Deleterious effect of gestagens from wastewater effluent on fish reproduction in aquatic environment: A review.

Gestagens are common pollutants accumulated in the aquatic ecosystem. Gestagens are comprised of natural gestagens (i.e. progesterone) and synthetic gestagens (i.e. progestins). The major contributors of gestagens in the environment are paper plant mill effluent, wastewater treatment plants, discharge from pharmaceutical manufacturing, and livestock farming. Gestagens present in the aquatic environment interact with progesterone receptors and other steroid hormone receptors, negatively influencing fish reproduction, development, and behavior. In fish, the gonadotropin induces 17α, 20ß-dihydroxy-4-pregnen-3-one (DHP) production, an important steroid hormone involved in gametogenesis. DHP interacts with the membrane progestin receptor (mPR), which regulates sperm motility and oocyte maturation. Gestagens also interfere with the hypothalamic-pituitary-gonadal (HPG) axis, which results in altered hormone levels in fish. Moreover, recent studies showed that even at low concentrations exposure to gestagens can have detrimental effects on fish reproduction, including reduced egg production, masculinization, feminization in males, and altered sex ratio, raising concerns about their impact on the fish population. This review highlights the hormonal regulation of sperm motility, oocyte maturation, the concentration of environmental gestagens in the aquatic environment, and their detrimental effects on fish reproduction. However, the long-term and combined impacts of multiple gestagens, including their interactions with other pollutants on fish populations and ecosystems are not well understood. The lack of standardized regulations and monitoring protocols for gestagens pollution in wastewater effluent hampers effective control and management. Nonetheless, advancements in analytical techniques and biomonitoring methods provide potential solutions by enabling better detection and quantification of gestagens in aquatic ecosystems.

Bacterial cell immobilized packed bed reactor for the elimination of dissolved organics from biologically treated post-tanning wastewater and its microbial community profile.

In conventional, the biologically treated tannery wastewaters are rich in dissolved organics and the application of reverse osmosis (RO) to biologically treated tannery wastewater was challenged with fouling and failure of RO membrane due to existence of lingering dissolved organic compounds. In present investigation the bacterial cell immobilized packed bed reactor (CIPBR) was operated to remove the dissolved organic compounds in biologically treated post-tanning wastewater to avoid membrane fouling in RO. The efficient microbial syndicate to eliminate dissolved organics in post-tanning wastewater was isolated and immobilized on to the carbon silica matrix (CSM) in the range of 2.98 ± 0.2 × 107 cells gm-1 of CSM and the same was used as a carrier matrix in the packed bed reactor. The CIPBR established the CODtot, CODdis and BOD removal efficiency by 61 ± 4%, 57 ± 4% and 87 ± 3% respectively with CODtot, CODdis and BOD remained in the treated wastewater as 236 ± 21 mg/L, 228 ± 21 mg/L, and 12 ± 3 mg/L under continuous operation. The removal of dissolved organic compounds from the post-tanning wastewater was confirmed using UV-Visible and FT-IR spectroscopic studies. Among the total microbial community, the phylum Proteobacteria played most abundant role with 48.47% of relative abundance for the removal of dissolved organics in biologically treated post-tanning wastewater. The significance of the study is to replace the tertiary treatment unit operation in the conventional ETP/CETP to remove dissolved organics in wastewater.

Towards sustainable system configuration for the treatment of fish processing wastewater using bioreactors.

The wastewater generated from fish processing industry contains a credible level of biodegradable proteins and low biodegradable fats, oils, and grease (FOG). The conventional biological treatment of fish processing wastewater (FPWW) containing high concentration of FOG faces the challenges of clogging, hindrance to sedimentation due to the formation of hydrophobic sludge along with lipids, flocculation of sludge with poor activity, dewatering of sludge due to the presence of lipids, and formation of aminated offensive odors. The present investigation employed baffled moving bed biofilm reactor (BMBBR), up-flow anaerobic sludge blanket (UASB) reactor, fluidized immobilized cell carbon oxidation (FICCO) reactor, and chemoautotrophic activated carbon oxidation (CAACO) reactors in series to treat FPWW. Five treatment options were evaluated to elevate the correct option for the treatment of FPWW. The treatment option V had established the removal efficiency of COD, 99 ± 0.1%; protein, 99 ± 0.2%; lipids, 100%; and oil and grease, 100%.

An innovative approach to minimize excess sludge production in sewage treatment using integrated bioreactors.

The present investigation deals with an application of integrated sequential oxic and anoxic bioreactor (SOABR) and fluidized immobilized cell carbon oxidation (FICCO) reactor for the treatment of domestic wastewater with minimum sludge generation. The performance of integrated SOABR-FICCO system was evaluated on treating the domestic wastewater at hydraulic retention time (HRT) of 3hr and 6hr for 120days at organic loading rate (OLR) of 191±31mg/(L·hr). The influent wastewater was characterized by chemical oxygen demand (COD) 573±93mg/L; biochemical oxygen demand (BOD5) 197±35mg/L and total suspended solids (TSS) 450±136mg/L. The integrated SOABR-FICCO reactors have established a significant removal of COD by 94%±1%, BOD5 by 95%±0.6% and TSS by 95%±4% with treated domestic wastewater characteristics COD 33±5mg/L; BOD5 9±0.8mg/L and TSS 17±9mg/L under continuous mode of operation for 120days. The mass of dry sludge generated from SOABR-FICCO system was 22.9g/m3. The sludge volume index of sludge formed in the SOABR reactor was 32mL/g and in FICCO reactor it was 46mL/g. The sludge formed in SOABR and FICCO reactor was characterized by TGA, DSC and SEM analysis. Overall, the results demonstrated that the integrated SOABR-FICCO reactors substantially removed the pollution parameters from domestic wastewater with minimum sludge production.