water samples. The samples were collected at Milesovka, the Czech meteorological observatory. The input data set contains the samples acquired during 234 fogs and 14 rime events. The fog and rime samples were collected in the period of 2000-2004. Methods employed for sampling fog and rime water and differences in the pollutant concentrations are described. The following components were analyzed: conductivity, acidity (pH), cations Na⁺, K⁺, NH₄ ⁺, Mg²⁺, Ca²⁺, and anions F⁻, Cl⁻, NO₃ ⁻, SO₄ ²⁻. The attention was exclusively devoted to the precipitation originating in fogs (no falling precipitation particles were considered). Differences in the relative content of selected ions in the annual average samples of rime and fog are presented together with their absolute values. The importance of rime contributions to total precipitation amounts is demonstrated by maximum values of the rime weight detected at the Milesovka Observatory. The absolute maximum of 52.3 kg m⁻² was registered at Milesovka Mt. on December 28, 2002.

As global water resources decline, reuse of domestic greywater for the irrigation of home gardens is quickly becoming widespread in many parts of the world. However, the sanitary implications of reusing greywater to water edible crops remain uncertain. This study examined the benefits and risks associated with domestic greywater reuse for the purposes of vegetable garden irrigation. Untreated (settled only) and treated (settling and slow sand filtration) greywater collected from a family home was analyzed for basic water quality parameters over a period of 8 weeks. During that time, both greywaters were used to irrigate individually potted plots of lettuce, carrots, and peppers in a greenhouse. Tap water was used as control. Upon maturity, plants were harvested and the edible portions tested for fecal coliforms and fecal streptococci, common indicators for the presence of pathogenic microorganisms. Heavy metals were not detected in the greywater, but both fecal coliforms and fecal streptococci were present in high levels, averaging 4 x 10⁵/100 mL and 2,000/100 mL of greywater, respectively. Despite these high counts, no significant difference in contamination levels was observed between crops irrigated with tap water, untreated greywater, and treated greywater. Fecal coliform levels were highest in carrots and fecal streptococcus levels were highest on lettuce leaves. However, contamination levels for all crops were low and do not represent a significant health risk. Plant growth and productivity were unaffected by water quality, owing to the low N, P, and K levels of the greywater. These results reinforce the potential of domestic greywater as an alternative irrigation source.

The potential of almond shells was assessed for adsorption of heavy metal ions such as Pb²⁺ and Cd²⁺ from aqueous solution. Almond shells were pretreated separately with 0.4 mol/L NaOH, 0.4 mol/L HNO₃, and distilled water and their adsorption abilities were compared. Batch adsorption experiments were carried out as a function of the initial ion concentration, pH, and adsorbent dosage. Adsorption isotherms of metal ions on adsorbents were determined and correlated with common isotherm equations such as Langmuir, Freundlich, and BET models. The alkali-modified almond shells had adsorption capacities for Pb²⁺ from 2 to 9 mg/g and for Cd²⁺ from 2 to 7 mg/g, which was much higher than acid- and water-pretreated adsorbents. Experimental results showed that the best pH for adsorption was 5-6 and the adsorption values decreased with lowering pH. Isotherm models indicated the best fit for Langmuir model for alkali-modified almond shells. In comparing the parameters of the models, it was observed that the affinity of almond shells for adsorption of lead is stronger than affinity for adsorption of cadmium.

Leaching of trace metals and greenhouse plant growth (Collard greens; Brassica oleracea var. acephala) response studies were conducted in two types of soils with contrasting characteristics amended with varying rates (0 to 24.70 Mg ha⁻¹) of poultry litter (PL) or 1:1 mixture of PL and fly ash (FA). Leaching of Cr, Zn, Cd, Cu, and Pb from soils amended with PL or PL + FA (1:1) increased with increasing rates of amendment. Leaching losses were greater from coarse-textured soil compared to that from medium-textured soil. Crop performance study indicated that growth as well as trace elements concentrations increased with increasing rates of amendments only up to 12.35 Mg ha⁻¹. Trace element concentrations in plant parts were greater in plants grown in Candler fine sand (CFS) compared to that grown in Ogeechee loamy sand (OLS). Trace element concentrations were greater in the above ground plant parts (leaf and stem) than those in roots. This study demonstrated beneficial effects of PL or mixture of PL + FA amendments to soils at rates not exceeding 4.94 Mg ha⁻¹. Further field studies are recommended to evaluate the long-term impact of using poultry litter and fly ash on plant growth and tissue trace metal concentration as well as environmental impact.