Circular economy potential and contributions of petroleum industry sludge utilization to environmental sustainability through engineered processes - a review

The petroleum industry activities unavoidably generate a large quantity of sludge named Petroleum industry sludge (PIS). The generation rate has been increasing because of the ascending energy demand. It is a potential energy resource. PIS has been shown to contain hazardous constituents that may have negative consequences on the environment and public health. Thus, the treatment and disposal of this waste is a global issue. Numerous treatment methods have been demonstrated to reduce sludge volume and toxicity and recover petroleum components. The sludge qualities affect how effective they are. These treatment strategies can reduce the toxic substances in sludge and reduce their detrimental effects on human health and the environment. However, because of the sludge's tenacious character, only a few technologies can meet strict environmental laws while using a sizable amount of water, electricity, and chemicals. PIS treatment methods that are both waste-free and cost-effective are currently unavailable. In terms of environmental engineering significance, this study adopted the systematic review to discuss the waste to resource potential applications of PIS for reusability in sustainable construction, wastewater treatment applications, and gas generation. PIS application ineffective microorganism biofertilizer production, levan production, rubber tires manufacturing, metal catalysts synthesis, carbon–clay composites for use in sensors and electronic devices were also discussed. That is not enough, this review also found that the adoption of the circular economy that represents a new direction to create value and prosperity by elongating product lifespan and moving the waste from the end of the supply chain to the outset is very important. Thus, the circular economy potential of PIS to achieve self-cycle operation through the concept of “wastes-treat-wastes” in the petroleum industry was extensively discussed

Removal of nutrients from pulp and paper biorefinery effluent : operation, kinetic modelling and optimization by response surface methodology

This study investigated the effectiveness of extended aeration system (EAS) and rice straw activated carbon-extended aeration system (RAC-EAS) in the treatment of pulp and paper biorefinery effluent (PPBE). RAC-EAS focused on the efficient utilization of lignocellulosic biomass waste (rice straw) as a biosorbent in the treatment process. The experiment was designed by response surface methodology (RSM) and conducted using a bioreactor that operated at 1–3 days hydraulic retention times (HRT) with PPBE concentrations at 20, 60 and 100%. The bioreactor was fed with real PPBE having initial ammonia-N and total phosphorus (TP) concentrations that varied between 11.74 and 59.02 mg/L and 31–161 mg/L, respectively. Findings from the optimized approach by RSM indicated 84.51% and 91.71% ammonia-N and 77.62% and 84.64% total phosphorus reduction in concentration for EAS and RAC-EAS, respectively, with high nitrification rate observed in both bioreactors. Kinetic model optimization indicated that modified stover models was the best suited and were statistically significant (R 2 ≥ 0.98) in the analysis of substrate removal rates for ammonia-N and total phosphorus. Maximum nutrients elimination was attained at 60% PPBE and 48 h HRT. Therefore, the model can be utilized in the design and optimization of EAS and RAC-EAS systems and consequently in the prediction of bioreactor behavior

The effect of groundnut shell ash and metakaolin on geotechnical properties of black cotton soils

Groundnut shell ash (GSA) and metakaolin (MK) were investigated for their stabilizing prospects in highly expansive clay soils due to the rising cost of traditional stabilizers and the need for cost-effective utilization of waste materials for useful engineering applications (black cotton soil). The natural soil’s index qualities revealed that it belongs to A-7-6 in the AASHTO classification system and CH in the USCS classification system. This implied that the soil is unsuitable for most engineering purposes. The natural soil’s liquid limit and plasticity index values of 60.2% and 30.1%, respectively, which indicated that the samples were malleable. The soaked CBR for natural soil is 1.67%, but it rises to 3.26% when 10% GSA and 10% MK are added. This value fell short of the recommended CBR values for pavement materials. The samples’ durability measured based on their resistance to strength loss, fell short of the recommended strength by 80%. This concludes that the groundnut shell ash and metakaolin cannot be used as standalone for stabilization of black cotton soil. However, when compared to the un-stabilized soil, the strength of UCS increased from 128.03 kN/m2 to 482 kN/m2 after 28 days of curing

Sequential batch reactors for aerobic and anaerobic dye removal : a mini-review

One of the most challenging aspects of environmental conservation is the treatment of dye wastewater. Thus, this mini-review discussed the issues and major advances in the application and performance assessment of the aerobic, anaerobic, anaerobic-aerobic, aerobic-anaerobic, and anoxic–aerobic REACT-operated SBR systems with regards to bio-decolorization and COD removal rates. In SBRs run in aerobic modes, it is possible to cultivate aerobic granular sludge for color removal. To be precise, SBR has a higher COD removal efficiency with a lower color removal efficiency. Under anaerobic conditions, lesser COD removal was observed for several dyes studied in this chapter. In an alternating anaerobic-aerobic SBR system, color removal tends to occur during the anaerobic phase, while the aerobic phase is required to further reduce the effluent COD concentration. However, molecular oxygen drastically reduced color removal in SBR during dye wastewater treatment. This chapter discusses the aerobic-SBR treatment process for dye removal. The discussion focused on dye wastewater treatment using aerobic granules, granular activated carbon, adsorbents, biocarrier white rot fungi, varying dye mixtures, dye concentrations and SBR operational parameters. Adsorbents, membranes, biocarriers, exported microbial cultures, and various operational conditions have also been used in sequential anaerobic/aerobic batch reactors to enhance system performance. This chapter assessed the different treatment mechanisms and dynamics and concluded that combining two treatment methods significantly yields better color, DOC, and BOD5 removal than a single biological or chemical treatment

Parametric optimization and kinetic modelling for organic matter removal from agro-waste derived paper packaging biorefinery wastewater

The state-of-the-art paper packaging biorefinery utilizes cellulose fibrous material from paddy straw and papaya latex to produce packaging products. This in turn generate wastewater with high organic matter content that if disposed without treatment will pollute water bodies and affect aquatic life below water. Therefore, to comply with "clean water and sanitation" (SDG 6) and "life below water" (SDG 14), this study assesses the efficacy of an extended aeration activated sludge (EAAS) in the treatment of paper packaging biorefinery wastewater (PPBW) by employing paddy straw-derived activated carbon as a biosorbent. Findings revealed that the system was able to achieve 95–98.2% and 90.62–94.96% biological oxygen demand (BOD 5 ) and chemical oxygen demand (COD) reduction, respectively. The maximum organic matter removals were achieved at 2-day hydraulic retention time (HRT) and 60% PPBW concentration. To evaluate substrate removal rates, the first-order, modified Stover–Kincannon and Grau second-order models were used. In the modified Stover–Kincannon model, high correlation coefficients values R2 of 0.99986 and 0.99991 were obtained for COD and BOD 5 , respectively. Twenty grams COD/L/day and 50 gBOD 5 /L/day were obtained as Umsr for COD and BOD 5 , respectively, and 20.402 g/L/day and 56.295 g/L/day as K V constants for COD and BOD 5 , respectively. The COD and BOD 5 biokinetic constant values for the Grau second-order organic matter removal rate constant kS were 36 day −1 and 0.78 day −1 , respectively. Here, 0.9989 and 0.99928 were the obtained R2 values for COD and BOD 5 , respectively. The EAAS bioreactor system described by modified Stover–Kincannon model was proven to best suit the experimental data. Therefore, the model can be used in designing an EAAS system and consequently predict the bioreactor behaviour. The result of this study provided a benchmark for the actual implementation of PSAC in PPBW treatment for COD and BOD 5 removal. It has been proven that PSAC biosorbent sourced from a natural agro-waste material is essential and could be used as an efficient substance for organic matter removal. Operating expenses and associated savings were such that PASC was more attractive in an economic analysis of wastewater treatment demands. It is environmentally benign and offers a green treatment option to the PPBW. It could be an alternative to chemical materials because it is harmless to human health and proffer sustainable solution to potable water production

Sources of water contamination by heavy metals

This chapter titled “Sources of Water Contamination by Heavy Metals” provides an extensive discussion of the various sources of heavy metals in water bodies. Heavy metals are defined and their properties and uses are outlined. The chapter examines the different sources of heavy metals, including natural, anthropogenic, and from diverse sources such as waste materials and industrial processes. The sources, characteristics, uses, and impacts of individual heavy metals including arsenic, nickel, zinc, lead, mercury, copper, chromium, and cadmium are also discussed in detail. Furthermore, the chapter evaluates the different indexing approaches for heavy metal pollution including the heavy metal pollution index (HPI), the contamination index (CI), the evaluation index of heavy metals (HEI), and the heavy metal index (HMI). The analytical methods for heavy metal detection are also discussed, including broad categories such as spectroscopic detection, electrochemical detection, and optical methods of detection. This chapter will be useful to researchers and professionals in the fields of environmental science, chemistry, engineering, and water resources management who are interested in understanding the sources and impacts of heavy metal contamination in water bodies. The information provided in this chapter will also be useful for the development of effective strategies for the prevention and mitigation of heavy metal pollution in water bodies

Trend and current practices of coagulation-based hybrid systems for pulp and paper mill effluent treatment : mechanisms, optimization techniques and performance evaluation

This paper presents an overview of pulp and paper mills (PPM) production processes, the resulting release of wastewater effluent loaded with wide range of pollutants and associated environmental impacts. The review highlighted the different types of functional materials and their modified forms employed as coagulants for pulp and paper mills industries effluent (PPME) treatment that have been intensively studied as a promising strategy for PPM to achieve cleaner and sustainable treatments in accordance with sustainable development goals (SDGs) “6-Clean water and sanitation”, “9-Industry, innovation, and infrastructure”, and “12-Responsible consumption and production”. Standalone coagulation treatment processes are inherently ineffective towards meeting the increasingly stringent discharge requirements, coupled with their higher energy demand, and increased operational and maintenance costs. Owing to the recalcitrant nature of PPME contaminants, this review explored the effectiveness of the coagulation processes for decontamination of PPME. Furthermore, the review provides a state-of-the-art coagulation-based hybrid systems employed for enhanced PPME treatment. The process limitations, influencing factors and optimization techniques are highlighted. The review also highlights how sustained research in the subject area impacts on achieving cleaner production. The review also discusses coagulant classifications and the synergistic, antagonistic and shock load toxic effects of hybrid coagulants on toxicant biodegradation and their associated system efficiency. Moreover, it offers a guide for the development and application of sustainable hybrid-based coagulants for PPME treatment. The findings presented herein provide a vital theoretical foundation for sustainable solutions to improve coagulation-based hybrid systems efficiency and their scale-up towards potential commercialization

Toxic effects of xenobiotic compounds on the microbial community of activated sludge

The presence of xenobiotic compounds in biological wastewater treatment processes with activated sludge may reduce microbial communities, disrupt microbial diversity, and diminish system performance. Shock loads and unusual operating events in these biological systems have negative impacts on their efficiency and reliability for pollutant degradation, thereby posing high risk to microorganisms and water quality of receiving treated water bodies. The severity and characteristics of the occurring damage are determined by the toxic contaminant's degree, nature and mode of application. This review highlights the effects of metabolic uncouplers, heavy metals, carbon nanotubes, pharmaceuticals and personal care products, nanoparticles, and phenolic compounds stress on microbial biomass in activated sludge systems. The synergistic, antagonistic, and shock load toxic effects of hybrid substances exposure in an activated sludge sequential batch reactor (SBR) system on organic and nutrient removal, system efficiency, and toxicants biodegradation are discussed. The findings can be used to provide a theoretical foundation and professional assistance for optimizing the shock impacts of these toxic substances on biological wastewater treatment systems, which will help to reduce their negative effects on treatment system efficiency