[en] This paper first presents a systematic study of the basic process of biologic phosphorus elimination as employed by the original 'Phoredox (Main Stream) Process'. The conditions governing the process and the factors influencing its performance were determined by trial operation. A stationary model was developed for the purpose of modelling biologic phosphorus elimination in such a main stream process and optimising the dimensioning. The validity of the model was confirmed by operational data given in the literature and by operational data from the authors' own semitechnical-scale experimental plant. The model permits simulation of the values to be expected for effluent phosphorus and phosphate concentrations for given influent data and boundary conditions. It is thus possible to dimension a plant for accomodation of the original Phoredox (Main Stream) Process or any similar phosphorus eliminating plant that is to work according to the principle of the main stream process. (orig./EF)

[en] Highlights: • Reduce CO₂ emission is a referential index for future sludge disposal. • Synergetic digestion technology of kitchen waste and sludge contributes to the CO₂ reduction. • Synergetic digestion technology reduced more CO₂ emission than sludge landfill. • Synergetic digestion technology should be effectively promoted and applied. - Abstract: With the popularization of municipal sewage treatment facilities, the improvement of sewage treatment efficiency and the deepening degree of sewage treatment, the sludge production of sewage plant has been sharply increased. Carbon emission during the process of municipal sewage treatment and disposal has become one of the important sources of greenhouse gases that cause greenhouse effect. How to reduce carbon dioxide emissions during sewage treatment and disposal process is of great significance for reducing air pollution. Kitchen waste and excess sludge, as two important organic wastes, once uses anaerobic synergetic digestion technology in the treatment process can on the one hand, avoid instability of sludge individual anaerobic digestion, improve sludge degradation rate and marsh gas production rate, and on the other hand, help increase the reduction of carbon dioxide emissions to a great extent. The paper uses material balance method, analyzes and calculates the carbon dioxide emissions from kitchen waste and sludge disposed by the anaerobic synergetic digestion technology, compares the anaerobic synergetic digestion technology with traditional sludge sanitary landfill technology and works out the carbon dioxide emission reductions after synergetic digestion. It takes the kitchen waste and sludge synergetic digestion engineering project of Zhenjiang city in Jiangsu province as an example, makes material balance analysis using concrete data and works out the carbon dioxide daily emission reductions. The paper analyzes the actual situation of emission reduction by comparing the data, and found that the synergetic digestion of kitchen waste and sludge can effectively reduce the carbon dioxide emission, and the reduction is obvious especially compared with that of sludge sanitary landfill, which has a certain effect on whether to promote the use of the technology.

[en] Highlights: • Earthworm growth biomass and activity decreased with the VF depth. • Earthworm gut microbial communities were dominated by Gammaproteobacteria. • δ¹⁵N and δ¹³C in earthworms decreased with time, and increased with the VF depth. • Effect of earthworm feeding in enhanced VSS reduction was analyzed quantitatively. • Earthworm feeding had low contribution to the enhanced VSS reduction. - Abstract: Previous studies showed that the presence of earthworm improves treatment performance of vermifilter (VF) for sewage sludge stabilization, but earthworm eco-physiological characteristics and effects in VF were not fully investigated. In this study, earthworm population, enzymatic activity, gut microbial community and stable isotopic abundance were investigated in the VF. Results showed that biomass, average weight, number and alkaline phosphatase activity of the earthworms tended to decrease, while protein content and activities of peroxidase and catalase had an increasing tendency as the VF depth. Earthworm gut microbial communities were dominated by Gammaproteobacteria, and the percentages arrived to 76–92% of the microbial species detected. ¹⁵N and ¹³C natural abundance of the earthworms decreased with operation time, and increased as the VF depth. Quantitative analysis using δ¹⁵N showed that earthworm feeding and earthworm–microorganism interaction were responsible for approximately 21% and 79%, respectively, of the enhanced volatile suspended solid reduction due to the presence of earthworm. The finding provides a quantitative insight into how earthworms influence on sewage sludge stabilization in vermifiltration system

[en] Highlights: • The maximum denitrification rate was lowest in PHBV/PLA supported system. • The relative abundance of denitrification bacteria was highest in CH₃COONa system. • PHBV/PLA and glucose systems showed abundant hydrolysis and fermenting bacteria. • The FPKM value of functional genes for DNRA process was highest in glucose system. Solid and liquid organic substances as carbon sources for denitrification process were deeply explored. In this study, the effect of three carbon sources, referred to as poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/poly (lactic acid) (PHBV/PLA) polymer, glucose and CH₃COONa, on denitrification performance, microbial community and functional genes were investigated. It was found that maximum denitrification rates of 0.37, 0.46 and 0.39 g N/(L·d) were achieved in PHBV/PLA, glucose and CH₃COONa supported denitrification systems, respectively. Meanwhile, Illumina MiSeq sequencing revealed that three carbon sources led to different microbial community structures. It can be seen that Brevinema/Thauera/Dechloromonas, Tolumonas/Thauera/Dechloromonas, Thauera dominated in the PHBV/PLA, glucose and CH₃COONa supported denitrification systems, respectively. Transcriptome-based analysis further indicated that the glucose supported denitrification system showed the highest FPKM values (the fragments per kilobase per million mapped reads) of the genes participating in the dissimilatory nitrate reduction process, corresponding to the greatest effluent NH₄⁺-N concentration. A better knowledge of effect of different carbon sources on denitrification process will be significant for nitrate removal in practice.

[en] Highlights: • The effects of Fe₃O₄ on performance and microbial process of AFR digestion were investigated. • The Fe₃O₄ addition enhanced the metabolism of carbohydrate and protein in Anaerolineae. • Hydrogenotrophic methanogenesis was the dominant pathway in the AFR digestion system. • Methanoculleus was involved in fermentation process acting as a versatile hydrolyzer. • Fe₃O₄ acted as biostimulator for Anaerolineae other than electron conduit in methanogenesis. Antibiotic fermentation residue (AFR) is a kind of protein-rich biosolids that would be utilized as valuable substrates for biogas production. However, the effectiveness of conductive material supplementation and its effect on the microbiome in anaerobic digestion of AFR have not been fully elucidated. The objective of this study is to access the impact of Fe₃O₄ addition on anaerobic digestion of AFR and reveal its microbial mechanism. By adding Fe₃O₄ at concentration of 150 mg/gTS to two typical AFRs, the methane yield was decreased while the methane production rate was significantly enhanced by 48% and 21%, respectively. Genomic analyses revealed that the Fe₃O₄ addition altered the microbial community by selecting the unknown genus of Anaerolineae with the metabolic capacity of carbohydrate hydrolysis and proteolysis. Meanwhile, the hydrogenotrophic methanogenesis was the dominant pathway in the AFR digestion system, which was mostly contributed by the Methanoculleus and Methanolinea. More interestingly, Methanoculleus might possess fermentative capability involved in the versatile hydrolysis pathway. Although the genes related to electrically conductive pili were detected, the induction of direct interspecies electron transfer by Fe₃O₄ supplementation was not confirmed in this study. In summary, except the accelerated methane production rate, Fe₃O₄ addition functioned as biostimulator for Anaerolineae other than electron conduit in anaerobic methanogenesis in the AFR digestion system.

[en] Highlights: • Direct and indirect GHGs emissions of all WWTPs in Shanghai were 243,320 and 511,851 tCO₂-eq in 2016. • Average GHGs emission intensity for Shanghai WWTPs was 0.290 kgCO₂-eq/m³. • IPCC2006 underestimated both direct N₂O and CH₄ emissions due to the out-of-date default values. • ODIM made use of the local operational data to achieve more accurate city-level estimation. • The indirect emission intensity of WWPTs with low COD and NH₃-N concentrations was twice than others. Due to the rapid wastewater treatment plants (WWTPs) development and the China's 2060 goal of carbon neutrality, the contribution of greenhouse gas (GHG) emissions from WWTPs should not be overlooked. Thus, the GHG accounting method, featured with site-specific and real operation data targeting city-level WWTPs, is scientifically and pragmatically called for. In this paper, we compared IPCC (IPCC 2006 and IPCC 2019), optimized IPCC and operational data integrated methods (ODIM) for the direct N₂O and CH₄ emissions for total 50 WWTPs in Shanghai. Data for all WWTPs were collected for ODIM and indirect GHG emissions evaluation, covering frequently used wastewater treatment processes in China such as anaerobic anoxic oxic, oxidation ditch, sequencing batch reactor, anoxic oxic, biofilm and membrane bio-reactor. The factors affecting the total GHG emissions intensity were also analyzed. The results showed that, in comparison with IPCC 2019, IPCC 2006 underestimated both direct N₂O and CH₄ emissions for a total percentage of 87%. What's more, IPCC 2019 overestimated by a percentage of 355% compared to ODIM due to the general default values. ODIM considered the significant differences in emission factor values of specific treatment process, making use of the local operational data to achieve more accurate city-level estimation with direct GHG emissions of 243,320 tCO₂-eq in 2016. While indirect emissions were 511,851 tCO₂-eq, accounting for 68% of total direct and indirect emissions. Average GHGs emission intensity for Shanghai WWTPs was evaluated as 0.290 kgCO₂-eq/m³ while the specific WWTP intensity varied between 0.268 and 0.738 kgCO₂-eq/m³. In detail, WWTPs with AAO process, large-scale (>100 k m³/day), high load rate (80%–100%), low theoretical oxygen consumption (0.2– 0.4 kgO₂/t), influent COD of 150– 250 mg/L, NH₃-N of 15– 25 mg/L and discharge limits B demonstrated lower amounts of total GHG emissions than other WWTPs. Shanghai cases in this study provided a reference for future city-level WWTPs GHG management in China.

[en] Highlights: • The adsorption of five target PCPS was also affected by pH, the optimal pH for the removal of five target PCPS was 7.0. • The removal pathway of PCPs by MBR was mainly through the adsorption and biodegradation of activated sludge. • The biodegradability of the five target PCPS was EHMC > DEP > HHCB ≈ AHTN > DEET. • The removal of PCPs was greatly affected by the types of substrates, and the adsorption capacity of perlite was the strongest. Personal care products (PCPs) are contaminants of emerging concern because of their continuous input into the environment. In this study, membrane bioreactor (MBR) and constructed wetland (CW) methods were used to investigate the effect and mechanism of conventional pollutant and PCP removal from greywater. The effluent of both the MBR- and CW-treated greywater met the reclaimed water reuse standard in China. Conventional pollutants and five target PCPs had a higher removal efficiency in the MBR than in the CW. The removal rates of the PCPs, including Tuina musk (AHTN), were >80% using MBR and CW methods. The main pathway of removing PCPs in the MBR was sludge adsorption and biodegradation, whereas the contribution of the membrane module was weak. The main pathway of removing PCPs in the CW was the combined action of plant absorption, microbial biodegradation, and substrate adsorption, depending on the PCP type. Ethyl hexyl methoxycinnamate (EHMC) has strong biological oxidizability and was mainly removed by biodegradation, whereas Jiale musk (HHCB) and AHTN were mainly removed by adsorption. Six types of CW substrates were investigated, and perlite showed the best adsorption effect for the five target PCPs. The optimal substrate adsorption pH was 7. This study provides important technical information on the effective removal of conventional pollutants and PCPs in greywater and the preparation of high-quality reclaimed water.

[en] Highlights: • THP and anaerobic digestion (AD) improve sludge dewaterability. • THP destroys cell walls and promotes bound water release. • The CST value of THP as pre-/post-treatment of AD was reduced by 58.1% and 59.3%. • The hydrophobicity of sludge surface has increased. • THP as pre/post-treatment for AD on dewaterability was not significant. It is known that sludge dewaterability improves during the thermal hydrolysis process (THP); however, the effect of thermal hydrolysis and anaerobic digestion (THP-AD) on sludge dewaterability is unclear. Further, the difference between thermal hydrolysis as pre-treatment for anaerobic digestion (pre-THP-AD) and as post-treatment (post-THP-AD) is also unclear. Based on the evolution of the interaction between organic matter and moisture, the mechanism of pre-THP-AD and post-THP-AD improving the sludge dewaterability was explored. The capillary suction time values of pre-THP-AD and post-THP-AD increased by 58% and 59%, respectively, and the proportion of free moisture increased by 10.44% and 10.59%, respectively, compared with the conventional anaerobic digestion (CAD) process. The cell structure was destroyed and most organic matter was converted into dissolved form through THP, organic matter degraded during AD, the interaction between moisture and organic matter declined, and the mechanically bound moisture transformed into free moisture. Additionally, the intensity of hydrophilic functional groups, such as amide I decreased and amide II disappeared after (pre- and post-) THP-AD. The surface hydrophobicity of sludge samples was enhanced and sludge dewaterability improved. The mechanism of pre-/post-THP-AD enhanced sludge dewaterability based on the interaction between moisture and organic matter; additionally, this will provide a reference for optimised moisture-sludge separation processes and guidance for the optimisation of engineering operation parameters.

[en] Highlights: • Lincomycin mycelial residue compost (LMRC) application enhanced soil fertility. • Soil microbial community composition presented temporary shifts as LMRC amended. • Antibiotic level in soil dropped to no effect concentration with 0.5% LMRC addition. • Antibiotic amount in groundwater and pakchoi was acceptable with 0.5% LMRC addition. • 0.5% LMRC application hardly affected ARGs in soil, groundwater and pakchoi. Antibiotic mycelial residue, a kind of organic bio-waste, after composting with the subsequent land application is an effective way to achieve its resource utilization. However, its influences on soil quality and ecological safety in the practical agricultural field and related environmental media, e.g., groundwater and vegetables, remain investigated. In the present study, a field experiment with vegetable plants was conducted to study the influences of lincomycin mycelial residue compost (LMRC) on soil quality, and antibiotics and ARGs' fate. In particular, soil physicochemical properties and microbial community composition were analyzed. Moreover, antibiotics and ARGs' evolution in soil, vegetable, and groundwater were determined. The results showed that the LMRC amendment enhanced soil fertility with the increases of organic matter, total nitrogen, and available P/K. Enzyme activities except catalase and urease were promoted, and they were positively related to the LMRC application ratio. Soil microbial community composition presented temporary shifts as LMRC added, and the low application amount soil showed no significant difference with control at the end of the experiment. Similarly, lincomycin concentration in soil was far lower than the background, and it decreased below the predicted no-effect concentration in groundwater. Besides, the detected lincomycin in pakchoi grew in 0.5% and 1% LMRC amended soil was lower than acceptable daily intake (30 μg/kg). Low application rate (0.5%) of LMRC caused no significant changes of tested ARGs in soil, vegetables, and groundwater. Information obtained from this study provides reasonable application strategies for LMRC that with environmental acceptable antibiotic and ARGs.

[en] Highlights: • A specious relevance between theory and practice has always been argued. • AD approach of straw based on classical theory has been challenged. • Optimum temperature of AD deserves further exploration and updating. • A multi-stage operation strategy based on compositions is a potential approach. Anaerobic digestion (AD) of straw is a highly complex and dynamic process. The temperature range of mesophilic (30–40 °C) and thermophilic (50–65 °C) are usually recommended in textbook notion. The two-phase strategy is usually applied based on the classical theory, including acidification-phase and methanation-phase. However, both the optimized temperature parameter and the enhanced multi-phase strategy solely focus on the local AD process. A specious relevance between theory and practice during AD process of straw has always been argued. Classical AD theory was not necessarily the sufficient approach to guide the anaerobic biological transformation of straw. More profound investigations of optimum temperature are still needed, uniquely synergistic mechanisms of functional microorganisms, as well as process stability, should be taken into account. Besides, additional research should focus on the matching between the physicochemical properties and process parameters/strategies choosing. A multi-stage operation strategy based on straw material composition is a potential operation approach to improve its efficiency. Furthermore, more comprehensive attention should be paid to the collaborative response mechanism by coupling substrate, temperature, and microbial in complex AD systems for straws.