Investigation of improving biomethanization processes of cattle manure

In this study, the improving of treatment efficiency and biomethane production has been investigated with the addition of wastes containing high levels of organic matter to cattle manure (CM) in different operation conditions. In this experimental study, 5 parallel 6.15 L upflow anaerobic sludge blanket (UASB) reactor has been used. These reactors have been operated at mesophilic conditions (36.5-37°C) with organic loading rate (OLR) of 10.000 mg TCOD/L. The wastes that will be fed to the reactors were treated with single and two-stage pretreatment in the first and second period, respectively. In the experimental studies, wastes containing high levels of organic matter are added to CM at the rates of 5%, 10%, 20%, 40% and 50%, and their effects to the production of biogas have been observed. In the first reactor (R1), only cattle manure (CM) was used for control purposes. In the second reactor (R2), grass wastes were used as additional waste. In the third reactor (R3), 33.3% grass wastes, 16.7% homemade organic wastes (kitchen organic wastes), 16.7% industrial organic wastes (50% cottonseed meal and 50% olive press cake mix), and 33.3% sludge mixtures were used as additional wastes. In the fourth reactor (R4), 50% homemade organic wastes and 50% industrial organic waste mixtures were used as additional wastes. In the fifth reactor (R5), sludge mixtures were used as additional wastes. Studies were conducted under two different hydraulic retention time (HRT) of 20 and 10 days. Parameters such as pH, alkalinity, total chemical oxygen demand (TCOD), dissolved chemical oxygen demand (DCOD), total solids (TS), volatile solids (VS), suspended solids (SS) and volatile suspended solids (VSS) were monitored in the reactors, influent and effluent of the reactors. The other parameters such as biological oxygen demand (BOD), total Kjeldahl nitrogen (TKN), Ammoniacal nitrogen (NH3-N), total phosphorus (TP), orthophosphate (PO4-3-P) and chloride (Cl-) were monitored in the reactors, influent and effluent of the reactors. Moreover, SEM (Scanning Electron Microscope) photographs have been taken of anaerobic floccular and granular sludge that was formed from the later stages of the study in the reactors and their EDX (Energy Dispersive X-ray) analysis have been carried out. In the thesis, by developing artificial neural network (ANN) based modeling and simulation studies for the treatment process, the integrity of the relationship between the experimental data of anaerobic system and the daily amount of biogas production has been demonstrated. Furthermore, in the thesis, cost analysis studies have been conducted for the biogas plants that can be established in our country's domestic industry. As a result of the experimental studies, in the R1, R2, R3, R4 and R5 reactors, at the period of HRT 20 days and HRT 10 days, on average %79±4, %78±4, %80±4, %81±6, %80±5 and %76±7, %74±8, %79±6, %79±8, %80±5 TCOD removal as well as 0.63±0.19, 0.68±0.23, 0.64±0.17, 0.75±0.21, 0.67±0.23 and 0.92±0.24, 0.95±0.30, 0.97±0.27, 1.10±0.29, 0.95±0.28 L/day biogas productions are realized. In R2 reactor, the most positive contribution to the daily production of biogas was found to be 27% in the case of adding 20% (as TCOD) grass waste to cattle manure (HRT: 20 days). In R3 reactor, the most positive contribution to the daily production of biogas was found to be 13% in the case of adding of a mixture of 20% (as TCOD) all wastes (grass waste, homemade-industrial organic wastes and sludge) to cattle manure (HRT: 20 days). In R4 reactor, the most positive contribution to the daily production of biogas was found to be 23% in the case of adding a mixture of 20% (as TCOD) homemade and industrial organic wastes to cattle manure (HRT: 10 days). In R5 reactor, the most positive contribution to the daily production of biogas was found to be 26% in the case of adding 20% (as TCOD) sludge to cattle manure (HRT: 10 days). In addition, modeling studies show that there is a positive contribution to the daily production of biogas in the case of mixing up to 30% additional wastes to cattle manure used in experimental studies. Moreover, it was determined that while feeding (<1 mm sieve wastes) the raw wastes after reducing their diameters to a certain value (<5 mm) has positive contribution to biogas production performance, further shredding them (<1 mm) cause performance degradation.