Advanced light-tolerant microalgae-nitrifying bacteria consortia for stable ammonia removal under strong light irradiation using light-shielding hydrogel

A review on recent advancement in algal-bacterial aerobic granular sludge: From inoculation approaches to operation strategies

In recent years, the environmental unsustainability of traditional wastewater treatment processes, alongside the growing emphasis on carbon neutrality and self-sufficiency in wastewater treatment plants (WWTPs), has drawn attention to algal-bacterial aerobic granular sludge (AGS) systems. This review synthesizes recent advances in algal-bacterial AGS, focusing on the latest research on its granulation mechanisms under both hydrostatic and hydrodynamic conditions and providing a comprehensive overview of cultivation strategies based on various sludges. We discuss the latest reports on the impacts of process operation strategies for algal-bacterial AGS and emphasize the operation performance and design of different bioreactor configurations. Challenges for commercialization and sustainable applications are highlighted; future application directions are also posted. In summary, algal-bacterial AGS exhibits significant potential in simultaneous efficient wastewater treatment and bioresource recovery, targeting circular bioeconomy and sustainable wastewater industry.

A critical review on the symbiotic effect of bacteria and microalgae on treatment of sewage with biofertilizer production

Wastes like sewage, kitchen and industrial are the major sources of environmental pollution and health hazards. Sewage contains 99.9% water and 0.1% solid waste including urinal waste and faecal matter alongwith large amounts of nitrate, nitrite, ammonium and phosphate ions. Sewage may also contain a variety of harmful contaminants like analgesics, antihypertensive drugs, antibiotics, dioxin, furans, polychlorinated biphenyls, chlorinated hydrocarbon pesticides, chlorine derivatives and plasticizers etc. making it more harmfull to environment and public health. Hence, sewage must be adequately treated by an effective process before its final discharge into the environment. Biological treatment of sewage is an emerging idea in recent years, which has diverse economic and environmental advantages. Sewage treatment by bacteria and microalgae has numerous advantages as it removes various excessive nutrients from waste with large biomass production and also prevents the utilization of toxic chemicals in conventional treatment process. Microalgae-bacterial biomass have potential to be used as biofertilizers, bio-stimulants and bio-seed primers in agricultural field as these contain various biologically active substances like polysaccharides, carotenoids, free fatty acids, phenols, and terpenoids. This review paper mainly discussing the sewage characteristics and different kinds of organic and inorganic pollutants it contained alongwith its harmfull impacts on environment and public health. It also deals the different conventional as well as emerging treatment technologies and different factors affecting the treatment efficiency. In addition, the utilization of developed microalgal and bacterial biomass as biofertilizer and its effects on crop plant alongwith future prospects has been also discussed in detail.

Comprehensive Advancements in Hydrogel, and Its Application in Microalgae Cultivation and Wastewater Treatment

Microalgae are recognized as a sustainable resource to produce biofertilizers, biofuels, and pigments, with the added benefits of environmental sustainability, such as carbon sequestration and pollutant removal. However, traditional cultivation methods face challenges like low biomass productivity and high operational costs. This review focuses on the innovative use of hydrogels as a medium for microalgae cultivation, which addresses these challenges by enhancing nutrient permeability, light distribution, and overall growth efficiency. Hydrogels provide a three-dimensional matrix that not only supports higher biomass yields but also facilitates the removal of pollutants from wastewater, contributing to circular economy goals. The review also explores the environmental benefits, challenges, and prospects of integrating hydrogel technology into microalgae cultivation systems. By highlighting influencing factors through which hydrogels improve microalgal productivity and environmental outcomes, this work aims to provide insights into the potential of hydrogel-based systems for sustainable development.

Assessment of water quality and emerging pollutants in two fish species from the mallorquin swamp in the Colombian Caribbean

The Mallorquín Swamp, an important ecosystem in Atlántico, Colombian Caribbean, underwent environmental monitoring at eight points during rainy, transition, and dry seasons. This was to assess water quality, seasonal variation, and the bioaccumulation of metals, emerging pollutants, and organic compounds in the fish Ariopsis canteri and Mugil incilis. Water parameters were analyzed using descriptive statistics and multifactorial ANOVA with the Tukey HSD test for seasonal differences. Normality and variance of the fish results were verified, and differences between groups were evaluated using ANOVA or Kruskal-Walli's method when data transformation failed. Spearman correlation was used to relate the results. Water sampling revealed variations in temperature, dissolved oxygen, salinity, and nutrient levels. Significant differences in alkalinity and hardness were observed across seasons and sample points. The most probable number (MPN) levels of Total coliform and E. coli peaked near areas with domestic wastewater inputs, reaching 5.4x106 and 4.0x106 MPN, respectively, indicating potential microbiological contamination of water. Fish samples revealed high concentrations of persistent substances such as methylmercury, polycyclic aromatic hydrocarbons (PAHs), and emerging pollutants. Heavy metal analysis showed elevated iron levels (5.28 ± 0.657 mg/L), while emerging pollutants, including ibuprofen (218 μg/L) and naproxen (343.89 μg/L), exhibited high concentrations near human settlements. Ariopsis canteri showed higher bioconcentration tendencies for methylmercury (238.5 ± 100 μg/kg), and acenaphthene (7782 ± 4123.8 μg/kg), possibly influenced by its feeding habits and habitat preferences. In contrast, Mugil incilis exhibited higher bioaccumulation trends of PAH (2376.23 ± 599.63 μg/kg acenaphthene) and emerging pollutants like galaxolide (139.49 ± 34.98 μg/kg), possibly due to its mobility and exposure to various contaminants in their environment. These findings emphasize the need to monitor and manage aquatic ecosystems' health to mitigate anthropogenic influences on water quality and biodiversity. This research serves as a reference for global conservation efforts, emphasizing the need for comprehensive monitoring and regulatory frameworks to protect aquatic environments and ensure their sustainability for future generations.

Microalgae-bacteria nexus for environmental remediation and renewable energy resources: Advances, mechanisms and biotechnological applications

Microalgae and bacteria, known for their resilience, rapid growth, and proximate ecological partnerships, play fundamental roles in environmental and biotechnological advancements. This comprehensive review explores the synergistic interactions between microalgae and bacteria as an innovative approach to address some of the most pressing environmental issues and the demands of clean and renewable freshwater and energy sources. Studies indicated that microalgae-bacteria consortia can considerably enhance the output of biotechnological applications; for instance, various reports showed during wastewater treatment the COD removal efficiency increased by 40%-90.5 % due to microalgae-bacteria consortia, suggesting its great potential amenability in biotechnology. This review critically synthesizes research works on the microalgae and bacteria nexus applied in the advancements of renewable energy generation, with a special focus on biohydrogen, reclamation of wastewater and desalination processes. The mechanisms of underlying interactions, the environmental factors influencing consortia performance, and the challenges and benefits of employing these bio-complexes over traditional methods are also discussed in detail. This paper also evaluates the biotechnological applications of these microorganism consortia for the augmentation of biomass production and the synthesis of valuable biochemicals. Furthermore, the review sheds light on the integration of microalgae-bacteria systems in microbial fuel cells for concurrent energy production, waste treatment, and resource recovery. This review postulates microalgae-bacteria consortia as a sustainable and efficient solution for clean water and energy, providing insights into future research directions and the potential for industrial-scale applications.

Oxygen affinity and light intensity induced robust phosphorus removal and fragile ammonia removal in a non-aerated bacteria-algae system

Non-aerated bacteria-algae system gaining O2 through photosynthesis presents an alternative for costly mechanical aeration. This study investigated oxygen supply and performance of nutrients removal at low and high light intensity (LL and HL). The results showed that P removal was high and robust (LL 97 ± 1.8 %, HL 95 % ± 2.9 %), while NH4+-N removal fluctuated dramatically (LL 66 ± 14.7 %, HL 84 ± 8.6 %). Oxygen generated at illumination of 200 μmol m-2 s-1, 6 h was sufficient to sustain aerobic phase for 2.25 g/L MLSS. However, O2 produced by algae was preferentially captured in the order of heterotrophic bacteria (HB), ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB). Oxygen affinity coupled with light intensity led to NOB suppression with stable nitrite accumulation ratio of 57 %. Free nitrous acid (FNA) and light stimulated the abundance of denitrifying polyphosphate accumulating organism (DPAO) of Flavobacterium, but with declined P-accumulating metabolism (PAM) of P release, P/C, K/P and Mg/P ratios. Flavobacterium and cyanobacteria Leptolyngbya, along with biologically induced CaP in extracellular polymeric substances was the key to robust P removal. AOB of Ellin6067 and DPAO of Flavobacteria offer a promising scenario for partial nitrification-denitrifying phosphorus removal.