Tank Sludge Research Articles

Dynamic analysis of biogas tank

Global warming is a phenomenon that makes us increasingly aware of the importance of protecting nature. Lack of drinking water and waste disposal belong to today’s biggest problem. This is the main reason why we try to recycle, use more renewable energy sources and treat waste ecologically. Drinking water tanks, sludge tanks for wastewater treatment and also tanks for biogas production, so-called fermenters, are becoming gradually more important. For built-up areas, respecting space usability, it is more appropriate to design tanks with a rectangular floor plan (so-called rectangular tanks). We can also use a system of rectangular tanks and thus achieve the most efficient use of space that is intended for them. In this article will be determined whether the proposed rectangular tank, intended for biogas production, has bearing capacity for dynamic loads. Construction of the tank itself must respect the design of the structure, as well as the building material, in order to prevent damage to its structure caused by the filling (it may also contain substances that could contaminate the environment and groundwater). This will ensure the integrity and load-bearing capacity of the tank and there is no risk of leakage. Selected tank is loaded with a standard response spectrum to see how it deforms, using finite element analysis in program ANSYS.

Remediation of phenanthrene contaminated soil through persulfate oxidation coupled microbial fortification

The technology of chemical oxidation coupled microbial remediation of polycyclic aromatic hydrocarbons contaminated soil was efficient and friendly, but the research on the compatibility of chemical oxidation and the bioremediation is insufficient. This study was to explore the compatibility of persulfate oxidation coupled microbial degradation and promote the remediation of phenanthrene contaminated soil. The results showed that the addition of persulfate with the participation of Fe2+ caused the soil environment to be acidic and the soil pH with the lower concentrations (20, 50 mmol/L) of persulfate returned to neutral after 14 days. The content of fulvic-like and humic-like increased after adding persulfate at the same time. Persulfate inhibited the activity of soil dehydrogenase and polyphenol oxidase, simultaneously, the oxidation species generated during the persulfate oxidation process and the acidic environment (pH=4.13) led the soil microbial abundance and diversity to decrease significantly. Besides, the phenanthrene degradation bacterial consortium was screened through a gradual domestication process, which derived from activated sludge in the coking plant wastewater aeration tank of Xuzhou Weitian Chemical Co., Ltd. The efficient degrading bacteria were identified as Pantoea (95%) using high-throughput sequencing, with the 84% degradation rate of phenanthrene after the 7th day. Comparing persulfate oxidation, the removal rate of phenanthrene in the soil was increased by 33% after 63 days of the combined remediation. Adding 20 mmol/L persulfate and inoculating domesticated high-efficiency degrading bacteria Pantoea was recommended in the remediation of PAHs contaminated soil.

Soft Sensing for On-Line Fault Detection of Ammonium Sensors in Water Resource Recovery Facilities.

The increasing demand for online sensors applied to advanced control strategies in water resource recovery facilities has resulted in the increasing investigation of fault-detection methods to improve the reliability of sensors installed in harsh environments. The study herein focuses on the fault detection of ammonium sensors, especially for effluent monitoring, given their potential in ammonium-based aeration control applications. An artificial neural network model was built to predict the ammonium content in the effluent by employing the information from five other sensors installed in the activated sludge tank: NH4+, pH, ORP, DO, and TSS. The residual between the model prediction and the effluent ammonium sensor signal was utilized in a fault-detection mechanism based on principal component analysis and Shewhart monitoring charts. In contrast to previous studies, the present work utilizes typical faults collected from a 1 year historic dataset of an actual sensor setup. Treatment process anomalies, calibration bias faults, and fouling drifts were the most common issues identified from the historic dataset, and they were promptly identified by the proposed fault-detection methodology. Once a fault is detected, the model prediction can be actively used in place of the sensor for process control without affecting the treatment process by utilizing faulty datasets.

INFLUENCE OF THE SIDE VENTILATION ON THE DURABILITY OF THE FUNCTIONING OF DRYING BEDS WITH NON-SATURATED FLOW IN TREATEMENT OF SEPTIC TANK SLUDGE

The non-saturated Flow Drying Beds allow efficient treatment of septic tank sludge. However, they are vulnerable to clogging. To ensure the sustainability of this technology, through an additional supply of oxygen from the lateral surface, a flow model coupled with the variation of the biofilm has been developed. The calibration, validation and comparison of the simulated and experimental results were made from the NASH criterion. The simulations focused on two types of reactors. A reactor with pores on its side surface is called a ventilated reactor (VR). The second is then called an unventilated reactor (UVR). The results show that the maximum applicable organic load is 43.3 mgO2 / cm2 / d at the UVR level and 51.8 mgO2 / cm2 / d at the VR level. In addition, the reduction in free flow porosity is 93.33% at the UVR level and 81% at the AR level. In addition, the results show that when the hydraulic head is less than 5 cm / d, the COD removal efficiency is 96.19% at the UVR level and 95.64% at the VR level. But, when the load is greater than 5 cm / d, the yield is 92.65% at the level of the UVR and of 94.95% at the level of the VR. Thus, in the context of a large-scale operation, lateral ventilation is essential. It guarantees good purification efficiency, slows down internal clogging of beds and accelerates its reversibility when it occurs.

Treating crude oil storage tank sludge by catalytic process and recovering valuable hydrocarbons

Present work deals with management of the sludge deposited at the bottom of the crude oil storage tanks. As a routine practice, this sludge is disposed of by land-filling and during its bioremediation it can quite likely emit methane gas with much higher global warming potential than that of carbon dioxide. Further loss is involved in this disposal method is that of valuable hydrocarbon cuts, and as we report here, exceeding 90 wt% of the sludge comprises of these hydrocarbons. The management term mentioned in the beginning, refers to recovery of hydrocarbons afforded by zeolite catalysed cracking of the sludge and simultaneously, eliminating methane emission. Experiments were carried out using N2 or H2 as carrier gas and using parent and desilicated ZSM-5 and parent and dealuminated zeolite Y (with or without Pt impregnation) at 500 °C and 1 atm pressure. Products were clubbed according to carbon number range corresponding to gasoline, kerosene, gas oil/heavy oil, paraffin wax, and asphaltene/bitumen. Catalytic cracking served a more useful purpose affording higher proportion of valuable lighter products as compared to thermal cracking. The product distributions have been explained on the basis of catalyst properties. Coking behavior of the catalysts also has been briefly discussed.

A review on microbial diversity and genetic markers involved in methanogenic degradation of hydrocarbons: futuristic prospects of biofuel recovery from contaminated regions.

Microbial activities within oil reservoirs have adversely impacted the world's majority of oil by lowering its quality, thereby increasing its recovery and refining cost. Moreover, conventional method of extraction leaves behind nearly two-thirds of the fossil fuels in the oil fields. This huge potential can be extracted if engineered methanogenic consortium is adapted to convert the hydrocarbons into natural gas. This process involves conversion of crude oil hydrocarbons into methanogenic substrates by syntrophic and fermentative bacteria, which are subsequently utilized by methanogens to produce methane. Microbial diversity of such environments supports the viability of this process. This review illuminates the potentials of abundant microbial groups such as Syntrophaceae, Anaerolineaceae, Clostridiales and Euryarchaeota in petroleum hydrocarbon-related environment, their genetic markers, biochemical process and omics-based bioengineering methods involved in methane generation. Increase in the copy numbers of catabolic genes during methanogenesis highlights the prospect of developing engineered biofuel recovery technology. Several lab-based methanogenic consortia from depleted petroleum reservoirs and microcosm studies so far would not be enough for field application without the advent of multi-omics-based technologies to trawl out the bottleneck parameters of the enhanced fuel recovery process. The adaptability of efficient consortium of versatile hydrocarbonoclastic and methanogenic microorganisms under environmental stress conditions is further needed to be investigated. The improved process might hold the potential of methane extraction from petroleum waste like oil tank and refinery sludge, oil field deposits, etc. What sounds as biodegradation could be a beginning of converting waste into wealth by recovery of stranded energy assets.

Factors Affecting the Prevalence of Fecal Pathogen Infections: Approaches for Health Risk Protection

Septic tank sludge or fecal sludge (FS) is often discharged on public areas without any treatment, causing environmental and adverse public health effects. Millennium Development Goal 7c (MDG 7c) targets improved access to water and sanitation because 85% of the world’s total FS is often discharged on public areas. Like other countries, Thailand faces fecal slugde management (FSM) problems leading to significant fecal pathogen infections, especially in the north and northeastern regions. This study assessed the effects of unsafely-managed FS on human health risks in two cities, Natan City and Tham Lod City in Thailand, that have relatively high liver fluke and diarrhea infections, and identified the factors relating to FSM practices that affect the prevalence of liver fluke and diarrhea infections due to FS. Specific measures were proposed in delivering integrated FSM solutions and health risk protection toward the Sustainable Development Goal No. 6 (SDG6) targets of safely managed sanitation and hygiene services. Based on data collected from these cities from February to May 2019, factors relating to FSM practices that affect the prevalence of liver fluke and diarrhea infections were identified and analysed using multiple regression analysis. Based on the findings, specific measures in delivering integrated FSM solutions and health risk protection toward the Sustainable Development Goals 6 (SDG 6) are proposed. Because no FS treatment facilities operate in Natan City and Tham Lod City, almost 100% of FS is discharged directly into open drains, resulting in diarrhea and liver fluke infections among local people. The findings identified the factors relating to FSM practices that affect the prevalence of liver fluke and diarrhea infections and proposed specific measures in delivering integrated FSM solutions and health risk protection, such as promoting education programmes, avoiding direct FS discharges into open drains and nearby streams, and providing innovative FSM technologies to eradicate fecal pathogen infections.

Comprehensive Survey of the Silt Reservoir Structures Technical Condition

The aim of this work is to obtain information about the condition of the sludge tank supporting and enclosing building structures, identifying and fixing existing defects in order to assess their possible impact on structures during its further operation. Archival surveys were carried out, site documentation was selected and studied, load-bearing structures engineering measurements were carried out, building structures were inspected, and the structural condition was photographed selectively, graphic materials were made, technical conclusions were drawn up with conclusions and recommendations for further structures safe operation in order to achieve this goal. The technical surveying included a building structures external examination with damages fixation. The structures general technical condition of the, the presence and nature of the defect’s propagation were previously visually recorded, and then refined using measuring equipment. Verification calculations were also carried out with the design and current load analysis on the sludge tank elements, and the tank supporting structures concrete strength was determined by the ultrasonic method.

The efficiency improvement of faecal sludge management with rate increase of biodegradation in septic tanks and pit latrines

The article discusses the environmental and economic aspects of faecal sludge management in an individual residential sector, proposes approaches to solving the problem, discusses findings in improving the effectiveness of the biodegradation rate of faecal sludge and domestic wastewater in a septic tank, and evaluates the using adequacy of biological additives for accelerating faecal sludge biodegradation.

Ultrasound Velocity-Based Phase Content Measurement of Oil Sludge in Storage Tank

Oil sludge presents a harmful but economically valuable waste. A large amount of oil sludge is produced during the processes of extraction, refining, storage, and transportation of petroleum. The contents of oil, water, and slag in the oil sludge are important parameters that determine the economic value of oil sludge and the choice of oil recovery methods. Most existing phase-content measurement methods can be applied only to the oil-water two-phase mixtures. A simple, low cost, and fast ultrasonic velocity based method is proposed in this paper. The proposed method can realize the three-phase content measurement of oil sludge in storage tanks. First, a semi-empirical model of water content in the oil-water mixture, which describes the relationship between ultrasound velocity and water content in the mixture, is derived. Next, the effect of the temperature on the ultrasound velocity is investigated. Within a certain temperature range, ultrasonic waves in water have different velocity characteristics that depend on temperature than that in oil. Then the effect of the slag on the ultrasound velocity is analyzed experimentally. Based on these effects, a three-phase content measurement method based on ultrasound velocity is proposed. A prototype of three-phase content measurement is developed and experiments are carried out to validate the proposed method. Experimental results show that the proposed method can realize the three-phase content measurement of oil sludge in the storage tank, achieving the root mean square error (RMSE) of the water content of 1.48% and the RMSE of the slag content of 0.73%.

Sludge Reduction in a Full-scale Wastewater Treatment Plant Using Ultra-fine-and Micro-bubble Ozonation

ABSTRACT Biological wastewater treatment plants (WWTPs) produce large amounts of excess sludge. One approach to reduce sludge is treatment with ozone, which promotes sludge disintegration and solubilization. Here we report the first application of ultra-fine- and micro-bubble (UFB/MB) ozonation to sludge reduction in a full-scale WWTP. UFB/MB ozonation using a spiral liquid-type UFB generator was applied to concentrated excess sludge in the storage tank instead of to return sludge. At an ozone dose of 15 mgO3 gSS–1, a 92% reduction in sludge accumulation rate was achieved during a 237-day ozonation period with ozonation relative to a 100-day no ozonation period without ozonation. This reduction was larger than expected, and was partly due to a 20–30% greater average concentration of suspended solids in the influent during the no ozonation period. Addition of UFB/MB ozonation to the existing activated sludge process did not reduce the water quality in the effluent. We can conclude that UFB/MB ozonation for concentrated excess sludge in the storage tank using a spiral liquid-type UFB generator remarkably reduced the ozone dose required to sludge reduction by more than half of the reported conventional ozonation (30–150 mgO3 gSS–1) without the negative impact on effluent water quality.

Estimating the minimum number of SARS-CoV-2 infected cases needed to detect viral RNA in wastewater: To what extent of the outbreak can surveillance of wastewater tell us?

There is increasing interest in wastewater-based epidemiology (WBE) of SARS-CoV-2 RNA to serve as an early warning system for a community. Despite successful detection of SARS-CoV-2 RNA in wastewaters sampled from multiple locations, there is still no clear idea on the minimal number of cases in a community that are associated with a positive detection of the virus in wastewater. To address this knowledge gap, we sampled wastewaters from a septic tank (n = 57) and biological activated sludge tank (n = 52) located on-site of a hospital. The hospital is providing treatment for SARS-CoV-2 infected patients, with the number of hospitalized patients per day known. It was observed that depending on which nucleocapsid gene is targeted by means of RT-qPCR, a range of 253–409 positive cases out of 10,000 persons are required prior to detecting RNA SARS-CoV-2 in wastewater. There was a weak correlation between N1 and N2 gene abundances in wastewater with the number of hospitalized cases. This correlation was however not observed for N3 gene. The frequency of detecting N1 and N2 gene in wastewater was also higher than that for N3 gene. Furthermore, nucleocapsid genes of SARS-CoV-2 were detected at lower frequency in the partially treated wastewater than in the septic tank. In particular, N1 gene abundance was associated with water quality parameters such as total organic carbon and pH. In instances of positive detection, the average abundance of N1 and N3 genes in the activated sludge tank were reduced by 50 and 70% of the levels detected in septic tank, suggesting degradation of the SARS-CoV-2 gene fragments already occurring in the early stages of the wastewater treatment process.

Lipid Production and Waste Reutilization Combination Using Yeast Isolate Rhodotorula mucilaginosa LP-2

For transforming the massive amounts of extensive wasted glycerol from the procedure of biodiesels production, oleaginous yeasts were isolated from an activated sludge tank located at a biodiesel manufacturing factory in this study. One of the isolated oleaginous yeast proved with the most lipid production potential was identified as Rhodotorula mucilaginosa LP-2 by 18S rDNA sequencing. The optimal conditions for lipid production among strain R. mucilaginosa LP-2 were investigated. The optimum temperature for maximum lipid productivity was 33 °C. The most suitable carbon and nitrogen sources for strain R. mucilaginosa LP-2 to accumulate lipids were pure glycerol and yeast extract, respectively. C/N ratio was also demonstrated to be the significant factor for intracellular lipid accumulation. Cell growth and lipid production were both inhibited when the C/N ratio was higher than 85. The highest lipid yield was observed at C/N ratio of 65 due to a significant impact on the degree of fatty acid desaturation of this strain.

Analysis of the features of activated sludge biocenosis in aeration tanks at wastewater treatment plants

Application of the method of microscopy and visual analysis of the composition of activated sludge in aeration tanks. The advantage and ease of use of the microscopy. Detection of violations in the biocenosis of activated sludge at early stages. Characteristics and diversity of microorganisms in activated sludge. Consequences of accidents at sewage treatment plant.

Study on septic sludge utilization to coordinate with agricultural wastes to produce compost fertilizer

IVietnam, little attention is being paid to the management and treatment of septic tank sludge to take advantage of the number of nutrients in this available resource. This paper presents the potentials and performance of the compost production on the mixing of septic tank sludge and agricultural residues as coffee husk, coconut husk, peat. It added supplementary by 5% bioproducts of Trichoderma sp and 30 ml of molasses in 45days. The results showed the highest quality compost, being mixes of septic tank sludge and coffee husks with total N = 4.01%, total P = 0.41%, total K2O = 3.68% and accepting for the Vietnam standards of fertilizer regulations, resulted also illustrated that E.coli concentration in septic tank sludge sample decreased 2.5 - 3.3 times compared to the previous sample. The second one, the composting efficiency was surveyed on the growth of green mustard plant during 31 days by basal fertilizing and top dressing of this compost at 10 days. The growth of the green mustard plant showed the high compost efficiency septic tank sludge and coffee husk based on 28.21cm of height and 62.5g / plant weight. Especially, NT4 combining from septic tank waste, coffee husk with chemical fertilizers was a good formula by getting the best result in all treatment by combined of compost and chemical fertilizer was at the top dressing period, seems the high compost efficiency in helping Brassica juncea grow well by growing green mustard, being 31.25cm of height and 95.83g / plant weight.

A method to estimate the direct nitrous oxide emissions of municipal wastewater treatment plants based on the degree of nitrogen removal

The greenhouse gas nitrous oxide (N2O) is produced in activated sludge tanks as a byproduct of nitrification and heterotrophic denitrification. Insufficient knowledge on how microbiological N2O generation and degradation pathways impact N2O emissions in activated sludge tanks still hampers the development of effective mitigation strategies. Our research contributes to overcome this gap by quantifying N2O emissions through extensive measurement campaigns at ten full-scale wastewater treatment plants and correlating them to relevant operating parameters by multivariate regression analysis. Measurements revealed that N2O production depends mainly on the activity of nitrifying bacteria and is triggered by high ammonium concentrations. In contrast, well-performing heterotrophic denitrification plays a key role as a sink of N2O in activated sludge tanks. Following these patterns, low loaded plants achieving high nitrogen removal (83–92%) exhibited the lowest N2O emission intensity (0.0012 ± 0.001 kg N2O–N emitted per kg TKN in the influent wastewater). The regression analysis corroborated these results by revealing a negative linear correlation between the N2O emission factor and the total nitrogen removal degree of the plants. The regression model represents a novel estimation method that links N2O emissions with plant performance and provides a significant improvement over approaches applying fixed N2O emission factors.

Impact of Use Septic Tank Sludge for the application as Pozzolanic Material in high performance concrete

The disposal of septic tank sludge (SS) delivered from wastewater treatment plants is progressively getting to be a risk to the environment for includes Organic compounds which are scary to the public health and environment; over-volumes are every day created and deficiency of relevant landfill sites for wastes. This study aims to explore the impact of septic tank sludge as partial substitutions of ordinary Portland cement (PC) within the production of high-performance concrete (HPCs). The water/binder (W/B) ratio of all kinds of blends is fixed at 0.36 with total binder content of 492 kg/m3. The concrete mixtures, in portion, are replaced with 0%, 5%, 10%, 15% and 20% of SS, individually. The impact of SS used to be analyzed through physical and chemical tests. The workability test of HPC was once decided to utilize the slump flow, Meanwhile compressive strength and tensile strength splitting experiments were conducted to investigate the impact of septic tank sludge on the hardened properties of HPC. The results demonstrated that SS may be a responsive pozzolanic material (PM) ; consequently which could be used as PM in concrete mixes. The concrete blend contains 5% cement substitution with SS illustrated to improve hardened properties of concrete at the all-age of specimens evaluated by comparing to concrete control. Sensibly, the substitution of 20 % septic tank sludge is desirable for creating high-performance concrete.

The Removal of Residual Concentration of Hazardous Metals in Wastewater from a Neutralization Station Using Biosorbent-A Case Study Company Gutra, Czech Republic.

This article deals with the possibility of using a biosorbent in the form of a mixture of cones from coniferous trees to remove the residual concentration of hazardous metals contained in hazardous waste, which is disposed of in a neutralization station. The efficiency of the tested biosorbent in removing Ni, Zn, Cu, and Fe was monitored here. Laboratory research was carried out before the actual testing of the biosorbent directly in the operation of the neutralization station. With regard to the planned use of the biosorbent in the operational test, the laboratory experiments were performed in a batch mode and for the most problematic metals (Ni and Zn). The laboratory tests with real wastewater have shown that the biosorbent can be used to remove hazardous metals. Under the given conditions, 96% of Ni and 19% of Zn were removed after 20 min when using NaOH activated biosorbent with the concentration of 0.1 mol L−1. The inactivated biosorbent removed 93% of Ni and 31% of Zn. The tested biosorbent was also successful during the operational tests. The inactivated biosorbent was applied due to the financial costs. It was used for the pre-treatment of hazardous waste in a preparation tank, where a significant reduction in the concentration of hazardous metals occurred, but the values of Ni, Cu, and Zn still failed to meet the emission limits. After 72 h, we measured 10 mg L−1 from the original 4,056 mg L−1 of Ni, 1 mg L−1 from the original 2,252 mg L−1 of Cu, 1 mg L−1 from the original 4,020 mg L–1 of Zn, and 7 mg L−1 from the original 1,853 mg L−1 of Fe. However, even after neutralization, the treated water did not meet the emission limits for discharging into the sewer system. The biosorbent was, therefore, used in the filtration unit as well, which was placed in front of the Parshall flume. After passing through the filtration unit, the concentrations of all the monitored parameters were reduced to a minimum, and the values met the prescribed emission limits. The biosorbent was further used to thicken the residual sludge in the waste pre-treatment tank, which contributed to a significant reduction in the overall cost of disposing of residual hazardous waste. This waste was converted from liquid to solid-state.

Experimental investigation of petrochemical industrial wastewater treatment by a combination of integrated fixed-film activated sludge (IFAS) and electro-Fenton methods

The toxic and dangerous wastewater from the petrochemical industry should be effectively treated before it is discharged into the environment. In this study, the electro-Fenton (EF) process was performed as a pre-treatment for petrochemical wastewater that resulted from olefin, methanol, aromatic, ammonia, and urea units. The effects of the solution pH, electric current, hydrogen peroxide (H2O2) concentration, and reaction time on chemical oxygen demand (COD) removal and sludge volume index (SVI) values were investigated. The treated wastewater of an EF process was used as feed for an integrated fixed-film activated sludge (IFAS) process. The effect of the ratio of the inlet wastewater volume to the activated sludge in the aeration tank and the influence of the fixed media and retention time on the IFAS system capacity were evaluated. The results showed that an increase in the electric current and H2O2 concentration led to an improvement in the COD removal while increasing the pH had a negative effect on the wastewater treatment. Furthermore, the initial pH of 3, electric current of 160 mA, H2O2 concentration of 65 mM, and reaction time of 30 min were introduced as optimum conditions for the subsequent stage of the treatment. Finally, the IFAS system demonstrated better performance than the conventional activated sludge (AS) method.

Fate and seasonal change of Escherichia coli resistant to different antibiotic classes at each stage of conventional activated sludge process.

This study investigated the impact of each treatment stage of the activated sludge process on the fate of antibiotic resistant bacteria (ARB) in wastewater treatment plants (WWTPs). Wastewater and sludge samples were collected monthly at each stage of a commercial-scale WWTP. After 20-25 strains of indicator Escherichia coli were isolated from each sample on Chromocult Coliform Agar, antibiotic resistance of the isolates to amoxicillin (AMX), ciprofloxacin (CIP), norfloxacin (NFX), kanamycin (KM), sulfamethoxazole/trimethoprim (ST) and tetracycline (TC) were tested with the Kirby-Bauer disk diffusion method. As a result, activated sludge in the aeration tank and return sludge had higher abundance of antibiotic resistant E. coli than influent wastewater and secondary treatment effluent. AMX resistant E. coli was enriched in return sludge at the secondary clarifier. Higher temperature was also likely to cause an increase of AMX resistant E. coli in sludge. The antibiotic resistance profile of E. coli in secondary treatment effluent was more dependent on activated sludge than influent wastewater. These results suggested that activated sludge in WWTP possibly serves as a reservoir of ARB, and that behavior of ARB in WWTP differs by antibiotic classes.