scholarly journals Implementation of fuzzy optimization approach to facultative wastewater stabilization ponds problem considering fuzzy parameters

2021 ◽  
Keyword(s):  
Fuzzy Optimization ◽  
Optimization Approach ◽  
Stabilization Ponds ◽  
Fuzzy Parameters ◽  
Wastewater Stabilization Ponds

Nitrification in bulk water and biofilms of algae wastewater stabilization ponds

2007 ◽  
Vol 55 (11) ◽  
pp. 93-101 ◽  
Author(s):  
M.A. Babu ◽  
M.M. Mushi ◽  
N.P. van der Steen ◽  
C.M. Hooijmans ◽  
H.J. Gijzen
Keyword(s):  
Model Equation ◽  
Bulk Water ◽  
Balance Model ◽  
Nitrification Rate ◽  
Relative Contribution ◽  
Activity Test ◽  
Stabilization Ponds ◽  
Wide Range ◽  
Water Columns ◽  
Wastewater Stabilization Ponds

Nitrogen removal in wastewater stabilization ponds is poorly understood and effluent monitoring data show a wide range of differences in ammonium. For effluent discharge into the environment, low levels of nitrogen are recommended. Nitrification is limiting in facultative wastewater stabilization ponds. The reason why nitrification is considered to be limiting is attributed to low growth rate and wash out of the nitrifiers. Therefore to maintain a population, attached growth is required. The aim of this research is to study the relative contribution of bulk water and biofilms with respect to nitrification. The hypothesis is that nitrification can be enhanced in stabilization ponds by increasing the surface area for nitrifier attachment. In order to achieve this, transparent pond reactors representing water columns in algae WSP have been used. To discriminate between bulk and biofilm activity, 5-day batch activity tests were carried out with bulk water and biofilm sampled. The observed value for Rnitrbulk was 2.7 × 10−1 mg-N L−1 d−1 and for Rbiofilm was 1,495 mg-N m−2 d −1. During the 5 days of experiment with the biofilm, ammonia reduction was rapid on the first day. Therefore, a short-term biofilm activity test was performed to confirm this rapid decrease. Results revealed a nitrification rate, Rbiofilm, of 2,125 mg-N m−2 d−1 for the first 5 hours of the test, which is higher than the 1,495 mg-N m−2 d−1, observed on the first day of the 7-day biofilm activity test. Rbiofilm and Rnitrbulk values obtained in the batch activity tests were used as parameters in a mass balance model equation. The model was calibrated by adjusting the fraction of the pond volume and biofilm area that is active (i.e. aerobic). When assuming a depth of 0.08 m active upper layer, the model could describe well the measured effluent values for the pond reactors. The calibrated model was validated by predicting effluent Kjeldahl nitrogen of algae ponds in Palestine and Colombia. The model equation predicted well the effluent concentrations of ponds in Palestine.

A robust fuzzy optimization approach for reverse logistics network design with buyback offers

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Masoud Amirdadi ◽  
Farzad Dehghanian
Keyword(s):  
Reverse Logistics ◽  
Fuzzy Optimization ◽  
Model Performance ◽  
Return Rate ◽  
Optimization Approach ◽  
Mathematical Methods ◽  
Content Type ◽  
Logistics Network ◽  
Reverse Logistics Network ◽  
Actual Return

Purpose In this paper, the authors aim to investigate the relationship between buyback policy and the potential number of used products that could be collected by developing a robust fuzzy reverse logistics network. Design/methodology/approach In this approach, the authors seek to determine the amount of buyback based on the condition of used products at the time of return. In this process, the authors also take into account that apart from the condition of used products, other factors exist that the actual return rate could be dependent on them. This matter propelled us to make a novel distinction between the probability of return estimated from appropriate buybacks offered to consumers, and the actual return rate of used products using fuzzy mathematical methods. Besides that, a compatible robust fuzzy optimization method has been implemented on the model to deal with uncertain properties of it and simultaneously fortifying its responses against any possible effect of return rate fluctuation. Findings To analyze and evaluate the model performance, the authors decided to apply a series of exhaustive randomly generated experiments onto it. Also, the authors introduced a Lagrangian relaxation solution methodology to facilitate and improve the solving process of the model. Then, the evaluation of the results enabled us to demonstrate the model validity, and underscore its utility to deal with problems with more sophisticated used product collection process that practitioners tend to encounter in the real-world circumstances. Originality/value This study suggests a novel way to design the return rate of used products in a reverse logistics network with buyback offers through a complete set of factors affecting it. Furthermore, the procedure of developing the model encompasses several important aspects that significantly decrease its complexity and improve its applicability.

Innovative Hybrid Genetic Algorithms and Line Search Method for Industrial Production Management

2010 ◽  
pp. 142-160 ◽  
Author(s):  
Pandian M. Vasant
Keyword(s):  
Production Management ◽  
Optimization Problems ◽  
Fuzzy Optimization ◽  
Computational Techniques ◽  
Optimization Approach ◽  
Non Linear Programming ◽  
Decision Variables ◽  
Line Search Method ◽  
Non Linear ◽  
Management Optimization

Many engineering, science, information technology and management optimization problems can be considered as non linear programming real world problems where the all or some of the parameters and variables involved are uncertain in nature. These can only be quantified using intelligent computational techniques such as evolutionary computation and fuzzy logic. The main objective of this research chapter is to solve non linear fuzzy optimization problem where the technological coefficient in the constraints involved are fuzzy numbers which was represented by logistic membership functions by using hybrid evolutionary optimization approach. To explore the applicability of the present study a numerical example is considered to determine the production planning for the decision variables and profit of the company.

Fuzzy Optimization Approach

2007 ◽  
Vol 2024 (1) ◽  
pp. 82-91 ◽  
Author(s):  
Y. Sazi Murat ◽  
Shinya Kikuchi
Keyword(s):  
Fuzzy Optimization ◽  
Optimization Approach
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