Doses Of Sewage Sludge Research Articles

Sewage Sludge Application in Eucalyptus urograndis Plantation: Availability of Phosphorus in Soil and Wood Production

Phosphate fertilizers used in planted forests mainly come from scarce and non-renewable sources, and there is a need for new sources of phosphorus (P). An alternative is the use of sewage sludge (SS), rich in organic matter, nitrogen and P. The objectives were to evaluate the soil P availability and its effect on wood production in 22-months old Eucalyptus urograndis plantation treated with SS. A field experiment was set up in a randomized complete block design, four replicates, with the following treatments: control without fertilization; mineral fertilization (MF); 14.5 Mg ha-1 of SS + 22 kg ha-1 of P (S1P1); 29 Mg ha-1 of SS (S2); 29 Mg ha-1 of SS + 17.5 kg ha-1 of P (S2P2); and 43.5 Mg ha-1 of SS (S3), dry base. Of total P in SS, 65% was in organic form, and 42% was in labile + moderately labile forms. S2P2 and S3 positively altered the pattern of soil P distribution, with more P in the labile and moderately labile fractions than non-labile fraction, along 0-20 cm depths, than MF and control. There were higher microbial and available P as a function of SS dose. Wood volume and biomass were highly related to soil P availability as a function of SS dose. Within the SS treatments, S2P2 resulted in higher gains of volume and biomass of wood. The SS application at recommend rate, supplemented with 66% of recommended P fertilizer dose in Eucalyptus plantations, can reduce the use of P fertilizer by 33%, N fertilizer by 100% and maintain comparable soil P availability and wood production.

ECOTOXICOLOGICAL ASSESSMENT OF THE SOILFERTILIZED WITH SEWAGE SLUDGE

Sewage sludge and its management constitute one of the most important environmental problems. The introduced the Sewage Sludge Directive 86/278/EEC advocate utilization of sewage sludge in agriculture. However, this method is limited mainly by the availability of heavy metals and pathogens. An ecotoxicological assessment of sewage sludge doses applied to soil, recommended in the Polish Regulation of the Minister of Environment of 6th February 2015 on municipial sewage sludge, was carried out. The sewage sludge was added to soil in the amounts of 3, 6, 9, and 15 Mg/ha. The produced mixtures were subjected to physicochemical and ecotoxicological tests, involving the biomass and mortality tests of Eisenia fetida earthworms. The sewage sludge had a statistically significant impact on the increase in: electrical conductivity, total exchangeable cations, organic matter content, organic carbon, nitrogen and heavy metals of the considered soil. The impact on the biomass of earthworms was different; after 7 days in the mixtures with 3 Mg/ha and 6 Mg/ha sewage sludge addition, the biomass increased approximately by 1.3-fold, in comparison to non-modified soil. At 9 Mg/ha, it reduced by 1.3-fold, whereas at 15 Mg/ha – by 16-fold, in relation to the initial value. The studies indicated that the ecotoxicological assessment of wastes may be employed as environmental safety control measure of the sewage sludge application in agriculture.

Impacts of Using Mineral Fertilization Combined with Sewage Sludge in the Amendment of Luvisol on Oat Crop. II. Influence on Metal Accumulation

The objective of the present paper was to investigate the effects of sewage sludge application on metals (Cu, Mn, Zn, Cd, Co, Pb) accumulation in oat (Avena sativa L.) grains, Somesan variety. It were used various doses of sewage sludge corresponding to equivalent doses of 0-600 kg N/ha associated or not with NPK mineral fertilization. The results evidenced that copper and zinc levels in oat grains increased significant with sewage sludge fertilization starting with a dose equivalent with 200 kg N/ha. Mineral fertilization led to significant decrease of copper content in comparison with sewage sludge treatments only. For manganese, fertilization with sewage sludge has produced a significant decrease, this trend being accentuated up to the equivalent dose of 300 kg N/ha. For cadmium, application of sewage sludge in an equivalent dose of 200 kg N/ha led to concentrations in oat grains higher than 1 mg Cd/kg (imposed limit for grains used for animal feed). This behavior is a consequence of high cadmium content of sewage sludge (of 7.2 times over maximum admitted limit). Cobalt contents of oat grains increased with sewage sludge doses, but the levels are between normal values and concordant with literature data. Application of sewage sludge in an equivalent doses of 500 and 600 kg N/ha generated a significant increase of lead content in oat grains, average values being 1.87 and 2.17 mg Pb/kg, respectively.

Modeling and optimizing the removal of cadmium by Sinapis alba L. from contaminated soil via Response Surface Methodology and Artificial Neural Networks during assisted phytoremediation with sewage sludge

The study was aimed to model and optimize the removal of cadmium from contaminated post-industrial soil via Sinapis alba L. by comparing two modeling approaches: Response Surface Methodology (RSM) and Artificial Neural Networks (ANN). The experimental design was done using the Box–Behnken Design method. In the RSM model, the quadratic model was shown to predict the closest results in comparison to our experimental data. For ANN approach, a two-layer Feed-Forward Back-Propagation Neural Network model was designed. The results showed that sewage sludge supplementation increased the efficiency of the Sinapis alba plant in removing Cd from the soil. After 28 days of exposure, the removal rate varied from 10.96% without any supplementation to 65.9% after supplementation with the highest possible (law allowed) dose of sewage sludge. The comparison proved that the prediction capability of the ANN model was much higher than that of the RSM model (adjusted R-square: 0.98, standard error of the Cd prediction removal: 0.85 ± 0.02). Thus, the ANN model could be used for the prediction of heavy metal removal during assisted phytoremediation with sewage sludge. Moreover, such approach could also be used to determinate the dose of sewage sludge that will ensure highest process efficiency.

Sewage Sludge as a Soil Amendment for Growing Biomass Plant Arundo donax L.

Sewage sludge (SS) is a waste originated from wastewater treatment that could be considered an interesting source of organic matter and nutrients for agricultural production. Our experiments aimed to assess the effect of SS on the growth parameters and the biomass yield of giant reed (Arundo donax L.) plants. Experiments were carried out in pots during two growing seasons, where samples of dried SS were applied in doses of 5 or 15 t ha−1. The number of shoots per plant was significantly higher with the application of 5 t ha−1 of SS into arable soil compared to the control treatment and did not increase with the dose of SS. On the other hand, the height of the plants was gradually elevated with the dose of SS. The diameter of the shoots was positively affected by the dose of 15 t ha−1, and it was the only parameter with significant differences between the used types of SS. The biomass yield increased by 1.2–2.7× depending on the type and dose of SS. Cu and Zn uptake, as micronutrients present in SS, and their accumulation in the aboveground parts were significantly higher for plants cultivated in the presence of SS.

Impacts of Using Mineral Fertilization Combined with Sewage Sludge in the Amendment of Luvisol on Oat Crop I. Influence on Yield and Mineral Nutrition

The present paper illustrates the results obtained on oat (Avena sativa L.), Somesan variety, concerning growth, grains and straw yields and also of macroelements accumulation (N, P, K, Ca, Mg) when various doses of sewage sludge were applied associated or not with mineral fertilization. Sewage sludge application produced significant increase of plant height starting with equivalent dose of 100 kg N/ha, meanwhile the highest height was observed in the case of plants fertilized with doses equivalent with 300 and 400 kg N/ha. With the increase of sewage sludge dose it has been observed the straw yield increase, this being statistically assured starting with sewage sludge equivalent dose of 100 kg N/ha. Sewage sludge fertilization, accompanied or not by mineral fertilizers, evidenced that nitrogen contents in oat grains increases with applied sewage dose, being significant from an equivalent dose of 200 kg N/ha. Low sewage doses equivalent with 200-300 kg K/ha evidenced for potassium concentration in oat grains a significant decrease in comparison with untreated variant, meanwhile mineral fertilization generated a significant increase of potassium levels in oat grains. Calcium contents in oat grains present a significant increase after sewage sludge fertilization and at a dose equivalent with 600 kg N/ha, the calcium levels (0.24%) increased 3 times in comparison with untreated variant (0.08%). Sewage sludge fertilization, associated or not with mineral fertilizers, did not produced significant changes of magnesium levels in oat grains, found concentrations being considered as normal values.

Kireçli Bir Mera Toprağında Arıtma Çamuru Dozlarının ve Uygulama Zamanının Ekstrakte Edilebilir Metal Konsantrasyonuna Etkisi

The objective of this study was to determine the effect of the increasing doses of sewage sludge and different application times on DTPA (diethylenetriaminepentaacetic acid) extractable nutrients and heavy metal concentration in calcareous soil for three years. For this purpose, sewage sludge was applied at different rates (0, 4.1, 8.2, 16.4 t ha-1) and periods (spring and autumn) to meet the nitrogen fertilizer requirement of grass-legume mixtures. Experiment results showed that cumulative sludge applications significantly increased DTPA extractable metal concentrations for 0-20 cm. Sludge application in spring period reduced the soil pH and increased the extractable metal concentrations compared to the autumn. Sludge application doses increased DTPA-Zn concentration for all soil depths and years. At the end of the experiment, it was determined that the heavy metal contents in the soil did not reach the levels that would have a negative effect on plant production. The fact that Van soil is rich in lime and alkaline pH of the soil, where the experiment was carried out, caused the solubility of heavy metals from sewage sludge to be low and toxic effect not to be seen. However, long-term sludge application should be followed in soil.

Evaluation of the Potential of Sewage Sludge for Manufacturing Substrate for Passion Fruit Seedlings

Brazil is the world’s largest producer and largest consumer of passion fruit, producing approximately 0.1 million tons. However, crop management techniques are deficient in the use of alternative sources of fertilizer, an extremely relevant aspect in reducing production costs, as some nutrients are imported at high costs. Thus, this study was intended to calculate the percentage of an optimal dose of sewage sludge according to the regression model for each morpho-agronomic trait of yellow passion fruit. A completely randomized design (CRD) was adopted, consisting of four treatments, 0; 25; 50; and 75%, with 20 replicates considering one plant per replicate. Treatments were T1 (0 without sewage sludge addition), T2 (75% soil + 25% sewage sludge); T3 (50% soil + 50% sewage sludge); and T4 (25% soil + 75% sewage sludge). Regression coefficients were above 80%. Morpho-agronomic traits obtained optimal doses at a concentration of 50% of sewage sludge for the manufacture of the substrate. The conclusion reached was the substrate based on sewage sludge in the proportion of 50% combined with 50% of soil was superior to the other ones for seedling production.

Phytotoxicity assay to assess sewage sludge phytoremediation rate using guaiacol peroxidase activity (GPX): A comparison of four growth substrates

Waste disposal such as sewage sludge (biosolids) in phytoremediation is a sustainable remediation alternative for fertilizers, therefore there is a need to develop a test that will allow to determine phytoremediation dose of biosolids from the best-for-plant-growth point of view. In order to determine the doses of biosolids to degraded soils, tests based on germination of seeds and root elongation are commonly used, but also, they are subjected to large errors caused by low repeatability of results and differentiation. That is why there is a need to introduce new testing solutions that will be of use based on more reliable indicators such as biochemical activity of selected plant enzymes. The aim of the study was to demonstrate high efficiency of the guaiacol peroxidase activity (GPX) in plant-based toxicity tests used as an optimal dose amendments indicator in heavy metal degraded soil phytoremediation process. GPX were measured in underground and above ground parts of Sinapis alba L. and Brassica rapa L. in relation to germination index (GI) and biomass cultivated on four different substrates (raw degraded soil, sterilized degraded soil, water extract from degraded soil solidified with agar, water extract from degraded soil solidified with Murashige-Skoog medium). Each testing soil substrate was enriched with sewage sludge (food industry origin) in the percentage share (w/w) of 5, 10, 15, 20 and 25. The process was carried out under controlled conditions of the phytotronic chamber for a period of 14 days. The obtained values were compared for each plant separately and for all substrates and amendments rates of sewage sludge. GPX activity was expressed as a percentage increase or decrease in relation to the GPX in soil substrates without addition of sewage sludge which allowed to determine their positive or negative impact on substrate toxicity. Results of GPX activity showed that the water-based soil extracts solidified with agar give more accurate results in relation to the tests on raw soil. It has been demonstrated that the optimal phytoremediation dose of sewage sludge was in the range of 15–20%, with values of 5% and 25% respectively favoring or inhibiting plant development expressed in GPX activity. The most differentiating GPX values were obtained for the roots.Measurement of GPX activity in the roots of Sinapis alba L. cultivated on soil agar-based tests is a good, new and easy additional or alternative to the old tests based on germination and increase biomass measuring as an indicator in the assessment of optimal phytoremediation sewage sludge.

Nutrition and physiology of hybrid Eucalyptus urograndis in soil fertilized with sewage sludge

Sewage sludge is a residual pollutant product from the treatment of urban effluent and must be adequately processed before final disposal in order to avoid environmental contamination. The use of sewage sludge in agricultural and forestry areas can improve the physical, chemical and biological properties of soil; it can also be a source of nutrients, increasing crop productivity. Accordingly, this study aimed to evaluate the growth and development of hybrid Eucalyptus urograndis (Eucalyptus grandis x E. urophylla) seedlings cultivated in soil with different doses of sewage sludge. To accomplish this, hybrid E. urograndis seedlings were cultivated for 120 days in pots containing soil (dystrophic Red-Yellow Latosol -LVA) with different doses of sewage sludge (0, 30, 60 or 90 Mg ha-1). The experiment was carried out in a randomized complete block design consisting of four treatments, three replications with four plants per replication, totaling 48 plants. Biometric, biomass and physiological variables (chlorophyll, gaseous exchange, stomatal conductance and transpiration); in addition to macro- and micronutrient contents in leaves and soils of each treatment were evaluated. The treatments with sewage sludge were statistically superior to control treatment for all variables. Therefore, we recommend the application of 60 Mg ha-1 sewage sludge for the growth of hybrid Eucalyptus urograndis seedlings. Conversely, 90 Mg ha-1 sewage sludge inhibited hybrid E. urograndis root growth. Moreover, the use of sewage sludge as organic fertilizer in tropical soils is a viable and sustainable alternative for Eucalyptus cultivation.

QUALITY OF RAPESEED OIL AFTER DIFFERENT APPLICATIONS (AMENDMENTS) OF SEWAGE SLUDGE IN SOILS

Application of sewage sludge rich in organic matter and nutrients such as nitrogen, phosphorus and potassium tend to improve crop yields. Nevertheless, this use is limited because of their heavy metal content. The objective of this work is to study the effect of sewage sludge on the accumulation of metallic trace elements in seeds and rapeseed oil. For this purpose, two different types of sludge by their metal composition were tested. Compared to the control, the supply of industrial sludge increases the metallic load of seeds and rapeseed oil. This increase is noted with the highest doses 50 and 100 t/ha. The same trend was observed during the two years of application. This effect is due to the richness of these slurries in chrome, cadmium and lead. This modification of the metal composition was accompanied by the decrease in the oil content. Analysis of the fatty acid composition of total lipids shows an increase in the percentage of oleic acid at the expense of linoleic and linolenic acids. On the other hand, the increase of 18: 1 at the expense of linoleic and linolenic acids may be the result of metal-induced alteration. For urban sludge, we noticed a variation in Cr, Co, Cu, Ni and Zn contents in the seeds depending on the doses. However, for Cd and Pb no variation was recorded. An increase in metal trace element levels was well reported at the seed level during the second amendment. We also detected a decrease in oil content with the contribution of industrial sludge. The composition of the total lipids in fatty acids shows an increase in the percentage of oleic acid (C18: 1) at the expense of linoleic (C18: 2) and linolenic (C18: 3) acids under the effect of heavy metals brought by the industrial sludge while no difference is recorded with urban sludge regardless of the dose. No significant differences in heavy metals were observed with the addition of the different doses of urban sludge even after two years of application. Urban sludge has no effect on oil content or fatty acid composition. However, we detected increases in most heavy metals, especially for high doses of industrial sewage sludge.

Assessment of phytomeliorative efficiency of Kochia scoparia (L.) schrad.


 Phytomeliorative efficiency of the annual grass Kochia scoparia (L.) schrad was assessed. The experiments were conducted on the solonetz of the southern chernozem. It was revealed that the application of high doses of sewage sludge (from 50 to 200 t / ha) contributed to an increase in the yield of green mass of Kochia scoparia by 133–362%. After the combined action of annual grass crops and organic fertilizers, the soil density decreased from 1.47 g / cm3 in the solonetz to 1.25 / cm3 in the variant with a dose of 200 t / ha, water resistance for three years of research increased by 37.8%, water permeability increased by more than 5 times.

How do properties and heavy metal levels change in soils fertilized with regulated doses of urban sewage sludge in the framework of a real agronomic treatment program?

This field study was performed to assess the variation in chemical and agronomic properties and total and extractable concentrations of heavy metals in soils fertilized with regulated doses of urban sewage sludge (USS) for 6 consecutive years in the framework of an agronomic treatment program. Chemical and agronomical properties, total contents and extractable concentrations of Cd, Cr, Cu, Hg, Ni, Pb and Zn were determined in agricultural soils treated with USS for 6 consecutive years, agricultural soils cultivated using mineral fertilizers and uncultivated soils representative of the local geochemical background. USS application caused a decrease in pH and an increase in extractable concentrations of Cr, Cu, Pb and Zn. No organic carbon, total nitrogen and total phosphorus enrichment trend was observed in the treated soils due to biodegradation of the organic compounds supplied by USS. The decomposition of USS organic matter was presumably the main process responsible for the pH decrease in the USS-fertilized soils. There was no heavy metal accumulation in treated soils, and total heavy metal contents were below the corresponding maximum threshold concentrations set by European and Italian legislation. Increased availability of Cr, Cu, Pb and Zn was found in treated soils due to an increase in their extractable concentrations in the treatment period. The results of this study suggest that the environmental risks related to the accumulation and availability of heavy metals in agricultural soils fertilized with USS are limited when treatment observes recommended doses in agronomic treatment programs.

Phytoremediation of sewage sludge by Cymbopogon martinii (Roxb.) Wats. var. motia Burk. grown under soil amended with varying levels of sewage sludge

Sewage sludge used as agriculture fertilizers contains a conspicuous amount of potentially toxic metals. In order to prevent the contamination in the food chain, there is an urgent need for the development of sewage sludge clean up technology. The use of non-food, multi-harvest aromatic crops for phytoremediation of sewage sludge has many benefits. Besides the eco-friendly approach, plant biomass generated can be used to extract economically important essential oil free of heavy metals. Cymbopogon martinii was grown in soil (s) amended with different ratios of sewage sludge (ss), that is, 100s:0ss (control), 80s:20ss, 60s:40ss, 40s:60ss, 20s:80ss, and 0s:100ss. The experiment was conducted in a plastic sack under an open environment for 1 year and harvesting was done thrice. Plant growth and essential oil yield were significantly increased with the increasing dose of sewage sludge. Accumulation of toxic metal (Cd, Cr, Pb, Ni) and micronutrient (Fe, Zn, Cu, Mn) increased significantly in the shoot tissues confirmed by estimation of bioaccumulation and bioconcentration, and scanning electron microscopy and X-ray microanalyses. Soil enzyme activities were significantly improved with the plant growth period and increased doses of sludge. Results showed C. martinii acts as hyper-accumulator and thus could be used for phytoremediation of sewage sludge.

Effect of biochar addition to sewage sludge on cadmium, copper and lead speciation in sewage sludge-amended soil

The goal of the present work was to evaluate the speciation of cadmium (Cd), copper (Cu) and lead (Pb) in sewage sludge (SL) amended soil and SL-biochar (BC) amended soil in a long-term field experiment. SL or SL with biochar (at the dose of 2.5%, 5.0% or 10%) were applied to the soil. The dose of SL in the soil was 11 tdw/ha. At the beginning of the study, after 12 and 18 months the distribution of Cd, Cu and Pb was determined between the following fractions: (1) water soluble, exchangeable and bound to carbonates (F1), (2) bound to Fe–Mn oxides (F2), (3) bound to organic matter (F3) and (4) bound to quartz, feldspars, etc. (F4). The soil, SL and biochar were characterized by different distribution of Pb, Cu and Cd. The highest mobility of Cd and Cu was observed in the control soil, while Pb in SL. Addition of SL to the soil caused the increased of the mobility index of Cu and Pb, increasing the risk associated with the presence of these metals in the mobile soil fraction (F1). However, the addition of biochar to SL before application to the soil modified the distribution of studied elements. The most mobile and bioavailable fractions (F1) were transferred to less bioavailable (F2, F3) and potentially immobile fractions (F4).

MICRONUTRIENT CONTENTS IN THE PROFILE OF A RECOVERED SOIL WITH SEWAGE SLUDGE AND NATIVE SPECIES OF ATLANTIC FOREST

The use of sewage sludge in agriculture and recovery of degraded areas has been shown as a promising alternative for its final destination. Studies on micronutrient levels after sludge application are necessary to avoid soil contamination at toxic levels. The objective of this work was to verify the micronutrient contents in the soil profile and pH, up to one-meter-deep, nine years after the application of sewage sludge and planting of native species of the Atlantic Forest. The experiment was implemented in a degraded Quartzeneic Neosol and conducted in randomized blocks with four replicates and eight treatments, consisting of six doses of sewage sludge (0, 2.5, 5, 10, 15 and 20 Mg ha-1, with supplementation of potassium due to low concentration in the residue), besides the control treatment, mineral fertilization and only potassium supplementation. After nine years, the contents of all micronutrients evaluated presented a significant response to the application of the treatments, and the application of sewage sludge provided an increase in their contents. Soil pH remained stable at sites receiving mineral fertilization and potassium supplementation. Only manganese and zinc showed mobility in the soil profile. The application of sewage sludge in degraded soil increases the micronutrient content and decreases its movement in the soil profile, and the application of the maximum dose of the residue does not provide toxic levels of these elements in the soil in the long term.

Analysis of Migration of Polycyclic Aromatic Hydrocarbons from Sewage Sludge Used for Fertilization to Soils, Surface Waters, and Plants

In this paper, we discuss the effect sewage sludge (SS) application has on the contamination of polycyclic aromatic hydrocarbons in fertilized soils and groundwater. Morver, the contents of these compounds in plant biomass was analyzed. For six months, composted sewage sludge was introduced into sandy soil. The research was conducted under lysimetric experiment conditions with the possibility of collecting soil leachate in natural conditions. The following doses of sewage sludge were used: 0, 10, 20, 30, and 40 t/ha calculated per experimental object containing 10 kg of sandy soil. The examinations were carried out within a three-year time frame. Dactylis glomerata grass was grown on the fertilized soils. Every year, the content of polycyclic aromatic hydrocarbons (PAHs) was collected from fertilized objects and analyzed in soil leachate, which can contaminate surface water. The following six polycylic aromatic hydrocarbons defined by Polish standards were determined: benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene, dibenz(a,h)anthracene, and benzo(g,h,i)perylene, indeno(1,2,3-cd)pyrene. Further, the content of PAHs in soils and the bioaccumulation of these compounds in cultivated plants were evaluated after each year. The results of the study showed that the increase in the dose of sewage sludge used for soil fertilization led to the rise in the amount of polycyclic aromatic hydrocarbons analyzed in the soil. The compounds migrated to cultivated plants. This phenomenon was observed especially in the first year following soil fertilization with sewage sludge. Excessive accumulation of PAHs (especially benzo(a)pyrene) was observed in plant biomass in the first year of a lysimetric experiment after sewage sludge fertilization with doses greater than 10 t/ha. The increase in bioaccumulation of this compound in plant biomass compared to control objects was 138%, 288%, and 505% after application of 20, 30, and 40 t/ha, respectively. Fertilization with sewage sludge did not cause contamination with PAHs in water leachates from the soils.

Evaluation of the effectiveness of land reclamation based on microbiological and biochemical parameters assessed in an ozokerite mining and processing landfill sown with Trifolium hybridum and Dactylis glomerata

The aim of the study was to analyse the microbiological and biochemical activity of a reclaimed landfill produced during extraction and processing ozokerite and sown with Trifolium hybridum and Dactylis glomerata. The analyses were carried out in the third year after application of two doses of sewage sludge, spent mushroom substrate, sawdust, and manure to the landfill soil. The following parameters were determined: the total number of oligotrophic bacteria and filamentous fungi, the number of cellulolytic and lipolytic bacteria and fungi, respiratory activity, the activity of dehydrogenases, β-glucosidase, and lipase, and the activity of fluorescein diacetate hydrolysis. The results indicated that the wastes exerted a generally positive effect on the microbiological, biochemical, and enzymatic activities analysed in the reclaimed ground sown with both Trifolium hybridum and Dactylis glomerata. There was a negative effect on the total number of bacteria with low nutritional requirements, the number of cellulolytic bacteria, the number of lipolytic fungi, and the β-glucosidase and lipase activities only in some objects. The strength of the effects was dependent on the type and dose of the waste and on the plant species. The strongest impact on the analysed parameters was exerted by the manure, sewage sludge, and spent mushroom substrate, whereas the addition of sawdust was found to be the least beneficial. The higher dose of manure and the lower dose of spent mushroom substrate were the most beneficial doses of the wastes. The number of lipolytic bacteria and cellulolytic bacteria and fungi, as well as the fluorescein hydrolytic activity followed by the activity of dehydrogenases, β-glucosidase, and lipase were the most sensitive parameters.

The response of cucumber plants (Cucumis sativus L.) to the application of PCB-contaminated sewage sludge and urban sediment.

BackgroundThe increasing production of sewage sludge (SS) engenders the problem of its responsible utilization and disposal. Likewise, urban sediments (SED) are deposited at the bottom of urban reservoirs and sedimentation ponds, and these require periodical dredging and utilization. However, while the SS and SED deposits often contain nutrients such as nitrogen and phosphorus; however, they also contain a variety of hazardous compounds including heavy metals, Persistent Organic Pollutants (POPs) and microbial pollutants. Fortunately, some species of Cucurbitaceae can accumulate high levels of POPs, such as polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and polychlorinated biphenyls (PCB), in their tissues.MethodsSS was collected from the Lodz Municipal Wastewater Treatment Plant and SED from the Sokołówka Sequential Biofiltration System. The SS and SED samples were added to soil in flower pots at three concentrations (1.8 g, 5.4 g and 10.8 g per flower pot), and one pot was left as an unamended control (C). Soil PCB concentrations were determined before cucumber planting, and after five weeks of growth. Also, total soluble protein, total chlorophyll content, chlorophyll a/b ratio and degree of lipid peroxidation (TBARS) were examined in the leaves of the cucumber plants (Cucumis sativus L.) cv. Cezar after five weeks. Antioxidative response was assessed by ascorbate peroxidase (APx) and catalase (CAT) assay.ResultsThe initial PCB concentration in soil after application of SS or SED was dependent on the applied dose. After five weeks, PCB concentration fell significantly for all samples and confirmed that the dose of SS/SED had a strong effect. Soil remediation was found to be more effective after SS application. Total soluble protein content in the cucumber leaf tissues was dependent on both the type and the dose of the applied amendments, and increased with greater SS doses in the soil. The total chlorophyll content remained unchanged, and the chlorophyll a/b ratio was slightly elevated only after the application of the highest SS and SED dose. The use of SS and SED did not significantly affect TBARS content. APx activity fell after SS or SED application; however, CAT activity tended to increase, but only in the leaves of plants grown in SS-amended soil.DiscussionThe cultivation of cucumber plants reduces PCB concentration in soil amended with SS or SED; however, this effect is more evident in the case of SS. SS application also induced more intensive changes in the activity of enzymes engaged in antioxidative response and oxidative stress markers in plant tissues than SED. The levels of PCB in the SS may have triggered a more severe imbalance between pro- and antioxidative reactions in plants. Cucumber plants appear to be resistant to the presence of toxic substances in SS and SED, and the addition of SS and SED not only acts as a fertilizer, but also protects against accelerated aging.

The Effects of Sewage Sludge Applications on Growth, Yield and Flower Quality of Limonium sinuatum (Statice) under Salinity Conditions

In this study conducted in greenhouse conditions, the effects of sewage sludge application on plant growth, yield and flower quality of Limonium sinuatum (Statice) under salinity conditions were investigated. For this purpose, application of 25%, 50% and 75% sewage sludge doses and 50 mM and 100 mM salt treatment was preferred. Research was conducted as 3 replicates and according to two factor random plots experimental design and in such a way as to have 5 plants in each plot. During in the study, the number of the leaves, the number of flowers harvested per plant, flower peduncle length and thickness were determined. At the end of this study, the root length, the fresh and dry weight of upper parts of plant, the root fresh and dry weight were examined. As expected, while salt application negatively affected the vegetative growth parameters of the plant, yield and flower quality, the increasing sewage sludge doses affected all parameters examined during the research positively. In light of the findings of the current research, it has been determined that in the salty conditions the increasing sewage sludge application doses affected plant growth, yield and flower quality positively by removing the negative effect of salt.