Urban Sewage Treatment Research Articles

Research to Control the Pollution of Membrane Bioreactor by Activated Silica Filler

For the purpose of re-purification of domestic sewage, a new type of active silica packing was used to control the pollution of membrane bioreactors. The change law of membrane flux and its influencing factors during the long-term operation were investigated. In this paper will show the main filler to the membrane flux decay, as well as further study on the effect of domestic sewage treatment. After 42 days of continuous testing, the average membrane flux was designed at 84L/m2·h, the membrane bioreactor cleaning cycle increased by 30% to 40%, the membrane life expectancy increased by 30% to 40% and the sewage treatment speed increased by 25% to 35%. The treated reclaimed water has a COD of 11.7-18.1 mg/L, a BOD5 of 3.2-5.6 mg/L, an ammonia nitrogen of 8.54-9.10 mg/L, a hardness of 2.5 mmol/L, a turbidity of 1.91NTU, a chroma of 4, a suspended matter of 0.0001 mg/L, pH value of 7.20, a salt content of 0.07%, a conductivity of 960μs/cm and a TDS of 734mg/L, meeting the first-class requirements of the urban sewage treatment plant pollutant discharge standard and the integrated waste water discharge standard.

Economic assessment of an integrated waste to energy system for an urban sewage treatment plant: A numerical approach

The economic assessment of an integrated anaerobic digestion and gasification system for the exploitation of the residues from an urban sewage treatment plant is carried out. The obtained bio-fuels are used in a cogeneration unit to produce both electric and thermal energy.The analysis focuses on the water treatment plant of a touristic town, characterized by a highly variable number of inhabitants. Therefore, the amount of input biomass for the integrated plant results remarkably time dependent and the design accounts for the transient nature of the input.The performance of the integrated system is modelled by developing an ad-hoc dynamic library for the simulation of the energy conversion systems under the OpenModelica open source platform. The system's performance and economic assessment are modelled by means of equations and correlations that calculate the components' behaviour on a time dependent basis.The simulation demonstrates that the final wastes to landfill decrease by a 73% improving significantly the environmental impact of the plant. Furthermore, the proposed integrated system is able to produce the 25% of the electric energy required for the plant operation. Thus, the payback period of the integrated plant results to be lower than 3 years.

Emission Inventory of Greenhouse Gas from Urban Wastewater Treatment Plants and Its Temporal and Spatial Distribution in China

Urban wastewater treatment plants are considered important greenhouse gas resources with massive emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) during operation. Based on the emission factor approach of pollutant reduction, the 2014 emission inventory of greenhouse gases (CO2, CH4, and N2O) from urban wastewater treatment plants in China was established. In addition, the temporal and spatial distribution and influencing factors of greenhouse gas emissions were analyzed in this study. The results showed that total emissions of greenhouse gas from urban wastewater treatment plants in China was 7348.60 Gg (CO2-eq) in 2014, which included CO2, CH4, and N2O emissions of 6054.57 Gg, 27.47 Gg (769.08 Gg, CO2-eq), and 1.98 Gg (524.95 Gg, CO2-eq), respectively. The difference in greenhouse gas emissions among provinces was significant:high emissions appeared in the eastern areas of China, low emissions were observed in the northwest, and hardly any emissions were found in Xizang. From 2005 to 2014, annual greenhouse gas emissions from urban sewage treatment plants in China increased by 229.4%, and the rates of CO2, CH4, and N2O increased by 217.9%, 217.9%, and 520.3%, respectively. The regional economic development level and number of wastewater treatment plants were correlated the most with the emissions of greenhouse gasses, and the per-capita protein supply was closely related with the N2O emission.

Effects of Sewage Treatment on Microbial Community Structure of Surface Water in Xiantao Wetland

[Objective] The aim of study is to research the treatment of urban sewage by the semi natural wetland method in the high connectivity water system of the surface water and surface water in the inland waterway. [Methods] Microbial diversity and community structure in the surface water of eight samples on the Xiantao artificial wetland were investigated by using the Illumina Miseq sequencing technique and the resulting microbial data were statistically analyzed in combination with environmental variabl. [Results] The results showed that COD concentration had a very significant positive correlation with total microbial communities (r = 0.700, P t groups (r = 0.488, P

Effect of Methyl Paraben on Sludge Reduction

Activated sludge process is the most widely used sewage treatment technology, which accounts for more than 90% of urban sewage treatment processes and about 50% of industrial wastewater treatment processes. The essence of the activated sludge process is that microorganisms use the biodegradable organic matter in the sewage as nutrients for metabolism and meanwhile remove them, while large amounts of sludge would be generated inevitably during the sewage treatment process. The cost for the sludge treatment accounts for about 50% of the operating cost of the sewage treatment plant. In this study, the effects of uncoupler propyl paraben on sludge reduction and sewage treatment were conducted, and the results showed that the optimized concentration of propyl paraben for sludge reduction was 30 mg/l, which achieved 41% sludge reduction effect. Under the optimized propyl paraben concentration, the average removal rate of COD increased from 93.35% in the blank group to 94.53%; the average removal rate of NH4+-N increased from 65.47% in the blank group to 83.84%; the average removal rate of PO43--P from the 58.47% in the blank group increased to 67.36%; meanthile the sludge kept good settalbility during the sewage treatment process.

The Model of Urban Sewage Treatment under Possibility Measure

This paper was investigated the pro blem of urban sewage treatment under the possibility theory. An expected revenue decision model of urban sewage treatment with penalty parameter was established. Based on the possibility measure, the model was transformed into an equivalent nonlinear cons trained optimization model, and the existence of solutions of the model was proved. An example was given to verify the existence of solutions.

Influence of rapid rural-urban population migration on riverine nitrogen pollution: perspective from ammonia-nitrogen.

China is undergoing a rapid transition from a rural to an urban society. This societal change is a consequence of a national drive toward economic prosperity. However, accelerated urban development resulting from rapid population migration from rural to urban lands has led to high levels of untreated sewage entering aquatic ecosystems directly. Consequently, many of these regions have been identified as hot spots of riverine nitrogen (N) pollution because of the increasing level of urban point-source discharge. In order to address this concern, we assessed effects of urban development on ammonia-nitrogen (AN) loads using a panel data regression model. The model, expressed as an exponential function of anthropogenic N inputs multiplied by a power function of streamflow, was applied to 20 subwatersheds of the Huai River Basin for the years 2003-2010. The results indicated that this model can account for 81% of the variation in annual AN fluxes over space and time. Application of this model to three scenarios of urban development and sewage treatment (termed urbanization priority, sustainable development, and environmental priority) suggests that future N pollution will inevitably deteriorate if current urban environmental management and investment are not significantly improved. Stronger support for environmental management is very critical to alleviate N pollution and improve water quality. More effort should focus on improving sewage treatment and the N removal rate of the current sewage system in light of the increasing degree of urbanization.

Insufficient decontamination in Sewage treatment plants induce the risk of artificial selection of extended-spectrum β-lactamase producing Escherichia coli.

Quantitative data about extended-spectrum beta-lactamase producing E. coli (ESBLEC) in the wastewaters are scarce, especially in developing countries. These data could be useful to raise awareness about the potential risk of spreading ESBLEC strains in the community. Water samples were collected weekly over a 10-week period, from one urban sewage treatment plant (STP), one rural STP and one hospital complex's wastewater (HWW) in Turkey. Mean E. coli and ESBLEC loads were determined for each sampling point. For the 580 ESBLEC isolated, antimicrobial resistance profiles, phylogenetic grouping, presence of common beta-lactamese-typesand integrons were studied using PCR. The mean ESBLEC ratio was accounted for 0.58%, 0,12%, 1.53% of the total E. coli in urban, rural untreated wastewater and HWW, respectively. These values were higher for the outlets. The mean number of different antimicrobial classes to which the strains were resistant was highest in urban STP (4.0± 1.6). The antimicrobial resistance ratios of ESBLEC strains isolated from HWW were observed to be in between those of urban and rural STPs. The most common phylogenetic group was C composing (29.7%) and the most susceptible strains belonged to phylogroup B1. Wastewater treatments without sufficient decontamination, resulting in artificial selection of ESBLEC might lead to public health risk as these strains reach communities through environment. To avoid such risks and protect the human health as well as the environment, well-established decontamination measures imposing barriers against this artificial selection should be implemented.

Experimental study of the growth characteristics of microbial fouling on sewage heat exchanger surface

Urban sewage is widely used as a heat source in the heat pump system. However, the sewage contains large quantity of micro-organisms, which can encourage fouling on heat exchanger surfaces during operation. Microbial fouling can seriously affect the heat transfer efficiency. Iron bacteria (IB) and sulfate-reducing bacteria (SRB) are the main bacteria responsible for forming microbial fouling. This study investigated the fouling growth characteristics in heat exchanger. For this purpose, the IB and SRB from water in urban sewage treatment plants were separated and purified, and the runner state of sewage heat exchanger pipeline was simulated by designing the flow channel model. The wet and dry weights of the fouling formed by IB at different temperatures, fluid flow velocities and bacteria concentrations were analyzed via weighing method. The influence of these factors on the fouling formation by IB was further analyzed. In addition, a comparative study was conducted on the composite fouling after the addition of SRB. The results show that the fouling formed by IB is composed of iron precipitates and organics. At 20–40°C, the fouling rate of IB is faster, and the fouling generated is higher, when the temperature is higher. With the increase in flow velocity, the rate of fouling reduces, and the fouling gross decreases. The concentration of IB affects the rate of fouling so that the lower the initial concentration is, the faster the fouling rate of IB is. The structure of the composite fouling after adding SRB becomes more compact.

Plants Selection for Domestic Sewage Treatment in Jilin City

This experiment studied the removal efficiency of domestic sewage by testing 19 species of wetland plants along the Songhua River in Jilin City. It is shown that plants can purify domestic sewage, and the ability of removal efficiency is varied on different species. Rumex patientia var.callosus is the best in removal efficiency of TN(29.14%);Coleus blumei Benth. could effectively reduce output of TP and COD,the best removal efficiencies for TP is 58.04%, COD is 95.18%; Oenanthe javanica(Blume) DC. has better efficiency to increase DO in´sewage, and the maximum increase is 262.22%;Rumex.patientia var.callosus,Alisma orientale(Sam.)Juz.,Oenanthe javanica(Blume) DC.,Erigeron annuus (L. ) Pers. may be used as plants for the construction of sewage treatment landscape, because these plants have better comprehensive capacity for domestic sewage treatment.
 Water pollution has become a general and worldwide problem today. The application of wetland plants for waste water treatment features low cost,easiness to manage, high efficiency and etc.(Han Xiaoyuan etc.,2005;Li linfeng etc.,2006;Zhang Honggang,Hong Jianming,2006).Wetland plants can not only absorb nitrogen and phosphorus directly but also remove the heavy metals and organics in the waste water. (Xu Weiwei etc.,2005;Cheng Wei etc.,2005;C.C.Tanner,2001;Tang Shirong,2006;SAMAKEMoussa,2003;L.K.Mitchell,A.D Karathanasis,1995).According to current research reports,Phragmitas communis Trin, Juncus effuses Linn, Rush, and Iris japonica Thunb, Buttery Swordflag can efficiently remove nitrogen and phosphorus from the sewage (Deng Futang etc.,2005;Yuan Donghai etc.,2004;A. Fey,G. Benckiser,J.C.G. Ottow,1999).The constructed wetlands consisting of varied plants,such as Phragmitas communis Trin,Canna indica Linn. or Acorus gramineus Soland,Grassleaved Sweetflag,are effective in eliminating chemical oxygen demand(“COD”) in the waste water(Zhao Jiangang etc.,2006;Zhong Yushu etc.,2006;Yuan Donghai etc.,2004).Therefore wetlands can be used to reduce water pollution(Weng Meiya etc.,2005;Liu Zilian etc.,2005;Robert M. Seams,1995).So far most current studies have been developed in the South China with few in the Northeast area of China. 19 kinds of wetland plants growing along the Songhua River is selected in Jinlin City. We analyze and decide which plants are suitable for plant landscape application due to their better urban sewage treatment functions.

The start-up of denitrifying phosphorus removal system by using nitrite as electron acceptor

The inoculation of short-cut denitrifying polyphosphate-accumulating organisms (DPAOs) mainly included two-phase inoculation and three-phase inoculation. The short-cut denitrifying phosphorus removal bacteria were quickly inoculated by sequencing batch reactor (SBR) to treatment domestic wastewater. The results showed that the average effluent concentration of TP was 0.85 mg/L after 132 cycles by 44 days in two-phase inoculation. The removal rates of NO2--N, TP and COD were 94.73%, 95.47% and 89.96% after 126 cycles by 42 days in three-phase inoculation, and the effluent concentrations were separately 1.31 mg/L, 0.45 mg/L and 17.07 mg/L, which reached the first A class requirement of Urban sewage treatment plant pollutant discharge standard. It was indicated that the efficiency of three-phase inoculation was higher. Anoxic phosphorus uptake was influenced seriously by anaerobic residual carbon, and it was the difference of the two inoculations.

Assessment of the municipal water cycle in China

Water produced from municipal utilities accounts for nearly 10% of the sum water demand in China. The municipal water cycle that integrates processes of urban water supply, water use, sewage treatment, and water reclamation has been assessed for 655 cities across nine drainage areas in mainland China in 2012. These cities in total extracted 55km3 raw water for municipal use from surface waterbodies and ground aquifers, approximate to the countrywide freshwater extraction of Russia or Italy. After purification and transmission, 45km3 water was distributed to industrial, service, and domestic users. 36km3 of post-use sewage was collected and environmentally safely treated; merely 3.2km3 of the treated water was reclaimed. Driven by increasing urbanization, the municipal water demand in cities of China may grow 70% by 2030. The Hai River and the Huai River basins, which harbor 137 cities and occupy a majority of the densely populated North China Plain, are most exposed to physical water scarcity. The municipal water abstraction in these cities can remain constant by promoting demand-side and process conservation in the next two decades. Interbasin transfer and unconventional sources will provide municipal water double than the cities' need. Whereas the urban water security can be technically enhanced, the challenges are to better improve water use efficiency and mitigate economic and environmental costs of the municipal system.

Research on Upgrading and Reconstruction in Low Concentration Urban Sewage Treatment Plants

Research on Upgrading and Reconstruction in Low Concentration Urban Sewage Treatment Plants

Exploration on the technology for ozone reduction in urban sewage treatment

With the rapid development of China’s economy, urban water consumption is increasing. However, sewage treatment plants will produce large amounts of sludge after treatment of sewage. Generally, and the sludge treatment costs are relatively high. Therefore, the problem about how to deal with the sewage sludge becomes the hot issues. Municipal waste water treatment plant produces a lot of sludge. This paper summarized the abroad study of ozonation minimization technology. Introduction and discussion were made on the principle of ozonated efficiency of sludge minimization, the efficiency of sludge minimization and the relationship between efficiency and ozone dosage, as well the effect of return sludge ozonated on waste water treatment running and the sludge setting and the dewatering characteristic. The economic estimation was also made on this technology. It’s showed that sludge minimization technology exhibits extensive application foreground.

Combustion performance and slagging characteristics during co-combustion of Zhundong coal and sludge

Zhundong coal (ZDc) with a very large reserve is faced with severe problems of slagging and fouling during combustion in boilers because of the high-Na content. Sludge, the by-product of urban sewage treatment, is also faced with the problem in utilization. In this study, the co-combustion of ZDc and sludge was investigated in a laboratory-scale experimental apparatus before further studies in larger-scale setups. The experimental results confirm an interaction between ZDc and sludge during co-combustion, which was mainly caused by the Na catalytic action and improved the combustion performance of the co-fuels. The catalytic effect was particularly significant at low sludge mixing ratios. The reactions between Na-based compounds in ZDc and Si/Al/P-rich minerals in sludge, forming high-melting-point phosphates and aluminosilicates, not only increased Na retention in residual ash reducing the risk of fouling on tail-heating surfaces in boilers, but also raised the ash fusibility of the co-fuels avoiding low-temperature sintering. Even so, to prevent slagging, the high combustion temperature above 900 °C should be avoided during co-combustion because of the high Na retention in residual ash. Moreover, the high heavy metal retention in residual ash decreased the pollution caused by heavy metal volatilization during sludge combustion.

Evaluating the Potential of Biodiesel Production through Microalgae Farming in Photobioreactor and High Rate Ponds from Wastewater Treatment

In the last decade, the research works on microbial as a potential source of lipid for biodiesel production have been growing. In this work, the potential of a sludge from high-rate lagoons in urban sewage treatment, composed mainly by Chlorella sp., as oil source for biodiesel production, was studied. The potential of Chlorella sp. growth in photobioreactor under controlled conditions was also investigated. Low lipid content (up to 3%) was observed in both cases. The composition of both oils showed high amount of fatty acids and fatty acid based compounds, however there are also other non-fatty acid based lipids. Density and viscosity of biodiesel from biosolid oil were determined and the results showed that these physico-chemical properties do not match the specification required for biodiesel. The results showed that sewage sludge from Samambaia treatment station (DF, Brazil) and Chlorella sp. cultivated under the conditions described in this work are not potential sources of fatty material for biodiesel production.

Urban stormwater – greywater management system for sustainable urban water management at sub-watershed level

Urban water management involves urban water supply (import, treatment and distribution of water), urban wastewater management (collection, treatment and disposal of urban sewage) and urban storm water management. Declining groundwater tables, polluted and declining sources of water, water scarcity in urban areas, unsatisfactory urban water supply and sanitation situation, pollution of receiving water bodies (including the ground water), and urban floods have become the concerns and issues of sustainable urban water management. This paper proposes a model for urban stormwater and sewage management which addresses these concerns and issues of sustainable urban water management. This model proposes segregation of the sewage into black water and greywater, and urban sub-watershed level stormwater-greywater management systems. During dry weather this system will be handling only the greywater and making the latter available as reclaimed water for reuse in place of the fresh water supply. During wet weather, the system will be taking care of (collection and treatment) both the storm water and the greywater, and the excess of the treated water will be disposed off through groundwater recharging. Application of this model in the Patiala city, Punjab, INDIA for selected urban sub-watersheds has been tried. Information and background data required for the conceptualization and design of the sub-watershed level urban stormwater-greywater management system was collected and the system has been designed for one of the sub-watersheds in the Patiala city. In this paper, the model for sustainable urban water management and the design of the Sub-watershed level Urban Stormwater-Greywater Management System are described.

Isolation of lytic bacteriophages against pathogenic Escherichia coli strains in poultry in the northwest of Iran

In this study, 90 internal organ samples of poultry with symptoms of colibacillosis were obtained from Maragheh poultry farms in East Azerbaijan, Iran. In total, 70 bacterial isolates were confirmed as Escherichia coli (E. coli) strains using standard biochemical tests, and antibiotic sensitivity was determined by the disk diffusion method. Antibiotics used in this study included ampicillin, penicillin, nitrofurantoin, tetracycline, amoxicillin, ciprofloxacin, nalidixic acid, and sulfamethoxazole (n=8). Ciprofloxacin showed the highest susceptibility, while the lowest susceptibility was observed with penicillin and amoxicillin. Among the bacterial isolates, 50% showed resistance to at least five antibiotics, and 10 isolates with multidrug resistance were selected for bacteriophage (phage) isolation against recent E. coli isolates using spot test and double-layer agar overlay technique. In addition, water samples for phage isolation were provided from rivers, poultry farm sewages, and an urban sewage treatment center. In total, eight phages were successfully isolated from the urban sewage treatment center (total: 10). After enrichment, purification and titration, phages were further concentrated by polyethylene glycol precipitation. Lowest and highest bacteriophage titers were determined to be 1.05×106 and 1.9×109 PFU/ml, respectively. Host range of the isolated phages was assayed by spot testing, and antibacterial effects against four E. coli isolates were observed in one of the isolated phage suspensions, which was introduced as the most potentiated agent for phage therapy. In the morphological analysis of the selected phage using an electron microscope, we observed a hexagonal head with a diameter of 95 nm and contractile tail length of 90 nm, which indicated its similarity to the Myoviridae family. In conclusion, results of this study showed that bacteriophages could be appropriate alternatives to combat pathogenic E. coli strains with antibiotic resistance in poultry. Considering the changeable antibacterial effects of bacteriophages against different isolates of extraintestinal avian pathogenic E. coli, it is suggested that future investigations be conducted regarding the efficacy of lytic phages against different bacterial strains for the effective control of the associated infections in this region of Iran.

Phosphorus Removal Mechanism of Sulfur/Sponge Iron Composite Fillers Based on Denitrification

In order to improve the phosphorus removal effect in the denitrification and phosphorus synchronous removal process by sulfur/sponge iron composite fillers, the phosphorus removal effect by different fillers with the coupling microorganisms was studied to analyze the denitrifying phosphorus removal mechanism of the microbial coupling sulfur/sponge iron composite fillers. The research result showed that the phosphorus removal ratio of sponge iron/sulfur composite fillers was over 95%, which was increased by 30% as compared to only sponge iron filler. In addition, the effluent TP concentration was reduced to less than 0.1 mg·L-1. The analysis of X-ray diffraction(XRD)and total iron concentration indicated that the main phosphorus removal system products which were produced in the corrosion and phosphorus removal process of sponge iron were FeOOH, FeS and Fe4 (PO4)3 (OH)3 deposits and dissolved iron ions; FeS and FeOOH which were the hydrolysis products of Fe2+ and Fe3+ converted PO43- to Fe4(PO4)3(OH)3 by adsorption and deposition so that phosphorus removal could be achieved. After the reactor of microbial coupling sulfur/sponge iron carbon composite fillers became stable, the removal efficiency of TN and TP could reach 90% and more than 83%, respectively; Corrosion of sponge iron and phosphorus removal process could also be promoted by biological iron and H+ that was produced in the sulfur autotrophic denitrification process, the system could realize the combination of "heterotrophic synergy autotrophic" composite denitrification and chemical phosphorus removal, and efficient denitrifying denitrification synchronous phosphorus removal process could be achieved in the urban sewage treatment plant.

Estrogenic compounds in Tunisian urban sewage treatment plant: occurrence, removal and ecotoxicological impact of sewage discharge and sludge disposal.

The occurrence, fate and ecotoxicological assessment of selected estrogenic compounds were investigated at Tunisian urban sewage treatment plant. The influents, effluents, as well as primary, secondary and dehydrated sludge, were sampled and analyzed for the target estrogens to evaluate their fate. All target compounds were detected in both sewage and sludge with mean concentrations from 0.062 to 0.993 μg L-1 and from 11.8 to 792.9 μg kg-1dry weight, respectively. A wide range of removal efficiencies during the treatment processes were observed, from 6.3 % for estrone to 76.8 % for estriol. Ecotoxicological risk assessment revealed that the highest ecotoxicological risk in sewage effluent and dehydrated sludge was due to 17β-estradiol with a risk quotient (RQ) of 4.6 and 181.9, respectively, and 17α-ethinylestradiol with RQ of 9.8 and 14.85, respectively. Ecotoxicological risk after sewage discharge and sludge disposal was limited to the presence of 17β-estradiol in dehydrated-sludge amended soil with RQ of 1.38. Further control of estrogenic hormones in sewage effluent and sludge is essential before their discharge and application in order to prevent their introduction into the natural environment.