Sludge Slurry Research Articles

Effects of microwave irradiation at various temperatures on biosludge disintegration

ABSTRACT The waste biological sludge disintegration by using microwave irradiation was investigated at a ramping rate of 2°C/min and 5 min holding time at various target temperatures. Significant disintegration of biosludge was observed and the highest disintegration degree was determined about 82% at the temperature of 110°C. Increase of target temperature elevated the energy needs to 98, 123 and 148 kWh/kg TS at the temperatures of 75°C, 90°C and 110°C, respectively. The gradual increase of sugar and protein in the sludge slurry with increasing temperatures indicates successful degradation. The microwave pretreatment increased the specific surface area of the sludge by particle size reduction. The specific surface area of raw sludge was 70 m2/kg and rose to approximately 253.7 m2/kg at 110°C with an increment ratio of 260%. Although a significant NH4–N release was not observed, PO4–P concentrations increased from 11.0 mg/L to 16.3, 20.7 and 29.2 mg/L at the temperatures of 75°C, 90°C, 110°C, respectively. While the specific filter resistance of waste biological sludge was about 1.0 × 1013, increasing the microwave target temperature, the ability of dewatering decreased and the highest SFR value of 5.1 × 1014 was observed at the temperature of 110°C.

Flash drying of slurry-liquid sewage sludge based on avoidance of latent heat of phase change: Laboratory to pilot-scale evolution

Industrial slurry, municipal sewage, and other slurry-liquid sludges pose a formidable challenge for quick and comprehensive drying in a single step due to their large volume, and high water content. Conventional slurry sludge drying methods, driven by the necessity to overcome the latent heat associated with phase change, entail notable drawbacks, including high energy consumption, and suboptimal efficiency. In this study, we introduce a cyclone-based non-phase change drying process, specifically designed to achieve efficient, one-step drying of slurry-liquid sludge, all while operating at temperatures below the phase change of water. Our study focuses on the use of the industrial titanium gypsum slurry (TiGs) as the primary research subject, exploring the factors influencing the efficiency of cyclone non-phase change drying at both laboratory and pilot scales. Our results underscore the significant impact of temperature, gas velocity, and gas–solid ratio on the drying process of TiGs. Notably, in our pilot-scale experiments, employing an air volume of 1300 m3/h, a temperature of 90℃, and a gas–solid ratio of 16 m3/kg, we achieved an impressive reduction in water content in the TiGs, dropping from 72 % to 15 % in mere 30 s. Mechanistic investigations elucidated that the overall drying process includes several important processes, encompassing slurry hot air crushing, rotary granulation, and spin dewatering. Furthermore, our thermogravimetric and elemental analyses unveiled that the augmented expansion of pores facilitated low-temperature dehydration, thereby preserving the stability of the dried material's composition. Additionally, we ascertained that this technology also delivers highly effective drying for municipal wastewater.

Optimizing sludge dewatering efficiency with ultrasonic Treatment: Insights into Parameters, Effects, and microstructural changes

Sludge dewatering plays a critical role in the efficient and cost-effective management of wastewater treatment plants. Ultrasonic treatment has emerged as a promising technique for improving dewatering processes. This study aims to evaluate the impact of ultrasonic treatment on sludge dewatering characteristics. A series of experiments were conducted to evaluate the dewatering characteristics of sludge under ultrasonic treatment. Experimental data was collected, and the effects of ultrasonic parameters on dewatering efficiency were analyzed. Ultrasound has the capacity to disintegrate sludge flocs, liberate tightly bound water, and enhance sludge dewatering capabilities. The application of ultrasound leads to the breakdown of sludge flocs, which facilitates a substantial amount of organic acids or carbonates. This, in turn, modifies the pH value of the sludge. Additionally, ultrasound induces instantaneous high temperature and pressure within the liquid phase, consequently elevating the temperature of the sludge slurry. Optimum ultrasound energy density and duration of ultrasound treatment exist. For the sludge samples analyzed in this investigation, it was determined that the optimal ultrasonic energy density is 9.8 W, while the optimal duration of ultrasound treatment is 30 s. Excessively escalating the sound energy density or prolonging the duration of ultrasound may yield unfavorable outcomes in terms of sludge dewatering effectiveness. To enhance sludge dewatering, it is crucial to select appropriate ultrasonic energy density and duration of ultrasonic treatment. This study demonstrates the positive impact of ultrasonic treatment on the dewatering characteristics of sludge. The findings provide valuable insights into the potential of ultrasonic technology for enhancing sludge dewatering.

Investigation of lysing excess sludge slurry using hydrolase secreting thermophilic bacterial communities

Sludge reduction is a critical challenge in biological wastewater treatment. Combining excess sludge slurry lysis technology with traditional activated sludge processes is a promising approach for in-situ sludge reduction. Here, a strategy for excess sludge slurry lysis based on thermophilic bacterial communities (LTBC) was proposed. This investigation focused on the process of excess sludge slurry lysis dominated by thermophilic bacterial communities domesticated at different temperatures (55–75 °C). The evolution of sludge lysate was analyzed, and the mechanism of excess sludge slurry lysis under the action of thermophilic bacterial communities was elucidated through amplicon sequencing analysis. The results demonstrated that the aerobic thermophilic bacterial communities adapted to 75 °C exhibit the highest efficiency in sludge slurry lysis. During LTBC process, the removal efficiency of volatile suspended solids reached 53.9 ± 1.8% within 2 h, and 97.0 ± 1.0% of the protein and 96.0 ± 1.0% of the polysaccharide in the extracellular polymers was solubilized, and bacterial cell walls in sludge were disrupted. Fourier transform infrared spectroscopy and excitation-emission matrix spectroscopy of the sludge lysate demonstrated that the LTBC process was accompanied by humification process. The accumulation of humic acid primarily occurred at 55 °C and 65 °C, while fulvic acid occurred at 75 °C. The thermophilic bacterial communities adapted to 75 °C were dominated by Thermus and Thermaerobacter. Phylogenetic studies showed that the LTBC hydrolase system comprises enzymes related to protein hydrolysis, carbohydrate hydrolysis, and peptidoglycan hydrolysis, including metalopeptidase MepB, neutral α-glucosidase C, N-acetyl Muramyl-L-alanine amidase, and others enzymes. These results provide a theoretical basis for the application of LTBC technology in the reduction of sludge which generated in traditional waste water activated sludge processes.

Development and substantiation of an improved version of a main drainage facility classical scheme at a kimberlite mine developed by block caving method

Evidence demonstrates that as the production capacity of a kimberlite mine increases, there is a corresponding increase in the volumetric concentration of suspended solids in the mine water extracted from its watercollecting workings. The Udachny mine, known for its high productivity in comparison to other domestic kimberlite mines, experiences a higher concentration of suspended solids in the mine waters, leading to significant sludge settling within the primary drainage facility’s water-collecting workings. This determinal effect adversely affects the operational efficiency of pumping equipment and the reliability of LHDs. To address these issues, an enhanced version of the conventional main drainage facility scheme, specifically designed for kimberlite mine utilizing the block caving method, is proposed. This modified scheme aims to provide improved clarification of the mine water in the water-collecting workings and facilitate more efficient dewatering of the settled slurry sludges. Furthermore, a methodology has been developed to determine the time required for slurry sludge removal, the sedimentation characteristics of the solid phase, and the rheological properties of the liquid phase of the mine water.

Об обеспечении безопасной эксплуатации главной водоотливной установки рудника «Удачный»

Safety of the underground mining operations largely depends on the reliability of the functioning of the drainage facilities system. Practice shows that over the past few years, the reliability of the main drainage system of the underground kimberlite mine Udachny was noticeably decreased. One of the reasons for this was the low operational reliability of pumping equipment. External examinations of the failed parts of the flow part of pumps operating in the drainage systems of domestic kimberlite mines indicate the dominance of hydroabrasive wear in the overall picture of their multifactorial destruction. Mine waters pumped from the drainage mine workings of the Udachny mine is considered the most polluted among the mines of ALROSA. The main reason for the increase in the concentration of solid particles in the mine waters pumped to the daytime surface by the pumping equipment of the main drainage plant of the Udachny mine was the growing pollution of the waters coming from the drainage basins of the district drainage into its clarifying reservoirs. Such an intensive removal of mechanical impurities from the catchments of the district drainage into the clarifying tanks of the main drainage system is explained by an increase in the rate of siltation of the catchment tanks. And the rapid siltation of the catchments, in turn, is caused by the systematic removal of sludge-slurry pulp from the lower part of the skip trunk. It is established that the sludge slurry is formed during the overload of the extracted kimberlite ore from the feeder to the conveyor belt. There, its spilled part is washed off with water used for irrigation of diamond-bearing raw materials into the skip barrel. To reduce the rate of siltation of the drainage basins of the district drainage system, a mechanized complex for cleaning spilled rock mass was developed, described in the article.

Slurry phase biodegradation of heavy oily sludge and evidence of asphaltene biotransformation

Oily sludge management is a global environmental concern due to its hazardous nature. Oily sludge obtained from a refinery in India had 19–21% oil content. The oil was highly enriched in the asphaltene fraction. Slurry phase biodegradation of this oily sludge in presence of a 3-membered bacterial consortium was optimized in presence of Triton X-100 to increase the bioavailability of hydrocarbons. Triton X-100 at 4 times the critical micelle concentration (CMC) showed the highest degradation where oil removal of 53.1% was achieved from a 10% sludge slurry over 90 days. GCxGC analysis of n-alkanes present in the oily sludge after the biodegradation study showed an increase in the lower n-alkanes, i.e., dodecane and tridecane over the first 30 days, whereas the higher n-alkanes were removed to a much higher extent. Heptadecane showed the maximum extent of degradation with 94.9% removal in 90 days and an initial degradation rate of 0.079 day−1. The, maximum rate of degradation was observed for pentacosane (0.083 day−1) with 93.7% removal in 90 days. The increase in the lower n-alkanes may be attributed to biotic transformation of the asphaltene fraction which was also confirmed through FTIR and pyrolysis GCxGC analysis. Biodegradation was found to cause changes in the pyrolysis product of asphaltenes where four and three-ring pyrolysis products decreased while the one and two-ring pyrolysis products increased. In presence of the consortium asphaltene removal over 90 days was 12% whereas only 0.4% removal was obtained in the abiotic controls.

Sludge slurry treating using hydrothermal pre-treatment process and its property evaluation

Sludge slurry treating using hydrothermal pre-treatment process and its property evaluation

Enhancing sludge conditioning and dewatering characteristics by active surfaces modified with fast recombining immobilized nanoparticles

Nichrome is a composite of nickel chromium alloys and commonly used as resistance wire for heating equipment. In this study, ability of multilayered heterojunctions between Cr+3-TiO2 and Ni2+-TiO2 nanoparticles to disintegrate acidified slurry sludge was investigated experimentally. Recombination and photoactivity of the Cr3+ and Ni2+ nanoparticles were optimized alternating their atomic mass fractions in the nanocomposites by their heating ability, using a central composite statistical design approach. Effects of the applied method on sludge conditioning, stabilization, and drying behaviors were systematically investigated. Temperature increase (ΔT) at the highest volatile suspended solids (VSS) oxidation level in the treated sludge samples were 2 ± 1 °C, 5 ± 1 °C, and 20 ± 1 °C for “UV C + H2O2-no catalyst,” pure and Cr-Ni-TiO2 thin films (TFs), respectively. Obtained results also indicated that the modified TiO2 nanoparticles were able to decrease sludge bound water content by 45 ± 1% efficiency. Cr3+ and Ni+2 co-doped TF functioned to decrease the unit drying energy from 236 ± 10 kJ kg−1 H2Oevaporated to 140 ± 10 kJ kg−1 H2Oevaporated. Drying profiles of raw and treated the sludge samples were fitted to Henderson and Pabis Model. Drying constants (k) for raw and treated sludge samples by pure TiO2 and Cr-Ni-TiO2 TFs were found to be 0.11 ± 0.01 min−1, 0.12 ± 0.01 min−1, and 0.19 ± 0.01 min−1, respectively. VSS degradation followed pseudo-first-order reaction kinetics in the all assayed conditions and pseudo-first-order reaction rates (k obs) for pure and the modified TFs were determined as 6 × 10−4 min−1 and 4 × 10−3 min−1, respectively. 2,2′,5-Trichlorobphennyl, 2,2′,5,5′-Tetrachlorobiphenyl, 2,3′,4,4′,5-Pentachlorobiphenyl, and 2,2′,3,4,4,5,5′-Heptachlorobiphenyl were detected in raw sludge and after the photocatalytic oxidation through Cr3+ and Ni2+ co-doped TiO2 TF reactor, their total concentration was reduced from 4.36 mg kg−1 to 9.76 × 10−3 mg kg−1.

Determination of Pre-Consolidation Pressure by Different Method

One of the most important soil problems seen on fine-grained soils is the settlement problem. The primary consolidation settlement shows itself over time with the effect of water. Also, the settlement properties of soil change depending on the stress history. In this study, silt mixtures with three different sand percentages were prepared using the slurry sludge preparation method under 50kPa load, and pre-consolidation pressures were calculated by performing the oedometer experiment on the obtained samples. Using the collected oedometer data, the pre-consolidation pressures were calculated and compared by six different methods. As a result, the results equal to the vertical stress values applied for the three mixtures were obtained by Butterfield and Tavenas methods. Sand content was effective in Casagrande, Van Zelst, and Janbu methods, but not in Butterfield, Tavenas, and Shmertman.

Rheological studies of municipal sewage sludge slurries for hydrothermal liquefaction biorefinery applications

Hydrothermal liquefaction (HTL) is a thermochemical process that can convert organic materials in sewage sludge into crude-like oil. Knowledge of the rheology of sewage sludge as a feedstock is important for the design of a HTL Biorefinery as it provides essential information for pumping, pipeline design and heat transfer processes. This study aims at elucidating the rheological behaviour of sewage sludge slurries. Rheological parameters of sludge obtained from different stages in Wastewater Treatment Plants were estimated and used to calculate the pumping power required for slurry transportation in pipelines as part of the front-end engineering design stage for a biorefinery. Sludge slurries were determined to be Non-Newtonian with shear thickening characteristics. Statistically, the Herschel-Bulkley rheological model best fitted the experimental data with a yield stress. The apparent viscosity of municipal sewage sludge slurries measured within a shear rate range from 10 s−1 to 300 s−1 were determined to be between 0.008−0.05 Pa.s for stockpiled biosolids, 0.04−0.11 Pa.s for sludge without polymer dosage and 0.1−0.2 Pa.s for dewatered sludge with polymer. Power requirement for pumping sludge slurries were in the order: Stockpiled biosolid < Sludge without polymer dosage < Sludge with polymer dosage.

Nitric oxide reactivity accounts for N-nitroso-ciprofloxacin formation under nitrate-reducing conditions

The formation of N-nitroso-ciprofloxacin (CIP) was investigated both in wastewater treatment plants including nitrification/denitrification stages and in sludge slurry experiments under denitrifying conditions. The analysis of biological wastewater treatment plant effluents by Kendrick mass defect analysis and liquid chromatography - high resolution - mass spectrometry (LCHRMS) revealed the occurrence of N-nitroso-CIP and N-nitroso-hydrochlorothiazide at concentration levels of 34 ± 3 ng/L and 71 ± 6 ng/L, respectively. In laboratory experiments and dark conditions, produced N-nitroso-CIP concentrations reached a plateau during the course of biodegradation experiments. A mass balance was achieved after identification and quantification of several transformation products by LCHRMS. N-nitroso-CIP accounted for 14.3% of the initial CIP concentration (20 µg/L) and accumulated against time. The use of 4,5-diaminofluorescein diacetate and superoxide dismutase as scavengers for in situ production of nitric oxide and superoxide radical anion respectively, revealed that the mechanisms of formation of N-nitroso-CIP likely involved a nitrosation pathway through the formation of peroxynitrite and another one through codenitrification processes, even though the former one appeared to be prevalent. This work extended the possible sources of N-nitrosamines by including a formation pathway relying on nitric oxide reactivity with secondary amines under activated sludge treatment.

Persistence of three bisphenols and other trace organics of concern in anaerobic sludge under methanogenic conditions

ABSTRACT The degradation and distribution of bisphenol A (BPA), bisphenol S (BPS) and bisphenol AF (BPAF) were evaluated in dilute anaerobic sludge slurries amended with a single bisphenol or a mixture of all three and maintained under methanogenic conditions over a 28-d period. No significant degradation of the bisphenols was observed in methane-generating microcosms. Rapid sorption to sludge particles was the primary removal process with sorption observed: BPAF > BPA > BPS. Several other trace organic chemicals of concern in the sludge were detected using quadrupole time of flight mass spectrometry. Of those detected, triclosan and triclocarban had sufficiently high intensities to quantify changes over the 28-d period in the bisphenol-amended microcosms. Similar to the bisphenols, triclosan and triclocarban concentrations also did not significantly change over the 28-d period with concentrations quantified at 2021 ± 627 and 1864 ± 769 μg/kg dry weight, respectively. Findings exemplify that methane-generating microcosms do not appear conducive to significant degradation of trace organics of concern in anaerobic sludge digesters.

Valorization of biogas production through disintegration of waste activated sludge using visible light ZnO-ZnS/Ag2O-Ag2S photocatalyst

Abstract The key requirements for accelerating the anaerobic digestion process and clean energy production involve the disintegration of the recalcitrant structure of waste activated sludge and transforming it into soluble organic components for microbial degradation. Herein, the visible light-active ZnO-ZnS/Ag2O-Ag2S nanocatalyst was used for the photocatalytic solubilization of sludge to improve methane production through anaerobic digestion. The photocatalysis released the soluble substances in sludge slurry, in which soluble chemical oxygen demand was increased from 410 to 3892 mg L−1 after 6 h. The volatile solids content was only decreased by 13.1%, which indicated that a short period of pretreatment could avoid the mineralization of organic matter. Methane production was improved by 54% in photocatalytic pretreated sludge, where the cumulative methane production was up to 0.6985 mL g−1 of VS compared with 0.4533 mL g−1 of VS in untreated sludge. Similarly, a higher organic matter removal efficiency of 54% was achieved due to the increased bioavailability of organic compounds under the influence of the pre-solubilization of sludge during photocatalysis. Moreover, photocatalysis reduced the start-up time for methanogenesis from 23 to 13 days. Overall, this study determined the significance of visible light-active ZnO-ZnS/Ag2O-Ag2S photocatalysis for sludge treatment and cleaner energy production, while providing a useful reference for its industrial applications.

Continuous liquid fermentation of pretreated waste activated sludge for high rate volatile fatty acids production and online nutrients recovery

Raw sludge was pretreated, and the separated sludge liquid was used as substrate in a continuous operated up-flow anaerobic sludge blanket reactor to produce volatile fatty acids (VFAs). The highest VFA productivity of continuous fermentation with sludge liquid at an organic loading rate (OLR) of 10.0 kg COD/m3/d was about 5.0-fold and 4.0-fold higher than batch and semi-continuous fermentation with pretreated sludge slurry, respectively. Moreover, the liquid fermentation with an OLR of 10.0 kg COD/m3/d consumed the least energy, which was about 10.57% and 12.12% of batch and semi-continuous sludge fermentation, respectively. When combined with online nitrogen and phosphorus recovery, VFA production further increased by 20.67% and struvite recovery efficiency reached 1.98 ± 0.28 g/g PO43−. The process showed high VFA production, low energy consumption and good nutrients recovery by continuous liquid anaerobic fermentation, significantly increasing the economic potential of VFA production from waste activated sludge.

Additive adsorption behavior of sludge and its influence on the slurrying ability of coal–sludge–slurry and petroleum coke–sludge–slurry

Coal–sludge–slurry (CSS) and petroleum coke–sludge–slurry (PCSS) exhibit evident economic advantage in the recycling of sewage sludge without pre-drying, and they can be used as liquid fuel for combustion and gasification. The slurrying properties, which directly influence the industrial application of CSS and PCSS, are studied according to their additive adsorption properties. Furthermore, the effects of different sludge floc fractions on the adsorption capacity of additive were also determined. Sludge exhibited evidently higher additive adsorption capacity than coal and petroleum coke. A large amount of additive was adsorbed or trapped by the sludge when the sludge was co-slurryed with coal or petroleum coke, and the additives available to the coal or petroleum coke were reduced. Thus, the slurrying ability of coal and petroleum coke was adversely affected. The high interstitial moisture content and abundant oxygen-containing functional groups contributed to the high additive adsorption capacity of the sludge. When loosely and tightly bound extracellular polymeric substances were removed, the additive adsorption capacity of the sludge decreased significantly, and the additive available to the coal and petroleum coke increased during the co-slurrying of sludge with these materials. The maximum solid concentration (SCmax) of CSS and PCSS then increased.

Influences of different fractions of extracellular polymeric substances on the co-slurrying properties of sewage sludge with coal and petroleum coke

Coal–sludge–slurry (CSS) and petroleum coke–sludge–slurry (PCSS) can be used as liquid fuel or gasification material, thus providing a new approach for recycling sewage sludge without pre-drying. Given that slurrying properties directly influence the industrial application of CSS and PCSS, this study investigated the influences of different fractions of extracellular polymeric substance (EPS) on the slurrying viscosity (η100, average viscosity at a shear rate of 100s−1), maximum solid concentration (SCmax), and rheological behaviors of CSS and PCSS. Sodium methylene bis-naphthalene sulfonate (NNO) and sodium lignosulfonate (SLS) were used as the dispersants during CSS and PCSS preparation. At the two dispersants conditions, when raw sludge was mixed with coal slurry at a sludge-to-coal ratio of 17:100, SCmax decreased from 52.40% (coal slurry without sludge) to 42.99% and 42.32%, respectively. Similarly, when raw sludge was mixed with petroleum coke slurry with NNO and SLS as the dispersants, SCmax decreased from 72.25% to 61.59% and 61.28%, respectively. The high amounts of trapped water in the sludge and the strong linkage between sludge flocs decreased the SCmax of the slurry. After loosely and tightly bound EPS (LB-EPS and TB-EPS, respectively) were removed, the SCmax of CSS and PCSS increased again because dead water, which increased the water content of the slurry system but did not act as a lubricant or buffer, was removed with the removal of EPS. LB-EPS had more influence on SCmax than TB-EPS because LB-EPS trapped more water than TB-EPS. Thus, more trapped water was removed with the removal of LB-EPS. Shear stress versus shear rate curves were fitted using the Herschel–Bulkley model. The rheological parameters of CSS and PCSS with a η100 of 1000mPas were obtained by linear interpolation method. The rheological behaviors of CSS negligibly changed after the removal of EPS. The yield stress and pseudoplasticity of PCSS, however, increased and decreased, respectively. The rheological behaviors of PCSS likely changed after the removal of EPS because sludge particles could no longer link easily to form a spatial structure. Moreover, hydrophobic agglomerations between petroleum coke particles increased in the PCSS system.

Effect of Modified Sludge on the Particles Flocculation and Slurry Stability in the Co-slurry of Sludge and Petroleum Coke

Abstract Sewage sludge modified by Ca(OH)2 and Fe2(SO4)3 were used as make the slurry with petroleum coke, and changes in the size distribution and a total number of particles in the slurry were determined by Focused Beam Reflectance Measurement (FBRM) to explore the particles flocculation mechanism. In addition, the structural strength of petroleum coke sludge slurry (PCSS) was calculated by two mathematic models to illustrate the how the sludge improves the stability of PCSS. The results indicated that the absolute value of the Zeta potential of PCSS increased with the sludge addition and that PCSS stability improved. However, the absolute value of the Zeta potential decreased and the stability declined after the sludge was modified by Fe2(SO4)3 and Ca(OH)2. Petroleum coke particles were wrapped by sludge flocs, and small particles flocculated during their co-slurry process to form a spatial network structure, effectively prevented the settlement of petroleum coke particles and ultimately improved the stability of slurry. The calculation results obtained by the two mathematic models reveal that the shearing energy consumption per-unit-quality of PCSS using raw sludge is twice or thrice than that of PCWS. However, energy consumption was reduced after the sludge was modified by Fe2(SO4)3.

Effect of waste liquid produced from the hydrothermal treatment of both low-rank coal and sludge on the slurryability of coal sludge slurry

Effects of temperature and the amount of sludge on the physicochemical properties of the waste liquid products produced from the hydrothermal treatment (HT) of both low-rank coal and sludge were investigated. The slurryability of coal sludge slurry (CSS) prepared with HT solid and waste liquid product was also analyzed. An increase in the amount of sludge led to a decrease in the solid yield, calorificvalue and fixed carbon of solid products decreased, particularly the solid yield which reached 63.8wt% in the HT of sludge at 300°C. However, more than 85wt% carbon was retained in the solid products, which is beneficial for the energy densification. The Total Organic Carbon (TOC) content increased significantly with an increase in the amount of sludge and attained a concentration of 60g/L. The same trend was observed in the pH value of waste liquid, owing to the presence of ammonium nitrogen organics. Alkanes, phenols, and heterocyclic were the main organic compounds produced from the HT of Inner Mongolia Coal (IMC), Yunnan Coal (YNC) and sludge at 300°C, respectively. CSS prepared using the HT waste liquid instead of water has a higher fixed-viscosity concentration and better stability due to the presence of dissolved organic compounds and ions.

Testing of property changes in recycled bedding for dairy cows

The aim of this study was to analyse the change of the characteristics of different types of organic bedding in deepened stall base cubicles for dairy cows. The research was carried out in barn 1 using separated raw manure solids, in barn 2 using drum composted manure solids and for comparison a barn 3 was chosen, which used traditional straw as a bedding material. Dry matter of separated raw manure and drum composted recycled manure solids in sample 1 collected after 2–3 hours of bedding acclimatization in the stable were lower (P &amp;lt; 0.05) compared with sample 3 collected 2–3 hours before the new bedding was spread, but dry matter of straw in sample 1 was higher (P &amp;lt; 0.05) compared with sample 3. The values of the coefficient of thermal conductivity show that the bedding from recycled sludge slurry is a good insulant and absorbent. In addition, a determined increase of humidity at the end of the bedding interval does not cause dramatic changes of thermal performance.