Archives of Environmental Protection

To investigate and assess the effects of land use and its changes on concentrations of heavy metals (Pb, Zn, Cd, Cu, Mn, Ni, Fe) in the tributary of drinking water reservoir catchment, soils of different land use types (forest, arable land, meadows and pastures, residential areas), suspended sediment and bottom sediment were collected. Heavy metals were analyzed using atomic absorption spectrophotometry (AAS). The metal distribution pattern was observed, where Zn and Cd could be considered as main metal contaminants. The variation in the concentration level of Zn and Cd in studied soils showed the impact of pollution from anthropogenic activities. Also some seasonal variations were visible among the suspended sediment and bottom sediment samples which could be associated with land agricultural practices or meteorological conditions. The sediment fingerprints approach used for determining sources of the suspension in the catchment showed (Kruskal-Wallis H test, p<0.05), that only Mn and Ni were not able to be distinguished among the potential sediment sources. A multiple linear regression model described the relationship between suspended sediment and 4 types of soil samples. The results related suspended composition mostly to the samples from the residential land use. Considering the contemporary trend of observed changes in land use resulting in conversion of agricultural areas into residential and service structures these changes can be essential for the contamination of aquatic environment. This situation is a warning sign due to the rapid industrialization, urbanization and intensive agriculture in this region what can significantly affect the drinking water quality.

The aim of the study was to evaluate the degree of pollution of bottom sediments from small water reservoirs with heavy metals on the basis of geochemical criteria: the enrichment factor and the geo-accumulation index. The investigations concerned sediment from eight small water reservoirs located in the Kielce Highland. Selected heavy metals, including cadmium, chromium, copper, lead and zinc, were determined using inductively coupled plasma-atomic emission spectrometry method. Additionally, particle size distribution and the content of organic matter expressed as loss of ignition were designated. The concentration of heavy metals in sediments was characterized by a great variety. The sediments of Morawica and Rejów show very high and extremely high enrichment in Cr, Zn, Pb and Cd. The values of EF>20 indicate also an extremely high enrichment in Cd of sediments in Mostki. In addition, over 50% of the samples of sediment from Suchedniów, Kaniów, Mostki and Jaśle reservoirs (the value of EF for Cr exceeded 5) indicate a moderately high enrichment of this element. Results of the analysis of the I_geo values indicate that the tested sediments are characterized by moderately high (2<I_geo<3) or high (3<I_geo<4) pollution. The differences in individual enrichment factor and geoaccumulation index values may result in the nature of heavy metals, their pollution loads, as well as speciation forms of trace elements occurrence in sediment-water complex. These findings indicate that the integration of geochemical methods is necessary for an appropriate ecological risk assessment of heavy metals in bottom sediments.

The complexity and uncontrolled formation of struvite (MgNH₄PO₄·6H₂O) and its deposition in the technological equipment of wastewater treatment plants (WWTPs) are still the subject of research aimed at understanding the causes and proposing a remedial action. In order to reduce the intensity of the precipitation of struvite in wastewater treatment plants, it is recommended, among others, to limit flow velocity to below 1.5 m·s^-1. Literature analysis showed that there are no studies on the precipitation of struvite deposits in pipelines. Most studies focus on the deliberate precipitation of struvite, for example phosphorus recovery, resulting in a molar ratio of 1:1:1 (NH₄⁺:PO₄^3-:Mg²⁺). In fact, in WWTPs, such concentrations do not occur, but there have been cases of the precipitation of this mineral (and its mixtures) in the sludge parts. In this paper, the study aimed at determining conditions for the precipitation of deposits with a significant participation of struvite on the inner walls of steel pipes. The study was conducted at a non-stoichiometric concentration of ingredients at different pH values, as well as under dynamic conditions with flow velocity below 1.5 m·s^-1. A mathematical formula (ANOVA) that can be used to determine the mass of deposits in relation to the concentration of ammonium, phosphate, pH and flow velocity was developed. Computational models were developed on to investigate struvite precipitation under different pH levels (8.0–9.5) and ionic concentrations. The studies were carried out on solutions containing ammonium (NH₄⁺), phosphate (PO₄^3-), and magnesium (Mg²⁺), at a flow velocities of 0.4, 0.9 and 1.4 m·s^-1. In order to determine the mathematical formula thanks to which the mass of precipitates can be determined, a special pilot study installation was constructed. The XPS surface analysis of sludge from sewage treatment plants showed a similar composition of compounds with sediments obtained in own research. The presence of struvite was suggested, but the share of atomic percentage of bonds to which struvite was classified is small and amounts to less than 4%. This means that sediments precipitated in the technological installations are a mixture of various compounds of which pure struvite may constitute only a small part.

The objective of this study was to determine the suitability of the nanofi ltration (NF) process to recover the regenerating agent (NaOH) from spent solutions contaminated with organic compounds. NaOH recovery from 2 spent regenerant solutions after cleaning ultrafiltration (UF) membranes (polymeric 30 kDa, ceramic 300 kDa) fouled with natural humic water was carried out using 2 types of NF membranes: NP010P (Na₂SO₄ rejection: 35–75%) and NP030P (Na₂SO₄ rejection: 80–95%). It has been shown that the use of the NP030P membrane allows for very high separation effi ciency of organic compounds (up to 97% of color intensity reduction) from the tested solutions. It was also observed that the effectiveness of the process, in addition to the type of membrane used, also depends on the time of NF process – along with the elapsed time of the process, the hydraulic and separation properties of the tested membranes deteriorated. The obtained results showed that the use of both tested NF membranes allows for the recovery of NaOH to a degree that allows its re-use.

Due to insufficient operation efficiency, the studied treatment plant has undergone modernization. The aim of this study was to assess whether this modernization improved quality of the STP effluent and water quality in the receiver. The research period of fifty months covered time before and after the modernization. Samples were collected in four sites – upstream and downstream of the STP and by the sewage discharge. Electrolytic conductivity, water temperature and pH were measured onsite. Chemical analyzes were based on ion chromatography and determined the concentration of NH₄⁺, NO₃^-, NO₂^-, PO₄^3-, TDS. Microbiological analysis comprised serial dilutions to assess the number of mesophilic and psychrophilic bacteria and membrane filtration to enumerate E. faecalis, total and fecal coliforms as well as total and fecal E. coli. Values of most analyzed parameters did not improve after the modernization, or improved for a very short period of time (NH₄⁺), while some of them even increased, such as PO₄^3-, total and thermotolerant coliforms and E. coli. The maximum value of thermotolerant E. coli reached nearly 7 million CFU/100 ml and was observed after modernization. Also at the sites situated downstream of the STP some of analyzed parameters increased. The conducted modernization did not improve the quality of treated sewage and even a further deterioration was observed. It could have been a result of rapidly growing number of tourists visiting the studied area, thus generating large amounts of sewage causing STP overload coupled with poor water and wastewater management. Significant percentage of unregistered tourists hinders proper assessment of the STP target efficiency.

Recent studies have shown that over half of the world’s population lives in urban areas, with the number of people living in slums growing by over 20 million per year and people living in urban areas lacking access to adequate sanitation. This study presents a review of the challenges facing fecal sludge management (FSM). A globally relevant issue in developing urban centers, especially in selected developing countries in West Africa was discussed. Some key findings of the review are that effective sanitation in developing areas depends on the chain of services and that one of the largest problems in sanitation is FSM. This study presents the initial steps toward understanding the main issues involving FSM in developing cities of West Africa. Results are intended to be used as a support for decisions on policies, strategies for FSM, and investments for improved treatment facilities in the region. The study suggests that governments and private sector organizations should develop adequate measures for handling fecal sludge.

In this work microbiological air pollution at several commune sewage treatment plants (capacity up to 15,000 PE) was investigated. The bioreactors in all plants had a covered construction. The air samples were taken indoors as well as outdoors (both on the windward and leeward side) during different seasons. The samples were collected using the collision method. The presence of indicator organisms in the samples was determined according to the Polish Standards. Identification of individual indicators was performed on solid selective-differentiating substrates. To verify the presence of bacteria from Salmonella, Shigella, coliforms and enterococci species, the colonies observed on the MacConkey substrate were then sifted onto SS and Endo substrates. At all facilities (with one exception) the average CFU for the total number of bacteria and fungi did not exceed 1000/m³, which is the limit set by the Polish Standards for a pollution-free atmospheric air. Bacteria and fungi concentrations, observed at windward and leeward sides of all plants, were relatively low (<100 CFU/m³ and <1000 CFU/m³, respectively) and comparable. A sewage collection point had only a slight impact on the bioaerosol emission. The concentration of microorganisms in the immediate vicinity of covered reactors (aeration chambers) was rather low and remained below the limits sets by the Polish Standards at three facilities. The CFU of individual indicators, measured in rooms accessible for the personnel, was comparable to the CFU in technological rooms. However some indicators, e.g. a number of Actinomycetes, were significantly higher and reached >100 CFU/m³, which means significant air pollution. Similarly, the CFU of hemolytic bacteria had nonzero values. The only place where higher concentrations of bioaerosol were found was the centrifuge room, where digested sludge was dewatered. The number of fungi stayed below the limits there, but the amount of heterotrophic and hemolytic bacteria exceeded the limits and reached the values of ~10000 CFU/m³ and 800 CFU/m³, respectively; it means that the personnel working in this area is exposed to microbiological agents.

The study of the possibility of removing organic compounds from wastewater originating from the biodiesel purification stage by two catalytic processes, HSO₅^-/transition metal and Fenton method has been presented. The source of the ion HSO₅^- is potassium monopersulphate (2KHSO₅·KHSO₄·K₂SO₄) (Oxone) that may be decomposed into radicals (OH^., SO₄^-., SO₅^-.) by means of transition metal as Co(II). Different concentrations were used for both compounds and the combination ([Co²⁺] = 1.00μM/[HSO₅^-] = 5.00·10^-2 M) achieved the highest COD removal (60%) and complete decomposition of the oxidant was verified for contact times of 45 min. This process has some advantages comparing to the conventional Fenton method such as the absence of the costly pH adjustment and the Fe(III) hydroxide sludge which characterize this treatment process. The Fenton process showed that the combination of [H₂O₂] = 2.00M/[Fe²⁺] = 0.70 M was the best and archived COD removal of 80%. The treatments studied in this research have achieved high COD removal, but the wastewater from the biodiesel purification stage presents very high parametric values of Chemical Oxygen Demand (667,000 mgO₂/L), so the final COD concentration reached is still above the emission limit of discharge in surface water, according the Portuguese Law (Decree-Law 236/98). However, both treatments have proved to be feasible techniques for the pre-oxidation of the wastewater under study and can be considered as a suitable pre-treatment for this type of wastewaters. A rough economic analysis of both processes was, also, made.

Nine phyto-ashes from the biomass combustion of birch (Betula), oak (Quercus), red oak (Quercus rubra), horbeam (Carpinus), pine (Pinus sylvestris), poplar (Populus), maple (Acer), oilseed rape straw (Brassica napus) and wheat straw (Triticum aestivum) were blended with a biogas digestate at 1:1 mass ratio to give nine organic-mineral soil improvers. The concept of the research was to outline an eco-friendly and low cost soil improver for remediating degraded lands. These (i.e. phyto-ashes, improvers and the biogas digestate) were applied (0, 5, 10, 20, 40 t·ha^-1) to a soil metallurgically contaminated with Cu, Zn, Pb and Cd. Of several tested parameters, pH changes revealed that organic-mineral soil improvers may efficiently replace (linear R²>0.90****, P<0.001) phyto-ashes in soil remedial goals. Buffering properties expressed by the cation exchange capacity (CEC) improved progressively: 29, 52, 71, 100% (phyto-ash treatments) and: 18, 37, 44, 73% (improvers treatments) for the rates 5, 10, 20, 40 t·ha^-1, respectively as referred to the control CEC. The Dynamic Remediation Efficiency (DRE) indices for Cu, Zn, Pb, Cd revealed metal-specific geochemical reactions initiated by phyto-ashes, improvers and biogas digestate. The rates 5.0–10.0 t·ha^-1 for phyto-ashes and about 20 t·ha^-1 for improvers [1:1, i.e. Phyto-ash:Biogas digestate] are recommended. For biogas digestate, the rates 10–20 t·ha^-1 were found more efficient.

In this study, non-sintered ceramsite was prepared using coal gasification coarse slag obtained from a methanol plant. The basic performance and heavy metal leaching toxicity were analyzed. The results showed that seven out of nine non-sintered ceramsite groups were in accordance with the national standard of compressive strength (5 MPa), while only three groups met the national standard of water absorption index of less than 22%. The heavy metal concentrations in these three groups were found to be lower than that specified in National Class IV of surface water environment standards. The concentration of Cr was found to be 16.45 μg/L, which represents only 1% of the IV standard. The optimum mixing ratio, which showed high compressive strength (6.76 MPa) and low water absorption (20.12%), was found to be 73% coal gasification coarse slag, 15% cement, and 12% quartz sand. The characterization using Fourier transform infrared spectroscopy showed that the formation of gelatin in ceramsite enhances the performance of the ceramsite base and increases the immobilization of heavy metal. The study proved that the preparation of non-sintered ceramsite using coal gasification coarse slag reduces its environmental risk and achieves efficient utilization of the slag. Therefore, it can be concluded that it is a feasible and environmental friendly method for the disposal of coal slag.

Contamination of soil with heavy metals has become a worldwide environmental problem, and receives great attention. In this study, we aim to investigate soil pollution level affected by an industrial district nearby. The total amount of typical heavy metals in the soils (Hengyang Songmu Industrial Park, Hunan Province, China) was analyzed. In addition, the fraction analysis and laboratory simulation leaching via different pH rainwater was carried out to study the migration and transformation of heavy metals. The main results show that the contents of Cu, Zn, Pb, Cr and Cd in the samples were higher than the soil background values in Hunan Province. The heavy metals forms, analyzed by sequential extraction method, show that the proportion of the unstable form of Cd, Zn and Pb was more than 50%. I_geo values indicate that the heavy metal pollution degree of soil sample #5 at the investigated area is recorded in the order of Cd(6.42), Zn(2.28), Cu(1.82), Pb(1.63), and Cr(0.37). Cu, Zn, Pb, Cr and Cd in this area could pose a potential leaching risk to the environment which may affect the food chain and constitute a threat to human health. It would be necessary to take steps to stabilize and monitor the heavy metals in soil.