Sludge Of Sewage Treatment Plant Research Articles

The Influence Mechanism of Class Identification and Environmental Values on Garbage Classification Behavior

The current thermal measurement of sewage sludge in urban sewage treatment plants is mainly based on the determination method of coal calorific value. The calorific value of a secondary sewage treatment plant in a city was measured by an automatic calorimeter. The high calorific value of the sample is obtained by referring to the calorific value measuring method of coal. The results show that the sludge drying base heat value in the process section is relatively high, basically all above 12kJ/g. The theoretical analysis of the calorific value of the same batch of samples is in good agreement with the measured results.

Treatment and Disposal Technology of Surplus Sludge in Urban and Town Sewage Treatment Plant

with the continuous acceleration of urban and town construction, the output of urban and town sewage is also increasing. To a great extent, this promotes the technological development and capacity expansion of urban and town sewage treatment plants. In the process of sewage treatment, a lot of sludge is inevitable. However, many urban and town sewage treatment plants pay more attention to the treatment of sewage and ignore the treatment of sludge. In this way, the sludge without proper treatment can be disposed at will. In the long run, this will not only affect the surrounding environment, but also hinder the development of social economy. Therefore, the urban and town sewage treatment plant should pay enough attention to the application of surplus sludge treatment and disposal technology. In this paper, the main problems existing in the treatment and disposal technology of surplus sludge in urban and town sewage treatment plants, and the treatment and disposal technology of surplus sludge in urban and town sewage treatment plants are both explored and analyzed, hoping to contribute to the long-term development of urban and town sewage treatment plants.

Metabolism of 17β-estradiol by Novosphingobium sp. ES2-1 as probed via HRMS combined with 13C3-labeling

This study investigated the biodegradation and metabolic mechanisms of 17β-estradiol (E2) by Novosphingobium sp. ES2-1 isolated from the activated sludge in a domestic sewage treatment plant (STP). It could degrade 97.1% E2 (73.5 μmol/L) in 7 d with a biodegradation half-life of 1.29 d. E2 was initially converted to estrone (E1), then to 4-hydroxyestrone (4-OH-E1), before subsequent monooxygenation reactions cleaved 4-OH-E1 into a metabolite with long-chain ketones structure (metabolite P8). However, when 4-OH-E1 was cleaved through the 4,5-seco pathway, the resulting phenol ring cleavage product could randomly condense with NH3 to yield a pyridine derivative, accompanied by the uncertain loss of a carboxy group at C4 before the condensation. The derivative was further oxidized into the metabolites with both pyridine and long-chain ketones structure (metabolite N5) through a similar formation mechanism as for P8 performed. This research presents several novel metabolites and shows that E2 can be biodegraded into the metabolite with long-chain structure through three optional pathways, thereby reducing E2 contamination.

Generation and Emission of Ammonia During the Full-Scale Composting of Sewage Sludge

The generation and emission of ammonia (NH3) were studied using a continuous monitoring system in an established sewage sludge treatment plant. Results showed that NH3 generation within the pile differed from the emissions at the pile surface during composting. The maximum NH3 concentration reached 600 mg m−3 inside the composting pile and 200 mg m−3 in the outlet gas. The mass of N determined in NH3 generations was 9.97 g kg DM−1, which was 2.57 times higher than the mass of N in NH3 emissions. The highest NH3 generation and emission masses in one aeration cycle occurred during the mesophilic (10.19 mg kg−1) and early thermophilic (6.91 mg kg−1) phases. The relationship between NH3 generation rates and time during one aeration cycle and different composting phases could be expressed as a logarithmic equation, and the relationship between NH3 emission rate and time could be expressed as a quadratic equation.

The Effect of Hydrolysis on Properties of Soot and Tar During the Pyrolysis of Sewage Sludge

In this study, we evaluate the effect of hydrolysis treatment on the properties of tar and soot produced during the pyrolysis of sewage sludge at different operating temperatures (500–800 °C). The pyrolysis experiments were performed in a two-stage tubular fixed-bed reactor at atmospheric pressure. Raw sludge and hydrolysis-treated sludge (at pressure of 0.4 MPa and temperature 200 °C) samples were collected from local municipal sewage sludge treatment plant. The tar and soot samples obtained from pyrolysis at different temperatures were characterized by gas chromatography–mass spectrometry and scanning electron microscopy with energy dispersive X-ray spectroscopy, respectively. The results showed that increase in the pyrolysis temperature decreases the tar and soot yield for both raw and hydrolysis-treated sludge. The minimum tar yield was achieved with hydrolysis-treated sludge at 800 °C. The soot from raw sludge pyrolysis was of greater yield at high temperature than hydrolysis-treated sludge pyrolysis. The tar from pyrolysis of hydrolysis-treated sludge had more aliphatic character as compared to raw sewage sludge. The formation of heavy polycyclic aromatic hydrocarbons during pyrolysis of hydrolysis-treated sludge was lower at high temperatures than that of raw sludge. The aromatic hydrocarbons yield of hydrolysis-treated sludge was higher as compared to raw sludge at 800 °C.

Analysis of Causal Relationships for Nutrient Removal of Activated Sludge Process Based on Structural Equation Modeling Approaches

The removal process of activated sludge in sewage treatment plants is very nonlinear, and removal performance has a complex causal relationship depending on environmental factors, influent load, and operating factors. In this study, how causal relationships are expressed in collected data was identified by structural equation modeling. First, path modeling was attempted as a preliminary step in structural equation model (SEM) construction and, as a result, the nutrient-removal mechanism could not be sufficiently represented as a direct causal relationship between measured variables. However, as a result of the deduced SEMs for effluent total nitrogen (T-N) and total phosphorus (T–P) concentrations, accompanied by exploratory factor analysis to extract latent variables, a causal network was formed that describes the direct or indirect effect of the latent factors and measured variables. Hereby, this study suggests that it is possible to construct an SEM explaining the nutrient-removal mechanism of the activated-sludge process with latent variables. Moreover, nonlinear features embedded in the mechanism could be represented by SEM, which is a model based on linearity, by including causal relations and variables that were not derived by path analysis. This attempt to model the direct and indirect causalities of the process could enhance the understanding of the process, and help decision making such as changing the driving conditions that would be required.

Comparison of different mixing phenomena in anaerobic digestion using food waste and sewage treatment plant for green biofuel through simulations of velocity contours

ABSTRACTThree-dimensional computational fluid dynamics models have been developed for the comparison of diffuser-based biogas recirculation and impeller mixed anaerobic reactors with unmixed reactors for food waste co-digested with sewage treatment plant sludge for enriched with 60–73% of biogas. Enhanced biogas yield was observed in diffuser mixing, intensity of 2 L/min (0.28–1.180 L/g VSr), compared to impeller mixing of 200 rpm. pH of 5.94 from the feed slurry pH range of 7.0–8.4 shows sheathe-broken microbial SEM structure.

Anaerobic Digestion Process for the Production of Biogas from Cassava and Sewage Treatment Plant Sludge in Brazil

Due to the current need for alternative energy sources associated with the practice of actions to improve the environment, residual biomass has gained ground and importance in the energy sector, because of its high availability and cost-benefit, contributing to sustainable development. This study aimed to evaluate the process of anaerobic digestion using cassava wastewater, a pollutant and toxic residue of cassava processing, and sludge from a sewage treatment plant, to determine the best conditions for the production of biogas and to identify its chemical composition, specifically the levels of methane and carbon dioxide. To accomplish this, six anaerobic digestion media were produced and placed into 100-mL penicillin bottles. The experiments were carried out in triplicate, differentiated by the substrate/inoculum concentration (on a mass basis) and by the type of inoculum used (primary or secondary sludge). The best result was achieved using the following media: 80% cassava wastewater and 20% primary sludge, 4:1, which produced the highest methane content in the biogas over the shortest period of time, reaching 81.41% mol/mol of methane in 48 days of fermentation. In this way, biogas produced by cassava wastewater, both in large starch-producing factories and in smaller flour factories, can be used as a source of renewable energy, reducing production costs and providing an environmentally correct destination for this waste.

Mixing strategies of high solids anaerobic co-digestion using food waste with sewage sludge for enhanced biogas production

Mixing strategies of high solids anaerobic digesters using food waste (FW), codigested with sewage treatment plant sludge (STP) was evaluated for green and clean biogas production. Improper anaerobic digestion (AD) mixing leads to poor biogas yield at high organic loading rate (OLR). The present study evaluated the novel method of biogas recirculation using new ‘O’ shaped diffuser design for the AD mixing and compared the performance with the conventional mode of impeller driven mixing and unmixed mode for the optimum FW to STP ratio of 3:1 at high OLR The biogas recirculation frequency of 15 min/h produced maximum biogas (0.28–0.86 L/gVSr). An enhanced biogas yield was observed at intermittant biogas recirculation intensity of 2000 mL/min (0.25–0.92 L/gVSr). This was attributed to the synergistic effect of CO2 acidification and high VFA production at OLR of 6 gVS/Ld. Consequently, led to benefit of reduced digester pH (from 8.3 to 6.6), NH3 control (2380 mg/L), in-situ CH4 enrichment (88%) and sheath protected microbial morphology than the other mixing intensities. It is constructed that an optimum intermittent biogas recirculation could be used as an alternative mixing method for the large scale AD, for enhanced biogas yield, reduced impeller power consumption, and improved energy efficiency.

ECOLOGICAL AND MICROBIOLOGICAL ASSESSMENT OF SEWAGE SLUDGE OF WASTE TREATMENT PLANTS IN THE CITY OF ODESA

Objective. Investigate the number of microorganisms – representatives of various ecological trophic groups in mechanically dewatered and naturally disinfected sewage sludge (SS) of the biological sewage treatment plants (BSTP) “Pivnichna” and “Pivdenna” of the City of Odesa to determine their suitability for microbiological parameters for use as fertilizers in agriculture.
 Methods. Microbiological, statistical.
 Results. It was established that SS of BSTP “Pivdenna” and “Pivnichna” in the City of Odesa, bacteria that consume organic and mineral nitrogen compounds, phosphate-mobilizing microorganisms, are actively developing, due to the presence of the corresponding trophic substrates. By the number of ammonifiers, microorganisms that consume mineral compounds of phosphorus and bacteria capable of hydrolyzing the organophosphates, spore microorganisms, the waste is inferior to traditional organic manure – animal manure. The functional orientation of microbiological processes in the studied substrates is determined on the basis of the obtained data, calculations of the mineralization-immobilization factors and the oligotrophic index. The parameters of the mineralization-immobilization factors (0.04-0.2) in the SS indicate the predominance of synthesis processes over the destruction of organic matter. The oligotrophic index (an indicator of the supply of substrates with easily digestible nutrients) shows insignificant content of nutrients available for microorganisms in SS from BSTP “Pivnichna” (OI = 1.0) and a high level of supply with nutrients of SS from BSTP “Pivdenna” (OI = 0.1). In general, according to microbiological parameters, investigated SS are suitable for use as fertilizing substrates in agriculture.
 Conclusion. Taking into account the obtained data and taking into account the results of previous studies on the compliance of SS with sanitary regulations, it can be considered that the use of SS as fertilizers will have a positive effect on the functioning of agrocenoses.

하수처리장 슬러지의 특성에 관한 연구 -분뇨와 공단폐수를 병합한 도시하수-

하수처리장 슬러지의 특성에 관한 연구 -분뇨와 공단폐수를 병합한 도시하수-

Screening and Application of Phthalic Acid Degrading Bacteria

O-phthalic acid is a kind of important pollutant, which accumulates in the environment with the extensive use of plastics and other products. Meanwhile, phthalic acid is one of the high content of allelopathic autotoxic substances secreted by tobacco. The accumulation of phthalic acid in soil is an important cause of tobacco continuous cropping effect. In order to degrade phthalic acid accumulated in environment, the barrier effect of tobacco continuous cropping caused by phthalic acid accumulation in soil can be removed. A strain capable of degrading phthalic acid was isolated from sludge of sewage treatment plant and compared with 16 s DNA. The homology between this strain and Enterobacter sp. is 99%. The optimum growth conditions are as follows: pH7 at 30°C, 500 mg/L of o-phthalic acid, inoculation concentration ≥ 1.2% and its highest degradation rate of o-phthalic acid is 74%. The results of pot experiment showed that the degradation efficiency of o-phthalic acid in soil was about 40%, which alleviated the inhibitory effect of o-phthalic acid accumulation on tobacco growth.

Seasonal movement of trace-element discharge in a typical south-Indian suburban community.

Four conventional activated sludge sewage treatment plants (STPs) in Southern India were chosen to investigate the occurrence of major ions and trace metals in dissolved fraction of the wastewater. Samples were collected from inlet and outlet of STPs during the pre-monsoon and monsoon seasons. Except for a few elements (Mn, Mo and Ni), the concentrations of the rest increased at the outlet of STPs, suggesting that there is an addition of these elements during the treatment process. The increase in concentrations at the STP outlet ranged from 1.25 times for Mn to 3,254 times for Ag during the pre-monsoon. In the monsoon, the increase ranged from 1.75 (Fe) to 1,510 (Ag). This suggests that there is a substantial anthropogenic input of these elements as they pass through the treatment process. Removal rates of elements in STPs also varied. 59% of Mn was removed during the treatment process during pre-monsoon as compared to 67% removal during monsoon.

Renewable Alkenes from the Hydrothermal Treatment of Polyhydroxyalkanoates-Containing Sludge.

Polyhydroxyalkanoates (PHA) are a key constituent of excess sludge produced by Aerobic Sewage Sludge Treatment plants. The accumulation of significant amount of PHA inside aerobic microbial cells occurs when a surplus of an easily degradable carbon source (e.g., volatile fatty acids, VFA) is found in combination with other nutrients limitation. Herein, hydrothermal treatment (HT) of PHA-containing sludge at 300 and 375 °C was demonstrated to be effective in converting most (>70% w/w) of the bacterial PHA stored inside microbial cells into alkene/CO2 gas mixtures. Simultaneously, most of non-PHA biomass was converted into water-soluble compounds (50% carbon yield) that were acidogenic fermented to produce volatile fatty acids, ideal substrate to feed aerobic bacteria and produce more PHA. According to results here presented, HT of excess sludge with moderate (13%) PHA content can produce about 50 kg of alkenes per tonne of suspended solids treated, with a significant reduction of sludge mass (80% reduction of wet sludge volume) and consequent disposal cost.

Biosafety assessment of municipal wastewater after treatment by Serratia sp. ISTVKR1

The previously described potent biodegrading bacterial strain Serratia sp. ISTVKR1 isolated from sludge of Vasant Kunj Sewage Treatment Plant (VK STP) was used for the study of detoxification of municipal wastewater contaminants with the help of in vitro bioassays conducted on human liver cancer cell line HepG2. The strain has previously been shown to reduce wastewater contaminant load as revealed by a sevenfold reduction in COD and removal of some organic contaminants in the GC–MS analysis of wastewater post-72-h bacterial treatment. Cytotoxicity, genotoxicity and dioxin-like behavior of real municipal wastewater (collected from inlet of VK STP) was assessed before and after bacterial treatment using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), alkaline comet and 7-ethoxyresorufin-O-deethylase (EROD) assays, respectively. The bacterial strain was inoculated into MSM broth (pH = 7.2) containing 50% v/v filter-sterilized influent of VK STP and incubated up to 240 h at 30 °C and 130 rpm. Physicochemical and toxicological analyses were performed for the culture samples. The results of bioassays revealed an increase in cell viability by 40.16% and a reduction in the % EROD activity by 58.4% in the 240-h bacteria-treated sample as compared to the 0-h sample. Genotoxicity as indicated by tail moment (TM) and olive tail moment (OTM) was found to reduce by five- and threefold, respectively, after 240-h bacterial treatment. The results of the study confirmed the potency of the bacterial strain in detoxification of wastewater contaminants.

Thermoeconomic analysis of a biogas-fueled micro-gas turbine with a bottoming organic Rankine cycle for a sewage sludge and food waste treatment plant in the Republic of Korea

Biogas plants experience changes in biogas production due to seasonal weather changes, waste composition variation, operating methods, and other factors. These natural changes affect the economics of the subsystems. Generally, profit can be produced by selling the raw gas or the purified biomethane to the local gas distribution network, or by selling generated electricity in a dedicated power plant. Biogas plants are basically designed for sewage treatment and processing food waste produced from nearby urban areas. In this study, we analyzed the thermoeconomics of a biogas-fueled micro-gas turbine (MGT) system, which is coupled with a bottoming organic Rankine cycle (ORC) for a target biogas plant in Busan, Republic of Korea. Both systems were designed for heating a biodigester using heat in the exhaust gas. For the MGT, we considered a series of commercial multi-unit systems, and the partial-load performance was derived from the performance curves. For the ORC, we first designed an exergy-optimized cycle using n-pentane, a widely used working fluid, and then the partial-load performance was analyzed. The economic parameters were expressed based on the system size. We analyzed the system economics based on the annual utilization ratio (the produced power to the available maximum power) and the net present value (NPV). The effect of system control, methane concentration, and overhaul periods were analyzed. A membrane biogas upgrade system is considered for the comparison. In particular, we have found the followings: first, the biogas power generation systems showed the optimal system scales to provide the maximum NPVs according to the seasonal changes; second, the economics of the system were very sensitive to changes in the biogas methane ratio, electricity prices and overhaul periods; and third, in Korea, where electricity prices are low and natural gas prices are high, the competitiveness of power generation system is very low compared to a system that sells biogas directly.

The effect of hydrolysis on combustion characteristics of sewage sludge and leaching behavior of heavy metals

ABSTRACTThe aim of this paper is to present the effect of hydrolysis treatment on the thermal reaction characteristics of sludge and the leaching test of heavy metals contained in the sludge. Raw and hydrolysis-treated sludge (at temperature of 200°C and pressure 0.4 MPa) samples were collected from local municipal sewage sludge treatment plant. Thermogravimetric analysis was carried out between 25°C and 900°C at the heating rate of 10°C/min and 20°C/min under incineration and pyrolysis atmospheres. The leaching behavior of toxic heavy metals in the sludge was studied along with ash composition. The heating rate significantly changed the thermogravimetric and differential thermogravimetric curve profiles for studied fuels under different atmospheres. After hydrolysis treatment, the heavy metals of hydrolysis-treated sludge becomes more stable. The leaching concentration of Cr, Mn, Cu and Pb in hydrolysis-treated sludge were greatly reduced, when compared to raw sludge; however, no significant change was observed in Cd concentration. The X-ray diffraction pattern of bottom ash of hydrolysis-treated sludge was significantly reduced than raw sludge. This decrease is due to possible reduction in grain growth, which degrades the crystallinity of hydrolyzed sludge, implying that the hydrolysis treatment of sewage sludge could be a promising and beneficially safe disposal technology.

Draft genome sequence of Chryseobacterium limigenitum SUR2T (LMG 28734T) isolated from dehydrated sludge.

The type strain SUR2 of the novel species Chryseobacterium limigenitum was isolated from a dehydrated sludge of the municipal sewage treatment plant in Dogoše near Maribor in Slovenia. The draft genome, with 60 contigs, 4,697,725 bp, 34.4% of G+C content, was obtained using the Illumina HiSeq 2500-1 platform. Joint Genome Institute Microbial Genome Annotation Pipeline (MGAP v.4) has identified 4322 protein-coding sequences including resistance genes against arsenic and other heavy metals. In addition, a subclass B3 metallo-β-lactamase, which confers resistance to penicillins, cephalosporins and carbapenems, was also present in the genome. The genome sequence provides important information regarding bioremediation potential and pathogenic properties of this newly identified species.

Efficient enzymatic degradation used as pre-stage treatment for norfloxacin removal by activated sludge.

Norfloxacin is often found in wastewater treatment plants, groundwater, and even drinking water causing environmental concerns because of its potential undesirable effects on human health or aquatic ecosystems. However, conventional treatments cannot deal with norfloxacin efficiently. This work proposes an efficiently enzymatic degradation of norfloxacin by chloroperoxidase (CPO). 82.18% degradation efficiency of norfloxacin was achieved after 25min reaction time at pH 5.0 with an enzyme concentration of 1.5×10-9molL-1. HPLC-MS was used to determine the intermediates or final products. The product analysis and determination of the chemical oxygen demand indicated if the enzymatic degradation by CPO was carried out before the usually existing bioremediation techniques (usually activated sludge) in sewage treatment plant, the effluent containing norfloxacin can be decontaminated more efficiently and thoroughly than that only by activated sludge treatment. The eco-toxicity tests using a green algae, Chlorella pyrenoidosa, indicated that the toxicity of degraded products of norfloxacin was lower than the parent norfloxacin molecule. CPO-catalyzed degradation of norfloxacin is a promising alternative for treating effluent containing norfloxacin.

Thermodynamic Performance Analysis of a Biogas-Fuelled Micro-Gas Turbine with a Bottoming Organic Rankine Cycle for Sewage Sludge and Food Waste Treatment Plants

In the Republic of Korea, efficient biogas-fuelled power systems are needed to use the excess biogas that is currently burned due to a lack of suitable power technology. We examined the performance of a biogas-fuelled micro-gas turbine (MGT) system and a bottoming organic Rankine cycle (ORC). The MGT provides robust operation with low-grade biogas, and the exhaust can be used for heating the biodigester. Similarly, the bottoming ORC generates additional power output with the exhaust gas. We selected a 1000-kW MGT for four co-digestion plants with 28,000-m3 capacity. A 150-kW ORC system was selected for the MGT exhaust gas. We analysed the effects of the system size, methane concentration, and ORC operating conditions. Based on the system performance, we analysed the annual performance of the MGT with a combined heat and power (CHP) system, bottoming ORC, or both a bottoming ORC and CHP system. The annual net power outputs for each system were 7.4, 8.5, and 9.0 MWh per year, respectively.