Sludge Production Research Articles

Development of an environmentally sustainable technique to minimize the sludge production in the textile effluent sector through an electrokinetic (EK) coupled with electrooxidation (EO) approach.

This study presents an environmentally sustainable method for minimizing sludge production in the textile effluent sector through the combined application of electrokinetic (EK) and electrooxidation (EO) processes. AAS and XRF analyses reveal that utilizing acidic electrolytes in the EK method successfully eliminates heavy metals (Cu,Mn, Zn, and Cr) from sludge, demonstrating superior efficiency compared to alkaline conditions. In addition, the total removal efficiency of COD contents was calculated following the order of EK-3 (60%), EK-1 (51%) and EK-2 (34%). Notably, EK-3, leveraging pH gradient fluctuations induced by anolyte in the catholyte reservoir, outperforms other EK systems in removing COD from sludge. The EK process is complemented by the EO process, leading to further degradation of dye and other organic components through the electrochemical generation of hypochlorite (940ppm). At an alkaline pH of 10.0, the color and COD removal were effectively achieved at 98 and 70% in EO treatment, compared to other mediums. In addition, GC-MS identified N-derivative residues at the end of the EO. This study demonstrates an integrated approach that effectively eliminates heavy metals and COD from textile sludge, combining EK with EO techniques.

Thermal methods of sludge processing—are they suitable for pharmaceuticals and illicit drugs removal from sewage sludge?

AbstractThe presented work aimed to investigate the effect of thermal treatment on sludge from wastewater treatment plants (WWTPs) in the Slovak Republic on the content of pharmaceuticals (PhACs) and illicit drugs. Sludge samples from eight WWTPs (total flows of 6900–62,500 m3/day, number of population equivalents over 40,000 for each WWTP, production of sludge 400–3300 tons DM/year) were treated with thermal processes in the temperature range of 80 to 550 °C. More than 100 compounds were studied in the sludge samples, but in this article, we deeply focused on the fate of the thirteen most concentrated and frequently found PhACs (azithromycin, carbamazepine, cetirizine, citalopram and its metabolite N-desmethylcitalopram, diclofenac, fexofenadine, sertraline and its metabolite norsertraline, telmisartan, trazodone, valsartan, and verapamil). The thermal processes used showed a decrease in PhAC concentrations already at 80 °C when the total concentration of selected PhACs decreased to 81%. In thermally treated sludge samples at 250 °C, only telmisartan at all studied WWTPs and diclofenac at WWTP Banská Bystrica stayed above the limits of quantification (LOQs), while the temperature of 550 °C led to a decrease in all thirteen PhACs below LOQs.

Reuse of Sewage Sludge as Organic Agricultural Products: An Efficient Technology-Based Initiative

Rapid urbanisation has led to a dramatic increase in sewage sludge production. There are limited methods of managing sewage sludge along with high energy and monetary investment. A cost-effective, environment-friendly, and sustainable solution needs to be developed for the management of sewage sludge. In the current study, sludge from the Jagjeetpur sewage treatment plant (STP) had been collected, composted, and characterized during January and February 2022. A comparison of STP sludge compost and compost made from farmyard manure showed the presence of essential agricultural nutrients in them, due to which they find application for plant growth. Two products, Jaivik Poshak and Jaivik Prom, containing farmyard compost, were compared with the amended version of the same, containing compost from STP sludge instead of normal compost. The results showed that the modified Jaivik Poshak was the best for maintaining pH and increasing electrical conductivity. The available nitrogen in the soil upon its application increased by 1.6 times (p<0.001) with respect to control, and it brought about 100% tomato seed germination within sixteen days. The above finding has been validated by goodness of fit value, factor analysis, and hierarchical analysis. The product, modified Jaivik Prom increased organic carbon content and brought about 5.81 and 8 times the enhancement in available phosphorous (p<0.001) and potassium (p<0.001) content in soil, respectively, with respect to the control set. The heavy metal content in the soil as a result of all types of treatment was within the permissible limit. This study thus proves that sludge from STP may be used for agricultural uses after proper fortification and testing to convert waste to wealth along with environmental sustenance.

Research the slurry thickening efficiency of aluminum companies in Vietnam using experimental settling column system

The thickening is the process of increasing the solid fraction in the slurry. The purpose of the process is to obtain a thicker sludge product and to obtain an overflow product with a minimum solid amount. The equipment used are traction thickener, cable thickener, caisson thickener, tray thickener, E-Cat thickener, lamella thickener, etc. This stage plays an essential role and greatly affects operations in mineral beneficiation factories. However, this is a problem for Aluminum companies in Vietnam because the amount of particles passing 1 mm is significantly higher than the design, leading to the overloading of thickeners. The overall productivity of the factories was affected and seriously reduced due to not being able to ensure the amount of feeding coarse particles and having to stop the operation to fix the problem. The requirement is to find and apply advanced technologies to improve the sedimentation process. This article presents the characteristics of bauxite slurry in Daknong and Lamdong companies. The amount of fine particles passing 0.02 mm reaches more than 62% (in the case of Daknong) and 72% (in the case of Lamdong) with the main minerals (gibbsite, goethite, kaolinite, ilmenite, etc.). On that basis, the survey was implemented to define the optimal type of flocculant aids (NALCO 85035 and HA - LB 080), flocculant dosage (40 grams/tons), and pH of the sludge (6.5 – 7). The obtained underflow product has a solid phase concentration of over 35% and the overflow has an amount of solid/water of less than 100 mg/l. Research was conducted on an experimental settling column system and it was recommended to pre-test a Lamella high-performance thickener for further research.

Enhancing methane production and interspecies electron transfer of anaerobic granular sludge by the immobilization of magnetic biochar

Supplementation of conductive materials has been proved to be a promising approach for enhancing microbial interspecies electron transfer (IET) in anaerobic digestion systems. In this study, magnetic bamboo-based biochar was prepared at temperatures of 400–800 °C via a ball milling/carbonization method, and it immobilized in mature anaerobic granular sludge (AGS) aimed to enhance methane production by improving the IET process between syntrophic microbial communities in the AGS. Results showed that the AGS with magnetic biochar immobilization demonstrated increased glucotrophic and acetotrophic methane production by 69.54–77.56 % and 39.96–54.92 %, respectively. Magnetic biochar prepared at 800 °C with a relatively higher Fe content (0.37 g/g magnetic biochar) displayed a stronger electron charge/discharge capacity (36.66 F/g), and its immobilization into AGS promoted methane production most. The conductivity of AGS increased by 52.13–87.32 % after incorporating magnetic biochar. Furthermore, the extracellular polymeric substance (EPS) of AGS showed an increased capacitance and decreased electron transfer resistance possibly due to the binding of magnetic biochar and more riboflavin secretion in EPS, which could contribute to the accelerated IET process in the inner AGS. In addition, the immobilization of magnetic biochar could promote the production of volatile fatty acids by 15.36–22.50 %. All these improvements may jointly lead to the enhanced methane production capacity of AGS. This study provided a fundamental understanding of the role of incorporated magnetic biochar in AGS in promoting anaerobic digestion performance.

First application of the novel anaerobic/aerobic/anoxic (AOA) process for advanced nutrient removal in a wastewater treatment plant

The stringent effluent quality standards in wastewater treatment plants (WWTPs) can effectively mitigate environmental issues such as eutrophication by reducing the discharge of nutrients into water environments. However, the current wastewater treatment process often struggles to achieve advanced nutrient removal while also saving energy and reducing carbon consumption. The first full-scale anaerobic/aerobic/anoxic (AOA) system was established with a wastewater treatment scale of 40,000 m3/d. Over one year of operation, the average TN and TP concentration in the effluent of 7.53 ± 0.81 and 0.37 ± 0.05 mg/L was achieved in low TN/COD (C/N) ratio (average 5) wastewater treatment. The post-anoxic zones fully utilized the internal carbon source stored in pre-anaerobic zones, removing 41.29 % of TN and 36.25 % of TP. Intracellular glycogen (Gly) and proteins in extracellular polymeric substances (EPS) served as potential drivers for post-anoxic denitrification and phosphorus uptake. The sludge fermentation process was enhanced by the long anoxic hydraulic retention time (HRT) of the AOA system. The relative abundance of fermentative bacteria was 31.66 - 55.83 %, and their fermentation metabolites can provide additional substrates and energy for nutrient removal. The development and utilization of internal carbon sources in the AOA system benefited from reducing excess sludge production, energy conservation, and advanced nutrient removal under carbon-limited. The successful full-scale validation of the AOA process provided a potentially transformative technology with wide applicability to WWTPs.

Decolorization of acid orange 7 in moving bed biofilm reactor packed with polyhydroxyalkanoate/activated carbon

Moving bed biofilm reactor (MBBR) using various carrier medium has been widely employed in wastewater treatment. This study aimed to investigate the feasibility of polyhydroxyalkanoate (PHA) and activated carbon (AC) composite (PHA/AC) as biofilm carrier to enhance MBBR treatment of azo dye acid orange 7 (AO7). Each PHA/AC carrier had a height of 0.40 cm and a cylindrical diameter of 1.25 cm. The biofilm on PHA/AC carrier was characterized using microscopic and chemical analysis. AO7 decolorization efficiency and kinetics were evaluated. The incorporation of AC in PHA was found to promote biofilm growth. Mature biofilm of 2075 ± 79.30 μm was successfully formed on PHA/AC carrier. Compared to a control reactor, the MBBR with 5 % (v/v) PHA/AC exhibited improved decolorization, with decolorization efficiency and first-order rate constant, kAO7, increasing from 78.2 % and 9.90 × 10−4 min−1 to 95.0 % and 1.70 × 10−3 min−1, respectively. The enhancement of decolorization in MBBR was attributed to the presence of anoxic zone within the biofilm that favored the azo bond cleavage. Batch studies on the effects of suspended activated sludge (AS) and biofilm amounts showed an additive effect on decolorization efficiency when combined. The combined suspended AS and biofilm also resulted a 3–4 folds increase in kAO7 value compared to AS alone. The results indicate that PHA/AC was an effective carrier and its biofilm exhibited high decolorizing ability for AO7. The enhancement provided by the PHA/AC biofilm makes it advantageous for developing efficient and environmentally-friendly wastewater treatment systems with compact design and minimal sludge production.

Effects of production temperature on the molecular composition and seed-germination-promoting properties of sludge-based hydrochar-derived dissolved organic matter

Sludge hydrothermal carbonization demonstrates potential for converting sludge into multifunctional carbon materials for soil remediation. However, the influence of dissolved organic matter (DOM) with unclear molecular characteristics in sludge-based hydrothermal carbon on plant growth has not been sufficiently investigated. Herein, the effects of hydrothermal temperature on the molecular transformation pathways and plant-growth-promoting properties of DOM were investigated via FT-ICR MS–based molecular network analyses and seed germination experiments. Results indicated that the highest DOM yield was achieved at 220 °C. During low-temperature (180 °C) hydrothermal treatment, the hydrolysis of biopolymers, as well as the partial condensation and cyclization of small-molecule intermediates, occurred in the sludge. This process produced unsaturated CHNO compounds containing one or two N atoms, which promoted seed germination. Further, the toxicity of DOM to plants increased with rising hydrothermal temperature. This was accompanied by S doping and aromatization reactions, which mitigated the effects of plant growth hormones. This study provides theoretical support for the optimization of sludge hydrothermal treatment and production of plant growth hormones, enhancing the ecological value of sludge-based hydrochar.

Regulating the distribution of phosphorus in sewage sludge hydrothermal carbonization products by complexation pretreatment

In this study, we investigated the effects of the concentrations of four pretreatment complexing reagents, namely ascorbic acid (AS), citric acid (CA), N, N-bis (carboxymethyl) glutamic acid (GLDA), and ethylenediaminetetraacetic acid (EDTA), on the phosphorus contents and forms in hydrothermally carbonized sludge products. The results showed that among the four complexing reagents, EDTA had the greatest effect on the phosphorus transfer from the solid phase to the liquid phase during the hydrothermal process of the sludge, followed, respectively, by GLDA, CA, and AS. The phosphorus proportion of the liquid phase was 63.96% under hydrothermal process temperature, reaction time, and EDTA concentration of 160 °C, 60 min, and 0.2 mol/L, respectively. The results showed formations of EDTA complexes with Ca, Fe, and Al in the sludge, releasing phosphorus bound to the metal ions into the liquid phase. The highest total phosphorus concentration in the liquid phase was 2533.31 mg/L following the increase in the hydrothermal process temperature from 100 to 160 °C. However, the Fe and Al-EDTA complexes were thermally decomposed after continuously increasing the hydrothermal process temperature to 240 °C, resulting in a readsorption of phosphorus to the solid phase with Fe, Al, and other metals and, consequently, decreasing the phosphorus content to 880.93 mg/L in the liquid phase. The results of this study provide a scientific basis for regulating phosphorus distribution in the solid and liquid phases of hydrothermally carbonized sludge products and effectively recovering phosphorus in the liquid phase.

Petroleum sludge formation and its treatment methodologies: a review.

Different petroleum operations produce huge amount of oil sludge annually. For instance, US EPA estimates the annual sludge production of each US refinery of 30,000 tons, while the average oily sludge produced from petrochemical industries in China is estimated about 3 million tons per year. In the last year, our center could recover about 30,206 barrels of raw oil from 32,786 barrels of tank bottom sludge (TBS) for different petroleum companies. This sludge causes huge economic losses besides its negative environmental impacts. The accumulation of sludge in the tanks results in reducing the tanks' capacity for storing liquid crude, accelerating the corrosion of the tanks, delay in the production schedule, and disturbing the whole production operation. There are diverse treatment methodologies such as solvent treatment, addition of certain chemicals, and centrifuging. Of course, the environmental regulations and the overall cost limitations are very important in deciding the preferred applicable method(s). Although several works handled the problem of sludge deposition and treatment from different aspects, we intend to introduce a different work. First, composition, formation, types, and properties of TBS were reviewed. Then, environmental and economic problems caused by TBS were revised. At last, different methodologies applied for treatment of oily TBS to recover oil and safe disposal of hazardous remains were investigated focusing on the most straightforward and environmentally friendly protocols. It is expected that this review attracts the experts in petroleum chemistry, and other relevant fields and provides a comprehensive understanding of current sludge control and treatment research.

Fe electrocoagulation technology for highly-efficient p-arsanilic acid removal from water: Feasibility and mechanisms

Conventional oxidation methods are effective for the removal of p-arsanilic acid (p-ASA) in water but are limited by complicated process. Herein, Fe electrocoagulation with Fe as anodes was used to efficiently remove p-ASA with 100% total arsenic removal within 60 min (1.75–20 A/m2). Current density significantly influenced sludge production, anode loss, and energy consumption (p-value < 0.05). Kinetic analyses showed a decline in arsenic removal rate with increasing initial pH (4.0–10.0). The changes in main elements of p-ASA (As and N) were analyzed to identify intermediate products using UPLC-Q-TOF-MS, HPLC-ICP-MS, and spectrometry. Hydroxyl radicals were confirmed as the primary reactive oxygen species. The active sites of p-ASA molecules were predicted by theoretical calculations and reaction paths were proposed. The toxicity of Fe-EC effluent was effectively reduced according to the analyses of ECOSAR and E. coli colonies method. The possible mechanisms of p-ASA removal, including oxidative degradation, electrostatic attraction, and ligand complexation, were proposed. Real water containing a p-ASA concentration of 250 μg/L was treated for 48 h using continuous-flow Fe-EC and arsenic concentrations of 2–30 μg/L in effluent were obtained. Overall, Fe-EC was a simple, cost-effective, and eco-friendly technology for the removal of p-ASA.

Effects of carbon diversion to primary sludge production on thermal hydrolysis pretreatment-enhanced anaerobic digestion

Solid mass flow through the WRRF (a) without primary settling, (b) with primary settling and a PS-to-WAS ratio of 1 : 1, and (c) with primary settling and a PS-to-WAS ratio of 3 : 1.

Sustainable treatment and recycling of oily sludge: Incorporation into gel -system to improve oil recovery.

Oily sludge is very difficult to treat in solid waste, how to achieve on-site treatment and recycling of the sludge is rarely reported. This research proposes a new treatment method for oily sludge by adding the oily sludge into the gel water plugging system designed for low-performing oilfields-sludge re-injection technology. The gel system of oily sludge can resist dehydration for 150 days at a high temperature up to 140 °C and a salinity of 2.11 × 105 mg/L, and its strength reaches grade I. The microstructure of the gel was revealed using scanning electron microscopy (SEM). The addition of oily sludge made the gel system microstructure develop a dense three-dimensional network structure, which can effectively improve the strength and temperature resistance of the gel system. Differential scanning calorimetry (DSC) experiments show that the gel with oily sludge can maintain temperature resistance even at 188 °C. Laboratory displacement experiments show that the breakthrough pressure of the gel system can reach 3418 kPa/m, and the plugging rate is above 98%. The performance of the system was improved by adding oily sludge into the gel as an enhancer, which provided a research idea for harmless treatment, resource utilization and clean production of oily sludge.

Catalysing water treatments: A Comprehensive Examination of sludge, its treatment and Energy Valorisation Solutions

The escalating production of sewage sludge in WasteWater Treatment Plant (WWTP) due to urban population growth and its management poses a substantial risk to the energetic and environmental efficiency of WWTP. This paper aims to explore the potential for sludge as a renewable energy source to reduce reliance on traditional energy through a systematic literature review of peer-reviewed articles and case studies. This overview demonstrated that various treatment methods such as anaerobic digestion, incineration, gasification, and pyrolysis are the most used and the most promising in terms of their energy outputs and effectiveness. The paper discussed the complexity of sludge composition, its financial burden on WWTP, and the crucial role in the success of these systems. Moreover, a comparative analysis of the different valorisation techniques was conducted that highlighted the energy production potential existing within each method and its underlying constraints while emphasising on the proper sludge management for overall efficiency. Finally, this paper recommended the need for sustainable, cost-effective approaches, considering legal standards for efficient WWTP.

Minimizing biological sludge generation in a sidestream enhanced biological phosphorus removal (S2EBPR) system: full-scale evaluation and modeling insights

This study evaluates sewage sludge production in real-scale and models sidestream enhanced biological phosphorus removal (S2EBPR) systems under various mixing, organic feeding, and solids retention time (SRT) conditions.

Economic Foundations and Prospects for The Use of Environmentally Safe Biofertilizer from Wastewater Sludge: The Case of Russia

The article presents conclusions based on the results of analytical and experimental work devoted to the formation of economic foundations and the determination of prospects for the use of environmentally safe biofertilizer from wastewater sludge. In Russia, wastewater sludge production is estimated at 2.5 million tons of dry matter per year and accounts for 30-45% of the total amount of production and consumption waste. The purpose of this article is to develop the composition of an organic fertilizer from wastewater sludge, an economic justification for the feasibility and experimental confirmation of the safety of using the resulting fertilizer in soils. Based on analytical studies of wastewater sludge processing directions, the capacity and needs of the biofertilizer market, a comparative analysis of the main producers and consumers of these products, an economic justification for the feasibility of producing biofertilizer from wastewater sludge is presented. As a result of comparative studies, a fertilizer was created from wastewater sludge and sunflower husks. Fertilizer has a positive effect on the growth and development of plants. Using the example of peas of the Alpha variety, it was found that with a 1:1 component ratio and a 20% dose of soil application, the biomass of the root system increased by 18.5%, the root length by 54.6%, and the stem length by 77.1%. The germination of pea seeds has increased by 2 times. The germination energy corresponded to the control indicator. Experimental samples of a new biofertilizer from WS and sunflower husks comply with the requirements of GOST 59 748-2021 «Technical principles of wastewater sludge treatment» and SanPiN 1.2.3685-21 «Hygienic standards and requirements for ensuring the safety and (or) harmlessness of environmental factors to humans». With the identified demand for biofertilizers, a net profit of 191350 thousand rubles is planned with a payback period of 5.7 years. The net present value of the project will amount to 23919 thousand rubles with an internal rate of return of 30.3%.

Совершенствование схемы и режима внутреннего водооборота пенной сепарации алмазосодержащих кимберлитов

The object of this study is the process of enrichment of diamond-containing kimberlites by foam separation. The subject of the research is the recycled water of the foam separation unit. The purpose of the study is to increase the foam separation process efficiency in the enrichment of diamond-containing kimberlites by improving the scheme and regime of internal water circulation. The objectives of the study are to study the effect of sludge on the surface condition and floatability of diamonds, to analyze the composition of sludge products and to establish the causes of the increase in the concentration of sludge in recycled water, to substantiate the approach to the choice of technologies and the development of schemes for desliming recycled waters of the foam separation cycle. To determine the degree of sludge influence on the surface composition and floatability of diamonds, the technique of electron probe X-ray spectral analysis has been used and experiments have been conducted on foam separation of a diamond-kimberlite mixture. Industrial tests of the modes and schemes of clarification of recycled water are carried out at the enrichment plant No. 3 of the Mirninsky Mining and Processing Plant (MPP). The results of X-ray electron spectroscopy show that there is a proportional dependence of the decrease in diamond floatability on the proportion of hydrophilic coatings on the diamond surface. For the destruction of organic-air-mineral aggregates, which are an essential source of sludge, it is proposed to use highly turbulent classification modes in a hydrocyclone, which allows separating grains of hydrophobic kimberlite minerals from drops of apolar collector. In the final stage of clarification of recycled water, it is proposed to use flotation classification technology in a three-product clarifier, which ensures the production of an aqueous phase purified from precipitating and surfacing fractions. The test results of the developed schemes and modes of recycled water desalination in the foam separation department of the processing plant No. 3 of Mirninsky MPP have showed a decrease in the concentration of sludge in recycled water by 2 times, a reduction in the consumption of flotation reagents by 7-10 % and an increase in diamond recovery by 1.2 %.

Potential of ash from agricultural waste as substitute of commercial FeCl3 in primary treatment of landfill leachate

Due to the ever increasing global population, higher volumes of industrial waste discharges to landfill have caused major problems for the environment. This study investigated the performance of rice straw ash (RSA) as a natural coagulant under different conditions for the treatment of landfill leachates by coagulation-flocculation and microfiltration, with and without addition of FeCl3. The highest performing treatment conditions (RSA = 2.48 g/L, FeCl3 = 4.98 g/L, settling time = 54.75min) were achieved with the combined use of RSA and FeCl3 as coagulant and led to a sludge volume index of 41.65 mL/g, 51.27% COD removal and 76.48% total suspended solid removal. In contrast, FeCl3 alone achieved slightly better COD and total suspended solid removal rates, however it resulted in higher sludge volume index and sludge production. The combined use of RSA and FeCl3 reduced the consumption of these two coagulants by 78.76% and 46.69% respectively. Functional groups and thermal stability of the flocs showed that RSA + FeCl3 synergistically enhance the mechanisms of the coagulation-flocculation process, including adsorption by particle's bridging, charge neutralization and size of flocs. Combining the coagulants resulted in increased van der Waals forces and lower attractive forces of the inter-colloidal energy barrier in the leachate. Additionally, the highest and lowest heavy metals removal rates for treatment by microfiltration were found for Fe (92.15%) and Mg (7.63%), with a total heavy metals removal efficiency in the range of 6.08–90.78%. The findings of this study show that RSA can serve as a natural eco-friendly coagulant both alone and in combination with FeCl3 in the leachate treatment.

Comparative life cycle assessment of sewage sludge treatment in Wuhan, China: Sustainability evaluation and potential implications

Owing to the relentless growth of sewage sludge production, achieving low-carbon development in sewage sludge treatment and disposal (STD) is becoming increasingly challenging and unpredictable. However, the STD varied spatially, and city-specific analysis is deemed necessary for sustainable evaluation. Therefore, a lifecycle-based greenhouse gas (GHG), energy, and economic analysis were conducted by considering six local STD alternatives in Wuhan City, China, as a case study. The findings indicated anaerobic digestion combined with digestate utilization for urban greening (ADL) and incineration in existing power plants (INCP) exhibited the least GHG emissions at 34.073 kg CO2 eq/FU and 644.128 kg CO2 eq/FU, while INCP generated the most energy at −2594 kW.h/FU. The economic evaluation revealed that ADL and INCP were more beneficial without accounting for land acquisition. Scenario analysis showed that the energy recovery from ADL and INCP is significantly influenced by the hydrolysis yielding rate and sludge organic content. Perturbation sensitivity indicates that regional emission factor of electricity and electricity fee highly influence the overall GHG emission and cost. The results of this study could assist policymakers in identifying viable solutions to the cities experiencing the same sludge treatment burdens.

Autotrophic denitrification based on sulfur-iron minerals: advanced wastewater treatment technology with simultaneous nitrogen and phosphorus removal.

Autotrophic denitrification technology has many advantages, including no external carbon source addition, low sludge production, high operating cost efficiency, prevention of secondary sewage pollution, and stable treatment efficiency. At present, the main research on autotrophic denitrification electron donors mainly includes sulfur, iron, and hydrogen. In these autotrophic denitrification systems, pyrite has received attention due to its advantages of easy availability of raw materials, low cost, and pH stability. When pyrite is used as a substrate for autotropic denitrification, sulfide (S2-) and ferrous ion (Fe2+) in the substrate will provide electrons to convert nitrate (NO3-) in sewage first to nitrite (NO2-), then to nitrogen (N2), and finally to discharge the system. At the same time, sulfide (S2-) loses electrons to sulfate (SO42-) and ferrous ion (Fe2+) loses electrons to ferric iron (Fe3+). Phosphates (PO43-) in wastewater are chemically combined with ferric iron (Fe3+) to form ferric phosphate (FePO4) precipitate. This paper aims to provide a detailed and comprehensive overview of the dynamic changes of nitrogen (N), phosphorus (P), and other substances in the process of sulfur autotrophic denitrification using iron sulfide, and to summarize the factors that affect wastewater treatment in the system. This work will provide a relevant research direction and theoretical basis for the field of sulfur autotrophic denitrification, especially for the related experiments of the reaction conversion of various substances in the system.