A two-stage system analysis of real and pseudo urban human settlements in China

2021 ◽  
Vol 293 ◽  
pp. 126272
Author(s):  
Qirui Xue ◽  
Xiaohua Yang ◽  
Feifei Wu
Keyword(s):  
System Analysis ◽  
Two Stage ◽  
Human Settlements ◽  
Stage System ◽  
Urban Human Settlements

The anaerobic treatment of a ligno-cellulosic substrate offering little natural pH buffering capacity

1998 ◽  
Vol 38 (4-5) ◽  
pp. 29-35 ◽  
Author(s):  
C. J. Banks ◽  
P. N. Humphreys
Keyword(s):  
Ph Control ◽  
Anaerobic Treatment ◽  
Buffering Capacity ◽  
Single Stage ◽  
Stable Operation ◽  
Reactor Performance ◽  
Two Stage ◽  
Ph Buffering ◽  
Stage System ◽  
The Stability

The stability and operational performance of single stage digestion with and without liquor recycle and two stage digestion were assessed using a mixture of paper and wood as the digestion substrate. Attempts to maintain stable digestion in both single stage reactors were unsuccessful due to the inherently low natural buffering capacity exhibited; this resulted in a rapid souring of the reactor due to unbuffered volatile fatty acid (VFA) accumulation. The use of lime to control pH was unsatisfactory due to interference with the carbonate/bicarbonate equilibrium resulting in wide oscillations in the control parameter. The two stage system overcame the pH stability problems allowing stable operation for a period of 200 days without any requirement for pH control; this was attributed to the rapid flushing of VFA from the first stage reactor into the second stage, where efficient conversion to methane was established. Reactor performance was judged to be satisfactory with the breakdown of 53% of influent volatile solids. It was concluded that the reactor configuration of the two stage system offers the potential for the treatment of cellulosic wastes with a sub-optimal carbon to nitrogen ratio for conventional digestion.

Two-stage system for robust neutral/lombard speech recognition

2007 ◽  
Author(s):  
Hynek Bořil ◽  
Petr Fousek ◽  
Harald Höge
Keyword(s):  
Speech Recognition ◽  
Two Stage ◽  
Stage System

Innovation comprehensive solutions for off-gases cleaning in steel industry. Technical solutions for dusty gas flows cleaning

2021 ◽  
Vol 77 (5) ◽  
pp. 593-601
Author(s):  
D. A. Serebryanskii ◽  
M. N. Korolev ◽  
M. V. Antonov ◽  
I. O. Tyapkova
Keyword(s):  
Raw Materials ◽  
Gas Flows ◽  
Two Stage ◽  
Gas Cleaning ◽  
Hard Particles ◽  
Centrifugal Filter ◽  
Maximum Permissible Concentrations ◽  
Pneumatic Transportation ◽  
Stage System ◽  
Technical Solutions

Metallurgical production associates with such processes as crushing, drying and pneumatic transportation of raw materials, roasting, melting etc., in the process of which hard particles and harmful gaseous components are emitted into atmosphere. At pneumatic transportation of raw materials and sand, their concentration in the atmosphere as a rule exceeds maximum permissible concentrations. Existing facilities of dusty flows cleaning in some cases don’t ensure sanitary norms ГН 2.1.6.3492‒17. Technical solutions  proposed  to  clean  gases  in  a  centrifugal  filter,  a  facility  of  complex  gas  cleaning – cyclo-filter and two-stage  system  of high-concentrated gas-dust flows cleaning. Description of the centrifugal filter, cyclo-filter, two-stage facility of gas cleaning design presented. The facility comprises centrifugal filter and ceramic pulse filter. Industrial tests of the centrifugal filter ЦФ2-6-1 under conditions of a system of pneumatic transportation of sand established, that efficiency of gas-dust flows cleaning of sand particles in a  six-channel  filter  can  reach 98.65%.  Application of  two-stage  system  of  gas  cleaning  comprising  centrifugal  filter  and  ceramic pulse filter ФКИ enables to reach residual hard particles concentration at the exit of such a facility of 5 mg/m3, having initial dust level of 127878 mg/m3. Application of such a complex two-stage cleaning facility allows to reach values of 0.1 of maximum permissible concentrations near the source of emissions.

scholarly journals Transformations, threats and the bond of chlorine in the processes of burning the wastes

2019 ◽  
Vol 213 ◽  
pp. 02046
Author(s):  
Danuta Król ◽  
Sławomir Poskrobko
Keyword(s):  
Combustion Chamber ◽  
Combustion Process ◽  
Animal Waste ◽  
Two Stage ◽  
Bone Material ◽  
Gas Products ◽  
Stage System ◽  
Gas Space ◽  
Exhaust Purification ◽  
Purification Plant

The aim of the study was to present the possibility of reducing the emission of HCl to the atmosphere and the possibility of limiting the formation of PCDD/F in the technologies of incineration of waste fuels and incineration of animal waste. Waste fuel and animal biomass were burned in a two-stage system i.e.: Io-gasification and IIo-combustion of gas products of gasification. As part of the implementation, the reduction of HCl emissions to air was investigated when Ca(OH)2 was added as an additive to the fuel from waste. Ca(OH)2 bonded HCl releasing into the gas space in the combustion process. HCl binding in the combustion chamber not only limited its emission to the atmosphere. Its elimination also limited the possibility of creating PCDD/F. In case of animal waste, HCl was captured with CaO produced from the decomposition of bone material (hydroxyapatite). The efficiency of this process was low. It was thus necessary to remove it in the built-in exhaust purification plant.

Optimization of subsurface vertical flow constructed wetlands for wastewater treatment

2007 ◽  
Vol 55 (7) ◽  
pp. 71-78 ◽  
Author(s):  
G. Langergraber ◽  
Ch. Prandtstetten ◽  
A. Pressl ◽  
R. Rohrhofer ◽  
R. Haberl
Keyword(s):  
Grain Size ◽  
Specific Surface ◽  
Surface Area ◽  
Constructed Wetlands ◽  
Organic Load ◽  
Vertical Flow ◽  
Two Stage ◽  
Main Layer ◽  
Free Drainage ◽  
Stage System

Constructed wetlands (CWs) use the same processes that occur in natural wetlands to improve water quality and are used worldwide to treat different qualities of water. This paper shows the results of an Austrian research project having the main goals to optimize vertical flow beds in terms of surface area requirement and nutrient removal, respectively. It could be shown that a subsurface vertical flow constructed wetland (SSVFCW) operated with an organic load of 20 g COD.m−2.d−1 (corresponding to a specific surface area demand of 4 m2 per person) can fulfil the requirements of the Austrian standard regarding effluent concentrations and removal efficiencies. During the warmer months (May – October), when the temperature of the effluent is higher than 12 °C, the specific surface area might be further reduced. Even 2 m2 per person have been proven to be adequate. Enhanced nitrogen removal of 58 % could be achieved with a two-stage system (first stage: grain size for main layer 1–4 mm, saturated drainage layer; and second stage: grain size for main layer 0.06–4 mm, free drainage) that was operated with an organic load of 80 g COD.m−2.d−1 for the first stage (1 m2 per person), i.e. 40 g COD.m−2.d−1 for the two-stage system (2 m2 per person). Although the two-stage system was operated with higher organic loads a higher effluent quality compared to a single-stage SSVFCW (grain size for main layer 0.06–4 mm, free drainage, organic load 20 g COD.m−2.d−1) could be reached.

Expired food products and used disposable adult nappies mesophilic anaerobic co-digestion: Biochemical methane potential, feedstock pretreatment and two-stage system performance

2021 ◽  
Vol 168 ◽  
pp. 309-318
Author(s):  
Konstantina Tsigkou ◽  
Dimitris Zagklis ◽  
Panagiota Tsafrakidou ◽  
Paraskevi Zapanti ◽  
Georgios Manthos ◽  
...  
Keyword(s):  
System Performance ◽  
Food Products ◽  
Biochemical Methane Potential ◽  
Two Stage ◽  
Methane Potential ◽  
Stage System
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