Wastewater Sludge Research Articles

Synergistic effect of innovative bentonite and poly aluminum chloride (PAC) combination for excess and digested sludge thickening and dewatering

Urban wastewater sludge dewatering is one of the challenging issues that wastewater treatment plants face today and needs sustainable solutions. This study aimed to evaluate the effectiveness of the bentonite and poly aluminum chloride (PAC) combination as physical and chemical conditioners for sludge conditioning. This research has shown that the optimal dose for conditioning untreated excess and anaerobically digested sludge is a 0.3% PAC-to-bentonite ratio (1.8 g/g PAC + 6 g/g bentonite for anaerobically digested sludge and 0.324 g/g PAC + 1.08 g/g bentonite for biological excess sludge). Additional tests on extracellular polymeric substances proved that this method can significantly affect parameters such as total organic carbon, protein, and polysaccharides in sludge samples. It was found that time to filtration and specific resistance to filtration parameters were also reduced by 78% and 72% in anaerobically digested sludge and by 90% and 66% in untreated excess sludge respectively when this combination was used. Significant changes in other parameters such as sludge particle size, zeta potential, and others demonstrate the effect of PAC and bentonite combination on sludge types. In addition, the cost for preparing the solutions of both polymers at the considered optimal concentrations was calculated. For each ton of conditioned sludge, the cost ranges between 77$ and 94$. It has been demonstrated that the combination of bentonite and PAC, along with other conventional materials such as acidic modified bentonite, facilitates the dewatering process effectively despite the smaller clots in the sludge after conditioning, which reduces the porosity of the sludge and prevents dewatering.

From Practices to Penalties: Twenty-Three Years of Water and Wastewater Sludge Management in São Paulo State, Brazil

From Practices to Penalties: Twenty-Three Years of Water and Wastewater Sludge Management in São Paulo State, Brazil

Studies on semi-cylindrical solar tunnel dryer for drying wastewater sludge

Drying plays an important process for wastewater sludge management, as it can minimise the volume of wastewater sludge before disposal, and consequently the cost of storage, handling and transport. In this study, the wastewater sludge was dried by using a solar tunnel greenhouse drying system. The performance of the dryer for drying wastewater sludge has been analyzed through no load and full load test. The three full load drying tests recorded that the temperature inside the tunnel dryer fluctuated around 55±5°C; while the no load drying test, the temperature of the drying tunnel maintained within 60±5°C; as compared to the ambient temperature of 30±5°C. The average moisture content of solar dried sludge decreased from 88.69 - 90.84% to 7.78 – 13.30% in the mixing conditions and 14.78 – 19.52% in the non-mixing conditions, in 5 days. The study suggests that the semi-cylindrical solar tunnel dryer of wastewater sludge has given satisfactory results within five days.

Anaerobic Digestion Technology for Biogas Production: Current Situation in Nigeria (A Review)

In view of the nation's vast agricultural resources, crop residues, animal manure, municipal waste, and wastewater sludge may be transformed into renewable energy, potentially a source of revenue. Biogas production offers cleaner, sustainable solutions across the nation. The compass of supportive policy and regulation emerges, guiding investment toward transformative shores. Various "Waste-to-Energy" academic researches and pilot projects illuminate paths to energy generation, waste management and sustainability with the prospects of a viable bioeconomy. The application of anaerobic digestion technology contributes to a greener and more sustainable energy future. In Nigeria, biogas production holds multifaceted benefits which include energy sustainability waste management, and climate change mitigation. By harnessing organic waste, energy source diversification reduces reliance on fossil fuels. Biogas mitigates environmental pollution, converts waste to value, which is key to climate goals. Sustaining biogas production requires incentives, research, expertise, public awareness, and infrastructure. Collaboration and strategic partnerships will likely accelerate Nigeria's biogas production potential. In conclusion, this review underscores the immense potential of biogas production in Nigeria. It seeks to enliven the discussion for fostering efficient management of the abundant organic resources, supportive policies, public engagement, technological advancements, and partnerships that can bring about a wider implementation of biogas production projects across Nigeria towards a greener and sustainable energy future.

The Effect of Municipal Biosolids on the Growth, Physiology and Synthesis of Phenolic Compounds in Ocimum basilicum L.

The continuous development of drinking water networks is leading to the production of increasing amounts of waste water and sewage sludge. Secondary-treated sewage sludge is called biosolids and can be used as fertilizers in agriculture due to its rich nutrient content. The aim of this study was to evaluate the effects of biosolids mixed with an eroded soil on the morphology, physiology and synthesis of bioactive compounds in basil. The study was performed in pots under laboratory-controlled conditions. In total, four substrates were tested: S1 biosolids 100%, S2 biosolids 15% + eroded soil 85%, S3 eroded soil 100% and S4 control (commercial growing substrate). At the morphological level, a significant increase in plant height, number of branches, fresh biomass and dry biomass was found in the S2 variant. At the physiological level, photosynthesis and chlorophyll content did not vary significantly, but the quantum yield of PSII (ΦPSII) was significantly higher at S1 and S2. The oxidative status evaluated by determining the activity of SOD, POD and CAT enzymes was better in S2 and S3 compared to S3. Regarding the synthesis of bioactive compounds (rosmarinic acid, caffeic acid and gallic acid), it was stimulated in S1 and S2. In conclusion, biosolids application stimulated the stress response mechanisms in basil plants by increasing the quantum yield chlorophyll fluorescence and catalase activity, alleviating the negative effects of eroded soil.

Sorption of methylene orange on biocarbon sorbent, obtained by pyroly-sis of wastewater sludge

Water pollution and deterioration of air and water quality is a rapidly growing problem directly related to the generation of waste water and the accumulation of significant amounts of wastewater sludge (WWS). One of the methods for recycling WWS is their pyrolytic processing into biochar adsorbents for purification from various pollutants. The type of adsorbent and its properties play a key role in the efficiency of the purification process, which explains the relevance of the search for alternative materials for water treatment processes. The purpose of the study was to create a biocarbon sorbent during the pyrolysis of wastewater sludge and determine its sorption capacity for the methylene orange dye. To obtain samples of biocarbon sorbent, dried and crushed samples of wastewater sludge were exposed to a temperature of 500 °C for 1.5 hours in a vacuum chamber with a heating rate to a given temperature of 5°C/min. Elemental analysis of the resulting sorbent allowed to establish a decrease in the content of carbon, oxygen, and sulphur: for C by 2.50 at.%, for O by 9.91 at.%, for S by 0.4 at.%, relative to WWS. Scanning electron microscopy confirmed a significant reduction in the particle size of biochar compared to the original WWS sample. In the initial WWS sample, after the sample preparation stage, the dispersion of particle sizes was 10-70 µm, and after pyrolysis of the sediment, the dispersion decreased to the range of 10-45 µm. The percentage of biochar yield was calculated, constituting 42% of the weight of the initial WWS and studies on the sorption of methylene orange were carried out. The sorption capacity of biochar for the anionic dye methylene orange after 120 min of sorption was 4.9 mg/g, the degree of solution purification reached 82%. The kinetics of dye sorption was correctly described by a pseudo-second-order equation and indicated the polymolecular nature of sorption.

Valorization of Textile Sludge and Cattle Manure Wastes into Fuel Pellets and the Assessment of Their Combustion Characteristics.

The textile wastewater sludge (TWS) treatment and disposal are environmentally challenging due to toxic organics and metals. At the same time, cattle manure (CM), with better combustion performance, i.e., calorific value and uniform burning capability, is still underutilized in many parts of the world. This study evaluated and assessed the TWS and CM blending compatibility to convert them into fuel pellets for the direct combustion option and to stabilize toxic contaminants in TWS. After initial drying, grinding, and particle size control of the raw TWS and CM, both were blended at different ratios. The blended and nonblended TWS and CM samples were converted into pellets and analyzed for proximate and ultimate analyses, namely, moisture content, fixed carbon, CHNO, gross calorific value (GCV), bulk density, ash content, and metals, to evaluate the efficacy for energy applications. Out of three blended ratios, i.e., 75:25 (W/W%; CM/TWS), 50:50, and 25:75, the 75:25 blended pellet composition was found appropriate for fuel application. For the 75:25 blend, the obtained GCV was 12.77 MJ/kg, elemental carbon was 27.5%, volatiles were 41.7%, and residue ash was 42.8% of the total weight. Moreover, the blending ratios of 75:25 and 50:50 revealed that elemental and metal (Fe, Cu, Zn, Ni, Cr, Na, Mg, Mn) concentrations in TWS were stabilized to below threshold limits in the obtained residue ash for safe handling. The explored methods of TWS and CM waste processing, blending, and pelletization proposed a new technique for their sustainable waste valorization into energy sources.

Electrochemical Oxidation of Synthetic Wastewater Sludge on Ni Foam for Nutrient Recovery

Continued growth of the world’s population as well as shifting socio-economic trends have been tied to increasing demands for food and water. Due to upcoming worldwide environmental crises, there needs to be a shift towards a circular economy, where key nutrients are not lost but repurposed. For example, high-yield food crops depend on the application of nitrogen and phosphorus-based fertilizers, which are respectively made using highly energy intensive methods, like the Haber-Bosch process, and non-renewable limited resources, such as phosphate rock. In addition, water that has been contaminated by human activity is being treated in a multitude of manners, with the overarching drawbacks being high energy consumption and, in some cases, the production of a secondary waste stream. In particular, wastewater sludge is a nutrient-rich waste stream with high levels of nitrogen and phosphorus stored in organic bonds that is most commonly sent to landfills for disposal.In this talk, we focus on the electrochemical oxidation of wastewater sludge for the recovery of ammonia and other nutrients. We used a synthetic wastewater sludge composition to better understand the contributions of each component on the formed end-products. We probed the potential dependence of these end-products by conducting fixed-potential tests in a H-cell with Ni foam electrodes. This work contributes to the ongoing efforts in the Center of Advancing Sustainable and Distributed Fertilizer Production (CASFER).

Influence of perlite/biosolid composition on growth and uptake of Cd and Mn by radish (Raphanus sativus L.) under greenhouse conditions

The effects of different perlite/biosolid compositions upon the uptake of Cd and Mn, and the growth of radish plants (Raphanus sativus L) was investigated by using inductively coupled plasma optical emission spectroscopy, and inductively coupled plasma mass spectrometry (ICP-OES and ICP-MS). Mn and Cd were added in soluble forms to perlite/biosolid compositions. Notably, Mn concentrations in different plant parts were found to increase with increase in biosolid compositions, in the order [Mn]leaves > [Mn]shoot > [Mn]roots. This is plausible for Mn, in conformity with the essential role Mn plays during photosynthesis, in metabolic processes, and oxidation–reduction processes in cells. Results indicate that Mn concentrations in plant parts increased up to ~ 50% (wt/wt) perlite/biosolid application rates. In contrast the Cd uptake concentrations in plant parts decreased in the order [Cd]roots > [Cd]shoots > [Cd]leaf. Thus, toxic Cd tends to be sequestered in the roots vis-à-vis Mn that is translocated to the leaves. These results suggest that radish plants sequester Cd in the roots. Biosolids therefore play an important role in sequestering and binding of Cd. The observed concomitant increase in biomass yields implicates the rich contribution of N and P from biosolids. The results from the greenhouse experiments lead to the conclusion on the role played by the biosolids in cleanup and remediations for Cd and Mn, which increased in plant parts with composted wastewater sludge—compositions.

Increasing efficiency of irrigation reclamation in potato and soybean agrocenoses using sludge

The purpose of the study was to assess effect of different doses of wastewater sludge on productivity of irrigation water use by agrocenoses of potatoes (Zhukovsky rannii) and soybeans (VNIIOZ 31), on their yield, as well as the index of soil contamination and seed production. Agrometeorological conditions of the periods of vegetation experiments are characterized as dry with hydrothermal coefficient value of no more than 0.39. Considering the current climatic conditions, regulations for watering potatoes and soybeans were drawn up. It was established that application of WWS in doses of 20, 40 and 60 tha-1 had different effects on crops total water consumption. In potato crops, irrigation rate varied from 2590 m3ha-1 in the control to 1850 m3ha-1 in WWS60 variant, and in soybean crops, it varied from 3700 in the control to 2960 m3ha-1 in WWS60 variant. At the same time, amount of irrigation water to obtain a ton of potato and soybean yield in the control averaged 124.5 and 1298.2 m3t-1, respectively, against 118.372.8 and 1213.1886.2 m3t-1 for variants WWS20, WWS40 and WWS60, which corresponded to increase in water use productivity from 5.0 to 41.5 % and from 6.6 to 31.7 %, respectively. Laboratory studies of soil samples of the arable layer showed that pollution index in relation to heavy metals Cd, Pb, Zn, Cu varies from 2.54 in variant WWS20 to 4.04 in variant WWS60, which indicates the absence of soil contamination. Evaluation of potato tubers for values of starch, dry matter, nitrates and heavy metals demonstrates sufficiently high quality and acceptable level of contamination of the seeds.

Fast prediction and control of air core in hydrocyclone by machine learning to stabilize operations

Operation stability significantly impacts hydrocyclone separation performance during wastewater treatment, sludge processing, and microplastic removal from water. The air core inside a hydrocyclone is an important indicator of operation stability. This paper presents a machine learning model designed for fast prediction and control of air core profiles. The model is built upon a modified graph neural network (GNN). It is trained by the data generated from a well-established and validated computational fluid dynamics (CFD) model. This GNN-based surrogate model has undergone two modifications to enhance its prediction accuracy. One is data smoothing, to mitigate the adverse effects of the drastic data change in spatial distributions. The other is the loss function modification to incorporate the air core information acquired by the CFD model. The predicted air cores are compared with the original GNN and random forest (RF) against the CFD results. It shows that the new surrogate model can reproduce air profiles and have higher accuracy than other models in predicting spatial distribution results among different error metrics. Furthermore, this surrogate model is combined with the genetic algorithm to optimize the air core. The proposed machine learning model framework offers a promising avenue for the prediction and control of hydrocyclones.

Development of a Hybrid Technological Scheme for the Treatment of Anaerobically Fermented Sludge (Digestat) of Wastewater of the Food Industry

The issue of dewatering and disposal of sewage sludge is one of the most urgent due to the acute shortage of land resources, the negative ecological burden on water resources, soils and the atmosphere of these sludges in case of their accumulation without proper treatment. Anaerobic stabilization of food production wastewater sludge is one of the most widespread methods of processing this type of sludge due to the possibility of obtaining an important energy resource – biogas. The sludge obtained after anaerobic stabilization in methane tanks is called digestate, and it also needs treatment and further disposal. Digestate can be used as a fertilizer if sanitary and hygienic requirements are met. The development of a technological scheme for processing wastewater digestate is a complex issue that does not have one correct solution. A hybrid technological process for processing wastewater digestate of the food industry is proposed on the basis of experimental studies. Experimental studies include dewatering anaerobically stabilized sludge on a multi-disc dehydrator using dilution of the sludge itself due to its significant viscosity, addition of coagulant and flocculant. Cake with a moisture content of about 65–80% can be transported and used as fertilizer for agriculture. The separated filtrate from the digestate according to the technological scheme is proposed to be purified on two stages of membranes. The efficiency of cleaning the liquid fraction of the digestate on a two-stage membrane installation according to two variants showed the following results: variant 1 (VSEP + RO) – 95%, variant 2 (ZI + RO1 + RO2) – 94%. The VSEP system uses a hermetic RO membrane, so a two-pass membrane process (VSEP+RO) is suitable to achieve the end goal (permeate obtained can be reused), while a ZI membrane requires a three-pass membrane process to achieve the same goal. The achieved parameters make it possible to use the obtained permeate for the production needs of the enterprise or in the technological scheme of the digestate processing itself for dilution of the sediment or for the preparation of reagent solutions. The resulting products (cake and concentrates after membranes) can be used as fertilizers.

Effect of Gamma-Irradiated Ceramic Wastewater Sludge on Photosynthetic Pigments of Phaseolus Vulgaris L. (Cv. Valentino and Cv. Nebraska) Plants

The common bean plant is a highly polymorphic species, annual herb, erect and bushy, 20–60 cm tall, or twining with stems 2–3 m long, with a taproot and nitrogen nodules which the bacteria could convert nitrogen gas and stores it in the common bean plant roots. Leaves are alternate, green, or purple, trifoliolate, stipulate, petiolate, markedly pulvinus at base; leaflets ovate, entire; acuminate, 6–15 cm long, 3–11 cm wide. Many soils have been contaminated with several pollutants, mostly arising from wastes of human activities such as the use of pesticides, sewer sludge, mining and smelting sources, radioactive substances, and industrial dischargers. These different contaminants can degrade the soil and cause a negative impact on the plant due to disturbing nutrient cycling within ecosystems and subsequently human health. This study aimed to elucidate the mechanism by which the plant may cope with heavy metals stress represented in this study in the form of industrial ceramic wastewater sludge. And, evaluating the role of gamma radiation on ceramic wastewater sludge, could reduce the percentage of the endogenous levels of heavy metals in ceramic sludge. This study investigates the influence of Photosynthetic pigments of the two common bean cultivars Valentino and Nebraska which are grown in light soil clay/sand (1:1) incorporated with ceramic-wastewater sludge (CWWS) non-irradiated (1% and 2%) and gamma-irradiated (2.5 kGy and 10 kGy) for 30 days. The application of non-irradiated CWWS induced an elevation in the contents of chlorophylls a, b, and carotenoids in the two cultivars while a reverse trend was observed in the leaves of both cultivars treated with gamma irradiated CWWS.

Effects of Rubber Factory Wastewater Sludge Compost on the Growth Parameters of Rubber Seedlings: A Nursery Study and Environmental Perspective

Conducted at the University of Jambi's Teaching and Research Farm in Mendalo Indah Village, this three-month study from September to November 2022 utilized a Completely Randomized Design (CRD) with a single variable: rubber factory wastewater sludge compost application. Five treatment levels were tested: a0 = 25 g NPKMg dose, a1 = 100 g rubber factory wastewater sludge compost + 20 g NPKMg dose, a2 = 200 g rubber factory wastewater sludge compost + 15 g NPKMg dose, a3 = 300 g rubber factory wastewater sludge compost + 10 g NPKMg dose, and a4 = 400 g rubber factory wastewater sludge compost + 5 g NPKMg dose. Statistical analysis, employing ANOVA and the Honestly Significant Difference (HSD) test, determined treatment effects at a 5% significance level. The study assessed various rubber plant growth parameters, such as live seedling percentage, shoot emergence, budded shoot height, leaf count, stem diameter, root count, shoot and root dry weight. Notably, the application of 400 g of rubber factory wastewater sludge compost significantly influenced plant growth, specifically enhancing shoot emergence, stem diameter growth, and budded shoot height.

Effects of high-concentration influent suspended solids on aerobic granulation in sequencing batch reactors treating real textile wastewater

The formation of aerobic granular sludge (AGS) in real textile wastewater (TWW) is time-consuming and challenging. The present study investigated the effects of high-concentration influent suspended solids (SS) on aerobic granulation, pollutant removal, microbial activity, and community in the real TWW treatment by using two sequencing batch reactors (R1: 41.7 ± 22.8 mg influent-SS/L; R2: 416.1 ± 21.4 mg influent-SS/L). The results showed that complete granulation was achieved in R1 within 97 days (SVI30: 34.5 mL/g, SVI30/SVI5 = 0.91), while it only required 52 days in R2 (SVI30: 18.2 mL/g, SVI30/SVI5 = 0.92). The high-concentration influent SS also enhanced compactness and settleability of AGS. Long-term adaption of sludge improved the COD removal from real TWW, which was possibly due to the increase in phyla Firmicutes and Actinobacteria abundances. The real TWW did not adversely affect the nitrification process as indicated by the high NH4+-N removal in both reactors (>93 %). Although the formation of compact AGS in R2 did not exhibit better removal performance under the present experimental condition, it exhibited the potential for better COD removal from real TWW as indicated by the higher microbial activity and functional bacterial abundances in R2 than in R1.

Enhancing Optimal Resource Recovery from Municipal Wastewater Sludge: Selection of Appropriate Waste to Energy Technologies for Zvishavane Urban, Zimbabwe

Enhancing Optimal Resource Recovery from Municipal Wastewater Sludge: Selection of Appropriate Waste to Energy Technologies for Zvishavane Urban, Zimbabwe

Rapid static feeding combined with Fe2+ addition for improving the formation and stability of aerobic granular sludge in low-strength wastewater

Aerobic granular sludge (AGS) needs a long start-up time and always shows unstable performance when it is used to treat low-strength wastewater. In this study, a rapid static feeding combined with Fe2+ addition as a novel strategy was employed to improve the formation and stability of AGS in treating low-strength wastewater. Fe-AGS was formed within only 7 days and showed favorable pollutant removal capability and settling performance. The ammonia nitrogen (NH4+-N) and chemical oxygen demand (COD) concentration in the effluent were lower than 5 mg/L and 50 mg/L after day 23, respectively. The sludge volume index (SVI) and mixed liquid suspended solids (MLSS) was 37 mL/g and 2.15 g/L on day 50, respectively. Rapid static feeding can accelerate granules formation by promoting the growth of heterotrophic bacteria, but the granules are unstable due to filamentous bacteria overgrowth. Fe2+ addition can inhibit the growth of filamentous bacteria and promote the aggregation of functional bacteria (eg. Nitrosomonas, Nitrolancea, Paracoccus, Diaphorobacter) by enhancing the secretion of extracellular polymeric substances (EPS). This study provides a new way for AGS application in low-strength wastewater treatment.

Long-Term Effect of Wood Ash and Wastewater Sludge Fertilization on Tree Growth in Short-Rotation Forest Plantations on Abandoned Agricultural Land: A Case Study

Short-rotation forest plantations on former agricultural land capture CO2, provide bioeconomic materials, and mitigate climate change. This study aimed to enhance our understanding of the long-term effects of wood ash and wastewater sludge fertilization on various tree species (birch, hybrid aspen, grey alder, black alder, and hybrid alder) in short-rotation forestry plantations on abandoned agricultural land where tree growth measurements were taken over an 11-year period. After 11 years, the highest aboveground biomass (AGB) was observed for hybrid aspen clone No. 4 under wastewater sludge treatment (109.0 t ha−1), birch under wood ash treatment (34.3 t ha−1), black alder under wastewater sludge treatment (33.6 t ha−1), grey alder under wastewater sludge treatment (40.9 t ha−1), hybrid alder under control conditions (36.2 t ha−1), and hybrid aspen clone No. 28 under wood ash treatment (37.2 t ha−1). The average survival rate was 73% in control plots, 81% under wastewater sludge treatment, and 78% under wood ash treatment. Short-term positive impacts on tree growth were observed, effects that were not consistent over the long term. The impact of these treatments on tree growth varied between species, and the effects tended to diminish over time, which must be considered before fertilization.

Polydimethyldiallylammonium chloride inhibits dark fermentative hydrogen production from waste activated sludge

Polydimethyldiallylammonium chloride (PDDA) is an excellent flocculant for wastewater purification and sludge dewatering, but whether it poses a threat to hydrogen production from waste activated sludge is not known. In this study, the effect and underlying mechanism of PDDA on the dark fermentation of sludge was investigated. The results showed that PDDA reduced cumulative hydrogen production from 3.8±0.1 to 2.4±0.1 mL/g volatile suspended solids at 40 g/kg total suspended solids. PDDA impeded the dark fermentation process by inhibiting the activity of key enzymes, presenting a stronger inhibitory effect on the hydrogen production process than the hydrogen consumption process. Additionally, PDDA inhibited Firmicutes by enriching other microorganisms, thereby impeding hydrogen production via the acetate pathway. This study deepens the understanding of the potential effects of PDDA on sludge treatment and provides a theoretical basis for alleviating the negative effects of quaternary ammonium-based cationic flocculants.

Nanoparticle-assisted biohydrogen production from pretreated food industry wastewater sludge: Microbial community shifts in batch and continuous processes

Biohydrogen production from industrial waste has gained a significant attention as a sustainable energy source. In this study, the enrichment of biohydrogen production from pretreated dissolved air flotation (DAF) sludge, generated from food industry wastewater treatment plants, was investigated using SiO2@Cu-Ag dendrites core–shell nanostructure (NS). The effect of NS on the changes of the microbial community and biohydrogen yield was evaluated through batch and continuous tests. In batch mode, various nanomaterial doses were investigated with several concentrations ranging from 20 to 50 mg/L for hydrogen production using glucose as a substrate. The optimum core–shell NS amount was 40 mg/L, achieving a maximum H2 yield of 163 mL/g volatile solids (VS) compared to the control's 79 mL/g VS. However, 50 mg/L NS inhibited most bacteria in the sludge. The continuous experiment used a continuous stirring tank reactor (CSTR) with 40 mg/L SiO2@Cu-Ag core–shell NS and pretreated industrial sludge as substrate. The H2 yield increased to 115 L/kg VS compared to the control reactor's 89 L/kg VS. The gas analysis showed compositional proportions of 83 % H2, 7 % CO2, and 4.5 % methane, while the microbial community analysis indicated the development of hydrogen-producing species such as Clostridium. In conclusion, SiO2@Cu-Ag core–shell NS addition enhanced anaerobic degradation of organic matter and its conversion to biohydrogen. The selected nanomaterial can be used for an effective continuous treatment system for industrial sludge while promoting dark fermentation.