Nuri Azbar

A Review of Waste Management Options in Olive Oil Production

In this article, treatment and disposal alternatives of olive oil mill wastes and technical requirements for their management are covered. Waste characteristics, treatment options with regard to the economic feasibility, and challenges of existing waste disposal practices in olive growing countries are mentioned. Attention is drawn to present-day techniques of waste management. The search concerning the environmentally acceptable, economically feasible, and practically applicable methods of disposal of olive oil mill wastes is referred. In the management schemes, compliance with environmental regulations and economic and social benefits of the olive oil production are the goals that must be simultaneously achieved.

Effect of process configuration and substrate complexity on the performance of anaerobic processes

The roles of substrate complexity (molecular size of the substrate) and process configuration in anaerobic wastewater treatment were investigated to determine optimal methanogenic technology parameters. Five substrates (glucose, propionate, butyrate, ethanol, and lactate) plus a mixed waste (60% carbohydrate, 34% protein, and 6% lipids) were studied under five reactor configurations: batch-fed single-stage continuous stirred tank reactor (CSTR), continuously fed single-stage CSTR, two-phase CSTR, two-stage CSTR, and single-stage upflow anaerobic sludge blanket (UASB). The substrate feed concentration was 20,000 mg/L as COD. The solids retention time (SRT) and hydraulic retention time (HRT) in the CSTR reactors were 20 d, while HRT in the UASB was 2 d. All reactors were operated for at least 60 d (equal to 3SRT). Substrate complexity was observed to be less significant under two-phase, two-stage and UASB reactor configurations. Two-phase CSTR, two-stage CSTR, and single-stage UASB configurations yielded the lowest effluent chemical oxygen demands (130-550, 60-700, and 50-250 mg/L, respectively). The highest effluent chemical oxygen demands were detected when feeding glucose, propionate, and lactate to continuously fed single-stage CSTRs (10, 400, 9900, and 4700 mg/L COD, respectively) and to batch-fed single-stage CSTRs (11, 200, 2500, and 2700 mg/L COD, respectively). Ironically, the one stage CSTR--most commonly utilized in the field--was the worst possible reactor configuration.

Overview of anaerobic treatment: thermophilic and propionate implications.

Difficulties in achieving low propionate concentrations in anaerobically treated effluents are frequently reported in the literature (Ahring, 1994; Kugelman and Guida, 1989; Rimkus et al., 1982), especially at thermophilic temperatures, with concentrations as high as 1000 to 9600 mg/L sometimes produced. This paper will detail the effect of several variables on the performance of both mesophilic and thermophilic regimes. Studies concerning the effect of the following four important factors on performance are included: reactor configuration, inorganic nutrient supplementation, substrate characteristics, and the unique role of microbial consortia proximity in enhancing performance. Reactor configuration modifications, essential nutrient additions, and the importance of close microbial proximity were all found to contribute to improvement in thermophilic anaerobic digestion in all the studies. It was found that, in substrates that shunt significant amounts of the electron donor through propionate, performance was critically related to reactor optimization, with propionate removal efficiency considerably improved using intact upflow anaerobic sludge blanket granules, less so in a homogenized granule slurry blanket, and noticeably reduced even more when the completely stirred reactor configuration of homogenized granules was used. The critical importance of extremely close microbial consortia proximity in maintaining hydrogen intermediates at very low levels to efficiently convert propionate to hydrogen and acetate was demonstrated. Compared to mesophilic digestion, thermophilic digestion manifested elevated levels of propionate, except in the nonmixed reactors, which had close microbial consortia proximity. The reactor configuration with the best results was the anaerobic digestion elutriated phased treatment (ADEPT) scheme, in which the raw sludge was elutriated of its fermenting volatile fatty acids, as they are generated in a short 5- to 8-day solids retention time (SRT) in one reactor and the elutriate then metabolized by passing up through a methanogenic granule or slurry blanket (with its close microbial consortia proximity) in a separate reactor with a 20- to 50-day SRT. Loading rates and performance of the ADEPT reactor configuration were superior to the standard continuously stirred tank reactor, and ADEPT thermophilic temperatures allowed higher organic loading rates without high propionate concentrations in the effluent.

Comparative Evaluation of Bio-Hydrogen Production From Cheese Whey Wastewater Under Thermophilic and Mesophilic Anaerobic Conditions

Hydrogen production from cheese whey wastewater via dark fermentation was conducted using mixed culture under mesophilic (36°C ± 1) and thermophilic (55°C ± 1) conditions, respectively. The hydrogen yields and specific hydrogen production rates were found as follows: mesophilic: 9.2 mmol H2 /g COD (chemical oxygen demand) and 5.1 mL H2 /g VSS h; thermophilic: 8.1 mmol H2 / g COD and 1.1 mL H2 /g VSS h. The reaction mixture for the mesophilic condition was composed of acetate (0.3–14.7%) and iso-butyrate (85–98%), plus other volatile fatty acids. On the other hand, the reactor mixture for the thermophilic condition was composed of acetate (1–43%) and iso-butyrate (29–46%).

Comparative evaluation of a laboratory and full-scale treatment alternatives for the vegetable oil refining industry wastewater (VORW)

Abstract The efficiency of alternative treatment processes in producing a final effluent conforming to regulatory standards with regards to chemical oxygen demand (COD) and oil and grease (O&G) loads was assessed. The study was conducted in three principal stages: waste characterization, lab-scale treatability studies and full-scale applications. The effluent were characterized in terms of pH (6.3–7.2), total COD (13,750–15,000 mg l −1 ), soluble COD (COD s ) (6500–7000 mg l −1 ), biochemical oxygen demand (BOD 5 ) (4300–4700 mg l −1 ), O&G (3600–3900 mg l −1 ), total suspended solids (TSS) (3800–4130 mg l −1 ), total Kjeldahl nitrogen (TKN) (636–738 mg l −1 ) and total phosphorus (TP) (61–63 mg l −1 ). After analyzing various raw effluent parameters, lab-scale chemical treatability studies were conducted using Al 2 (SO 4 ) 3 ·18H 2 O and FeCl 3 ·6H 2 O. The results showed 88 and 84% influent COD reduction, while O&G removal was 81 and 93%, respectively. The removal of total suspended solids (TSS) varied from 78 to 86%. Lab-scale aerobic biological treatment reactors with a HRT of 24 h and food to microorganism ratio of 0.3–0.5 were also run to assess the process efficiency and determine the residual soluble COD in the effluent. Residual soluble COD was 59–70 mg l −1 . Based on the results from waste characterization and treatability studies, a continuous full-scale treatment system was constructed and operated in two vegetable oil refining plants with a different pretreatment flow scheme. The overall percentage removal of COD, TSS, and O&G was 92–96, 83–98 and 93–95%, respectively.

1,3-Propanediol production potential of Clostridium saccharobutylicum NRRL B-643

Owing to the significant interest in biofuel production in the form of biodiesel, vast amount of glycerol as a waste product is produced all over the world. Among the economically viable and ecologically acceptable solutions for the safe disposal of this waste, biotechnological conversion of glycerol into a valuable bioplastic raw material, namely 1,3-propanediol (1,3-PDO) seems to be very promising. In this study, 1,3-PDO production potential of Clostridium saccharobutylicum NRRL B-643 was studied and the results were compared with other types of anaerobic microorganisms (Clostridium spp., Pantoea agglomerans, Ochrobactrum anthropi, Chyreseomonas luteola, and Klebsiella pneumoniae) and aerobic microorganisms (Lactobacillus spp.). The results were important for understanding the significance of C. saccharobutylicum NRRL B-643 among other well-known 1,3-PDO producer species. According to the screening results only C. saccharobutylicum (B-643) was able to consume feed glycerol almost entirely. However, 1,3-PDO production yield was found to be 0.36mol/mol which is lower than that of Clostiridium beijerinckii (B-593). B-593 showed the highest value of production yields with 0.54 mol/mol. This microorganism is seen as a promising type for further 1,3-PDO studies, because it has the highest substrate utilization percentage among others. In this regard, this microorganism may have an important role in tolerating and converting glycerol during fermentation into 1,3-PDO.

Optimization of Basal Medium for Fermentative Hydrogen Production from Cheese Whey Wastewater

In this study, optimal basal medium composition for fermentative hydrogen production from cheese whey wastewater was investigated in batch tests. Twenty-five different basal medium formulas was prepared, each containing trace metals concentration (Co, Ni, Zn: 0–5 mg/l), macro elements concentration (Mg: 0–200 mg/l; Mn: 0–10 mg/l, Fe: 0–100 mg/l, Ca: 0–1000 mg/l), C/N ratio of 5–50, and yeast extract and l-cycteine concentrations (0–500 mg/l). Each of the experimental setups was conducted as triplicates in 100-ml serum vials at pH 5.5 under mesophilic conditions (36 ± 1°C). Granular biomass obtained from an industrial scale upflow anaerobic sludge bed bioreactor was used as an initial inoculum. Considering the hydrogen production efficiencies obtained in this study (max. 3.5 mol H2/mol lactoseconsumed and 218.6 ml H2 /g lactoseconsumed), a successful nutrient formulation for optimum hydrogen production from cheese whey was proposed as follows; CoCl2, NiCl2, ZnCl2: 1.25–2.5 mg/l; CaCl2: 250–500 mg/l: MgCl2: 50–150 mg/l; MnCl2: 2.5–5 mg/l; FeCl2: 50–100 mg/l; yeast extract: 125–250 mg /l; L-cysteine: 125–250 mg /l and C/N ratio: 30–40.

Use of ceramic‐based cell immobilization to produce 1,3‐propanediol from biodiesel‐derived waste glycerol with Klebsiella pneumoniae

Aims:  The feasibility of the continuous production of a valuable bioplastic raw material, namely 1,3‐propanediol (1,3‐PDO) from biodiesel by‐product glycerol, using immobilized cells was investigated. In addition, the effect of hydraulic retention time (HRT) was also analysed.

Experimental design methods for bioengineering applications

Abstract Experimental design is a form of process analysis in which certain factors are selected to obtain the desired responses of interest. It may also be used for the determination of the effects of various independent factors on a dependent factor. The bioengineering discipline includes many different areas of scientific interest, and each study area is affected and governed by many different factors. Briefly analyzing the important factors and selecting an experimental design for optimization are very effective tools for the design of any bioprocess under question. This review summarizes experimental design methods that can be used to investigate various factors relating to bioengineering processes. The experimental methods generally used in bioengineering are as follows: full factorial design, fractional factorial design, Plackett–Burman design, Taguchi design, Box–Behnken design and central composite design. These design methods are briefly introduced, and then the application of these design methods to study different bioengineering processes is analyzed.

Upgrading an existing treatment system to adopt cleaner production principals

In 1981, SEKA Cellulose and Paper Co. started pulp and newsprint paper production in Balikesir, Turkey. Production technology that was initially TMP (Thermo Mechanical Pulping) was converted to CTMP (Chemical Thermo Mechanical Pulping) in 1986. Finally in 1990, another unit operation was added to the whole system and hydrogen peroxide bleaching was employed in production. The existing wastewater treatment plant that was built in 1981 was projected to treat wastewaters generated from TMP production line. As the technology changes mentioned above were proceeding no precaution in the flow scheme of the treatment plant was taken to accommodate the change in wastewater characteristics. As a result of increase in the values of various pollution parameters such as wastewater flow, influent BOD5, COD, SS etc., existing treatment plant has been failing to comply with receiving media (Simav River which was already BOD limited due to the other industrial and domestic discharges) discharge limits. Current pollution loads to the treatment plant are higher than projected values and there are significant fluctuations in wastewater flow rate due to the sudden discharges from CTMP unit operations. In this study, two possible solutions to fix the current situation in terms of applying waste minimization strategy by using pollution prevention techniques in the plant and secondly modifying the existing treatment plant flow scheme are discussed.