Onstructed wetland applications have been limited by a large land requirement and capital investment. This study aimed to improve a shallow pond water hyacinth system by incorporating the advantages of engineered attached microbial growth technique (termed Bio-hedge) for on-site domestic wastewater treatment. A laboratory scale continuous-flow system consists of the mesh type matrix providing an additional biofilm surface area of 54 m²/m³. Following one year of experimentation, the process showed more stability and enhanced performance in removing organic matter and nutrients, compared to traditional water hyacinth (by lowering 33%–67% HRT) and facultative (by lowering 92%–96% HRT) ponds. The wastewater exposed plants revealed a relative growth rate of 1.15% per day, and no anatomical deformities were observed. Plant nutrient level averaged 27 ± 1.7 and 44 ± 2.3 mg N/g dry weight, and 5 ± 1.4 & 9±1.2 mg P/g dry weight in roots and shoots, respectively. Microorganisms immobilized on Bio-hedge media (4.06 × 10⁷ cfu/cm²) and plant roots (3.12 × 10⁴ cfu/cm) were isolated and identified (a total of 23 strains). The capital cost was pre-estimated for 1 m³/d wastewater at 78 US$/m³_inflow and 465 US$/kg BOD_{5 removed}. This process is a suitable ecotechnology due to improved biofilm formation, reduced footprint, energy savings, and increased quality effluent.

Crystal phase and morphology variations obtained by simple high-temperature annealing offer promising strategies for employing nanostructured manganese oxide as a cathode catalyst for microbial fuel cells (MFCs). This study examines the effectiveness of simultaneous-phase and morphology-controlled manganese dioxide nanomaterials, designed by annealing a hydrothermally synthesized flower-like δ-manganese dioxide precursor at 300–800 °C, as cathode catalysts for MFCs. MFCs with the best-performing catalyst cathode (at a reasonable mass loading) were also analyzed through cyclic voltammetry and electrochemical impedance spectroscopy. Among MFCs with non-annealed and annealed manganese dioxide cathodes (0.5 mg cm⁻²), those with the catalyst annealed at 500 °C (148 ± 7 mW m⁻², CE = 13 ± 1%) generated the most power (5–52%). MFCs with the catalyst annealed at 500 °C at a loading of 1 mg cm⁻² as the cathode delivered the highest maximum power density (213 ± 9 mW m⁻², CE = 13 ± 1%), representing 44% of that obtained using Pt/C at 0.5 mg Pt per cm² (483 ± 11 mW m⁻², CE = 18 ± 2%) and a comparatively low internal resistance (164 ± 2 Ω). Both cyclic voltammetry and electrochemical impedance spectroscopy results were consistent with empirical data. Compared with previously reported cathode materials, the annealed product from the precursor flower-like δ-manganese dioxide annealed at 500 °C (particularly at a loading of 1 mg cm⁻²) was a more reliable, efficient, and inexpensive sustainable cathode catalyst for scaled-up MFCs.

The purpose of this study is to examine the potential use of anaerobic baffled reactor (ABR) followed by Bio-rack wetland planted with Phragmites sp. and Typha sp. for treating domestic wastewater generated by small communities (751 mg COD/L, 500 SCOD mg/L, 348 mg BOD₅/L). Two parallel laboratory-scale models showed that the process planted with Phragmites sp. and Typha sp. are capable of removing COD by 87% & 86%, SCOD by 90% & 88%, BOD₅ by 93% & 92%, TSS by 88% & 86%, TN by 79% & 77%, PO₄-P by 21% & 14% at an overall HRT of 21 (843 g COD/m³/day & 392 g BOD₅/m³/day) and 27 (622 g COD/m³/day & 302 g BOD₅/m³/day) hours, respectively. Microbial analysis indicated a high reduction in the MPN of total coliform and TVC as high as 99% at the outlet end of the processes. The vegetated system using Phragmites sp. showed significantly greater (p <0.05) pollutant removal efficiencies due to its extensive root and mass growth rate (p <0.05) of the plant compared to Typha sp. The Phragmites sp. indicated a higher relative growth rate (3.92%) than Typha sp. (0.90%). Microorganisms immobilized on the surface of the Bio-rack media (mean TVC: 2.33 × 10⁷ cfu/cm²) were isolated, identified and observed using scanning electron microscopy (SEM). This study illustrated that the present integrated processes could be an ideal approach for promoting a sustainable decentralization, however, Phragmites sp. would be more efficient rather than Typha sp.

This study was undertaken to evaluate the potential future use of three biological processes in order to designate the most desired solution for on‐site treatment of wastewater from residential complexes, that is, conventional activated sludge process (CASP), moving‐bed biofilm reactor (MBBR), and packed‐bed biofilm reactor (PBBR). Hydraulic retention time (HRT) of 6, 3, and 2 h can be achieved in CASP, MBBR, and PBBR, respectively. The PBBR dealt with a particular arrangement to prevent the restriction of oxygen transfer efficiency into the thick biofilms. The laboratory scale result revealed that the overall reduction of 87% COD, 92% BOD₅, 82% TSS, 79% NH₃‐N, 43% PO₄‐P, 95% MPN, and 97% TVC at a HRT of 2 h was achieved in PBBR. The microflora present in the system was also estimated through the isolation, identification, and immobilization of the microorganisms with an index of COD elimination. The number of bacterial species examined on the nutrient agar medium was 22 and five bacterial species were documented to degrade the organic pollutants by reducing COD by more than 43%. This study illustrated that the present PBBR with a specific modified internal arrangement could be an ideal practice for promoting sustainable decentralization and therefore providing a low wastage sludge biomass concentration.

With population and economy growth, water usage, wastewater generation and treatment, treatment plants capacity and innovation ability in Iran have increased dramatically in the last decades. Currently, Iran is in the grip of severe water scarcity, with renewable water availability of less than 1700 m3 /capita/y. Total municipal wastewater generated in Iran is 4.61 billion m3 /y out of which only 42% is treated. The conventional activated sludge process accounted for the largest share (>60%) in municipal wastewater treatment in Iran. The treatment plants operational costs usually amount up to 0.2 US $/m3 wastewater. About 55% of treated municipal effluent is reused in Iran, with an emphasis on the agricultural sector. The electricity consumption in municipal wastewater treatment facilities amounts for 0.1% (241 million kWh/y) of the total electricity consumption of the country. Meanwhile, the current laws and policies are sometimes inefficient or do not prompt the ideal outcomes. Thus, the present study provides an overview of municipal wastewater treatment in Iran by describing the current situation and collecting data from 68 treatment plants, and defining key barriers and future policies needs towards Iran’s sustainable municipal wastewater management (up to 2040). Here, the opinions of 50 experts from the governmental sector, industry division, and faculty members were surveyed through the meetings of the technical and steering committee. Overall, sustainable municipal wastewater management in Iran would be obtained by developing water resources, increasing the population covered by wastewater facilities (90%), improving effluent discharge standards, and lowering energy usage to 0.45 kWh/m3 wastewater.