scholarly journals A Review on Rotating Biological Contactors

2019 ◽  
Vol 4 (2) ◽  
pp. 241-256 ◽  
Author(s):  
Sharjeel Waqas ◽  
Muhammad Roil Bilad
Keyword(s):  
Biological Processes ◽  
Operational Cost ◽  
Wastewater Treatment Process ◽  
Factors Affecting ◽  
Effluent Quality ◽  
Pros And Cons ◽  
Overall Performance ◽  
Low Costs ◽  
Rotating Biological Contactors ◽  
Effluent Characteristics

Rotating biological contactors (RBC) is a wastewater treatment process that provides a both acceptable effluent quality and organic removal efficiency at a comparatively very low costs. It is highly attractive due to simplicity of operation, low sludge production, small foot-print, low maintenance, and low operational cost. Complete nitrification/denitrification can be achieved by varying the disk submergence level and operating the process under both anaerobic/anoxic conditions in a single unit. In this review, pros and cons of RBC are discussed in detail along with the factors affecting its performances. Organic and hydraulic loading and hydraulic retention time are the main parameters followed by additional parameters such as rotational speed, media, disk submergence, dissolved oxygen level, influent and effluent characteristics, and step-feeding in affecting the performance of an RBC system. RBC has shown promising results for the removal of biodegradable matter, nitrogen and phosphorous removal. The approaches for hybridization of biological processes to improve their overall performance are also review. Such success story is assess so explore possibility of developing RBC based hybrid processes. Hybrid RBC can be form from in-combination with other processes for minimizing energy requirements and maximizing the efficiency of the system.

Performance Analysis of the Rotating Biological Contactor Process Based on Particle Fraction and Improvement of Final Effluent Quality

1991 ◽  
Vol 23 (7-9) ◽  
pp. 1457-1466 ◽  
Author(s):  
Kazuhiro Tanaka ◽  
Minoru Tada ◽  
Mitsuo Ito ◽  
Noritugu Shimizu
Keyword(s):  
Suspended Solids ◽  
Fine Particles ◽  
Wastewater Treatment Plants ◽  
Small Scale ◽  
Particle Fraction ◽  
Effluent Quality ◽  
Rotating Biological Contactors ◽  
Activated Sludge Processes ◽  
Fraction Method ◽  
Final Effluent

Biofilm processes are, in general, suitable for small-scale wastewater treatment plants. However, final effluent qualities of biofilm processes are not as good as those of activated sludge processes due to fine particles remaining in the effluents. To improve the effluent qualities of the Rotating Biological Contactors (RBC) process, the behavior of fine particles through the process and the removal of fine particles with solids-liquid separation methods, rapid filtration and coagulation-filtration, were investigated using the particle fraction method. The results are as follows:–An increase of the hydraulic retention time (HRT) in the RBC reactor reduced the amount of fine particles and increased the amount of coarse suspended solids of 44 µm or more in diameter, which are easily removed by clarification. Thus, the final effluent qualities were improved by the increase of HRT.–Suspended solids in effluent from the RBC process at the standard loading are so fine that improvement of the quality is not expected by only lowering the overflow rate of a final clarifier. In contrast, rapid filtration or a coagulation-filtration process is effective. The supended solid concentration and transparency of the effluent from the final clarifier was improved by a factor of two to four, and then BOD of the final effluent was removed by 40-85%.

scholarly journals Pots as alternative and sustainable fishing gears in the Mediterranean Sea: an overview

2021 ◽  
Author(s):  
Andrea Petetta ◽  
Massimo Virgili ◽  
Stefano Guicciardi ◽  
Alessandro Lucchetti
Keyword(s):  
Mediterranean Sea ◽  
Early Stage ◽  
Spiny Lobster ◽  
Mesh Size ◽  
Octopus Vulgaris ◽  
Target Species ◽  
Factors Affecting ◽  
Fishing Gears ◽  
Pros And Cons ◽  
The Mediterranean

AbstractStock overexploitation, bycatch, discards and gear impacts on the environment are outstanding issues for Mediterranean fisheries. The adoption of alternative fishing gears is an appealing solution to ensure a more sustainable exploitation of resources. We discuss the pros and cons of pots as alternative gears by reviewing their main designs, spatial distribution and target species in the Mediterranean basin. We assessed the technical factors affecting the catch efficiency of the different pot designs for four target species: spiny lobster, Palinurus elephas; Norway lobster, Nephrops norvegicus; common octopus, Octopus vulgaris and pandalid shrimps, Plesionika spp. We found that pot volume is important to catch Octopus; mesh size to catch Nephrops and Plesionika; entrance surface to catch Octopus, Nephrops and Plesionika; pot shape/colour and entrance shape/position to catch Octopus and Plesionika; and bait type to catch Octopus and Nephrops. The literature review shows that pot fisheries have several considerable advantages over conventional gears, especially in terms of discards, bycatch, seabed impacts (particularly compared with bottom trawls and passive set nets), size and species selectivity, gear depredation, catch quality and gear cost, besides saving time and labour. Disadvantages hampering their wider diffusion include ghost fishing, a low catch of finfish species, the narrow range of species targeted by each pot design and the current early stage of research. These data make a clear case for using pots as alternative gears to traditional ones in the Mediterranean Sea in some areas and seasons to catch certain target species.

scholarly journals The role of a chemical loop in removal of hazardous contaminants from coke oven wastewater during its treatment

2019 ◽  
Vol 17 (1) ◽  
pp. 1288-1300
Author(s):  
Anna Kwiecińska-Mydlak ◽  
Marcin Sajdak ◽  
Katarzyna Rychlewska ◽  
Jan Figa
Keyword(s):  
Chemical Treatment ◽  
Treatment Process ◽  
Oxygen Demand ◽  
Coke Oven ◽  
Main Role ◽  
Biological Processes ◽  
Coal Processing ◽  
Wastewater Treatment Process ◽  
Iron Based

AbstractCoke oven liquor is one of the most contaminated liquid streams generated by the coal processing industry, thus its proper treatment and utilization is crucial for sustainable and environmentally neutral plant operation. The conventional wastewater treatment process comprises of chemical and biological processes. Within the current research the detailed role of chemical treatment is described. Commercially available iron-based coagulants (PIX100, PIX100COP, PIX113, PIX116) were tested to understand their removal efficiency and impact on the stream parameters. The influence of iron dose in the range of 300-500 mgFe/L on the process performance was also examined.It was found that the main role of chemical treatment was to bind toxicants harmful to activated sludge microorganisms, i.e. free and complex cyanides and sulphides. Among the tested iron-based conventional coagulants ferrous salts were more efficient than ferric salts. It was also observed that efficiency of the process strongly depended on wastewater properties (especially in regard to pH, which should be in the range of 9-10) and the coagulant selection needed to be done individually for a given wastewater type. The removal rates of particular contaminants were diversified and for free cyanides, complex cyanides and sulphides they were in the range of 23-91%, -156-77% and -357-98%, respectively. The expected, simultaneous removal of chemical oxygen demand (COD) during the treatment was not observed and even the parameter value increased after the process due to probable formation of compounds less vulnerable to oxidation.

scholarly journals Comparative investigations of nonlinear and linear observers for a highly manoeuvrable target in sliding mode guidance

2017 ◽  
Vol 65 (2) ◽  
pp. 233-245
Author(s):  
Y. Wang ◽  
M. Sun ◽  
S. Du ◽  
Z. Chen
Keyword(s):  
Sliding Mode ◽  
Guidance System ◽  
Key Factors ◽  
Factors Affecting ◽  
First Order ◽  
Guidance Law ◽  
Linear Observer ◽  
Overall Performance ◽  
Twisting Algorithm ◽  
Different Levels

Abstract Target manoeuvre is one of the key factors affecting guidance accuracy. To intercept highly maneuverable targets, a second-order sliding-mode guidance law, which is based on the super-twisting algorithm, is designed without depending on any information about the target motion. In the designed guidance system, the target estimator plays an essential role. Besides the existing higher-order sliding-mode observer (HOSMO), a first-order linear observer (FOLO) is also proposed to estimate the target manoeuvre, and this is the major contribution of this paper. The closed-loop guidance system can be guaranteed to be uniformly ultimately bounded (UUB) in the presence of the FOLO. The comparative simulations are carried out to investigate the overall performance resulting from these two categories of observers. The results show that the guidance law with the proposed linear observer can achieve better comprehensive criteria for the amplitude of normalised acceleration and elevator deflection requirements. The reasons for the different levels of performance of these two observer-based methods are thoroughly investigated.

Behavior and Performance of Refrigerant Mixture HFC125/HC290 in Heat Pumps

2013 ◽  
Author(s):  
Xiaowei Fan ◽  
Fang Wang ◽  
Huifan Zheng ◽  
Xianping Zhang ◽  
Di Xu
Keyword(s):  
Energy Consumption ◽  
Heat Pumps ◽  
Operating Conditions ◽  
Environment Friendly ◽  
Factors Affecting ◽  
Refrigerant Mixture ◽  
Important Direction ◽  
Overall Performance ◽  
And Performance ◽  
Binary Refrigerant

The refrigerant mixtures provide an important direction in selecting new environment-friendly alternative to match the desirable properties with the existing halogenated refrigerants or future use in the new devices, in which, HFCs refrigerants with zero ODP combined with HCs refrigerants with zero ODP and lower GWP are of important value in the fields of application. In the present work, research on HFC125/HC290 (25/75 by mass) binary refrigerant mixture used in heat pumps was carried out, and parameters, factors affecting the performance were investigated, and compared with that of HCFC22 under the same operating conditions. It has been found that the new mixture can improve the actual COP by 2 to 13% and hence it can reduce the energy consumption by 20 to 31.5%. The overall performance has proved that the new refrigerant mixture could be a promising substitute for HCFC22.

Wastewater modification processes assessment in a stabilization reservoir

2008 ◽  
Vol 57 (7) ◽  
pp. 1037-1045 ◽  
Author(s):  
G. Mannina ◽  
G. Mancini ◽  
M. Torregrossa ◽  
G. Viviani
Keyword(s):  
Organic Matter ◽  
Performance Optimization ◽  
Flow Reactor ◽  
Batch Reactor ◽  
Mechanistic Model ◽  
Resource Planning ◽  
Treated Wastewater ◽  
State Variables ◽  
Factors Affecting ◽  
Effluent Quality

A semi-empirical mechanistic model able to simulate the dynamics of a stabilization reservoir was developed incorporating both settling of particulate components and chemical/biological processes. Several factors affecting the reservoir effluent quality were taken into account: hydraulics and hydrology, solar radiation, atmospheric reaeration, algae, zooplankton, organic matter, pathogen bacteria, and sediment-water interaction. The model quantifies the specific influence of each factor on effluent quality, evaluating the correlation between the different considered factors. State variables included in the model were: algae, dissolved oxygen, organic matter, zooplankton and indicator bacteria. The model was transferred into a computational code in order to provide a useful and versatile tool for water resource planning management issues. The model was verified by comparing simulated results with full-scale data collected from a small reservoir (Sicily, IT) filled with partially treated wastewater. The reservoir has a volume of 11,000 m3, a maximum depth of 6.3 m and a mean depth of about 5 m. The monitoring period lasted four months during which the reservoir operated in different hydraulics conditions: as a standard batch reactor and as a continuous flow reactor. The model was able to reproduce the behaviour of the principal simulated parameters thus representing a potential tool for the management and performance optimization of these peculiar storage/treatment systems.

scholarly journals A Novel Model with GA Evolving FWNN for Effluent Quality and Biogas Production Forecast in a Full-Scale Anaerobic Wastewater Treatment Process

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Zehua Huang ◽  
Renren Wu ◽  
XiaoHui Yi ◽  
Hongbin Liu ◽  
Jiannan Cai ◽  
...  
Keyword(s):  
Neural Network ◽  
Wastewater Treatment ◽  
Treatment Process ◽  
Biogas Production ◽  
Anaerobic Treatment ◽  
Production Rates ◽  
Wastewater Treatment Process ◽  
Effluent Quality ◽  
Anaerobic Wastewater Treatment ◽  
Novel Model

The anaerobic treatment process is a complicated multivariable system that is nonlinear and time varying. Moreover, biogas production rates are an important indicator for reflecting operational performance of the anaerobic treatment system. In this work, a novel model fuzzy wavelet neural network based on the genetic algorithm (GA-FWNN) that combines the advantages of the genetic algorithm, fuzzy logic, neural network, and wavelet transform was established for prediction of effluent quality and biogas production rates in a full-scale anaerobic wastewater treatment process. Moreover, the dataset was preprocessed via a self-adapted fuzzy c-means clustering before training the network and a hybrid algorithm for acquiring the optimal parameters of the multiscale GA-FWNN for improving the network precision. The analysis results indicate that the FWNN with the optimal algorithm had a high speed of convergence and good quality of prediction, and the FWNN model was more advantageous than the traditional intelligent coupling models (NN, WNN, and FNN) in prediction accuracy and robustness. The determination coefficients R2 of the FWNN models for predicting both the effluent quality and biogas production rates were over 0.95. The proposed model can be used for analyzing both biogas (methane) production rates and effluent quality over the operational time period, which plays an important role in saving energy and eliminating pollutant discharge in the wastewater treatment system.

A comparison of NH4/NO3 control strategies for alternating activated sludge processes

1999 ◽  
Vol 39 (4) ◽  
pp. 93-102 ◽  
Author(s):  
L. J. S. Lukasse ◽  
K. J. Keesman ◽  
A. Klapwijk ◽  
G. van Straten
Keyword(s):  
Activated Sludge ◽  
Time Delays ◽  
Control Strategies ◽  
Treatment Plant ◽  
Biological Processes ◽  
Effluent Quality ◽  
N Removal ◽  
Activated Sludge Reactor ◽  
The Difference ◽  
Activated Sludge Processes

Four control strategies for N-removal in alternating activated sludge plants (ASP's) are compared: 1. timer-based, 2. switching the aeration on/off when depletion of nitrate/ammonium is detected, 3. switching the aeration on/off when ammonium crosses an upper/lower-bound, 4. the newly developed adaptive receding horizon optimal controller (ARHOC) as presented in Lukasse et al. (1997). The comparison is made by simulating the controllers' application to an alternating continuously-mixed activated sludge reactor preceded by a small anoxic reactor for predenitrification. The biological processes in the reactors are modelled by the activated sludge model no. 1. Realistic influent patterns, measured at a full-scale wastewater treatment plant, are used. The results show that three totally different controllers (timer-based, NH4-bounds based and ARHOC) can achieve a more or less equal effluent quality, if tuned optimally. The difference mainly occurs in the sensitivity to suboptimal tunings. The timer-based strategy has a higher aeration demand. The sensitivity of the ARHOC controller to sub-optimal tuning, known measurement time delays and changing plant loads is significantly less than that of the other controllers. Also its tuning is more natural and explicit.

scholarly journals Non-volant modes of migration in terrestrial arthropods

2014 ◽  
Vol 2 (1) ◽  
Author(s):  
Don R. Reynolds ◽  
Andrew M. Reynolds ◽  
Jason W. Chapman
Keyword(s):  
Atmospheric Transport ◽  
Transport Processes ◽  
Biological Processes ◽  
Factors Affecting ◽  
Terrestrial Arthropods ◽  
Taxonomic Range ◽  
Migratory Movements ◽  
Dispersal Kernels ◽  
Typical Mode ◽  
Behavioural Adaptations

AbstractAnimal migration is often defined in terms appropriate only to the ‘to-and-fro’ movements of large, charismatic (and often vertebrate) species. However, like other important biological processes, the definition should apply over as broad a taxonomic range as possible in order to be intellectually satisfying. Here we illustrate the process of migration in insects and other terrestrial arthropods (e.g. arachnids, myriapods, and non-insect hexapods) but provide a different perspective by excluding the ‘typical’ mode of migration in insects, i.e. flapping flight. Instead, we review non-volant migratory movements, including: aerial migration by wingless species, pedestrian and waterborne migration, and phoresy. This reveals some fascinating and sometimes bizarre morphological and behavioural adaptations to facilitate movement. We also outline some innovative modelling approaches exploring the interactions between atmospheric transport processes and biological factors affecting the ‘dispersal kernels’ of wingless arthropods

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