Develo** a sustainable water and wastewater management plan based on water footprint in a part of a steel industry: a case of iron pellet production factory in southeastern Iran

Abstract

The steel industry is known for its high water consumption and wastewater production, making it crucial to evaluate the environmental sustainability of water use in this sector. A product's water footprint (WF) represents the total freshwater volume used to produce consumer goods. In this study, the WF concept was used to evaluate the sustainability of water consumption in a steel plant in southeastern Iran. The WF components, including blue and gray water, were calculated for the steel production process from extraction to pelletizing. The findings revealed that indirect WF, such as water used in energy production, was nearly equal to direct WF, representing water used in the production process. To reduce the WF, seven scenarios based on the 3Rs (Reduction, Reuse, Recycling) strategies were proposed. The M-TOPSIS method, a multi-attribute decision-making technique, was used to prioritize the scenarios based on their effectiveness in gray and blue WF reduction, financial worth (income–expense balance), and the priority of the 3Rs strategy. The results indicated that the scenario of wastewater reuse from nearby cities achieved the highest priority due to its significant impact on reducing blue WF (by 38%) at a reasonable cost. The findings demonstrate that the proposed methodology can be applied to similar production systems.

Appendices

Appendix A

An example of how to calculate the WF

For the WF of staff consumption, obtained from Fig. 3 (marked box), the value is 0.023 cubic meters per ton. To calculate the WF, Eqs. (A1) and (A2) are used as follows:

$$WF_{PD} = WF_{PC} + \frac{{WF_{PD} \left[ O \right]}}{{{\text{f}}\left[ O \right]}}$$

(A1)

$${\text{f}}\left[ O \right] = \frac{w\left[ p \right]}{{w\left[ O \right]}}$$

(A2)

${WF}_{PD}$: total WF of staff consumption (volume/mass); ${WF}_{PC}$: WF of staff consumption (volume/mass) of the processing stage; ${WF}_{PD}\left[O\right]$: staff consumption WF (volume/mass) of the mining stage; $\mathrm{f}\left[O\right]$: the weight ratio of the product (pellet) to the input material (iron ore) from the mining stage; $w[p]$: product quantity (mass); $w[O]$: amount of raw material input (iron ore) from the mining stage (mass).

Now considering that we have the following data for a period of one year:

-WF of mining stage personnel: 0.006 cubic meters per ton.

-The amount of water consumed by the staff of the processing stage: 32,850 cubic meters.

-Amount of product (pellet): 2,396,500 tons.

-The amount of raw material input (iron ore) from the mining stage: 3,823,000 tons.

Using Eqs. (A1) and (A2), we calculate the indirect internal WF of staff consumption:

$$WF_{PC} = \frac{{32850 m^{3} }}{2396500 ton} = 0.014 \frac{{m^{3} }}{ton}$$

$$WF_{PD} \left[ O \right] = 0.006 \frac{{m^{3} }}{ton}$$

$${\text{f}}\left[ O \right] = \frac{2396500}{{3823000}} = 0.627$$

$$WF_{PD} = 0.014 + \frac{0.006}{{0.627}} = 0.014 + 0.009 = 0.023 \frac{{m^{3} }}{ton}$$