Arumuganainar Suresh

Waste activated sludge (WAS), a byproduct of livestock wastewater treatment, poses significant disposal challenges due to its low biodegradability and potential environmental impact. Anaerobic digestion (AD) offers a sustainable approach for methane recovery and sludge stabilization. This study evaluates the biomethane potential (BMP) of WAS and its co-digestion with swine slurry (SS), water lily (Nymphaea spp.), and lotus (Nelumbo nucifera) shoot biomass to enhance methane yield. Batch BMP assays were conducted at substrate-to-inoculum (S/I) ratios of 1.0 and 0.5, with methane production kinetics analyzed using the modified Gompertz model. Mono-digestion of WAS yielded 259.35–460.88 NmL CH₄/g VS_added, while co-digestion with SS, water lily, and lotus increased yields by 14.89%, 10.97%, and 16.89%, respectively, surpassing 500 NmL CH₄/g VS_added. All co-digestion combinations exhibited synergistic effects (α > 1), enhancing methane production beyond individual substrate contributions. Lower S/I ratios improved methane yields and biodegradability, highlighting the role of inoculum availability. Co-digestion reduced the lag phase limitations of WAS and plant biomass, improving process efficiency. These findings demonstrate that co-digesting WAS with nutrient-rich co-substrates optimizes biogas production, supporting sustainable sludge management and renewable energy recovery in livestock wastewater treatment systems.

This study evaluated housing designs and bedding systems to improve air quality in swine facilities, focusing on odor and particulate matter (PM) reduction. Three experimental animal house designs (M1, M2, M3) were tested: M1 used circulating airflow with negative pressure, M2 featured a plug flow air pattern with a perforated plastic bed, and M3 employed a sawdust bedding system with recirculating ventilation. Nine fattening swine were housed in each 12 m² house over 110 days (6 May to 26 August 2018). Appropriate air samples were collected, and odorous compounds, volatile organic acids (VOA), PM, and bacterial concentrations measured. Results showed that M3 had the lowest ammonia (NH₃) levels (5.9 ± 1.5 ppm) and undetectable hydrogen sulfide (H₂S), while M1 recorded the highest NH₃ (9.1 ± 2.2 ppm). VOA concentrations were significantly lower in M3 (75 ± 1.3 ppbv) compared to M1 (884 ± 15 ppbv) and M2 (605 ± 10.3 ppbv). PM10 levels were highest in M3 (312 ± 11 μg/m³) and lowest in M1 (115 ± 3 μg/m³), and thus bacterial counts were elevated in M3 (2117 ± 411 cfu/min), whereas M1 showed the lowest bacterial count of 1029 ± 297 cfu/min. The sawdust bedding system effectively reduced odorous compounds, highlighting its potential for odor control. However, higher PM levels in M3 emphasize the need to balance environmental management with animal welfare. These findings suggest that optimizing housing designs and bedding systems can enhance air quality in swine facilities while addressing sustainability and welfare concerns.

Reducing odor and particulate matter (PM) in confined swine houses is critical for environmental sustainability and animal welfare. This study evaluated the effects of different housing designs and bedding systems on aerial environmental conditions in swine confinement facilities. Three experimental swine house models (M1, M2, and M3) were constructed with distinct ventilation and bedding configurations. M1 employed circulating airflow with negative pressure and a recirculating ventilation system. M2 featured a plug flow air pattern with negative pressure and a perforated plastic bed, while M3 utilized a sawdust bedding system with recirculating ventilation. Each model housed nine fattening swine in a 12 m² area, and the study was conducted over 110 days (May 6–August 26, 2018). Measurements included odorous compounds, volatile organic acids (VOA), and PM concentrations. Ammonia (NH₃) levels were highest in M1 (9.07 ppm) and lowest in M3 (5.94 ppm). Hydrogen sulfide (H₂S) was undetectable in M3, while M1 and M2 recorded measurable levels. VOA concentrations were significantly lower in M3 (84.86 ppbv) compared to M1 (884.29 ppbv) and M2 (605.31 ppbv). PM10 levels exhibited notable variations, with concentrations of 115.25 μg/m³ in M1, 218.83 μg/m³ in M2, and 312.00 μg/m³ in M3. However, bacterial concentrations were highest in M3. The sawdust bedding system (M3) significantly reduced volatile fatty acids and odorous compounds compared to pit-based systems, while the ventilation system influenced odor control. Although M3 had higher PM levels, the findings emphasize the need for swine farming systems to balance environmental management with animal welfare considerations.

Poultry litter waste management poses a significant global challenge, attributed to its characteristics (odorous, organic, pathogenic, attracting flies). Conventional approaches to managing poultry litter involve composting, biogas generation, or direct field application. Recently, there has been a surge of interest in a novel technology that involves the bioconversion of organic waste utilizing insects (known as entomoremediation), particularly focusing on black soldier fly larvae (BSFL), and has demonstrated successful transformation of various organic waste materials into insect meal and frass (referred to as organic frasstilizer). Black soldier flies have the capacity to consume any organic waste material (ranging from livestock litter, food scraps, fruit and vegetable residues, sewage, sludge, municipal solid waste, carcasses, and defatted seed meal) and convert it into valuable BSFL insect meal (suitable for animal feed) and frass (serving as an organic fertilizer). The bioconversion of poultry litter by black soldier flies offers numerous advantages over traditional methods, notably in terms of reduced land and water requirements, lower emissions, cost-effectiveness, swift processing, and the production of both animal feeds and organic fertilizers. This review focuses on the existing knowledge of BSFL, their potential in bioconverting poultry litter into BSFL meal and frass, and the utilization of BSFL in poultry nutrition, emphasizing the necessity for further innovation to enhance this sustainable circular economy approach.

Slaughterhouse waste (SW) poses significant environmental challenges due to its complex composition, but anaerobic digestion offers a way to recover valuable biogas from SW. This study investigated the anaerobic co-digestion of beef cattle slaughterhouse waste (BCSW) with either cattle feces (CF) or swine slurry (SS). The biomethane potential, maximum methane yield (M_max), lag phase duration, and effective digestion time (T_eff) for the individual substrates and the combinations were analyzed. BCSW alone exhibited M_max of 578.5 Nml CH₄/g VS_added with a lag phase of 11 days, while CF and SS alone exhibited M_max of 397.2 and 289.8 Nml CH₄/g VS_added, respectively. Co-digestion of BCSW and SS resulted in M_max increase of 48–75.5%, with negligible effects on T_eff compared to solitary SS digestion. Similarly, co-digestion of BCSW and CF increased M_max by 6.2–40.4%, with no significant impact on T_eff compared to solitary CF digestion. However, both co-digestions led to a reduction in M_max (12.1–27%) when compared to BCSW digestion alone. Co-digestion with SS shortened the lag phase duration by 2.8–7.8 days and accelerated T_eff by 5.8–8.3 days due to SS’s high concentrations of essential micronutrients like cobalt and nickel which aid digestion. This study concluded that co-digestion of BCSW with SS is an effective strategy for enhancing methane production and digestion efficiency, offering a viable approach for proper disposal of BCSW while improving biogas output.

The codigestion of slaughter waste with animal manure can improve its methane yield, and digestion parameters; however, limited studies are available for the effectiveness of anaerobic codigestion using swine slaughter waste (SSW) and swine slurry (SS). Hence, this study was conducted to determine the characteristics of SSW and the effect of anaerobic codigestion with (SS) and explored the potential of CH₄ production (M_max), the lag phase period (λ), and effective digestion time (T_eff). SSW contains fat and protein contents of 54% and 30% dry weight within 18.2% of solid matters, whereas SS showed only 6% and 28% within 4.1% of solid matters, respectively. During sole anaerobic digestion, SSW produced a high M_max (711 Nml CH₄/g VS_added) but had a long duration λ (~9 days); whereas SS produced a low M_max (516 Nml CH₄/g VS_added) but had a shorter duration λ (1 day). Codigestion increased the M_max from 22–84% with no significant T_eff compared to sole SS digestion. However, the low M_max of SS and high M_max of SSW, resulted in a 7–32% decrease in M_max at codigestion compared to SSW sole digestion. Codigestion improved the digestion efficiency as it reduced λ (3.3–8.5 days shorter) and T_eff (6.5–9.1 days faster) compared to SSW sole digestion. The substrate-to-inoculum ratio of 0.5 was better than 1; the volatile solid and micronutrient availability may be attributed to improved digestion. These results can be used for the better management of SSW and SS for bio-energy production on a large scale.

Synthetic dyes are toxic and their release into the environment harms the ecosystem. Phycoremediation of synthetic dyes with acclimatized and native species has advantages over other methods. In this study, textile effluent-acclimatized microalgae species of Oscillatoria were grown in Bold’s Basal Medium (BBM), dried, powdered using sonication, and optimized the removal malachite green (MG), using the response surface methodology (RSM). The effects of algal biosorbent concentration (AC), pH, and contact time (CT) were studied with 1 g L⁻¹ MG in an aqueous solution, and the interaction model exerted significance (p < 0.001). The removal of MG was higher at alkaline pH (90% at pH 8.5) than at acidic pH (70% at pH 4). Under the optimized conditions of 1.2 g L⁻¹ AC, 8.5 pH, and 30 min CT, the MG removal was documented at 90.8% with the biosorption capacity of 757 mg g⁻¹. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analysis revealed the occurrence of different electronegative functional groups, aromatic vibrations, and the crystalline nature of the biosorbent. The algal sorbent exhibited a good performance of 80.9% for the removal of the crude color in real textile effluents. This microalgal sorbent is an attractive option for promoting large-scale applications. Graphical Abstract This study used an algal (Oscillatoria sp.,) biosorbent isolated from textile effluents, and it was acclimatized to a particular effluent (synthetic dye). This biosorbent was prepared using the sonication method and sieved using a 50-µm mesh. With this novel approach of biosorbent preparation (acclimatization and sonication), this study demonstrated the maximum adsorption capacity of malachite green at 757 mg g⁻¹ biosorbent under optimized conditions (1.2 g of biosorbent, pH 8.5, and a contact time of 30 min). This algal biosorbent and preparation methods will have a huge impact on the wastewater treatment technology and possible applications at a large scale.

Rapid industrialization leads to serious environmental hazards due to the increase in the release of pollutants into the environment. Industries that use synthetic dyes for different applications are a predominant source for dye contaminants by releasing the dye in wastewater with pretreatment or without treatment directly into the water bodies, making serious water pollution in the environment. Therefore, it is imperative to safeguard the environment from such contaminants and their associated negative impacts. The conventional treatment method that is used to treat dye-contaminated wastewater is generally costly and has a possibility to produce secondary metabolites. Due to the above problems, the biological method is preferable to treat effluent or dye-contaminated wastewater. Phycoremediation is an algae-based eco-friendly dye abatement technique from contaminated environments. This review highlights the phycoremediation of dyes and its underlying mechanisms along with the information on synthetic dyes, classification, hazardous effects, and other major techniques of dye abatement. This review provides a comprehensive insight into several influencing factors such as pH, temperature, contact time, the dose of algae biomass, and agitation speed, as well as functional groups involved in the phycoremediation process.

Ethiopia, albeit tagged as an underdeveloped nation, boasts astounding biodiversity, a vibrant culture, and the use of numerous traditional bio-techniques and processes. However, the adoption and application of modern biotechnology do not seem to have kept pace here vis-a-vis the rest of the world. In this regard, this survey was conducted among the members of the Addis Ababa Science and Technology University to gauge their attitude towards biotechnology. In this survey, assessment of the response of 2117 participants revealed 72% optimistic and 16% antagonistic attitude towards biotechnology in contrast to a 12% ‘no idea’ response. Religion and gender did not seem to dictate the response. However, domain-specific knowledge (85% supporters), education level (90%, 73%, 41% proponents at doctorate, undergraduate and < 12th-grade level respectively) and age (81% and 63.9% optimistic populace under 19 years and > 30 years respectively) exerted significant influence (p < 0.001). The supportive attitude of the academic staff (84%) surpassed that of their non-academic counterparts (55%). The study provided insight into the perception of a university fraternity towards biotechnology and attested to the indispensability of disseminating contextual information among the general public to facilitate the expansion of the domain as well as policy-making and implementation.

The context-specific, complex issue of ‘vaccine hesitancy’ is explicated in terms of delay or refusal of vaccination despite the availability of vaccine services. Although eleven million beneficiaries were administered the COVID-19 vaccine in India from 16th January 2021 till 20th February 2021, however, proportionately a low turnout has been registered in various parts of the country, possibly attributable to hesitance/apprehension towards the current vaccination. In this backdrop, we report the response (collected between Feb 1, 2021 and Feb 15, 2021) of 358 voluntary respondents who participated in an online questionnaire-based pan-India survey, executed to assess their knowledge and acceptance towards the current COVID-19 vaccination program in its first phase. The survey questionnaire consisted of demographic characteristics of the respondents and queries pertaining to knowledge (7 items) and acceptance (3 items). The overall correct rate and the average knowledge score of the participants were 78 % and 5.46 ± 1.4/7 respectively. The acceptance score was 3.50 ± 1.6/5 while 70 % of participants agreed against the 20 % of respondents who neither agreed nor disagreed to take the vaccine. Around 66 % believed that the vaccines, currently being administered in India are safe. Fear about possible side effects (44 %) and inadequacy of comprehensive clinical trial data (29 %), seemed to be the major players in fortifying the vaccine hesitancy among the respondents, exhibiting negative acceptance. Although maximum respondents demonstrated a good level of knowledge (82%) and acceptance (88%), significant differences were observed among some demographic variables. In general, a positive correlation was observed between knowledge and acceptance against a negative correlation, observed in specific provinces. Despite the good acceptance and knowledge, a considerable fraction of the participants (30%) expressed hesitancy. Counselling, mobilization, and feedback from vaccinated individuals about safety should be encouraged. However, due to the limited sample size, we must be cautious when generalizing these findings. Nevertheless, the major elucidations of this study may be utilized in planning vaccination campaigns in further phases.