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1. Evaluation of Physicochemical Treatment Technologies for Landfill Leachate Induced Dissolved Organic Nitrogen (DON).

   Md Redowan Rashid, Md Ashik (June 2023, AEESP Research and Education Conference, Northeastern University, June 20-23, 2023)

   Landfill leachate contains high levels of dissolved organic nitrogen (DON) that can be detrimental to aquatic life and water quality because it promotes the growth of harmful algal blooms (HABs). This study used physicochemical treatment technologies such as Fenton treatment and Granular Activated Carbon (GAC) adsorption to assess the breakdown and removal of landfill leachate-induced DON. The physicochemical treatments were applied to effluents of two bioreactors treating blended wastewater and landfill leachate. Bioreactor-1 (R1) was fed with high organic landfill leachate, and bioreactor-2 (R2) was fed with low organic landfill leachate. For R1 effluent, the Fenton treatment removed 66±9.2% COD and 52.4±8.7% DON at an optimum dosage of 200mg/L H2O2 and 1000mg/L FeSO4.7H2O. On the other hand, GAC removed 94.4±4.9% COD and 85.9±4.6% DON at an optimum dosage of 10g/L GAC. For R2 effluent, the Fenton treatment removed 75.8±6.6% COD and 60.3±3.2% DON at an optimum dosage of 200mg/L H2O2 and 1000mg/L FeSO4.7H2O. On the contrary, GAC treatment removed 92.2±4.3% COD and 92.3±3.7% DON at an optimum dosage of 10g/L GAC. Moreover, fluorescence spectrophotometry combined with parallel factor analysis (PARAFAC) was employed to provide insight into the DON degradation mechanisms. The study found that Fenton treatment and GAC adsorption both can effectively reduce DON in landfill leachate. However, GAC treatment was superior to Fenton treatment in eliminating DON from landfill leachate, while Fenton treatment may convert DON into inorganic nitrogen. The study emphasizes properly handling landfill leachate to avoid nitrogen contamination and harmful algal blooms in aquatic ecosystems. 

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2. Investigating microbial dynamics and potential advantages of anaerobic co-digestion of cheese whey and poultry slaughterhouse wastewaters

   https://doi.org/10.1038/s41598-022-14425-1  

   Abdallah, M.; Greige, S.; Beyenal, H.; Harb, M.; Wazne, M. (June 2022, Scientific Reports)

   Abstract Resource recovery and prevention of environmental pollution are key goals for sustainable development. It is widely reported that agro-industrial activities are responsible for the discharge of billions of liters of wastewater to the environment. Anaerobic digestion of these energy rich agro-industrial wastewaters can simultaneously mitigate environmental pollution and recover embedded energy as methane gas. In this study, an assessment of mono- and co-digestion of cheese whey wastewater (CWW) and poultry slaughterhouse wastewater (PSW) was conducted in 2.25-L lab-scale anaerobic digesters. Treatment combinations evaluated included CWW (R1), PSW (R2), 75:25 CWW:PSW (R3), 25:75 CWW:PSW (R4), and 50:50 CWW:PSW (R5). The digestion efficiencies of the mixed wastewaters were compared to the weighted efficiencies of the corresponding combined mono-digested samples. R4, with a mixture of 25% CWW and 75% PSW, achieved the greatest treatment efficiency. This corresponded with an average biodegradability of 84%, which was greater than for R1 and R2 at 68.5 and 71.9%, respectively. Similarly, R4 produced the highest average cumulative methane value compared to R1 and R2 at 1.22× and 1.39× for similar COD loading, respectively. The modified Gompertz model provided the best fit for the obtained methane production data, with lag time decreasing over progressive treatment cycles. PCoA and heatmap analysis of relative microbial abundances indicated a divergence of microbial communities based on feed type over the treatment cycles. Microbial community analysis showed that genusPetrimonasattained the highest relative abundance (RA) at up to 38.9% in the first two cycles, then subsequently decreased to near 0% for all reactors.Syntrophomonaswas highly abundant in PSW reactors, reaching up to 36% RA.Acinetobacterwas present mostly in CWW reactors with a RA reaching 56.5%. The methanogenic community was dominated byMethanothrix(84.3–99.9% of archaea). The presence of phosphate andAcinetobacterin CWW feed appeared to reduce the treatment efficiency of associated reactors. DespiteAcinetobacterbeing strictly aerobic, previous and current results indicate its survival under anaerobic conditions, with the storage of phosphate likely playing a key role in its ability to scavenge acetate during the digestion process. 

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3. Successful Implementation of Biofilm Anammox in IFAS A2O Process for Simultaneous N and P Removal in Main Stream Treatment Train

   Hong, S; Winkler, MKH; Wang, Zhiwu; Goel, R (October 2023, WEFTEC Proceedings)

   Soklida, Hong; Mari-KH, Winkler; Zhiwu, Wang; Goel, Ramesh (Ed.)

   This research studied integrated fixed film activated sludge (IFAS) technology to simultaneously remove N and P in real municipal wastewater by combining anammox biofilms with flocculent activated sludge for enhanced biological P removal (EBPR). The study was conducted in a sequencing batch reactor (SBR) operated as a conventional A2O (anaerobic-anoxic-oxic) process with an 8.8 h hydraulic retention time. After achieving steady-state operation, the reactor showed robust performance, with average removal efficiencies of 91.3±4.1% for total inorganic nitrogen (TIN) and 98.4±2.4% for phosphorus (P). Denitrifying polyphosphate accumulating organisms (DPAOs) were responsible for 15.9% of P uptake during the anoxic phase, while biofilms showed anammox activity in the aerobic step. The IFAS configuration with a low solid retention time (SRT) of 5 days prevented the washout of biofilm anammox bacteria and allowed selective washout of unwanted organisms. The results demonstrated the successful coexistence of anammox bacteria with other bacteria for efficient nutrient removal in real wastewater conditions. 

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4. Evaluating landfill leachate treatment by organic municipal solid waste-derived biochar

   https://doi.org/10.1039/D1EW00376C  

   Bentley, Matthew J.; Solomon, Michelle E.; Marten, Brooke M.; Shimabuku, Kyle K.; Cook, Sherri M. (October 2021, Environmental Science: Water Research & Technology)

   Transforming the organic fraction of municipal solid waste (OFMSW) into biochar to reduce fugitive landfill emissions and control organic micropollutants (OMP) during landfill leachate treatment could provide a new circular economy organics diversion approach. However, research on landfill leachate treatment under consistent, representative conditions with biochar derived from the wide range of OFMSW components is needed. Further, the competitive nature of leachate dissolved organic matter (DOM) for biochar adsorption sites has not been examined. To this end, biochars were produced from seven diverse OFMSW types and batch tested using two representative organic contaminants. To evaluate leachate DOM impact on OMP removal and fouling mitigation with biochar enhancement methods, experiments were performed with three background matrices (deionized water, synthetic leachate, real leachate) and two enhancement methods (ash-pretreatment, double-heating). Since evaluating all possible OFMSW feedstock combinations is infeasible, fundamental relationships between individual feedstocks and biochar properties were evaluated. Overall, biochar performance varied substantially; the dose to achieve a given target removal spanned an order of magnitude between the OFMSW feedstocks. Also, the presence of leachate DOM more negatively impacted the performance of all biochars relative to the benchmark adsorbent activated carbon. Finally, the enhancement methods altered biochar pore structure by increasing micropore and slightly decreasing non-micropore surface areas, resulting in improved adsorption capacity (by 23 to 93%). By providing the basis for a low-cost, enhanced leachate treatment method, this study could incentivize a novel organics diversion approach that reduces climate change impacts, harvests energy from waste, and reduces landfill air emissions. 

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5. Integration of EBPR with mainstream anammox process to treat real municipal wastewater: Process performance and microbiology

   Hong, S; Winkler, MKH; Wang, Z; Goel, R (February 2023, Water research)

   The mainstream application of anaerobic ammonium oxidation (anammox) for sustainable N removal remains a challenge. Similarly, with recent additional stringent regulations for P discharges, it is imperative to integrate N with P removal. This research studied integrated fixed film activated sludge (IFAS) technology to simultaneously remove N and P in real municipal wastewater by combining biofilm anammox with flocculent activated sludge for enhanced biological P removal (EBPR). This technology was assessed in a sequencing batch reactor (SBR) operated as a conventional A2O (anaerobic-anoxic-oxic) process with a hydraulic retention time of 8.8 h. After a steady state operation was reached, robust reactor performance was obtained with average TIN and P removal efficiencies of 91.3 ± 4.1% and 98.4 ± 2.4%, respectively. The average TIN removal rate recorded over the last 100 d of reactor operation was 118 mg/L⋅d, which is a reasonable number for mainstream applications. The activity of denitrifying polyphosphate accumulating organisms (DPAOs) accounted for nearly 15.9% of P-uptake during the anoxic phase. DPAOs and canonical denitrifiers removed approximately 5.9 mg TIN/L in the anoxic phase. Batch activity assays, which showed that nearly 44.5% of TIN were removed by the biofilms during the aerobic phase. The functional gene expression data also confirmed anammox activities. The IFAS configuration of the SBR allowed operation at a low solid retention time (SRT) of 5-d without washing out biofilm ammoniumoxidizing and anammox bacteria. The low SRT, combined with low dissolved oxygen and intermittent aeration, provided a selective pressure to washout nitrite-oxidizing bacteria and glycogen-accumulating organisms, as relative abundances. 

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