Organic Sludge Research Articles

Synergistic co-digestion of solid-organic-waste and municipal-sewage-sludge: 1 plus 1 equals more than 2 in terms of biogas production and solids reduction

Making good use of existing water infrastructure by adding organic wastes to anaerobic digesters improves the energy balance of a wastewater treatment plant (WWTP) substantially. This paper explores co-digestion load limits targeting a good trade-off for boosting methane production, and limiting process-drawbacks on nitrogen-return loads, cake-production, solids-viscosity and polymer demand. Bio-methane potential tests using whey as a model co-substrate showed diversification and intensification of the anaerobic digestion process resulting in a synergistical enhancement in sewage sludge methanization. Full-scale case-studies demonstrate organic co-substrate addition of up to 94% of the organic sludge load resulted in tripling of the biogas production. At organic co-substrate addition of up to 25% no significant increase in cake production and only a minor increase in ammonia release of ca. 20% have been observed. Similar impacts were measured at a high-solids digester pilot with up-stream thermal hydrolyses where the organic loading rate was increased by 25% using co-substrate. Dynamic simulations were used to validate the synergistic impact of co-substrate addition on sludge methanization, and an increase in hydrolysis rate from 1.5 d−1 to 2.5 d−1 was identified for simulating measured gas production rate. This study demonstrates co-digestion for maximizing synergy as a step towards energy efficiency and ultimately towards carbon neutrality.

Enhanced anaerobic digestion of waste activated sludge of low organic content in a novel digester.

A novel digester, termed an internal circulation anaerobic digester (ICAD), was developed to intensify sludge digestion. It consists of reaction zone, settling zone, thickening zone, riser and downcomer. Internal circulation in the digester is intensified by backflow biogas. The mesophilic ICAD treating thermal pretreated waste activated sludge with volatile suspended solids (VSS)/suspended solids (SS) of 0.45-0.49 was conducted in this study to reduce and stabilize the low organic content sludge. The results showed that the VSS removal rate and biogas rate reached 46.0% and 0.72 m(3)/kg VSS(fed) at hydraulic retention time (HRT) of 15 days. VSS/SS and soluble chemical oxygen demand (SCOD) of the effluent sludge ranged from 0.39 to 0.41 and 274 mg/L to 473 mg/L, respectively, under various HRTs from 10 to 27 days. The degradation ability of ICAD derived from the improved mass transfer by internal circulation and long solid retention time at short HRT is compared with continuous stirred tank reactor.

Organic substrate transformation and sludge characteristics in the integrated anaerobic anoxic oxic–biological contact oxidation (A2/O–BCO) system treating wastewater with low carbon/nitrogen ratio

A novel two-sludge system of anaerobic anoxic oxic–biological contact oxidation (A2/O–BCO) was developed for high-efficiency utilization of influent carbon sources treating wastewater with low carbon/nitrogen (COD/N) ratio. Unlike traditional A2/O process, the oxidation of ammonium (NH4+-N) in this system mainly took place in the BCO reactor through nitrate (NO3−-N) recycling to provide electron acceptors for denitrifying phosphorus removal. The results showed that the A2/O reactor achieved the efficient utilization of carbon sources, with 75% chemical oxygen demand (COD) in the anaerobic zone being consumed to synthesize poly-β-hydroxyalkanoates (PHA). The PHA utilization rate in the anoxic zone was more than 70% with the denitrifying phosphorus removal of 97.83%. The batch tests of phosphorus accumulating organisms (PAOs) and denitrifying PAOs (DNPAOs) activities showed that the DNPAOs accounted for 73.80% of the PAOs in the system. The A2/O sludge of lower extracellular polymeric substances (EPS) production exhibited a better settling ability than conventional denitrification and phosphorus removal processes. The denitrifying phosphorus removal process of higher phosphorus percentage promoted the formation of granular sludge, which was confirmed by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The fluorescence in situ hybridization (FISH) results showed that PAOs became dominant with low amount of nitrifiers in the A2/O reactor, and nitrifiers were enriched in the BCO reactor.

Pengaruh cairan lumpur organik unit gas bio terhadap persentase kandungan bahan organik dan protein kasar padatan lumpur organik unit gas bio

The purposes of this study were to analyze: 1) the constitution and characteristics of sludge, solid sludge and sludge flour derived from Biogas Unit (BGU); 2) the influence of organic sludge liquid on the percentage of organic and crude protein content of the BGU organic sludge (BGUOS). The methods used in the study were observation and randomized controlled trial experiments. Data derived from field study were analyzed descriptively while data derived from experiments were analyzed using variance analysis. Differences were shown using the smallest significance- p test with CI 95%. The results showed that organic sludge constitution were odious, the organic sludge was clotting after drying process. In addition it became powder as soft as bran after dried, powdered and brooded. The experiment showed that the composition of BGUOS liquid gave influence to the amount of organic content and crude protein in the powder constitution of BGUOS. The fifth treatment brought the optimum percentage of the organic content and crude protein. The research concluded that BGUOS constitution was detestable in its form of sludge, however it could be transformed into bran constitution by drying and brooding treatment. The optimum amount of organic content and crude protein of BGUOS bran were gained by using 5 th treatment. The research suggest it is necessary to maintain BGUOS on the basis of local technology and to study the application of BGUOS solid powder or bran as fish and livestock feed. Keywords : Solid Biogas Unit Organic Sludge (Solid BGUOS), CP

Impact of temperature and duration of thermal treatment on different concentrations of anaerobic digested sludge: Kinetic similarity of organic matter solubilisation and sludge rheology

Municipal digested sludge is a dispersion of agglomerated particles or flocs in a liquid medium which exhibits yield stress, shear thinning behaviour and high irreversible temperature dependence.In this study, the rate of solubilisation of organic matter in digested sludge was investigated when sludge (at different solid concentrations) was exposed to thermal treatment between 50 and 80°C for 1 to 60min. The organic matter solubilisation was measured using chemical oxygen demand (COD) analysis on liquor of the thermally treated sludge. The effects of the abovementioned temperature range and heating duration on yield stress and the apparent viscosity of sludge at different solid concentrations have also been investigated.The results showed that the irreversible effect of temperature was much higher at higher concentrations, higher temperatures and longer duration of treatment. It was also observed that for any sludge concentration the kinetic of COD solubilisation, yield stress and apparent viscosity reductions followed a logarithmic correlation with duration of thermal treatment. This similarity was also pronounced in the linear relationship between solubilised COD and yield stress and apparent viscosity reductions in all tested concentrations and the durations of heat treatment. Modified form of Herschel–Bulkley was used to obtain a master curve, independent of temperature, concentration and duration of thermal treatment. Furthermore, a new model was proposed for the impact of temperature and the duration of thermal treatment on yield stress and apparent viscosity reduction.

Aerobic granular sludge to treat paper mill effluent: organic matter removal and sludge filterability

Recently, researchers working with aerated bioreactors identified a different microbial organization in the form of aerobic granules. In this configuration, bacteria clump together more tightly than conventional floc, which reduces biofilm formation on the membrane surface of membrane bioreactors and allows higher flux for longer time periods during filtration. This study examined the possible formation of aerobic granules treating paper mill effluent and compared the removal efficiency of organic matter from granular with the conventional flocculent sludge. The filterability of both types of sludge was also compared. Two reactors were operated in parallel with aerobic granular and flocculent sludge. Both systems achieved very high Biochemical oxygen demand (BOD5) and chemical oxygen demand (COD)-removal efficiencies. Sludge filtration tests showed a higher critical flux for granular sludge with total suspended solids (TSS) equal to 2,700 mg L−1. However, the opposite behavior was observed when the reactors were operated with a TSS value of 4,400 mg L−1.

Development of comprehensive oil sludge recycling method

Current efficiency of using fuel and energy resources in Ukraine and CIS countries can be defined as one that does not meet modern requirements. This issue is particularly acute in the oil processing industry. One reason is excessive loss of hydrocarbons, including through the accumulation of oil sludge in open barns. The paper describes one of the solutions to the urgent problem, namely comprehensive recycling of oil sludge formed during oil processing in refineries. The composition and properties of oil sludge formed in the Turkmenbashi Refinery (Turkmenistan) and PJSC NPK-Halychyna (Ukraine) were investigated. Fundamental possibility of recycling organic oil sludge by shallow thermal degradation at temperatures of 420‑460 °C was defined. It was shown that thermal degradation residual can be used as an additive to raw materials for the bitumen production in an amount of up to 10 % by weight. Based on the results, the current oil sludge utilization scheme was proposed.

Optimization and Process Analysis of Biodrying of Low Organic Matter Content Municipal Sludge

Optimization and Process Analysis of Biodrying of Low Organic Matter Content Municipal Sludge

Mathematical approach to application of industrial wastes in clay brick production—Part II: Optimization

The effects of organic and inorganic waste sludges, coal dust, fly and landfill ashes, soybean crust, sawdust, sunflower flakes and their ash addition to representative heavy clay were investigated. Changes introduced to shaping moist (SM), shrinkage (ΔSk) and weight loss (ΔGk) in Bigot’s curve critical point, and plasticity coefficient (PC) by Pfefferkorn were studied. The highest sensitivity to drying showed samples with coal dust addition, while the greatest plasticity and shaping moist was detected in samples with 50wt% of fly and landfill ashes.The influence of waste material used, its’ content and also firing temperature were independent parameters that influenced compressive strength, water absorption, firing shrinkage, weight loss during firing and volume mass as dependent parameters. Second order polynomial mathematical models predicted fired products characteristics, and were later used to determine the optimum conditions by Response Surface Method (RSM), coupled with Fuzzy Synthetic Evaluation algorithm (FSE), using trapezoidal function. The choice of the parameters optimal interval that characterized fired products (water absorption, compressive strength, weight loss during firing, firing shrinkage and volume mass), depended on a final usage of the raw material in heavy clay brick industry. The optimization results showed that sunflower hulls, wood sawdust, soybean husks and saturation sludge are best to be used in solid bricks production. Coal dust, landfill ashes and neutralization (inorganic) sludges are best to be used in hollow bricks production. Sunflower hulls ash can be added in higher quantity to heavy clay to produce blocks or in lower quantity in roof tiles. Fly ashes addition of 50wt% allows roof tiles production. The optimal temperature for solid bricks and hollow blocks production is found to be 900–950°C.

Advancements in waste water characterization through NMR spectroscopy: review.

There are numerous organic pollutants that lead to several types of ecosystem damage and threaten human health. Wastewater treatment plants are responsible for the removal of natural and anthropogenic pollutants from the sewage, and because of this function, they play an important role in the protection of human health and the environment. Nuclear magnetic resonance (NMR) has proven to be a valuable analytical tool as a result of its versatility in characterizing both overall chemical composition as well as individual species in a wide range of mixtures. In addition, NMR can provide physical information (rigidity, dynamics, etc.) as well as permit in depth quantification. Hyphenation with other techniques such as liquid chromatography, solid phase extraction and mass spectrometry creates unprecedented capabilities for the identification of novel and unknown chemical species. Thus, NMR is widely used in the study of different components of wastewater, such as complex organic matter (fulvic and humic acids), sludge and wastewater. This review article summarizes the NMR spectroscopy methods applied in studies of organic pollutants from wastewater to provide an exhaustive review of the literature as well as a guide for readers interested in this topic.

Organic matter and pollutants monitoring in reed bed systems for sludge stabilization: a case study.

In this study, results about sludge stabilization and pollutant monitoring in a reed bed system (RBSs) situated in Central Italy (Colle di Compito, 4,000 p.e.) were presented. In order to evaluate the process of sludge stabilization, parameters that highlighted the biochemical, chemical and chemico-structural properties of organic sludge matter have been followed during the entire period of operation (7 years). Moreover, the trend of heavy metals (bioavailable fractions and total content) and toxic organic compounds (LAS, NPE and DEHP) was monitored during all the period. The trend of all parameters related clearly demonstrated that sludge stabilization successfully proceeded in RBS. Moreover, through statistical analysis modelling, it is possible to determine how the stabilization process proceeded in terms of organic matter mineralization and humification, and how these processes influenced the content of pollutant compounds present in the stabilized sludges.

Drying temperature and water content–strength correlations

For water content determinations on organic soils, several researchers have adopted lower oven-drying temperatures in the range 35−90°C (instead of the standardised range for mineral soils of 100–110°C) in order to prevent possible charring, oxidation and (or) vaporisation of substances other than water. However, at too low a temperature, not all of the relevant water is driven off. One major consequence of using such a wide range of drying temperatures for more sensitive materials is to produce considerable disparity in interpolated index values and in deduced correlations between water content and other engineering properties. This paper discusses the pros and cons regarding the oven-drying temperature adopted for routine water content determinations on organic sludges and residues. It concludes by recommending a standardised oven temperature of 105–110°C or 105 ± 5°C, a 24-h drying period and a suggested minimum wet specimen mass of 50 g.

Mechanism of toxicity formation and spatial distribution in activated sludge treating synthetic effluent containing bisphenol A (BPA)

Organic sludge toxicity is a critical issue for sludge land applications. To investigate sludge organic toxicity formation and spatial distribution properties, sludge was acclimated using synthetic effluent containing various bisphenol A (BPA) concentrations in sequential aerobic activated sludge reactors (SBRs). Acute sludge toxicity, which was characterized by the inhibition rate of the luminescent bacterium Photobacterium phosphoreum, was the focus of this study. The original influent COD of the SBR was approximately 300 mg/L; the sludge retention time (SRT) and hydraulic retention time (HRT) were controlled at 20 d and 12 h, respectively. The results indicated that a positive correlation existed between sludge toxicity and the influent BPA concentration. Furthermore, the toxicity was centralized in the intracellular and inner sections of extracellular polymeric substance (EPS) in sludge flocs. BPA concentrations were controlled at 2.5 mg/L, 5.0 mg/L, 7.5 mg/L and 20 mg/L; the sludge toxicities, measured by comparing the control SBR with the blank, were 2.99%, 4.05%, 6.99% and 10.64%, respectively, at the end of 28-day operation. In the 12-h SBR treatment process, aqueous and sludge phase BPA was completely removed within 2 h. However, the maximum sludge toxicity appeared in the 8th hour. The DGGE analysis suggested that the existence of BPA in wastewater increased bacterial diversity in activated sludge. However, the bacterial similarity between sludge in SBRs decreased with increasing BPA concentration. Lastly, the bacterial similarity between blank sludge and control sludge of 20 mg/L BPA was 0.47.

Use of inorganic coagulants and polyelectrolytes to sonicated sewage sludge for improvement of sludge dewatering

The paper presents the research on the possible use of inorganic coagulants and polyelectrolytes for conditioning of sonicated and non-sonicated sewage sludges and the impact of conditioning process on the sludge rheological parameters and dewatering process. Dewatering of sludge with a high share of organic matter or sludge with a high percentage of fine fractions and colloidal suspensions causes clogging of the filter, and an increase in filtration resistance does not bring good technological and economic effects. To improve the degree of dewatering of such sonicated and non-sonicated sludges, coagulants and polyelectrolytes and their mixture in appropriate proportions and conditions could be used. The usage of both substances: PIX and polyelectrolyte helped to achieve a cleaner filtrate in comparison with when only polyelectrolyte is used. The rheological parameters of sludge, its structure as well as processes parameters, such as vacuum filtration and pressure filtration were determined during tests. The results show that during application in the conditioning of sonicated sludge, both chemical substances (inorganic coagulant and polyelectrolyte) resulted in a significant improvement of parameters used in order to determine the susceptibility to sludge dewatering.

Optimalisasi Proses Stabilisasi Lumpur Tekstil Dengan Semen

The Function of stabilization is to decrease leachate or chemical reaction which is potential to produce pollutant from waste. Three kinds of stabilization such as addition of the cement, lime and organic sludge had been done before. The result showed that the sludge can bind heavy metal. Analysis result showed that the decrease 'in presentation of heavy metal are Zn (79%), Cu (83,5 %), Fe (99,97 %), Mn (JOO %) and Cr (98,2 %). This experiment is continued to find the optimum amount of cement added to the sludge. The result showed that by addition of 5 % cement in textile sludge can hold the heavy metal.

Bioengineering approach for sewage sludge degradation through aerobic thermophilic process

The aerobic thermophilic sewage sludge treatment process was studied at various bioreactor scales through modified bioengineering design approach. The effectiveness of the biological system was controlled by varying the process operating conditions of bioreactor to enhance microbial degradation efficiency. The inactivation of pathogen each promoted by increase of temperature, while the residual CFU was lowered by reducing the total solids content of sewage sludge. The optimum sludge degradation through aerobic thermophilic process occurred in temperature range of 58 - 62oC but temperature more than 60oC was suitable for hygienic inactivation. Dual digestion systems of an aerobic theromophilic treatment followed by anaerobic thermophilic stabilization stage shows greater treatment and efficiency in degrading the organic sludge constituting up to seventy per cent. DOI: http://dx.doi.org/10.3329/jbas.v37i2.17556 Journal of Bangladesh Academy of Sciences, Vol. 37, No. 2, 159-163, 2013

Experimental Study of the Fry-Drying Phenomena of Organic Wastes in Hot Oil for Waste-Derived Solid Fuel

In sludge treatment, drying sludge using typical technology with high water content to a water content of approximately 10% is always difficult because of adhesive characteristics of sludge in drying. Many methods have been applied, including direct and indirect heat drying, but these approaches of reducing water content to below 40% after drying are very inefficient in energy utilization of drying sludge. In this study, fry-drying technology with a high heat transfer coefficient of approximately 500 W/m2·°C was used to dry swine excreta, sewage and industrial sludge. Also waste oil was used in the fry-drying process, and because the oil’s boiling point is between 240°C and 340°C and the specific heat is approximately 60% of that of water. In the fry-drying system, the sludge is input by molding it into a designated form after heating the waste oil at temperatures between 130°C and 150°C. At these temperatures, the heated oil rapidly evaporates the water contained in the sludge, leaving the oil itself. After approximately 8 - 10 min, the water content of the sludge was less than 10%, and its heating value surpassed 20,000 kJ/kg. Indeed, this makes the organic sludge appropriate for use as a solid fuel. The dried swine excreta, sewage and industrial sludge can be used in an incinerator like low-rank coal or solid fuel.

PERANAN AERASI DAN SILIKA SERTA LAMA PEMERAMAN TERHADAP KANDUNGAN UNSUR HARA PUPUK CAIR LUMPUR ORGANIK UNIT GAS BIO

Organic sludge biogas unit (O SBG U) is an organic product that is generally overlooked by the owner. Giving aeration and silica as treatment with longer curing 1, 2, 3, 4 and 7 days for prospective O SBG U liquid fertilizer is expected to change the percentage of the nutrient content of liquid manure O SBG U candidates become better liquid fertilizer. The results showed that the effect of treatment, curing time and the interaction between the percentage of liquid manure nutrient content O SBG U on p osphor (P), p otassium (K), s odium (Na) and calcium (Ca) was significantly different. Conclusion: The role of aeration and the addition of silica as well as their interactions and their long ripening turns very significant effect on the percentage of the nutrient content of liquid fertilizer O SBG U. Suggestion : t o make the aeration and the addition of silica to the fermentation time to increase the percentage of liquid manure nutrient content O SBG U should use aeration and if necessary by adding silica and brooded until on day 7

Mass balances of nitrogen and phosphorus in an integrated culture of shrimp (Litopenaeus vannamei) and tomato (Lycopersicon esculentum Mill) with low salinity groundwater: A short communication

This study re-examines the performance of an integrated shrimp-tomato system using the nutrients mass balance approach. A budget was calculated based on nutrients analysis, water management, feeding, fertilization, stocking, harvest and sludge removal. Nitrogen and P content in the input water (groundwater) were low, contributing 33.5% and 0.5%, of the total inputs, respectively. Most of the N (43.6%) and P (98.8%) entered to the system as shrimp food. Likewise, 15.2% and 2.5% of the input N, and 8.9% and 4.3% of the input P, were converted to harvested shrimp and tomato plants, respectively; 4.1% N and 24.6% P remained in the organic sludge, while the environmental losses expressed per unit of production were relatively low, 57kgNton−1 and 7.1kgPton−1 of product harvested. About 13.4% of input N was unaccounted for, and was assumed to be lost to the atmosphere via denitrification and volatilization. Comparison between these results and previous studies indicate that the shrimp-tomato system produces a relatively low recovery of N and P as harvested products, however, the main progress reached with this system is the reduction of the environmental losses of N and P in terms of kg of each nutrient per ton of the product harvested.

Stabilisation and mineralisation of sludge in reed bed systems after 10–20 years of operation

Sludge stabilisation and mineralisation during periods of operation between 10 and 21 years were investigated in three different systems receiving sludge from urban wastewater treatment plants situated in Denmark. Samples were taken along the entire profiles, in order to compare the effectiveness of the sludge stabilisation process. Particular attention was given to the stabilisation process occurring within the reed beds; in fact, parameters correlated to biochemical properties of organic sludge matter were determined. Statistical procedures were used to evaluate how the biochemical processes influence the quality of sludge organic matter. The level of total organic carbon and total nitrogen had a similar trend along the profile: their concentration decreased with increasing depth, reaching very low levels at the deepest layers. The same trend was also observed for the water-soluble carbon, N-NH(3), β-glucosidase and urease activities, and hydrolytic enzymes linked to C and N cycles: their values decreased dramatically with increasing depth, meaning that the level of mineralisation of the organic matter was higher in the deepest layers. The determination of extracellular enzymes bound to humic substances and humic carbon permitted evaluation of the stabilisation of organic sludge matter, and also allowed individuation of the ways in which the sludge was stabilised, in terms of mineralisation and humification of the organic matter.