Background
Mining activities can generate runoff water with complex characteristics, including acidic conditions and high concentrations of suspended solids. Proper characterization of this water is therefore essential to determine an appropriate treatment strategy and support effective mine water management.
PT Bumi Suksesindo (PT BSI), a gold mining company in Banyuwangi, East Java, faced challenges in managing runoff water from its mining areas. Initial observations indicated that some runoff water had an acidic character, particularly from areas influenced by mining and reclamation activities.
To better understand these conditions and identify an appropriate treatment approach, PT BSI conducted a Wastewater Characterization (WWC) study supported by Ganeca Environmental Laboratory.
Challenges
The mine runoff at PT Bumi Suksesindo presented varying water quality characteristics, including acidic conditions and elevated suspended solids. These variations made it challenging to determine a single treatment approach that could consistently deliver effective results. Rather than relying on a standard chemical dosage, a site-specific laboratory evaluation was required to identify the most suitable treatment chemical and dosage based on the actual characteristics of the wastewater. The key challenge was to determine:
Which chemical treatment would be most suitable for the characteristics of the mine runoff, and at what dosage could it provide effective treatment?
Solution
Ganeca Environmental Laboratory approached the challenge through a step-by-step laboratory study, starting with wastewater characterization and progressing to treatment evaluation.
1. Wastewater Characterization
The first stage focused on establishing the baseline characteristics of the runoff water. Key physical and chemical parameters were analyzed and compared with the applicable effluent quality standards for gold and/or copper mining activities under KepMenLH No. 202 Tahun 2004. The regulation specifies, among other parameters, a pH range of 6–9 and a maximum TSS concentration of 200 mg/L. This stage provided the baseline data needed to understand the main water quality challenges.
2. Sedimentation Test
The laboratory study was then continued with sedimentation testing to evaluate the natural settling behavior of suspended solids. This test helped determine the extent to which suspended particles could be removed through gravity settling and provided an initial understanding of whether chemical assistance would be required.
3. Jar Test
The next step was a jar test to evaluate potential chemical treatment alternatives.
Three chemical alternatives were tested at different dosages. The laboratory evaluation focused on the response of the wastewater, particularly changes in pH and TSS, to identify the most effective treatment condition. Rather than applying a predetermined chemical dosage directly in the field, the jar test provided a controlled laboratory environment to compare treatment alternatives and identify a more appropriate dosage for each wastewater characteristic.
Results and Benefits of Implementation
The laboratory study provided valuable insights into the characteristics and treatment response of the mine runoff. The results demonstrated the potential of chemical treatment to improve key water quality parameters and identified suitable treatment conditions based on the wastewater characteristics. The study therefore provided PT BSI with:
· A better understanding of its runoff water characteristics;
· Laboratory evidence of sedimentation and treatment behavior;
· An evaluation of alternative chemical treatments;
· A basis for selecting a suitable chemical and dosage; and
· Technical data to support further mine water management and sediment pond planning.