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The wastewater from the dumping site usually contains high pollutant levels. Biological process and physico-chemical treatments are among several technologies for wastewater treatment. Using microorganisms in the treatment of landfill leachate is an emerging research issue. Furthermore, bioremediation is a feasible approach for pollutants removal from landfill leachate which would provide an efficient way to resolve the issue of landfill leachate. In this study, the performance of yeast and bacteria isolated from kefir grains was assessed for landfill leachate treatment. Kefir grains microbial composition was evaluated by molecular approaches (Rep-PCR and 16S rRNA gene sequencing). The obtained outcomes denoted that high concentrations of lactic acid bacteria and yeast populations (over 10 7 CFU/ml) were found in the kefir grains and were essentially composed of Lactococcus lactis, Lactobaccillus kefirien, bacillus sp., L. lactis, and Kluyveromyces marxianus. The co-culture with 1% of inoculum size was demonstrated as the most efficient in the degradation of different contaminants. The overall abatement rate of chemical oxygen demand (COD), ammonium nitrogen (NH + 4 − N), and salinity were 75.8%, 85.9%, and 75.13%, respectively. The bioremediation process resulted in up of 75% removal efficiency of Ni and Cd, and a 73.45%, 68.53%, and a 58.17% removal rates of Cu, Pb, and Fe, respectively. The research findings indicate the performance of L. lactis and K. marxianus co-culture isolated from kefir grains for the bioremediation of LFL. © 2020 Water Environnment Federatio • Practitioner Points • Isolation and identification of microorganisms from kefir grains was carried out. • Biological treatment of LFL using monoculture of (Lactoccocus lactis; Kluyveromyces marxianus) and co-culture (5% of L. lactis and 5% K. marxianus) has been performed. • Biological treatment using co-culture strain is an effective approach to remove organic matter, NH + 4 − N and heavy metals.

Kefir grains are a microbial consortium of different genera of bacteria and yeasts. In this study, the performance of Tunisian Kefir grains during the biological treatment of a mixture of Gouda cheese whey and white wastewaters (GCW) in ratio 1:1 with very high organic matter concentration is investigated. The biological 2 process was evaluated and optimized through the response surface methodology. Under the optimum conditions, Kefir grains concentration of 1.02%, temperature at 36.68 °C, and incubation time of 5.14 days, the removal efficiencies of COD, PO4 3− , and NO3 − were 87, 37.48, and 39.5%, respectively.Interestingly, the reusability tests of the grains proved not only their high resistance to harsh environmental conditions but also their great potential for more practical applications. Particularly, different strains were isolated from the grains and identified as Kluyveromyces marxianus, Lactoccocus lactis, Lactobacillus kefiri, and Bacillus spp. using 16S rDNA sequence analysis and rep-PCR fingerprinting. At the biological level, the raw GCW (RGCW) has a negative impact on the Hordeum vulgare both on seed germination, and on the growth parameters of seedlings. Interestingly, after Kefir grains treatment, the treated GCW (TGCW) allow a seedlings growth and germination rate similar to those soaked in water.

Landfill leachate (LFL) is a very complex effluent that poses considerable threats to humans and to the environment. Selecting the appropriate process for leachate treatment still poses potential concern and challenge for the operation in municipal landfills. The current study aims to assess stabilized leachate degradation through coagulation by using different chemicals (Al 2 (SO 4 ) 3 , FeCl 3 , FeSO 4 ). Thereafter, a complementary process using two Candida strains (Candida kefyr and Candida glabrata) is investigated as a biological treatment of treated LFL. Furthermore, the phytotoxicity of treated LFL is examined by seed germination/root elongation tests using barley and tomato seeds. Upon experimentation and research, the results reveal that the optimum removal efficiency for chemical oxygen demand (COD) and ammonium (NH 4 + -N) is 73.3% and 53.5%, respectively, when using the combined process. The removal efficiency of toxic metal elements (Fe, Pb, and Zn) is improved significantly (up to 80%). In addition, physiological and biochemical analyses confirm that the combined process allows a significant toxicity reduction. The obtained outcome is encouraging and supports the possible use of the treated LFL as a fertilizer for plant growth.

Municipal solid waste leachate, a kind of wastewater, can severely damage the environment and contaminate the groundwater because of its high organic matter and toxic heavy metal concentrations. Due to its complex composition, this wastewater must be properly treated prior to being discharged into the environment. In recent decades, several biological approaches (e.g., bioremediation, phytoremediation, and bioreactors) and physicochemical processes (e.g., coagulation/flocculation, air stripping, and advanced oxidation processes) have proven effective at removing the organic load and the toxicity of this effluent. Physicochemical treatments have been applied as pretreatment or post-treatment steps for biological processes, but these methods do not always provide satisfactory results and can cause secondary pollution in some cases. In addition, owing to the high concentrations of organic matter, ammonia, and trace metals in landfill leachate, combined approaches to leachate treatment have been reported to be efficient. This article highlights the advantages and drawbacks of these approaches to the treatment of leachate by providing an updated overview of the various methods that have been successfully applied in this field. Further studies should focus on improving landfill leachate treatment to maximize removal performance.

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Landfill leachate production and management are identified as one of the greatest problems of sanitary landfill. In this research paper, the effect of the use of bactofugate (B) and the expired fermented milk ‘Lben’ (L) in the biological treatment of Jebel Chakir leachate was studied. Leachate samples were separately inoculated with both raw and reactivated (B) and (L) samples and incubated at 37 °C over 15 days. Both raw (L) and (B) inoculums ensure better results in terms of organic matter removal than the reactivated samples. However, the best removal performances were obtained with (L) inoculum. The chemical oxygen demand (COD) removal reached 50% with an initial COD concentration of 20.8 g L−1, whereas 80% of ammonia nitrogen (NH3-N) removal was recorded. Furthermore, heavy metal concentrations, especially of Cr3+ and Fe2+, were reduced during the treatment with average removal rates of about 90%. Then, further kinetic investigations were performed using the (L) inoculum with an equipped bioreactor with air incorporation. Important COD removal efficiency (46%) was recorded within only 24 h. Heavy metal concentrations were also reduced during this process. The findings indicate that expired fermented milk could be a promising alternative for the biological pre-treatment of landfill leachate.