A review on value-addition to plastic waste towards achieving a circular economy.

Plastic and mixed plastic waste (PW) has received increased worldwide attention owing to its huge rate of production, high persistency in the environment, and unsustainable waste management practices. Therefore, sustainable PW management and upcycling approaches are imperative to achieve the objectives of the United Nations Sustainable Development Goals. Numerous recent studies have shown the application and feasibility of various PW conversion techniques to produce materials with better economic value. Within this framework, the current review provides an in-depth analysis of cutting-edge thermochemical technologies such as pyrolysis, gasification, carbonization, and photocatalysis that can be used to value plastic and mixed PW in order to produce energy and industrial chemicals. Additionally, a thorough examination of the environmental impacts of contemporary PW upcycling techniques and their commercial feasibility through life cycle assessment (LCA) and techno-economical assessment are provided in this review. Finally, this review emphasizes the opportunities and challenges accompanying with existing PW upcycling techniques and deliver recommendations for future research works.

Ruminal content biochar supplementation for enhanced biomethanation of rice straw: Focusing on biochar characterization and dose optimization.

Anaerobic digestion (AD) of agricultural wastes is a promising approach for energy recovery and crop residue management. However, its recalcitrant chemical structure hinders microbial hydrolysis and reduces biomethane production under AD. Biochar supplementation has been proven to promote the digestibility and biomethanation of lignocellulosic substrates. Therefore, this study investigated the influence of different pyrolysis temperatures (450 °C, 550 °C, and 650 °C) on the physicochemical properties of biochar. Furthermore, the impact of ruminal content biochar supplementation (1 %, 2 %, and 3 %) on the AD of rice straw with rumen fluid as inoculum has been investigated. The ruminal content biochar (RUCB) supplemented reactors showed an increment in biomethane yield and the highest cumulative biomethane yield 243.11 mL/g volatile solids (VS)) was recorded at 2 % RUCB supplementation, followed by 227.12 mL/g VS at 1 % RUCB supplementation and 162.86 mL/g VS at 3 % RUCB supplementation (P > 0.05). Compared to the control reactors (128.68 mL/g VS), RUCB supplemented reactors exhibited 1.88-fold, 1.76-fold, and 1.26-fold increments in biomethane yield due to pH stabilization and facilitation of microbial biofilm formation on the biochar. The correlation analysis showed that biomethane production is positively correlated with VS reduction (R2 = 0.9852). This study proposed a potential strategy to utilize ruminal content waste as a feedstock for biochar production and its application in AD for accelerating the biomethanation of rice straw.

Unique case of colovesical fistula in a renal allograft recipient.

Colovesical fistula is commonly suspected in cases of diverticular disease, malignancy, trauma, iatrogenic injury or radiotherapy. In a case of allogenic live related transplant, this is rarely expected, especially after 20 years. The presence of gas in the bladder in the absence of history of instrumentation of urinary tract should prompt us to evaluate for colovesical fistula. Pneumaturia, faecaluria and recurrent urinary tract infection are tell-tale features of colovesical fistula, and when patients who are renal allograft recipient present with them, it should prompt a proper workup and swift surgical management, since the outcome is uniformly favourable. From our knowledge in this realm, we know that these are immunocompromised patients and have a high tendency to develop risk factors like malignancy and/or diverticular disease and eventually form colovesical fistula. An expected time period could be from 2 months to 6 years. But in our case, fistula formation occurred long after peak corticosteroid action, in the absence of conventional aetiologies.

Biomimicry of ruminant digestion strategies for accelerating lignocellulose bioconversion in anaerobic digestion.

Biomimicking ruminant digestion strategies (RDSs) into anaerobic digestion (AD) enables efficient bioconversion of lignocellulosic biomass. Understanding RDSs is essential to translate their features into designing and developing bioprocesses and bioreactors. Here, we discuss insights into recently developed bioinspired bioprocesses, bioreactors, and future AD systems based on RDSs.

Biochar application for greenhouse gas mitigation, contaminants immobilization and soil fertility enhancement: A state-of-the-art review.

Rising global temperature, pollution load, and energy crises are serious problems, recently facing the world. Scientists around the world are ambitious to find eco-friendly and cost-effective routes for resolving these problems. Biochar has emerged as an agent for environmental remediation and has proven to be the effective sorbent to inorganic and organic pollutants in water and soil. Endowed with unique attributes such as porous structure, larger specific surface area (SSA), abundant surface functional groups, better cation exchange capacity (CEC), strong adsorption capacity, high environmental stability, embedded minerals, and micronutrients, biochar is presented as a promising material for environmental management, reduction in greenhouse gases (GHGs) emissions, soil management, and soil fertility enhancement. Therefore, the current review covers the influence of key factors (pyrolysis temperature, retention time, gas flow rate, and reactor design) on the production yield and property of biochar. Furthermore, this review emphasizes the diverse application of biochar such as waste management, construction material, adsorptive removal of petroleum and oil from aqueous media, immobilization of contaminants, carbon sequestration, and their role in climate change mitigation, soil conditioner, along with opportunities and challenges. Finally, this review discusses the evaluation of biochar standardization by different international agencies and their economic perspective.

Biotechnological potential of rumen microbiota for sustainable bioconversion of lignocellulosic waste to biofuels and value-added products.

Lignocellulosic biomass is an abundant resource with untapped potential for biofuel, enzymes, and chemical production. Its complex recalcitrant structure obstructs its bioconversion into biofuels and other value-added products. For improving its bioconversion efficiency, it is important to deconstruct its complex structure. In natural systems like rumen, diverse microbial communities carry out hydrolysis, acidogenesis, acetogenesis, and methanogenesis of lignocellulosic biomass through physical penetration, synergistic and enzymatic actions enhancing lignocellulose degradation activity. This review article aims to discuss comprehensively the rumen microbial ecosystem, their interactions, enzyme production, and applications for efficient bioconversion of lignocellulosic waste to biofuels. Furthermore, meta 'omics' approaches to elucidate the structure and functions of rumen microorganisms, fermentation mechanisms, microbe-microbe interactions, and host-microbe interactions have been discussed thoroughly. Additionally, feed additives' role in improving ruminal fermentation efficiency and reducing environmental nitrogen losses has been discussed. Finally, the current status of rumen microbiota applications and future perspectives for the development of rumen mimic bioreactors for efficient bioconversion of lignocellulosic wastes to biofuels and chemicals have been highlighted.

Does site of buccal mucosa graft for bulbar urethra stricture affect outcome? A comparative analysis of ventral, dorso-lateral and dorsal buccal mucosa graft augmentation urethroplasty.

OBJECTIVE: To compare long- term outcomes of buccal mucosa graft (BMG) augmentation urethroplasty for long segment bulbar urethral strictures done by placing the graft ventrally, dorso-laterally and dorsally. MATERIAL AND METHODS: We conducted a single institution retrospective study on 112 who underwent BMG augmentation urethroplasty for non-traumatic bulbar urethral strictures between January 2005 to December 2014. The cases were divided into three groups based on the site of placement of BMG graft i.e. (a) Ventral (n=44), (b) Dorso-lateral (n=48) and (c) Dorsal (n=20). Follow-up period was from one year to five years. Patients with failed outcomes underwent urethroscopy or retrograde urethrogram to note the site of recurrence of stricture. RESULTS: Out of 112 cases 91 (81%) were successful and 21 (19%) failed. The success rates for ventral, dorso-lateral and dorsal BMG augmentation procedures were 89%, 79% and 70%, respectively (p=0.18). Among 21 failed cases, 12 cases (57%) had stricture at proximal anastomotic site, 4 cases (19%) at graft and 5 cases (24%) at distal anastomotic site (p=0.01). CONCLUSION: The overall success rate for BMG augmentation urethroplasty is equal for all techniques. Ventral onlay urethroplasty provides better exposure of proximal anastomotic site thus it is associated with minimum proximal anastomotic site recurrence rates. Patients with extensive spongiofibrosis and long segment strictures had higher rates of failure.