Eighteen maize seeds were sown in each pot and nine were left at 14 day after germination. The pot trial was carried out with four replicates. The pots were placed randomly in a block design and watered regularly with tap water. The soil used in the pot trial is rather nutrient poor. The plants were fer- tilized twice (15 and 25 days) with N (1.96 g/pot), K (5.03 g/pot), S (1.04 g/pot) and Mg (0.78 g/pot). Micronutrients were sprayed on the foliar (15, 25 and 35 days) using a commercial micronutri- ent fertilizer (Fetrilon: 0.5% B, 1.5% Cu, 4.0% Fe, 4.0% Mn, 0.1% Mo, 1.5% Zn, 2% Mg). This was done due to the different processing of the sew- age sludge ash products (e.g. different additives, heating procedures, relations between additives and sewage sludge ash, processing steps). Due to this it is most likely that the ash products do not differ only in their calcinations capacity (Table 1) but also in their plant nutrients contents and also in the plant availability of these nutrients. On the other hand, no additional nutrients are applied in the TSP and the P0 treatment. Therefore, plant nutrients except of P were applied in amounts which ensured a sufficient nutrient supply and prevent additional nutrient effects besides those from phosphate. To prevent micronutrient defi- ciency a micronutrient solution containing Mg was applied by spraying.
Background: Sewage sludge, the inevitable byproduct of municipal wastewater-treatment plant operation, is a key issue in many countries due to its increasing volume and the impacts associated with its disposal. According to the report of European Commission published in 2010, 39% of sewage sludge produced in the European Union is recycled into agriculture. Management options require extensive waste characterization, since many of them may contain compounds, which could be harmful to the ecosystem, such as heavy metals, organic pollutants, etc. The present study aims to show the results of 2 years’ sampling of sewage sludge—based on 130 samples collected from 35 wastewater-treatment plants situated in the North of Italy—and to assess its suitability as soil fertilizer regarding contents of nonylphenol (NP), nonylphenolethoxylates (NPnEOs), and phthalates (DEHP).
Magnesium–ammonium–phosphate (struvite) showed the lowest soil PTE accumulation risk among the inorganic fertilizers in this ranking due to a very high P content. Data on POPs were not available. Crystallisation of (struvite) takes place in sewage sludge before dewatering (Stuttgart process) or in processed water after primary clarification (Airprex process) and is a stoichiometric process in which a very little amount of pollutants is co-precipitated in the final product. This low PTE amount in struvite was also found by Kraus and Seis (2015). Struvite production has a P recovery rate of 7% (Airprex ) to 45% (Stuttgart Sludge Leaching), also depending on wastewater P content (Herzel et al. 2015b). Struvite would be very suitable for organic farming because of the favourable P-to-contaminant ratio combined with low water solubility and a high P fertilizer effective- ness (Mo¨ller et al. 2017).
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its effect on plant and soil (Ahmed et al. 2010) as well as the implications on the environmental have been studied (Usman et al. 2012). However, the presence of heavy metals such as Zn, Cu, Ni, Cd, Pb, Hg and Cr is restricting the use of sludge for agricultural purposes. Similarly, sewage sludge in Malaysia has acidic properties and contain high amount of heavy metal (Rosenani et al. 2004; Roslan et al. 2013). Application of sewage sludge in agriculture has become difficult in Malaysia as the fertilizer quality is difficult to standardize. Application of sewage sludge without proper management may have adverse impacts on human health and the environment (Tantawy et al. 2012).
Total S content in bulk soil, which was influenced by long-term applications of organic fertilizers, ranged from 158 to 298 mg S/kg soil in different treatments (Figure 1). It was significantly highest in the treatments COM2 and SS2. In these treat- ments the mean S application, calculated per year, during the whole experimental period was 35 and 49 kg S/ha in COM2 and SS2, respectively, while in treatment FYM2 only 20 kg/S ha were applied. Therefore the variation of total soil S may be as- sumed to be dependent on the amount of S applied. However, organic manures are a variable matrix, since their composition is a product of many fac- tors. We found that 47, 71 and 78% of the total S in farmyard manure, compost and sewage sludge, respectively, is organically bound. For this reason the extent of the increase of total S depends also on the type of the organic fertilizer, the share of organic S being highest with compost and sewage sludge. In both of these organic fertilizers only less than 30% of the total applied S is directly plant available. No such increase of total soil S was reported after 150 years supply of S containing mineral fertilizers (Knights et al. 2001), which may be traced back to the fact that with mineral fertilizers S is mainly applied as inorganic SO 4 2– which is water soluble
In the last few years, utilities have become interested in co-firing biofuels with coal and other fossil fuels, applying wood wastes and other solid forms of biomass to increase of capacity of power generating plants -. Initially, co-firing has been considered as a mean to reduce greenhouse gas emissions from fossil energy generation operations. Biomass co-firing with coal proved to be the most inexpensive method to generate green power in a utility plant , -. Also from the economic point of view prospect of the joint combustion of sludge and coal in power plants can be an attractive option since it allows the use of existing infrastructures, which are already equipped with the appropriate devices for flue gaseous emission control . Furthermore, in near future new regulations will highly restrict the actual disposal procedure of municipal sewage sludge. Based on soil and groundwater protection, sterner requirements will have to be met in regard to pollution level of sewage sludge, limiting its use as fertilizer .
The quality of radish is assessed mostly by its external aspect, flavor and nutritional values. Hence, in order to increase the size and productivity of the radish crop and to improve the appearance of radish, farmers need to use heavy fertilization with mineral fertilizers so as to achieve a good market quotation for their crop. It is min- eral fertilization which, in many cases, has the predominant impact on production in both technological and so- cioeconomic matters . The amounts of fertilizer normally applied to the soil do not generally limit the growth or the productivity of the crops; however, if it is used in excess, fertilizer can adversely affect the plant’s absorption of other nutrients  .
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based on ANOVA. The total ENT colonies was the highest in the soil amended with 50 % sludge concentration which was 1200 colonies/mL compared to all the other treatments. Tukey’s test further implied that the application of 50 % sludge concentration significantly increased the ENT colonies in the soil. Nonetheless, the total enterococci colonies have decreased to zero colonies/mL in the fourth week of study in 13 %, 38%, 44 % and ST5 plot due to the antagonistic relationships between the rhizospheric bacteria in the soil. Even the test plot for 50% sewage sludge showed significant decrease (63%) in the ENT colony counts over the period of four weeks. The treatment of soil with 13 % sludge concentration did not significantly increase nor introduce any ENT colonies throughout the study and no ENT colonies were detected in the treated soil.This has shown that the 13 % sludge concentration was safe to be applied as a fertilizer compared to all the other treatments.
TSP and RP that were tested in almost all experiments), we categorized them in two types (organic or inorganic) in order to investigate if there were some more general trends in the interaction between P fertilizer applied and the effect of the three BEs across the experiments. Clearly, BE2 and BE3 (both bacterial) applied with organic fer- tilizers were the best combinations and in particular when these BEs were combined with composted animal manures (for BE2 and BE3) or with the Danish sewage sludge (for BE2). In the Vörden soil, sewage sludge was also combined with BE2. But here, BE2 failed to exert any effect on the obtained biomass, showing again the complexity of these processes and why the interaction between soil and fertilizer type was significant in the per- formed two-way ANOVA (Table 6). In two cases (Buus and Castel soils), BE1 (fungal) was able to increase the aboveground biomass when combined with TSP, indi- cating that the three BEs have likely different modes of
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The mean contents of nitrogen in Jerusalem artichoke (Helianthus tuberosus L.) were simi- lar in the consecutive years of the study (Table 5 and 6). It was observed the contents of nitro- gen tended to increase in response to fertilization with sewage sludge and to decrease with a grow- ing dosage of fertilization with biomass ash. This may be justified with the fact that sewage sludge is a source of nitrogen, unlike ash which gener- ally does not contain this element. Furthermore, the decrease in nitrogen contents coinciding with higher dosage of ash fertilizer may be linked with the growth of crop. The mean contents of nitro- gen in overground part of Jerusalem artichoke, Gigant cultivar, amounted to 0,28g N·kg -1 d.w.
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Biological assays have been used for several decades in risk assessment and detection of wa- ter/sludge contamination have mainly involved aquatic invertebrates (chironomid larvae, mos- quitoes, dragon flies, prawns, shells and hydras), aquatic vertebrates such as fish and algae, and aquatic plants such as Lemna minor L. Based on these facts, it is obvious that the use of plants as indicators of contamination has been generally underestimated and rarely used in toxicological studies, compared to animal organisms [Moor and Kroege, 2010]. However, the significance of research that involves phytoindicators should not be neglected because such data show the bioavail- ability of contaminants and enable risk assess- ment and creation of protocols for remediation of contaminated sites [Gvozdenac et al., 2013].
The slurry material was pasteurised so that the test specimens would remain in a saturated state facilitating accurate measurement of the pore water pressure response. The 250 mm diameter hydraulic consolidation cell was placed in the drying oven and the oven temperature was gradually increased to 80 o C over a period of about five hours. The specimen was allowed to swell under undrained conditions inside the consolidation cell against an applied confining pressure of 100 kPa. Biogas stopped evolving after the specimen had been maintained at 80 o C for a period of three hours, which indicated that the specimen had been pasteurised successfully. The oven temperature was then gradually reduced back to ambient laboratory temperature. Sludge cakes were prepared at 130 % water content by consolidating the pasteurised material under an applied confining stress of 100 kPa with the specimen allowed to drain freely to atmosphere. This specimen preparation method was used as triaxial specimens prepared from dried compacted sludge material could not be fully saturated in the triaxial apparatus within a reasonable time frame.
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Compaction and swell tests were also conducted on thermally dried pellets of sewage sludge which are sometimes disposed to landfill. The dry material compacts poorly since the pellets remain as separate particles. The unconfined swelling capacity was assessed by measuring the increase in volume of a dry sludge powder when deposited in water. 7 The tests indicated that rehydration of the dry pellets to the equilibrium field WC can cause the soil body to approximately double in volume. This swelling causes softening of the sludge material which can lead to instability of the landfill. Hence, it is recommended that the sludge material should not be dried significantly below the optimum water content for compaction prior to landfill disposal.
The major part of the dry matter content of sewage sludge consists of nontoxic organic compounds, in general a combination of primary sludge and secondary microbiological sludge. The sludge also contains a substantive amount of inorganic material and a small amount of toxic components. There are many sludge-management options in which production of energy is one of the key treatment steps. The most important options are anaerobic digestion, co-digestion, incineration in combination with energy recovery and co-incineration in coal-ﬁ red power plants. The goal of our applied research is to verify, if the sludge from waste water treatment plants may be used as a biomass energy source in respect of the EU legislation, which would comply with emission limits or the proposal of energy process optimizing the preparation of coal/sludge mixture for combustion in the existing ﬂ uid bed boilers in the Czech Republic. The paper discusses the questions of thermal usage of mechanically drained stabilized sewage sludge from the waste water treatment plants in the boiler with circulated ﬂ uid layer. The paper describes methods of thermal analysis of coal, sewage sludge and its mixtures, mud transport to the circulating ﬂ uidised bed boiler, eﬀ ects on eﬃ ciency, operational reliability of the combustion equipment, emissions and solid combustion residues.
For Cd, the increased application rates of sewage sludge increased its content in the soil in both the water soluble and exchangeable forms, whereas the residual forms had decreased (Fig. 2a). However, there was no difference in the ex- changeable form of the first cycle (38%) and third cycle (37 %) treated with sewage sludge. According to Brummer (1986), the exchangeable form can be categorised as mobile and can be used to estimate the total available heavy metals. Cd content was also high in the carbonate form. There was a significant difference (p<0.05) between the two cycles treated with sewage sludge. The usage of sewage sludge may have influenced the increase in Cd associated with the carbonate fraction in the soil. However, no significant differences between the treatments were found in the percentage of Cd associated with the carbonate fraction and the range was 21 – 24 %. Chlopecka (1993) showed that Cd added to soil as carbonate is relatively mobile in acidic conditions and within a few years or less, may change to the exchangeable form.
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sludge samples were determined by use of electric muﬄ e furnace LMH 07/12 and ranged from 0.43 % to 21.45 % in case of solid content (A and C samples, respectively) and from 56.21 % to 67.80 % in case of ash free dry mass (A and B samples, respectively). All sludge samples exhibited non–Newtoninan character and temperature dependence. Several mathematical models (Arrhenius, Bingham Plastic, Casson Law, Exponential, Gaussian, and IPC Paste) were successfully used for characterization of ex- perimental data. So ware MATLAB® was used and satisfying correlations between experimental and computed results were obtained. The best match (R 2 = 0.999) was received with use of Gaussian model,
The Atterberg limits, particle size distribution, specific gravity of solids, loss on ignition and pH of the sludge material were measured. Material direct from the wastewater treatment plant had a liquid limit of 315%, a plastic limit of 55% and a plasticity index of 260%. When wet sieved, roughly 90% dry mass of the sludge material passed the 425m sieve indicating that the sludge largely comprised clay-sized particles. Material retained on this sieve comprised some organic fibers, grit particles and shredded plastic. The very high liquid limit and plastic limit values and colloidal activity (the plasticity index to clay fraction ratio) of the sludge are characteristic of calcium montmorillonite clay minerals (Yong & Warkentin, 1975). Similar liquid limit and plastic limit values were also reported for water treatment plant sludge by Wang et al (1992) and for paper mill sludge by Charlie (1977). Ignition of dry, powdered sludge material at 440 o C caused a 70% reduction of the sample dry mass. This loss on ignition (LOI) value is an indirect but fairly accurate measure of the organic content of the sludge material. Based on the Atterberg limits and this LOI value, the sludge material is organic clay of high plasticity according to the Unified Soil Classification System.
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showed that both sludge dewaterability and flocculant consumption presented the seasonal variation, which means sludge dewatering was harder and coupled with higher flocculant consumption in the winter (Liu et al., 2015). A new type belt super-pressure filter for sludge was introduced. This device can dewater the sludgefrom 99 ~97% moisture to 55% moisture. It shows that the expected operation effect of the device has been achieved in the application for treatment of papermaking and sanitary sewage sludge, which is beneficial to bury, burnand comprehensive utilization of sludge (Lian, 2013). Natural drying and mechanical dehydration are two main methods of sludge drying and dehydration. The mecha- nical dewatering method of traditional paper making sludge is not ideal due to the limitation of the structure function of the machine, and the water content of the sludge is more than 70%. Sludge is difficult to be used directly. Therefore, the application of screw press to squeeze dehydration is gradually developed (Richard, 2007).
The water quality of seven sewage reservoirs of Raipur city is shown in Table 1, Table 2. The water of all re- servoirs is colored with bad smell due to loading of biodegradable organics. The value of T, pH, EC, DO and RP of the water bodies (n = 7) was ranged from 28 - 33 ˚C, 6.6 - 9.4, 720 - 1543 µS/cm, 5.9 - 7.4 mg/L and 90 - 220 mV with mean value of 30 ± 2 ˚C, 7.2 ± 0.7, 1108 ± 262 µS/cm, 7.0 ± 0.4 mg/L and 137 ± 34 mV, respectively. The concentration of F − , Cl − , SO 2 4
The sludge containing concretes appears economically attractive given the low prices of raw industrial wastes. Wide scale application of this method can significantly improve the environmental situation in industrial regions. Utilization of sludge ash as raw materials in the production of pellet aggregates was reported by Bhatty et al. (1992), who observed a lower aggregate specific gravity and hence a better strength-to-weight ratio with no adverse effects on concrete strength. SSA has been used in mortars , concrete mixtures , in brick manufacture , as a fine aggregate in mortars , and in asphalt paving mixes . J.Monzo et. al observed that control paste has shorter initial and final setting times than pastes containing SSA. In addition, an increase of both setting times is observed when percentages of SSA do. SSA improves mortar strength at early curing time. Studies conducted By R. Khanbilvar showed that the design strength is still attainable for up to 30% (by weight) ash replacement.