Effects of free ammonia on volatile fatty acid accumulation and process performance in the anaerobic digestion of two typical bio-wastes

The effect of free ammonia on volatile fatty acid （VFA） accumulation and process instability was studied using a lab-scale anaerobic digester fed by two typical bio-wastes： fruit and vegetable waste （FVW） and food waste （FW） at 35℃ with an organic loading rate （OLR） of 3.0 kg VS/（m3-day）. The inhibitory effects of free ammonia on methanogenesis were observed due to the low C/N ratio of each substrate （15.6 and 17.2, respectively）. A high concentration of free ammonia inhibited methanogenesis resulting in the accumulation of VFAs and a low methane yield. In the inhibited state, acetate accumulated more quickly than propionate and was the main type of accumulated VFA. The co-accumulation of ammonia and VFAs led to an ＂inhibited steady state＂ and the ammonia was the main inhibitory substance that triggered the process perturbation. By statistical significance test and VFA fluctuation ratio analysis, the free ammonia inhibition threshold was identified as 45 mg/L. Moreover, propionate, iso-butyrate and valerate were determined to be the three most sensitive VFA parameters that were subject to ammonia inhibition.

Anaerobic treatment of source-separated domestic bio-wastes with an improved upflow solid reactor at a short HRT

Anaerobic treatment is the core technology for resource and energy recovery from source-separated domestic bio-wastes. The higher efficiency of an improved upflow solid reactor（IUSR） designed in this study was demonstrated in the treatment of concentrated black water and kitchen waste. The highest methane production of 48 L/person/day was achieved at the hydraulic retention time（HRT） of 7 days, while the other measures of performance at the HRT of 8.3 days were better than at the HRT of 7 or 10 days, achieving a methane production of 43 L/person/day, removal of total chemical oxygen demand（TCOD）of 89%, removal of soluble chemical oxygen demand（SCOD） of 92%, and conversion of chemical oxygen demand（COD） to methane of 71%. It is not recommended to decrease HRT lower than 7 days due to the instability of the initial period. The concentrations of volatile fatty acids（VFAs） in the IUSR were less than 10 mg/L, indicating that the anaerobic process was stable. Sludge bed development showed that sludge bed with high microbial activity was formed in the bottom and that the precipitation zone of effluents formed should preferably occupy 30% of the height of the IUSR. The effluents of the IUSR could be used for irrigation in agriculture in combination with a settling tank accompanied by disinfection to remove solids and pathogens.

Pd/Fe_(3)O_(4) supported on bio-waste derived cellulosic-carbon as a nanocatalyst for C-C coupling and electrocatalytic application

The current work describes the synthesis of a new bio-waste derived cellulosic-carbon supportedpalladium nanoparticles enriched magnetic nanocatalyst(Pd/Fe_(3)O_(4)@C)using a simple multi-step process under aerobic conditions.Under mild reaction conditions,the Pd/Fe_(3)O_(4)@C magnetic nanocatalyst demonstrated excellent catalytic activity in the Hiyama cross-coupling reaction for a variety of substrates.Also,the Pd/Fe_(3)O_(4)@C magnetic nanocatalyst exhibited excellent catalytic activity up to five recycles without significant catalytic activity loss in the Hiyama cross-coupling reaction.Also,we explored the use of Pd/Fe_(3)O_(4)@C magnetic nanocatalyst as an electrocatalyst for hydrogen evolution reaction.Interestingly,the Pd/Fe_(3)O_(4)@C magnetic nanocatalyst exhibited better electrochemical activity compared to bare carbon and magnetite(Fe_(3)O_(4)nanoparticles)with an overpotential of 293 mV at a current density of 10 mA·cm^(–2).

Stability assessment of emulsion of carotenoids extracted from carrot bio-waste in flaxseed oil and its application in food model system

The research was conducted on the stability assessment of emulsion of carotenoids extracted from carrot-pomace in omega-3 rich flaxseed oil,followed by converting this emulsion into freeze-dried powder,and its application as natural functional colorant in the preparation of flavored milk.The study indicated that emulsion was stable over a range of pH (5–9),temperature (forewarming to HTST pasteurization) and ionic strength (0.1–0.75 M NaCl) except at pH 4,sterilization temperature and 1.0 M NaCl based on zeta potential and particle size of emulsion analysed at these conditions.Ten percent (out of 8,10 and 12%) of freeze-dried emulsion was selected for addition as a natural functional ingredient in flavored milk on the basis of organoleptic evaluation.The fat,protein,total solids,total carotenoid content and antioxidant value (in terms of ABTS and reducing power assay) of developed product were significantly higher (p < 0.05) than control.The whiteness index of control was significantly higher (p < 0.05) than the developed product,while reverse was true for yellowness index.However,both the products showed total color difference of 34.65.The research concludes that carotenoid-rich emulsion can be efficiently freeze-dried and used as a functional natural colorant in flavored milk for providing it better bio-functional attributes over control.

Carbon and Nitrogen Mineralisation of a Lixisol in South Sudan Zone of Burkina Faso

In today’s environment where agriculture needs to produce sustainably, local fertilizer resources must be encouraged to achieve multiple crop performance and environmental goals. The purpose of this study was to investigate the effects of combined inputs of biowaste and inorganic fertilisers on the mineralization of carbon and nitrogen of a Lixisol under continuous upland rice growing conditions. To this end, agronomic trials were set up in 2018 and 2019, using a Fisher randomized complete block design with 6 treatments and four replications at Farako-ba research station. The treatments were: T1 (Control), T2 (NPK + Urea), T3 (7500 kgha of Chicken droppings);T4 (7500 kg/ha of chicken droppings + 100 kg/ha of urea);T5 (7500 kg/ha of chicken droppings + 500 kg/ha of Burkina Phosphate);T6 (7500 kg/ha of chicken droppings + 500 kg/ha of Burkina Phosphate + 100 kg/ha of urea). Highest respirometry was observed in treatments T3, T4 and T6 and treatment T4 significantly increased the mineralization coefficient by 15% after 21 days of incubation. T4 and T6 resulted in increases in ammonium ion of 74.15% and 100%, respectively, compared to the control. Likewise, treatments T4 and T6 resulted in a significant increase in nitrate ion of 104.83 and 103.25%, respectively. Biowaste combined with inorganic fertilizers may have a capacity to improve the availability of leachate nutrients under upland rice conditions.

Biogas Production from Sheep Manure by a Simulated Underground Burial System Heated with Cascade-Controlled Solar Water Heated System, as an Indicator of Biomass Potential Contribution to Power Mix in Jordan

This paper is aimed at exploring the potential of implementing biomass as one of the sources of energy in Jordan using a simulated underground burial system. A controlled solar energy heated system was employed to maintain the anaerobic bioreactor at 40°C (mesophilic range). Sludge and wastewater, from wastewater treatment plant, was used as a seeding material to activate bacteria. Production of biogas was observed after 3 days of incubation. On average, a total of 94 liters/sample were obtained at 25°C and atmospheric pressure. This amount of gas is equivalent to 258 liters/kg (Standard Temperature and Pressure, STP) of sheep manure. The biogas average composition was 65% methane and 35% CO2, and the retention time was 35 days. Control runs at room temperature did not produce appreciable amount of biogas within the 35 days of incubation. The potential of biomass was studied based on estimated sheep manure production for the period of 2010-2016 in Jordan. The results obtained from the designed process were used to estimate the bio-gas production indicating a promising process to produce biogas by a burial bio-waste system. Upon scale-up of this process, biomass from different sources can be processed within short residence time, which will result in appreciable reduction of land fill areas and significant production of biogas that will contribute to the energy power mix in a non-oil producing country, such as Jordan.

Influence of SiC Nanoparticles Reinforcement in Areca/Tamarind Hybrid Biopolymer Composites:Thermo-mechanical,Tribological and Morphological Features

Natural fibers are displacing synthetic fibers as reinforcement in polymer composites due to their ease of processing,low cost,wide availability,biodegradability and sustainability.In this study,industrially discarded agro-waste areca fruit husk and tamarind fruit fibers were processed and used as reinforcement with unsaturated polyester resin to create a hybrid composite containing SiC nano filler particles.The SiC nano filler particles were varied from 1 to 4 wt.%in incremental steps of 1 wt.%with a constant 40 wt.%fiber reinforcement to determine its impact on the thermo-mechanical,morphological,wear and hygro-aging properties of the developed hybrid composite.However,the composite made of 3 wt.%SiC nano filler particles exposed overall better properties with better tensile(9.137 MPa),flexural(104.056 MPa),impact(7.983 J/cm^(2)),hardness(91.577 HRRW),wear(2.2×10^(-6)µm),crystallite size(7.9 nm)and thermal stability(360℃).Further advancement in weight percent of filler material,has worsened the properties due to poor dispersion and agglomeration factors by reducing the tensile,flexural,impact and hardness characteristics by 4.6%,6.4%,4.5%and 2.18%respectively.Also,the microstructural investigation revealed the failure pattern,information on interfacial adhesion between the reinforcement,filler and matrix of the hybrid composites.In addition,the crystalline characteristics and availability of functional groups in hybrid polymer composite with 3 wt.%SiC nano filler particles were disclosed by X-ray diffraction(XRD)and Fourier Transform Infrared(FTIR)spectrum analysis,respectively.The above findings reflects that the produced hybrid polymer composites suits well for interiors of automobiles and maritime interior applications to support loads with in the specified range.

Effects of Organic Matter-Rich Amendments on Selenium Mobility in Soils

Soil organic matter (SOM) plays an important role in the Se dynamics in soil. The potential effects of vermicompost and digestate as important sources of SOM on selenium (Se) mobility were assessed in this study. Three soils differing in their physicochemical parameters, fluvisol, chernozem, and luvisol, were chosen, and three types of vermicomposts based on various bio-waste materials as digestate (vermicompost 1), kitchen waste with woodchips (vermicompost 2), and garden bio-waste (vermicompost 3) were used due to their high organic matter content. Additionally, digestate samples alone were applied. To evaluate the potential effect of vermicompost application on sorption characteristics of soils, batch sorption experiments were performed. The results showed a predominant effect on Se species in the soils, where selenite sorbed more intensively compared to selenate, regardless of the soil and ameliorative material applied. In the control, the soil sorption ability of selenite tended to decrease in the order: fluvisol > luvisol > chernozem. However, these differences were not significant. Moreover, the effects of the ameliorative materials depended on both soil and amendment used. In fluvisol, all the amendment applications resulted in a decrease in distribution coefficient ( K d values) of Se, whereas in chernozem, this effect was observed only for the digestate-based vermicompost 1. Increasing K d levels were reported in luvisol treated with digestate;the application of garden bio-waste-based vermicompost 3 tended to decrease the K d values. Further studies are required on long-term effects of these amendments on Se mobility in soils and the role of individual organic matter fractions in this context.

Prospects of Anaerobic Digestion Technology in China

As the world＇s largest developing country, China must face the problem of managing municipal solid waste, and the challenge of organic waste disposal is even more serious. Considering the characteristics of traditional waste disposal technologies and the subsequent secondary pollution, anaerobic digestion has various advantages such as reduction in the land needed for disposal and preservation of environmental quality. In light of the energy crisis, this paper focuses on the potential production of biogas from biowaste through anaerobic digestion processes, the problems incurred by the waste collection system, and the efficiency of the anaerobic digestion process. Use of biogas in a combined heat and power cogeneration system is also discussed. Finally, the advantages of anaerobic digestion technology for the Chinese market are summarized. The anaerobic digestion is suggested to be a promising treating technology for the organic wastes in China.

Rheology and microstructure effects of waste spent coffee grounds in modifying asphalt binder

Herein the biowaste by-product spent coffee grounds(SCGs)from coffee industry were incorporated into asphalt binders for performance enhancement.From the analysis of Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry(DSC),dynamic shear rheometer(DSR),and Brookfield viscosity rheometer,it is confirmed that SCGs have potential prospects as bio-waste modifiers in the application of sustainable pavements.Results demonstrated that the modification process was mainly based on physical reinforcement.Compared with that of the neat asphalt,the shearing stress-resistant ability and high-temperature performance of the SCGs modified binders with the appropriate addition presented a bit of improvement;whereas the binders with 1%and 3%SCGs exhibited remarkably enhanced low-temperature stability.However,notable weaknesses of practical performance were shown for the binder with excessive content of SCGs,indicating the necessity of proportion selecting before application.