The aim of the present study was to assess the effect of hydrothermal pretreatment on the solubilization and anaerobic digestion (AD) of Scenedesmus sp. biomass. At first, the microalgae was cultivated in 5% fresh leachate (FL) to recover nutrients such as nitrogen and phosphorus. Scenedesmus sp. grown in 5% FL obtained 100%, 77% and 97% removal efficiency of ammonium nitrogen (NH4+ - N), total Kjeldahl nitrogen (TKN) and phosphate phosphorous (PO43- -P), respectively. In the following step, the hydrothermal pretreatment of Scenedesmus sp. biomass was carried out at 120, 150 and 170 °C and retention time of 0, 30 and 60 min to evaluate its solubilization and biogas production through AD in batch test. Soluble chemical oxygen demand (sCOD) increased by 260% compared to untreated microalgae at 170 °C for 60 min. In comparison to untreated microalgae, the highest increase in biogas (70%) and methane yield (100%) was observed for 150 °C and 60 min pretreated microalgae as a consequence of hydrothermal pretreatment. Hydrothermal pretreatment has shown effectiveness in enhancing biomass solubilization and increasing biogas yield. Nevertheless, further research at the pilot scale is necessary to thoroughly evaluate the potential and feasibility of hydrothermal pretreatment for full-scale implementation.

The organic matter (OM) and nitrogen in Fresh leachate (FL) from waste compression sites pose environmental and health risks. Even though the constructed wetland (CW) can efficiently remove these pollutants, the molecular-level transformations of dissolved OM (DOM) in FL remain uncertain. This study reports the molecular dynamics of DOM and nitrogen removal during FL treatment in CWs. Two lab-scale vertical-flow CW systems were employed: one using only sand as substrates (act as a control, CW-C) and the other employing an equal mixture of manganese ore powder and sand (experimental, CW-M). Over 488 days of operation, CW-M exhibited significantly higher removal rates for chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and dissolved organic matter (represented by dissolved organic carbon, DOC) at 98.2 ± 2.5%, 99.2 ± 1.4%, and 97.9 ± 1.9%, respectively, in contrast to CW-C (92.8 ± 6.8%, 77.1 ± 28.1%, and 74.7 ± 9.5%). The three-dimensional fluorescence excitation-emission matrix (3D-EEM) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses unveiled that the influent DOM was predominantly composed of readily biodegradable protein-like substances with high carbon content and low unsaturation. Throughout treatment, it led to the degradation of low O/C and high H/C compounds, resulting in the formation of DOM with higher unsaturation and aromaticity, resembling humic-like substances. CW-M showcased a distinct DOM composition, characterized by lower carbon content yet higher unsaturation and aromaticity than CW-C. The study also identified the presence of Gammaproteobacteria, reported as Mn-oxidizing bacteria with significantly higher abundance in the upper and middle layers of CW-M, facilitating manganese cycling and improving DOM removal. Key pathways contributing to DOM removal encompassed adsorption, catalytic oxidation by manganese oxides, and microbial degradation. This study offers novel insights into DOM transformation and removal from FL during CW treatment, which will facilitate better design and enhanced performance.

Effects of sewage sludge (SS) and fresh leachate (FL) addition on corn straw (CS) digestion and underlying mechanisms were investigated. Co-digestion of CS, SS and FL significantly increased cumulative methane production by 7.2-61.1%. Further analysis revealed that co-digestion acted mainly on slowly degradable substrates and exerted dual effects on methane production potential, which was closely related to the volatile solids (VS) content. Antagonistic effects of co-digestion resulted from the dominance of norank_c_Bathyarchaeia, a mixotrophic methanogen that may generate methane inefficiently and consume existing methane. The synergistic enhancement of methane production (0.7-12.7%) was achieved in co-digestion with 33.5-45.5% of total VS added as SS and FL. Co-digestion with more balanced nutrients and higher buffering capacity enriched Actinobacteriota, Firmicutes, and Synergistota, thereby facilitating the substrate degradation. Furthermore, the predominant acetoclastic methanogens, increased hydrogenotrophic methanogens, and decreased methylotrophic methanogens in the digester combined to prompt the synergy.

Leachate from Municipal Solid Waste (MSW) incineration plants contains multiple antibiotics. However, current knowledge of antibiotics in such leachate is very limited compared to landfill leachate. In this study, the distribution, removal and ecological risks of 8 sulfonamides (SAs), 4 quinolones (FQs), and 4 macrolides (MLs) antibiotics in leachate from three MSW incineration plants in Shanghai were investigated. The results showed that 12 types of target antibiotics were detected at high concentrations (7737.3-13,758.7 ng/L) in the fresh leachate, exceeding the concentrations reported for landfill leachate. FQs were the dominant antibiotics detected in all three fresh leachates, accounting for >60 % of the total detected concentrations. The typical \"anaerobic-anoxic/aerobic-anoxic/aerobic-ultrafiltration\" treatment process removed the target antibiotics effectively (89.0 %-93.4 %), of which the anaerobic unit and the primary anoxic/aerobic unit were the most important antibiotic removal units. Biodegradation was considered to be the dominant removal mechanism, removing 78.11 %-92.37 % of antibiotics, whereas sludge adsorption only removed 1.02 %-10.89 %. Antibiotic removal was significantly correlated with leachate COD, pH, TN, and NH3-N, indicating that they may be influential factors for antibiotic removal. Ecological risk assessment revealed that ofloxacin (OFX) and enrofloxacin (EFX) in the treated leachate still posed high risks to algae and crustaceans. This research provides insights into the fate of antibiotics in leachate.

OBJECTIVE: Leachate comprises a solid waste decomposition product found fresh in collection trucks or as an effluent in landfills. This study aimed to assess the occurrence, concentrations, and genetic diversity of intact rotavirus species A (RVA) in solid waste leachate.
RESULTS: Leachate samples were concentrated by ultracentrifugation, treated with propidium monoazide (PMA), and exposed to LED photolysis. Treated and untread samples were extracted using the QIAamp Fast DNA Stool mini kit, and nucleic acids were screened for RVA employing a Taqman® Real-time PCR. The PMA RT-qPCR method detected RVA in eight out of nine truck samples and in 15.40% (2/13) of the landfill leachate samples. The RVA concentrations in the PMA-treated samples ranged from 4.57 × 103 to 2.15 × 107 genomic copies (GC) 100 mL-1 in truck leachate and from 7.83 × 103 to 1.42 × 104 GC 100 mL-1 in landfill samples. Six truck leachate samples were characterized as RVA VP6 genogroup I2 by partial nucleotide sequencing.
CONCLUSIONS: The high intact RVA detection rates and concentrations in truck leachate samples indicate potential infectivity and comprise a warning for solid waste collectors concerning hand-to-mouth contact and the splash route.

An integrated process of electrochemical pre-treatment with carrier-based membrane bioreactor (MBR) was constructed for fresh leachate from waste transfer stations with high organic and NH4+-N content. Results showed that within a hydraulic retention time 40 h, the removal efficiencies of chemical oxygen demand (COD), NH4+-N, suspended solids (SS) and total phosphorus (TP) were over 98.5%, 91.2%, 98.3% and 98.4%, respectively, with the organic removal rate of 18.7 kg/m3. The effluent met the Grade A Standard of China (GB/T31962-2015). Pre-treatment contributed about 70 % of the degraded refractory organics and almost all the SS, with the transformation of the humic-like acid to readily biodegradable organics. Biotreatment further removed over 50% of nitrogen pollutants through simultaneous nitrification and denitrification (SND) and consumed about 30% of organics. Meanwhile, the addition of carriers in the oxic MBR enhanced the attached biomass and denitrification enzyme activity, alleviating membrane fouling.

Plastic wastes are produced in a large amount everywhere, and are commonly disposed in landfills. So landfill leachate seems an obvious source of microplastics (MPs) and phthalate esters (PAEs) due to a huge usage as plastic additives and plasticizers. But this issue still lacks attention and the present study provides the first information on the levels of MPs and PAEs in the fresh landfill leachate of Bushehr port during different seasons. The mean levels of MPs and PAEs in the fresh leachate in all seasons were 79.16 items/L and 3.27 mg/L, respectively. Also, the mean levels of PAEs in MPs were 48.33 μg/g. A statistically significant difference was detected in the levels of MPs and PAEs among different seasons with the highest values in summer and fall. MPs with a size of >1000 μm had the highest abundance in all seasons. The most prominent shape, color, and type of MPs in the leachate were fibers black, and nylon, respectively. Dibutyl phthalate (DBP) and Di(2-ethylhexyl) phthalate (DEHP) were the most dominant PAEs present in the leachate samples. The results of this study revealed high hazard index (HI) and pollution load index (PLI) of MPs in all seasons. Dioctyl phthalate (DOP), DEHP, DBP, diisobutyl phthalate (DiBP), butyl benzyl phthalate (BBP), and diethyl phthalate (DEP) represented a high risk to the sensitive organisms. The results of this study showed that significant levels of MPs and PAEs may release into the surrounding environment from the landfill sites without sufficient protection. This issue is more critical when the landfill sites in particular are located near the marine environments like the Bushehr landfill that is located near the Persian Gulf, which can lead to serious environmental problems. Thus permanent control and monitor of landfills, especially in the coastal areas are highly needed to prevent further pollution.

Fresh leachate is commonly featured with high concentrations of degradable organic matters, which can impede the performance of traditional biological treatment, especially the anaerobic reactor. Aiming at improving the biological treatment process of fresh leachate, this study creatively proposed a microaerobic-IC-AO2 (MAICAO2) process and compared it with traditional biological process, then optimized the operating conditions. Meanwhile, this work investigated the transformation rules and molecular compositions of dissolved organic matters (DOM) during MAICAO2 process, particularly the hazardous DOM (antibiotics). The innovative MAICAO2 process can effectively remove 99% chemical oxygen demand (COD), 91% total nitrogen (TN) and 91% ammonia (NH4+-N) during the operation time, and the removal efficiencies of COD, TN and NH4+-N in MAICAO2 process increased approximately 2%, 14% and 13% compared to ICAOAO process. Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) confirmed that microaeration could ensure over 53% small molecular organic acids degrade before the subsequent anaerobic reaction so the system could resist the high concentration organic matters stress and improve the denitrification efficiency. Further analysis showed that different categories of antibiotics (including 6 sulfonamides, 4 tetracyclines, 2 macrolides, 4 quinolones and 2 chloramphenicols) could be effectively removed by MAICAO2 process with the total removal efficiency of 50%. This work proposed a new scenario for fresh leachate treatment by proposing the importance of the microaeration pretreatment during the biological treatment process.

To overcome phosphorus deficiency in municipal solid waste composting leachate, orthophosphate (OP) and pyrophosphate (PP) were separately added into leachate to evaluate the possibility of fermentative H2 production with leachate and phosphorus-rich streams as a full nutrient source. Results indicate H2 production is significantly promoted by OP addition but slightly facilitated by PP in some cases, depending on initial pH and P dosage. The highest hydrogen yield (1.95±0.07mol H2/mol glucose) was achieved at a COD/P ratio of 27.64 (mg/mg) with OP as phosphorus source at initial pH 5. For PP, a maximum yield of 1.58±0.09mol H2/mol glucose can be attained at the optimal COD/P ratio of 221.12 (mg/mg) and initial pH 5. OP promotes H2 production via dual approaches: supplying nutrient and relieving inhibition from excessive Ca(2+) on granule sludge. However, both the roles in nutrient supply and Ca(2+) removal by PP addition are limited.

With limited assessment, leachate treatment of a specified landfill is considered to be a significant source of greenhouse gas (GHG) emissions. In our study, the cumulative GHG emitted from the storage ponds and process configurations that manage fresh or aged landfill leachate were investigated. Our results showed that strong CH4 emissions were observed from the fresh leachate storage pond, with the fluxes values (2219-26,489 mg Cm(-2)h(-1)) extremely higher than those of N2O (0.028-0.41 mg Nm(-2)h(-1)). In contrast, the emission values for both CH4 and N2O were low for the aged leachate tank. N2O emissions became dominant once the leachate entered the treatment plants of both systems, accounting for 8-12% of the removal of N-species gases. Per capita, the N2O emission based on both leachate treatment systems was estimated to be 7.99 g N2O-N capita(-1)yr(-1). An increase of 80% in N2O emissions was observed when the bioreactor pH decreased by approximately 1 pH unit. The vast majority of carbon was removed in the form of CO2, with a small portion as CH4 (<0.3%) during both treatment processes. The cumulative GHG emissions for fresh leachate storage ponds, fresh leachate treatment system and aged leachate treatment system were 19.10, 10.62 and 3.63 Gg CO(2) eq yr(-1), respectively, for a total that could be transformed to 9.09 kg CO(2) eq capita(-1)yr(-1).