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Many fresh water bodies face a great challenge of an invasive weed called water hyacinth (WH) which has great impacts on the environment, ecology, and society. Food and Agriculture Organization (FAO) estimates that over nine million tons of Fish wastes (FW) are thrown away each year. The fish waste generated poses environmental and health hazards because in most cases it is either disposed into pits or discarded onto the open grounds. Both WH and FW are potential substrates for biogas production. However, utilization of FW substrate alone has a limitation of producing a lot of amounts of volatile fatty acids (VFAs) and ammonia. Their accumulation in the digester inhibits substrate digestion. Consequently, as stand-alone it is not suitable for anaerobic digestion (AD). This can be overcome by co-digestion with a substrate like WH which has high carbon to nitrogen (C/N) ratio prior to biodigestion. Experimental variable levels for biogas were substrate ratio (WH:FW, 25-75 g), inoculum concentration (IC, 5-15 g/250 mL), and dilution (85-95 mL). Design-Expert 13 was used for optimization and results analysis. Response surface methodology (RSM) was used to examine the effects of operating parameters and identify optimum values for biogas yield. Optimum values for maximum biogas with the highest methane yield of 68% were found to be WH:FW ratio, 25:75 g, 15 g of IC, and 95 mL for dilution. The yield was 16% and 32% greater than FW and WH mono-digestion, respectively. The biogas yield was expressed as a function of operating variables using a quadratic equation. The model was significant (P < 0.05). All factors had significant linear and quadratic effects on biogas while only the interaction effects of the two factors were significant. The coefficient of determination (R 2 ) of 99.9% confirmed the good fit of the model with experimental variables., (© 2023. The Author(s).)

Anaerobic digestion is used to treat effluents with a lot of organics, such as molasses distillery wastewater (MDW) which is the effluent of bioethanol production from molasses. The raw MDW requires a lot of dilution water before biodigestion, while the digested MDW has high level of recalcitrants which are problematic for its discharge. This study investigated ferric coagulation, Fenton, Fenton-like (with ferric ions as catalyst) processes and their combinations on the biodegradability of digested MDW. The Fenton and Fenton-like processes after coagulation increased the MDW biodegradability defined by (BOD5/COD) from 0.07 to (0.4-0.6) and saved 50% of H2O2 consumed in the classic Fenton process. The effluent from coagulation coupled to a Fenton-like process was used as dilution water for the raw MDW before the anaerobic digestion. The process was stable with volumetric loading of approx. 2.7 g COD/L/d. It resulted in increased overall biogas recovery and significantly decreased the demand for the dilution water., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Melanoidins are dark-coloured recalcitrant pollutants found in many industrial wastewaters including coffee-manufacturing effluent, molasses distillery wastewater (MDWW) and other wastewater with molasses as the raw material. The wastewaters are mostly treated with anaerobic digestion after some dilution to minimize the inhibition effect. However, the dark colour and recalcitrant dissolved organic carbon (DOC) mainly caused by melanoidin are not effectively removed. The aim of this study was to investigate the removal of colour and remnant DOC by different coagulants from anaerobically digested MDWW. From the six coagulants tested, ferric chloride had the highest melanoidin (48%), colour (92.7%) and DOC (63.3%) removal at pH 5 and a dosage of 1.6 g/l. Both polymer and inorganic salt coagulants tested had optimal colour, melanoidin and DOC removal at acidic pH. The molecular size distribution of synthetic melanoidins by liquid chromatography-organic carbon detection indicated a preferential removal of high-molecular-weight melanoidins over low weight melanoidins by the coagulation. Further studies should focus on how to improve biodegradability of the treated effluent for it to be reused as dilution water for anaerobic digestion.

Objective: To review recent research findings on the specific expression of endogenous retroviral sequences (ERVS) in reproductive tissues and their possible physiological roles. ERVS have been implicated in several biological events such as induction of resistance to exogenous retrovirus invasion, involvement in placental trophoblast formation, sperm maturation and differentiation; and stimulation of local immunosuppression to protect the foetus from immunological attack., Data Sources: Critical review of relevant articles and abstracts cited in international and local journals, literature searches on Medline and Medchem up to 2005., Data Synthesis: Retroviruses have been implicated in the induction of tumour and immunological disorders. Over the years, endogenous retroviruses (ERVs) and retroviral elements have been detected in the genome of many vertebrate species, including primates. The evidence for the presence of retroviruses in the primate tissues such as the placenta, ovary, breast, testis and epididymis has been documented using electron microscopic studies. Retrovirus-like particles were found budding from the basal membrane of syncytiotrophoblasts, as well as in tumour cell lines in embryonic carcinoma or teratocarcinomas. Apart from their pathological effects, recent evidence suggests that these ERVs may play useful roles in normal physiological events., Results: Recent studies indicate the expression of endogenous retroviruses in the testis, epididymis, placenta and breast. However, limited data exist on the detection of ERVs in the ovary. Overall, the precise functions for ERVs in these tissues are not well understood. In the testis and epididymis, speculative functions may include among others spermatogenesis and/or sperm maturation (differentiation) whereas in placenta they are possibly associated with trophoblast fusion and locally induced immunosuppression to protect the foetus from immunological attack. Experiments in our laboratory have indicated restricted expression of retroviral antigens including baboon endogenous retroviral proteins (BERV), ERV-3, HIV-1 gp41 and HERV-K env in the baboon ovary., Conclusion: ERVs are specifically expressed in different mammalian reproductive tissues and may have unique physiological roles.

Objective: To review research findings on the effects of khat (Catha edulis) chewing on reproductive functions., Data Sources: Retrieval and critical review of relevant articles and abstracts cited in international and local journals, literature searches on Medline and Medchem from 1961 to 2002., Data Synthesis: Analysis of published data and limited interviews of regular khat users revealed that khat chewing lowers libido in humans and may also lead to sexual impotence following long term use. In pregnant women, consumption of khat affects growth of foetus by inhibiting utero-placental blood flow and as a consequence, impairs foetal growth., Conclusion: Detailed studies on the effects of khat on reproduction are lacking. However, the limited available data reveal that chewing of khat has a negative impact on human reproductive health. Khat is genotoxic and has teratogenic effects on the foetus if regularly consumed by pregnant mothers. Since low birth weight is a well-established risk factor for both perinatal and young infant death, khat chewing during pregnancy may be one of the factors contributing to infant mortality in communities where khat is commonly chewed. Khat consumption affects the potency of male sexuality by affecting spermatogenesis and plasma testosterone concentration. However, the precise mechanisms by which khat may affect the male reproductive physiology have not been elucidated.