Economic valuation of recyclable metals of electronic wastes Case study: 6th district of Tehran

Introduction
In general and based on a simple division, the e-wastes can be considered as a subset of municipal solid waste which combines homemade, administrative, commercial and industrial wastes. Therefore, the electronic wastes have become one of the most important issues for global community. Because of much increasing of these wastes, collection and recycling of them are necessary. In economic terms, electronic waste recycling has high potential and today recycling of such material is considered as a profitable business for many credible firms such as Bodian in Sweden, Vias in Norway and Catriana in England.
Some studies, have been done to predict the e-waste production. Based on their proposed model, the time series of lifetime are used to estimate the e-waste production. In fact, they predicted lifetime process based on life cycle and disposal of electronic waste.
Material and methods
Case study
The case study of this article is 6th district one of the oldest areas of Tehran located in the city center. The area of this region is 2138.45 hectare that covers about 3.3% of the total area of city.
Analysis Method
Calculation of e-waste production
As mentioned, the 6th district was chosen as statistical society where the population is estimated about 215900 thousand people in 2012. Also the population growth rate of this district is -0.1. Accordingly, the population was calculated for 2021 using population estimation formula (equation 1).
       (1)                                                   P_t= p₀ (1+r₀)ⁿ                                                                      
Where P_t is the final population, p₀ is the initial population, r₀ is rate of growth and n is the number of years.
Using the information and from equation 1 we have that
P₂₀₂₁= 217000 [(1+(- 0.1)]¹⁷=213750
Sample size was calculated 380 people using Cochran`s formula with confidence level 95% and allowable sampling error 5%. These people were selected from residential, recreational, administrative and commercial centers by random cluster model.
- The e-waste production capita for 6th district of Tehran in 2011
- the electronic waste generated by the statistical sample ÷ the number of statistical sample𝗑the average number of family members = 5653÷(380𝗑4.3)=3.45
- The e-waste production capita for 6th district of Tehran in 2021
- the electronic waste generated by the statistical sample ÷ the number of statistical sample𝗑the average number of family members = 8763÷(380𝗑4.3)=5.36
- Total e-waste of 6th district in 2012
Total population of 6th district in 2012 𝗑 production capita = 215900 𝗑 3.45 = 744855
- Total e-waste of 6th district in 2021
Total population of 6th district in 2021 𝗑 production capita = 213750 𝗑 5.36 = 1145700
Then, the contribution of each metal such iron, aluminum and copper in total wastes should be calculated. For this purpose, first e-waste components and the share of them are determined and finally table 1 show economic value of metals contained in e-waste for 6th district.
Results
The weight of iron, aluminum and copper in e-waste for 6th district
Table (1): economic value of metals contained in e-waste for 6^th district





metal


production in 2012


Economic value for each ton of metal in London Metal Exchange on July 2012


Total economic value


Production in 2021 (ton)


Economic value for each ton of metal in London Metal Exchange on October  2012*


Economic value in 2021




Iron


357


136


48552


569


151


85919




Aluminum


35


1832


64120


54


1992


107568




copper


52


7421


385892


80


8210


656800




 


Sum of the total economic value in 2012= 498564$


Sum of the total economic value in 2021= 850287$





* Given that the prices of these metals for 2021 are not available, assuming the price is fixed until the year 2021, the prices of these metals in October 2021 have been considered.
(Source, Authors)
 
Conclusion
Electronic waste is a new kind of municipal solid waste that attracted many attentions in the last decade, as based on the United Nation Environmental Program (UNEP); Electronic waste has fastest growing waste streams among other kinds of municipal solid waste.
Two aspects of Electronic Wastes are more important than of other aspects. One of them is so existent of heavy metals and materials in the Electronic waste such as nickel, cadmium, lead and etc. that without recycling or informal recycling of these materials can damage to the environment and humans body. These materials contain 2.7% of Electronic Wastes weight.
Also therefore existence of valuable and recyclable materials such as gold, silver, aluminum, copper, iron and etc. in the electronic waste has caused the electronic waste to be called as urban mines. Also the valuable metals that exist in the Electronic Wastes include 60% of Electronic Waste weight.
This study estimated the total economic value of the metals iron, aluminum and copper in electronic waste generated in the 6th district of Tehran in 1392 and forecast for the year 1402 was shown that these wastes was very valuable to waste and should be recycled and used. To control and manage large quantities of e-waste, We needs to integrated electronic waste management system that shown in the fig 1.
 

 

Fig (1): comprehensive e-waste management system (Source, Authors)
This system is a combination of waste streams, waste collection, recycling and disposal methods, that its aim is achieving to the  environmental benefits, economic utility and social acceptability. Such system will be leads to a waste management system applicable in each area.
But to achieve to such system, we needs to consider all stakeholders and influential in the production and management of electronic wastes are to consider the role of public, private and public sectors in the management of electronic waste, environmental issues economical for the public and in particular.