A series of hydraulic experiments were conducted for quantitative evaluation on the detachment effect of benthic algae on uneven riverbeds caused by sediment loading. We focused on the shielding part created by the exposure height of gravel and the width between pieces of gravel. The experimental results showed that the shielding was affected by both the exposure height of gravel and the width between pieces of gravel, with the exposure height of gravel having the larger effect. In addition, it was suggested that the movement of the sediment was restricted by an uneven riverbed. In order to take into account the effect of the shielding, a shielding coefficient was introduced to examine the effective tractive force and effective amount of work. There was a positive correlation between effective tractive force and the effective amount of work with the detachment characteristic value. Thus, it is possible to estimate the detachment characteristic value in uneven riverbed using the effective tractive force and effective amount of work.

Using an inedible portion of mature mung bean biomass, methane fermentation experiments were carried out where the digestates were mechanically thickened to extend the solids retention time. The chemical analysis revealed that the conventional COD analytical method with dichromate could not perfectly oxidise the lignocellulosic compound. The measured COD was underestimated by about 10% from the elemental formulae of the biomass. In the kinetic analysis based on the IWA-ADM1 model, the enzymatic decomposition of the lignocellulosic compound limited the overall process performance, and was expressed in a first-order rate expression with 0.051 d⁻¹ and 0.071 d⁻¹ for the leaf fraction and the stem fraction respectively. During the continuous experiment, an unusual accumulation of soluble carbohydrates was recognised. This phenomenon was also modelled as a fragmentation of the lignocellulosic compound where very small unbiodegradable organic particles were released into the liquid. According to the steady-state calculation using the model, about 70% of the plant biomass COD could be converted to methane when the reactor was operated at the solids retention time of 100–200 days with a volumetric loading rate of 10–12 kg-COD/m³/d. The model also showed the reactor volume could be reduced by 6–7 times compared to conventional chemostat reactors.

Forward osmosis (FO) technology, though gaining interest in the last two decades, is still regarded as non-economically viable option. In the light of the recent advances in FO membrane technology and potential benefits of its integration with reverse osmosis (RO) for desalination, wastewater treatment and energy recovery, a comprehensive analysis for FO-RO integration was carried out. This integration considers a layout which concentrates FO feed (wastewater) and dilutes the draw solution, producing potable water via RO and methane from the concentrate through upflow anaerobic sludge blanket in a separate energy recovery unit. Compared to mainstream technologies exemplified by the seawater reverse osmosis (SWRO), membrane bioreactor followed by reverse osmosis (MBR-RO), and Hitachi’s REMIX water system, this study reveals that FO-RO integration for both potable water production and energy recovery has become economically viable with a 9% life cost advantage over MBR-RO and a 20% advantage over SWRO and conventional activated sludge process combined. Moreover, the FO-RO integration showed a cost benefit ratio of 1.17, reflecting its economic viability. With ongoing advancements in FO technology and energy recovery and the many overlooked advantages it offers, this integration has the potential to become the new norm for desalination and wastewater treatment.

This research investigated the effectiveness of UV 222 nm (UV222)/hydrogen peroxide (UV222/H₂O₂) and UV222/sulfate anion (UV222/S₂O₈²⁻) using a KrCl* excilamp (222 nm) in degrading tetracycline hydrochloride (TCH) antibiotics in water. The optimal production of hydroxy radicals occurred with a 0.05% H₂O₂ concentration in the UV222/H₂O₂ process. Additionally, UV222/H₂O₂ showed more significant degradation of organic dyes (methyl orange and methylene blue) compared to UV222 alone. Compared to UV222/H₂O₂, the processes involving UV222/S₂O₈²⁻ were found to be more effective in degrading methyl orange due to the prolonged half-life of sulfate radicals and their electron transfer mechanism. Similarly, the degradation of TCH was more efficient in UV222/S₂O₈²⁻ than in UV222/H₂O₂. The solution pH had minimal impact on TCH degradation in UV222/S₂O₈²⁻, while the presence of anions influenced the process. The degradation of TCH was not affected by Cl⁻ or SO₄²⁻, but it was enhanced by HPO₄²⁻. On the other hand, NO₃⁻ hindered TCH degradation. Additionally, in the UV222/S₂O₈²⁻ system, TCH degradation was three times greater in tap water than in deionized water. The UV222/S₂O₈²⁻ system showed potential for efficiently degrading TCH in real water samples, highlighting the applicability of UV222-based advanced oxidation processes in eliminating antibiotic contaminants from natural aqueous environments.