Proportion Of Sludge Research Articles

The investigation of co-combustion of sewage sludge and oil shale using thermogravimetric analysis

The co-combustion behaviors between sewage sludge and oil shale were investigated in this study. The TGA experiment was given a temperature spanning from 105°C to 1000°C by setting the heating rates 10, 20 and 30°C/min. The combustion characteristics, characteristic index, co-combustion interactions, activated energy and DAEM of blends were studied in this paper. The ignition temperature shifted to an earlier temperature when adding sludge. An inhibition interaction of co-combustion occurred at low temperature and the proportion of sludge with 10% showed the best promoting effects. The average activated energy reached the minimal also when the ratio of sludge was 10%. The average fractional residuals were less than 1.3%. Models showed a good recuperation with experimental data.

Combustion Characteristics and Slagging during Co-Combustion of Rice Husk and Sewage Sludge Blends

In this work, the thermal behavior of rice husk, sewage sludge, and their blends during combustion processes was investigated by means of thermogravimetric analysis (TGA), and the slagging characteristics were studied through X-ray fluorescence (XRF) and melting temperature. The effects of the proportion of rice husk and sewage sludge blends on the combustion process, ignition and burnout characteristics were also studied. The blends had rice husk percentages of 30, 50, 70 and 100%. The results indicate that there are four main stages of the material burning processes: dehydration, volatile oxidation, and decomposition/oxidation. The reactivity of the blends improved with increasing amounts of rice husk and the results suggest synergistic interactions between rice husk and sewage sludge during the co-combustion process. All co-combustion ashes showed a lower slagging potential owing to their high amorphous SiO2 content. On the basis of combustion properties and slagging characteristics of ash, the ratio of sewage sludge in the blends should not exceed 30%.

Sustainable use of tannery sludge in brick manufacturing in Bangladesh

Chromium-rich tannery sludge generated from tanneries has the potential to become a serious environmental burden in Bangladesh and a promising avenue for disposal of this sludge is by stabilizing it in clay brick products. But for sustainable industrial application of such technique it needs to be ensured first that the engineering properties of bricks as a building material are not diminished by addition of sludge, the process becomes energy efficient compared to alternatives and the use of such bricks do not pose any harmful environmental effects in the long run. In this study, clay bricks were prepared with different proportions of sludge (10%, 20%, 30% and 40% by dry weight) in both laboratory-controlled and field conditions and their suitability as a construction material was assessed based on their strength, water absorption, shrinkage, weight-loss on ignition and bulk density. For the sludge incorporated bricks, the compressive strength ranged from 10.98MPa to 29.61MPa and water absorption ranged from 7.2% to 20.9%, which in most cases met both the Bangladesh and ASTM criteria for bricks as a construction material. Volumetric shrinkage, weight loss and efflorescence properties of sludge-amended bricks were found to be favorable and it was estimated that an energy saving of 15–47% could potentially be achieved during firing with 10–40% tannery sludge-amended bricks. The quality of sludge-amended bricks made in the brick kiln was relatively inferior compared to bricks produced in the laboratory due to operating in a less-controlled environment with respect to maintaining adequate compaction and optimum moisture content. The leaching behavior of several heavy metals (Cr, As, Cu, Ni, Cd, Pb and Zn) from sludge-amended bricks has been found to be insignificant and far below the Dutch regulations and USEPA regulatory limits. Results from this study indicate that tannery sludge can be sustainably stabilized in clay bricks and large-scale application of this technique can be envisaged in the context of Bangladesh where brick remains a dominant building material.

VALORIZATION OF MUNICIPAL WASTEWATER TREATMENT PLANT SLUDGE AND AGRO-WASTE IN BUILDING MATERIALS WITH THERMAL INSULATION PROPERTIES

Considering the actual environmental issues, the waste management has become a major challenge in Europe and worldwide. Recycling the waste into sustainable products can be an alternative to landfill with positive effects on the costs and environmental pollution. In this respect, in the last years numerous studies and research emphasize the utilization of different type of waste to obtain materials for building applications. The aim of this paper is to assess the effect of using sewage sludge generated by the wastewater treatment plant (WWTP) of Braila city and waste from agro-waste of rapeseed stems as a partial replacement for clay, on thermal insulation properties of conventional building materials. The composite samples of 90 x 90 x 10 mm size, using clay and various proportions of sewage sludge and rapeseed waste (dried and grinded) were obtained in laboratory. The composite samples air-dried and calcinated for 1 hour at 950 C were characterized regarding the specific properties of construction material such as water absorption capacity, thermal conductivity, bulk density and liability to efflorescence. The obtained results emphasize that the inclusion of sewage sludge and rapeseed waste increases the water absorption and weight loss on ignition as results of large pores size formed in the composite material structure. This structure leads to decreasing of the density and thermal conductivity that gives good thermal insulation properties for tested samples.

Effect of Parameters on Anaerobic Digestion EGSB Reactor for Producing Biogas

The effect of hydraulic and organic loading rate on the anaerobic digest EGSB (Expanded Granular Sludge Blanket) reactor for producing methane gas from starch wastewater was studied. The results show that, when the hydraulic loading rate of reactor is in the range of 1 - 4m/h and the influent concentration of CODCr is in the range of 5000 - 10000mg/L, the EGSB reactor can operate stably. Under the volumetric organic loading rate of 30 kg/ (m3•d), the removal rate of COD is over 80%. The granular sludge in the reactor has good settleability, the proportion of granular sludge in the bottom of reactor with particle diameter larger than 1.5mm accounted for more than 75%.

Assessment of key parameters in tannery sludge management: A prerequisite for energy recovery

ABSTRACTEnvironmental regulations are getting more restricted related to landfilling of biodegradable waste. The solution to these problems is using the biodegradable portion of sludge waste for agricultural or thermal utilization. This paper is based on the physico-chemical analysis of different proportions of sludge with coal and rice husk for co-combustion to optimize the parameters like sulfur, ash, and gross heating value (GHV). A significant increase in GHV of secondary sludge with different combinations of coal and rice husk was observed as compared to primary sludge combinations representing 13.55–21.80 Mj/kg and 11.52–19.12 Mj/kg, respectively. The combination RSSC-1 (50% sludge and 50% coal) is highly significant with p < 0.01 and can be utilized as fuel because of the high GHV and low sulfur content. This study concludes that co-combustion of sludge in an eco-friendly manner, using modified thermal methods, may turn into a valuable fuel like traditional biomass.

Study of different ratios of primary and waste activated sludges to enhance the methane yield

AbstractThis work aimed the study of methane yield using different proportions of primary sludge (PS) and waste activated sludge (WAS) for anaerobic digestion (AD) conversion. Three trials were carried out: T1 (60 : 40, v/v), T2 (80 : 20, v/v) and T3 (100 : 00, v/v) to estimate the best proportion in comparison with a reference scenario, T0 (40 : 60, v/v). AD was performed in mesophilic conditions with a hydraulic retention time (HRT) of 15 days and an organic loading rate (OLR) expressed in total volatile solids (TVS) of 1.62 ± 0.06 kgTVS m−3 day−1. Biogas production for trials T1 and T2 increased from 45 to 71% in comparison with T0. The experimental methane production along trials was used to assess the energy recovery corresponding to increases from 32 to 55%. The most suitable trial to be implemented at real‐scale is T1, applying a lower PS solid retention time combined with an increase of WAS thickening.

The influence of clay fineness upon sludge recycling in a ceramic matrix

The feasibility of sludge recycling in the ceramic manufacture was evaluated through laboratory testing. Such residues have similar chemical and mineralogical composition with the raw mixture of the green ceramic body used in construction. Several ceramic masses with clay and various proportion of sludge have been synthesized and then characterized by their physical-mechanical properties. The fineness of the clay, the main component of the green ceramic body, has been considered for every raw mixture. The proportion of the sludge waste addition depends on the clay fineness and the sintering capacity also, increases with the clay fineness. The ceramic properties, particularly, the open porosity, and mechanical properties, in presence of small sludge proportion (7, 20%) shows small modification. The introduction of such waste into building ceramic matrix (bricks, tiles, and plates) has a very good perspective.

Using alum sludge for clay brick: an Irish investigation

Throughout the world, alum sludge is dewatered and the resultant cakes are discarded in landfill. This paper reports a study to investigate the possible incorporation of alum sludge as a partial replacement for clay in clay brick manufacturing. It is the first study of this problem in Ireland. Alum sludge cakes and clay were separately dried, ground and sieved in preparation for making test specimens. Cylindrical clay bricks were made at different temperatures (800, 1000, 1100, 1200 °C), incorporating different percentages (0, 5, 10, 15, 20, 30, 40% by dry weight) of alum sludge. The bricks were then subjected to compressive strength test and submersion. Loss on ignition, water absorption and weight reduction were calculated. It was found that bricks containing up to 20% sludge, fired at 1200 °C, or containing 5% sludge and fired at 1100 °C have met the European and Irish Standards as set out by Eurocode 6 – ‘Design of Masonry Structures’. The firing temperature and the increase in sludge content affected the final clay-sludge brick colour. By increasing the proportion of alum sludge, compressive strength decreased and the final weight of the brick was reduced. Firing temperatures that are too high may result in damage to the bricks during firing. This study has demonstrated the promising potential and prospects for Irish dewatered alum sludge cakes in clay-sludge brick making.

Municipal sludge: an effective soil supplement for improving plant growth

Studies were conducted to evaluate the effect of municipal sludge amendment in soil on the growth of crop plants. Tomato (Lycopersicon esculentum) var. Pusa Hybrid 2 and wheat (Triticum aestivum) var. PBW 343 plants were raised in pots containing soil supplemented with different proportions (~10, 20, 30 %) of sludge. Amendment of sludge in soil resulted in enrichment of nutrients such as phosphorus, nitrogen and potassium. Increased nutrient availability promoted growth and productivity in plants. The growth and productivity of the plants raised in sludge supplemented soil was comparable to those raised in manure and compost supplemented soil. The growth was significantly higher in all the soil amendments in comparison to control. The present findings suggested that municipal sludge can serve as a soil supplement.

Physico-Chemical Evaluation of Organic Wastes Compost-Based Substrates for Eucalyptus Seedlings Growth

ABSTRACTEucalyptus growth was evaluated in five compost-based substrates formulated with different proportions of sewage sludge, coffee husk, peat, chicken manure, cattle manure, pine bark, sawdust, and coconut fiber, compared to two commercial substrates (CS). Organic wastes compost-based substrates (OWS) and CS were characterized regarding the available contents of macro and micronutrients, sodium (Na+), pH, electrical conductivity (EC), and bulk density (BD). Substrate attributes and eucalyptus biomass production were submitted to principal component analysis (PCA) to detect patterns of clustering. The different proportions of organic wastes influenced the physico-chemical characteristics of OWS and, consequently, the eucalyptus biomass production. The highest biomass was observed in one of the CS that is rich in available boron (B) and calcium (Ca), less concentrated in most of the nutrients and with low EC and Na+ contents. The PCA allowed the verification that B availability was the attribute that explained most of the variation in eucalyptus biomass production.

Analysis of the competitive adsorption of pharmaceuticals on waste derived materials

To simulate complex pollutant conditions encountered in wastewater treatment plant influents, a solution containing three common pharmaceuticals was prepared. The adsorbents were exposed to various dilutions (1–100mg/L) of a solution containing equal amounts carbamazepine (CBZ), sulfamethoxazole (SMX), and trimethoprim (TMP). The adsorbents were composed of varying proportions of sewage sludge and fish waste, such that the former represented 100%, 90%, 75% and 25% of the composition, while the remainder consisted of fish waste. Adsorption isotherms were used to determine adsorption capacity for each pharmaceutical. To understand the surface changes during adsorption, analysis by TA-MS and potentiometric titration were carried out. The results were compared to those obtained for single-component pharmaceutical solutions. CBZ was consistently adsorbed from the multi-component solution in greater quantities than was either SMX or TMP on all adsorbents. The adsorption of SMX was most negatively impacted by the presence of multiple pharmaceuticals. The best adsorbent performance varied depending on the pharmaceutical, as the mechanism of adsorption varied between pharmaceuticals, with CBZ interacting more with the carbon phase of the material, whereas SMX and TMP were more apt to react with the inorganic content.

The Melting and Transformation Characteristics of Minerals during Co-combustion of Coal with Different Sludges

The co-combustion of sludge and coal in the existing coal-fired power plant is a promising way for the disposal of sludge. However, slagging in boilers is one of the potential problems if the sludge was mixed improperly with coal during co-combustion. In this paper, the ash fusion characteristics and mineral transformation behavior of a bituminous coal, an industrial sludge, a municipal sludge, and their mixtures have been studied. The results showed that the ash fusion temperatures of the mixed samples show a nonlinear relationship with the proportion of sludge. It was found that the variation of the ash fusion temperature of blended samples of coal with different sludges can be effectively predicted by a ternary phase diagram. Thermal analysis indicated that the decreasing of ash fusion temperature of the blends was caused by the melting phenomenon between the original minerals in coal and sludge which formed new minerals with a low ash fusion temperature. Mineral analysis showed that the formation of d...

Utilization of electrocoagulation-treated spent wash sludge in making building blocks

Minimization , utilization and disposal of industrial waste are very important from the environmental esthetic point of view. Sludge generated during the treatment of distillery spent wash by electrocoagulation process is highly complex in nature and requires proper disposal. In this context, the present study was conducted to employ the electrocoagulation-generated sludge as a partial replacement of cement while manufacturing the non-constructional building blocks. Various physiochemical and thermo-gravimetric characterization studies have been carried out on electrocoagulation-generated sludge and cement. Mortar specimens with different proportions of sludge ranging from 0 to 15 % by weight of cement were tested for density, compressive strength and leachability of heavy metals by standard method. Results from the analysis showed that the cement-based solidification of EC sludge reduces the heavy metal concentration in the leachate from cement–sludge mortars compared to the EC sludge alone. Reduction in the compressive strength of mortar with 7.5 % substitution of cement by EC sludge was <5 % against the control mortar (without sludge), thereafter the reduction was substantial. The optimum percentage of sludge that can replace the cement with marginal change in the physiochemical properties is found to be 7.5. This can be used in the manufacturing of the non-constructional building material within the industry for their different types of usages such as paving, pot making and fencing of garden without affecting the environment.

Essential and Nonessential Element Translocation in Corn Cultivated Under Sewage Sludge Application and Associated Health Risk

Sewage sludge has been used as a fertilizer in agriculture, but human exposure to toxins due to crop exposure has been reported. This study evaluated the uptake of essential and nonessential elements from soil (exposed to sewage sludge) to roots, shoots, and grains of corn, aiming to estimate the daily intake corn consumption to assess the associated health risk. Corn plants were grown in soil amended with 0, 5, 10, and 20 tons of sewage sludge per hectare (t/ha). Soil, root, shoot, and grain samples were analyzed by inductively coupled plasma mass spectrometry. In soil, sludge application at 10 and 20 t/ha enhanced the Zn, Cu, Mo, Cd, Pb, Hg, and Ni concentration compared to control soil. Normally, corn plants exhibited essential and nonessential element concentrations significantly higher in roots than in grains and shoots. Selenium was equally distributed in roots, shoots, and grains but Mo was preferentially stored in grains. Cadmium, As, and Pb were more efficiently trapped in roots than other elements. Considering the estimated daily intake, for Brazilians, the concentrations were below the toxicological or the dietary reference values. In conclusion, chemical elements were efficiently trapped in roots and therefore applying 5 t/ha proportion of sewage sludge might be a sustainable and cost-effective strategy, with a very lower risk of toxicity due to consumption of grains. In contrast, sewage sludge at 20 t/ha enhanced element levels in plant parts and in places with higher corn consumption, estimated daily intakes are expected to rise.

Kinetic study of the co-firing of bagasse–sludge blends

Thermogravimetry was used for the thermal and kinetic characterization of waste biomass as bagasse and sewage sludge and their blends, during the co-firing process for power generation. The kinetic evaluation was performed by a linear integral isoconversional method, applying different conditions of heating. In higher heating rates, kinetic process of combustion of all tested biomasses showed the lower values and the lower changes in activation energy up to 70 % for the conversion of all samples. Above this point, there was a continuous increase in this parameter for bagasse and the bagasse–sludge blends up to the end of the processes. However, in the case of sludge, there was a continuous decrease in energy, which suggests the occurrence of catalytic reactions. The results showed that under low heating rates, the sludge–bagasse blends exhibit profiles of kinetic decomposition very similar to bagasse, regardless the proportion of sludge employed, which may be due the contribution of the high amount of volatile organic materials present in bagasse (30 % higher than the sludge), which increase the reactivity of the sample during the devolatilization process. On the other hand, the kinetic study confirmed the occurrence of the kinetic compensation effect, which suggests a similar scheme of degradation between the biomass samples. Thermal characterization and kinetic study may surely provide valuable information to support the co-processing of waste biomass in order to maximize their fuel performance, ensuring its efficient use of both the environmental and the economic point of view.

Characterization of top phase oil obtained from co-pyrolysis of sewage sludge and poplar sawdust.

To research the impact of adding sawdust on top phase oil, a sewage sludge and poplar sawdust co-pyrolysis experiment was performed in a fixed bed. Gas chromatography (GC)/mass spectrometry (MS) was used to analyze the component distribution of top phase oil. Higher heating value, viscosity, water content, and pH of the top phase oil product were determined. The highest top phase oil yield (5.13 wt%) was obtained from the mixture containing 15% poplar sawdust, while the highest oil yield (16.51 wt%) was obtained from 20% poplar sawdust. Top phase oil collected from the 15% mixture also has the largest amount of aliphatics and the highest higher heating value (28.6 MJ/kg). Possible reaction pathways were proposed to explain the increase in the types of phenols present in the top phase oil as the proportion of poplar sawdust used in the mixture increased. It can be concluded that synergetic reactions occurred during co-pyrolysis of sewage sludge and poplar sawdust. The results indicate that the high ash content of the sewage sludge may be responsible for the characteristic change in the top phase oil obtained from the mixtures containing different proportions of sewage sludge and poplar sawdust. Consequently, co-pyrolysis of the mixture containing 15 % poplar sawdust can increase the yield and the higher heating value of top phase oil.

Influence of coal properties on the co-combustion characteristics of low-grade coal and city mud

&lt;div&gt; &lt;p&gt;In this paper, the effects of the mixing ratio and particle size of coal were investigated using a thermogravimetric analysis (TGA). A method of Achar-Brindley-Sharp-Wendworth (ABSW) was applied to a simultaneous calculation of the kinetic parameters (including the apparent activation energy, the reaction order and the frequency factor). Meanwhile, this study also revealed that both the burning performance and the characteristic parameters improved when sludge mixing ratio was smaller (10 wt.%). The ignition temperature advanced with an increase of the sludge proportion, while the combustion characteristic index dropped. As the sludge mixture ratio rose to 70 wt.%, the DTG curve reached three peaks at 293 &amp;deg;C, 580 &amp;deg;C and 748 &amp;deg;C Decreasing the coal particle size led to the advancement of the devolatilization, fixed carbon burning stage and maximum weight loss rate, and the reduction of the corresponding temperature. Additionally, the apparent activation energy and frequency factor of the mixture reduced when the proportion of the sludge mixing ratio went up. Also, the experiment results indicated that with the decline of the particle size distribution of coal, the apparent activation energy followed a downward trend, while the frequency factor increased.&lt;/p&gt; &lt;/div&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Effects of Sewage Sludge and Acacia dealbata Composts on Soil Biochemical and Chemical Properties

We studied the effects of different composts made of different mixtures of sewage sludge and Acacia plants on the soil biochemical and chemical properties. The proportions of mixed acacia plant and sewage sludge were: AL1/1 (50% acacia/50% sewage sludge), AL1/2 (33.3% acacia/66.6% sewage sludge), and AL1/3 (25% acacia/75% sewage sludge). Composts were added to the soil at a rate of 2%. Soil samples were collected during 150 days and analyzed for soil enzyme activities and chemical properties. An unamended soil was used as the control. Compared to the AL1/1 treatment, soil dehydrogenase, urease, phosphatase and β-glucosidase activities decreased respectively by 14.6%, 15.4%, 12.5%, and 19.3% for AL1/2 treatment and by 20.7%, 25.6%, 23.7%, and 28.4% for AL1/3 treatment. Soil water-soluble carbohydrates and polyphenols were the greatest in AL1/1. The lowest contents of heavy metals in the AL1/1 compost may be responsible for the increase of soil biochemical and chemical properties.

Evaluation of the Anaerobic Co-Digestion of Sewage Sludge and Tomato Waste at Mesophilic Temperature

Sewage sludge is a hazardous waste, which must be managed adequately. Mesophilic anaerobic digestion is a widely employed treatment for sewage sludge involving several disadvantages such as low methane yield, poor biodegradability, and nutrient imbalance. Tomato waste was proposed as an easily biodegradable co-substrate to increase the viability of the process in a centralized system. The mixture proportion of sewage sludge and tomato waste evaluated was 95:5 (wet weight), respectively. The stability was maintained within correct parameters in an organic loading rate from 0.4 to 2.2 kg total volatile solids (VS)/m(3) day. Moreover, the methane yield coefficient was 159 l/kg VS (0 °C, 1 atm), and the studied mixture showed a high anaerobic biodegradability of 95 % (in VS). Although the ammonia concentration increased until 1,864 ± 23 mg/l, no inhibition phenomenon was determined in the stability variables, methane yield, or kinetics parameters studied.