Cumali Kinaci

Stripping/flocculation/membrane bioreactor/reverse osmosis treatment of municipal landfill leachate

This study presents a configuration for the complete treatment of landfill leachate with high organic and ammonium concentrations. Ammonia stripping is performed to overcome the ammonia toxicity to aerobic microorganisms. By coagulation-flocculation process, COD and suspended solids (SS) were removed 36 and 46%, respectively. After pretreatment, an aerobic/anoxic membrane bioreactor (Aer/An MBR) accomplished the COD and total inorganic nitrogen (total-N(i)) removals above 90 and 92%, respectively, at SRT of 30 days. Concentrations of COD and total-N(i) (not considering organic nitrogen) in the Aer/An MBR effluent decreased to 450 and 40 mg/l, respectively, by significant organic oxidation and nitrification/denitrification processes. As an advanced treatment for the leachate, the reverse osmosis (RO) was applied to the collected Aer/An MBR effluents. Reverse osmosis provided high quality effluent by reducing the effluent COD from MBR to less than 4.0mg/l at SRT of 30 days.

Role of intermittent aeration in domestic wastewater treatment by submerged membrane activated sludge system

Abstract In this study, the treatment of domestic wastewater in a lab-scale submerged membrane activated sludge system (sMBR) was investigated under different aeration intervals. The COD concentration of the system effluent varied generally between 5 and 25 mg/l and the COD removal at the organic loads of 0.6–0.8 kg COD/m3.d was observed to be above 98%. The total phosphorus content of the filtrate was decreased to a level that was less than 1 mg/l under the aerobic conditions in which the aeration was continuously made. A dramatic increase in the total phosphorus content of filtrate was observed under the aerobic + anoxic conditions in which the aeration was made at differential intervals. The filtrate was free of suspended solid (SS) and total coliform bacteria and a percent removal of 100 was achieved in terms of these parameters. The influent turbidity removal was 97–99.8%. Generally, the removal of total Kjeldahl nitrogen (TKN) and ammonium nitrogen varied in the ranges of 87.8–99.1% and in the ranges of 89.4–99.8%, respectively. While the nitrate concentrations in the filtrate increased to 26.8 mg/l under the aerobic conditions, it was determined that this value was decreased to 2.4 mg/l under the aerobic + anoxic conditions.

Viability of microbial mass in a submerged membrane bioreactor

In this study the viability of biomass in a submerged membrane activated sludge system (sMBR) which treats domestic wastewater was investigated by dealing with non-biodegradable COD, specific oxygen uptake rate and MLVSS during operation for 100 days. It was shown that the viability of biomass in the bioreactor was reduced at the 50% level because of the accumulation of inert compounds and the reduction in the activities of poor biomass. After inoculating the bioreactor again, the specific OUR increased because of young biomass entering into the bioreactor. It was shown that there was an exponential relationship between OUR and MLVSS and there was a logarithmic relationship between specific OUR and MLVSS.

A modeling approach for iron concentration in sand filtration effluent using adaptive neuro-fuzzy model

Effluent iron concentration is an important water quality criterion used for the assessment of the performance of rapid sand filters, in addition to other criteria. This study deals with the prediction of effluent iron concentrations by adaptive neuro-fuzzy (ANFIS) model with input parameters including filter hydraulic loading rate, influent iron concentration, bed porosity and operation time. With trying various types of membership functions, two rule base generation methods, namely subtractive clustering and grid partition were used for a first order Sugeno type inference system. Models were evaluated using root mean squared error (RMSE), index of agreement (IA) and R^2 as statistical performance parameters. The fit between experimental results and model outputs showed good agreement for tap water and deionized water; testing RMSE values were 36.33 and 7.66@mg/L, the IA values were 0.996 and 0.971, and R^2 values were 0.99 and 0.89, respectively. It was concluded that neuro-fuzzy modeling may be successfully used to predict effluent iron concentration in sand filtration.

Pollution prevention and restoration in the golden horn of Istanbul

The pollution in the Golden Horn is one of the most important environmental problems of Istanbul. Alluvium carried by Alibey and Kagithane creeks, and domestic and industrial wastewater discharges are the major sources of the pollution. In the upstream, a part of 3 to 4 km long is almost completely filled with debris and organic solids. There is a high anaerobic activity in the sediment resulting in a heavy odor problem. Sea traffic is impossible since the depth of water is less than 10 cm at this part. A restoration feasibility project has been carried out for pollution prevention and evaluation of the restoration alternatives. For this purpose, first, characteristics of water quality and bottom sediment were determined. Second, pollution prevention measures and the alternatives for the dredging and disposal of the bottom sediment were evaluated. Istanbul Metropolitan Municipality has already started the dredging work by early 1997, and has completed the diversion of all domestic and industrial wastewater discharges out of the Golden Horn. This paper summarizes the studies for determining current status, evaluating the restoration alternatives, and also the progress of the on-going dredging work.

Comparison of a sMBR with a CASP system for wastewater reclamation and re-use

Abstract As a service to readers who understand German, French or Spanish better than English, the abstract for the research article in this issue follow in these languages.

Production of non-biodegradable compounds based on biomass activity in a submerged ultrafiltration hollow fibre membrane bioreactor treating raw whey

Raw whey including a high organic load in the range of 16–60 kg/m 3 per day was treated directly in a submerged membrane bioreactor (sMBR). The behavior of non-biodegradable compounds in the system and their effects on biomass viability were investigated by considering different sludge ages in the range of 10–75 days during an operation of 114 days. Non-biodegradable compounds were produced by dead and old organisms and then accumulated in the system. Furthermore, biomass viability decreased with an increase in sludge age. At sludge ages of 10 and 20 days, inert COD, which is a measure of non-biodegradable compounds, was removed together with the wasted sludge as a small amount of the system, but not taken away from the bioreactor at higher sludge ages due to the small amount of the wasted sludge. The production of non-biodegradable compounds was very clear at high sludge ages in the range of 30–75 days. Inert COD increased to 1.84 times at the fifth period when the sludge age was 75 days, based on the reduction of biomass viability. The ratio of mixed liquor volatile suspended solid to mixed liquor suspended solid (MLVSS/MLSS) decreased with time although both concentrations increased. The relationship between specific oxygen uptake rate (sOUR) and MLVSS was a logarithmic decreasing curve. The relationship between the sOUR and the Cs/C0 means that the ratio of inert COD concentration in the effluent to that in the influent was an exponent decreasing curve.

Quality of the Bottom Sediment Prior to Dredging in the Golden Horn of Istanbul

Abstract The Golden Horn has experienced severe pollution due to uncontrolled domestic and industrial wastewater discharges until recent years. A restoration project has been developed by our universities, upon a request from Istanbul Metropolitan Municipality. Two principal alternatives for the dredging and disposal of the bottom sediments were considered: disposing on the land and disposing in the sea. Both of these alternatives include several sub-alternatives. Characterization of the sediment quality is crucially important for selecting the best alternative considering the cost, environmental impact and public acceptance. However, only a few and rather old studies were present with which it was not possible to get a comprehensive information on the critical sediment characteristics. Therefore, the aim of this study was determination of spatial distribution of sediment characteristics. The project area, at which the sediment quality determined, covers the part of the Golden Horn remaining at the upstream of Valide Sultan Bridge. The number of sampling stations were thirteen and the sediment samples were collected from 0.0 m, 5.0 m and 10.0 m from the bottom surface. The following parameters were measured on each sample: Total solids, organic matter, total phosphorus, TKN, oil and grease, total sulphur, and sediment oxygen demand (SOD). Sediment oxygen demand parameter was further divided into three fractions, namely, biological (SOD-B) and chemical (SOD-C). Average organic content of the bottom sediment was around 10% while ammonia and sulfur exhibit very high levels. It is found that the bottom sediment is well stabilized with very low organic content below 5.0 m from the bottom surface. It can be said that, removing the upper 5 m of the bottom sediment will be enough for creating a relatively stable bottom surface which will cause oxygen depletion in the overlaying water at acceptable levels. High SOD values of the bottom sediment makes the alternatives considering disposal in the Marmara Sea and Black Sea inapplicable. High SOD-C values, especially, indicate that the sediment will cause a tremendous reduction in the oxygen concentration in a very short time at any marine environment, and even it may create anaerobic conditions. Therefore, disposal of dredged sediment into abandoned mines 4 km from the Golden Horn by a pressure pipeline has been chosen as the best applicable alternative.

Ozonation of Aqueous Solution of Alpha Endosulfan

Ozonation of alpha endosulfan and the effects of some parameters such as pH, temperature and partial pressure on ozonation were investigated and the kinetic constants were calculated in this study. Alpha endosulfan solutions were ozonated in a lab‐scale semi‐batch reactor under variable experimental conditions. Increase in dissolved ozone concentration had a positive effect on oxidation rate. Alpha endosulfan could be removed up to 94% at pH 4 for an ozonation time of 60 minutes. The oxidation reaction was found to be of second order and of first order with respect to both ozone and alpha endosulfan. The temperature dependent reaction expression of alpha endosulfan was obtained as kd = 0.889 exp(− 2.21 × 10− 3/T). It was concluded that, although the rate of reaction was lower than the rate of other pesticide oxidation reported in the literature, alpha endosulfan presented an obvious reaction to ozonation.

Simultaneous removal of ammonium and suspended solids in multipurpose filters

A multipurpose filter in which sand and clinoptilolite are used together as filter material is suggested for the simultaneous removal of suspended solids and ammonium in one single unit. The capacity of the clinoptilolite used was determined as 10.4 mg/g for 20 mg/l initial ammonium concentration. In addition, a packed column ion exchanger with clinoptilolite and a classical sand filter were also investigated for comparison. Ammonium and suspended solids removal rates were observed and compared for all columns. The results of the column analysis have revealed that the ammonium removal rate, which was only 20% in the sand column, was increased to 100% by replacing 50% of the sand with clinoptilolite; similarly, the suspended solids removal, which was only 17% in the clinoptilolite column, was increased to 75% by replacing 50% of the clinoptilolite with sand. As such, when ion exchange and filtration processes were carried out in a multipurpose column, high removals for both parameters could be obtained simultaneously. Multipurpose columns could be an alternative both for the upgrading of existing treatment plants or for new plants for simultaneous removal of ammonium and suspended solids, giving considerable savings in terms of land requirements.