Ahmad Soleh Setiyawan

Graphical abstract showing system dynamics modelling of a 1,200 L commercial septic tank to predict sludge accumulation and effluent quality. Blackwater inputs are simulated using STELLA and validated with field data. Results indicate 47.4 L/capita/year sludge accumulation, high pollutant removal efficiencies, and optimized desludging intervals based on household size. In Thailand, commercial septic tanks are increasingly used as onsite wastewater treatment systems in new residential buildings due to their ease of installation and effectiveness in collecting and treating blackwater. However, improper emptying of the tanks could reduce treatment efficiency. This study presents a system dynamics model using STELLA software to simulate the performance of a 1,200-L commercial septic tank under baseline influent solids composition derived from field measurement data. Simulations were conducted for households of one, three, five, and eight people. Under the baseline condition, the model predicted a first-year sludge accumulation rate of 47.44 L/capita/year, followed by a gradual decline over time. The removal efficiencies of total solids, total dissolved solids, total suspended solids, and total volatile solids were 59, 36, 86, and 80%, respectively. Sensitivity analysis, by varying the fixed suspended solids (FSS) fraction by ±10%, showed that changes in nonbiodegradable solid content influenced sludge accumulation rates and desludging intervals, with higher FSS fractions leading to increased accumulation and shorter desludging frequencies. This study supports decision-making for desludging intervals. The useful information can be contributed to tank producers, regulators, and service providers for the sustainable management of onsite sanitation systems.

Microbial Fuel Cell (MFC) technology has attracted interest for its dual role in wastewater treatment and energy generation. Aim: This study aimed to evaluate the performance of a Modified Septic Tank-Microbial Fuel Cell (MST-MFC) for office domestic wastewater treatment, focusing on organic matter, ammonia removal, and electricity generation. Methodology and results: In this study, synthetic wastewater was prepared to simulate the typical composition of domestic effluent from office buildings. The main variables measured in this study included pH, temperature, Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), and ammonia levels. A 196 L reactor (36 h HRT) with anoxic, anaerobic, aerobic, and sedimentation zones was equipped with three pairs of zinc–copper electrodes (2 cm spacing) placed in anaerobic (anode) and aerobic (cathode) chambers. Synthetic wastewater with controlled COD:N:P ratios was applied at two organic loading rates (OLRs): 7 and 11.94 mg COD/L.h. At the lower OLR, COD removal reached 100% versus 93.85% at the higher OLR. Ammonia removal was also higher (27.61% vs. 17.59%), while electricity generation peaked with 461.88 mV, 355.67 mW/m2, and 0.0970% Coulombic efficiency. Conclusion, significance and impact study: The MST-MFC showed strong potential for decentralized wastewater treatment with energy recovery, though limited ammonia removal indicates further optimization is needed, with OLR as a key factor.

Background: Polluted rivers may become reservoirs of antibiotic-resistant Escherichia coli (AREc), raising concerns about environmental health. While monitoring is crucial for recognizing their incidence and evaluating mitigation solutions, current approaches are limited due to high costs, labor-intensive methods, and a lack of standardized indicators. This study aims to identify the priority AREc as the monitoring target and evaluate the applicability of the β-glucuronidase enzyme detection method (MPR Method) as an alternative rapid method for profiling AREc in the Upper Citarum River. Methods: River water sampling was conducted along the river during two periods with varying rainfall levels. Total Escherichia coli (TEc) and twelve types of antibiotic-resistant Escherichia coli (AREc) were measured simultaneously by the Agar Method and the β-D-Glucuronidase detection (MPR Method). Results: Statistical data analyses indicate that Total Escherichia coli (TEc) concentrations in the Upper Citarum River increase during periods of higher rainfall (𝓍 = 2558 ± 360 CFU/mL). Erythromycin-resistant Escherichia coli dominates in both periods (Period I 𝓍 = 57.6 ± 25.9%, Period II 𝓍 = 49.96 ± 29.5%). However, tetracycline-resistant Escherichia coli and Extended-Spectrum β-lactamase-producing Escherichia coli (ESBL-Ec) are the most suitable indicators for AREc concentration due to their consistency and correlation with other AREc types. The MPR method achieved an accuracy of up to 87.2%, a sensitivity of 67.4%, and a specificity of 94%. Conclusion: The MPR Method was considered a better alternative for the AREc screening method, particularly in a high bacterial load aquatic environment.

Research on tripikon-S has been conducted to reduce organics and nutrients in domestic wastewater. This study aims to analyze the performance of modified tripikon-S with the addition of pumice as a support media in domestic wastewater treatment. The tripikon-S used is a modification of three...