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Water pollution remains a critical environmental issue in Indonesia, particularly exemplified by the algae bloom phenomenon in Bima Bay. As a potential solution, it is necessary to treat the water with phytoremediation, which involves the use of a combination of various aquatic plants. This study aims to evaluate the efficacy of Ipomoea aquatica, Pistia stratiotes, and Eichhornia crassipes, along with Effective Microorganism 4 (EM4) as a bioremediator, in reducing pollutants in Bima Bay. This study adopts a quasi-experimental pre-test-post-test control group design. Results show that the initial Chemical Oxygen Demand (COD) in the river water was 539.7 milligrams per liter (mg/L), while the phosphate (PO4) concentration was 0.16 mg/L. Phytoremediation using the Ipomoea aquatica (water spinach), Pistia stratiotes (water lettuce), and Eichhornia crassipes (water hyacinth) plants has demonstrated the effective reduction of river water COD level by 5.3 mg/L to 95.5 mg/L. However, the method proved ineffective in reducing river water PO4 level, with an increase of 0.03 mg/L to 0.32 mg/L. The Kruskal-Wallis test yielded statistically significant results, indicating notable differences in COD and PO4 levels in river water across various measurement periods within each treatment group. The findings indicate that phytoremediation using Ipomoea aquatica, Pistia stratiotes, and Eichhornia crassipes with EM4 as a bioremediator is an effective approach for reducing COD levels in river water. However, this method proved less effective in reducing PO4 levels, which may continue to pose challenges in addressing water pollution in Bima Bay.

Electricity subsidies in Indonesia remain high and tend to increase. Existing studies generally propose electricity subsidy reform through economic price adjustment; however, this option potentially arises political and social conflicts. The government and the State Electricity Company have also undertaken several measures to decrease electricity supply costs but those measures remain ineffective due to increasing energy prices needed as fuels for power generations. Our study analyses the effectiveness of two alternative grants for LED lamps and rooftop photovoltaic (PV), to reduce electricity subsidies for low-income residential customers with 450 VA and 900 VA electricity capacity limits. The analysis result is that replacing existing lamps with LED lamps for all those customers will cost the government US$ 313.7 million but potentially decrease electricity subsidies to US$ 208.7 million/ year for 15 years. On the other hand, installing the rooftop PV system is ineffective to bring down the electricity subsidies. The investment cost of the on-grid rooftop PV system is between US$ 827.6 and US$ 1,310.3 per house, while the electricity subsidy savings for 20 years are between US$ 724.1 and US$ 744.8.