Characterization and evaluation of the anaerobic treatability of a dairy wastewater.

In this study, the characteristics, anaerobic treatability, and energy potential of wastewater samples taken from a dairy products industry were investigated. It was determined that the wastewater has a high organic load (COD = 2800 mg O2/L) and a large proportion of this load is biodegradable. The biochemical methane potential (BMP) value of wastewater was measured as 1118.71 ± 122 ml CH4/L. Volatile solids (VS) removal of 67.25 ± 4.98% was achieved during batch tests and the obtained methane yield was calculated as 411.59 ± 22.8 ml CH4/g VS. Peak methane formation rate and lag time of microorganisms were determined as 163.42 ± 3.83 ml CH4/g VS d and 0.584 ± 0.023 d, respectively. Rate constant for the first-order kinetic model was 0.384 ± 0.072 d-1. The volatile fatty acid (VFA) yield was measured as 155.19 mg COD/g VSS. It was concluded that the wastewater can be treated anaerobically without any inhibition and it has great energy potential. PRACTITIONER POINTS: Dairy wastewater has a large organic load and that most of the organics can be easily biodegradable. Although there are many components considered to be toxic for anaerobic treatment in wastewater, they were found to be very under the inhibition thresholds and did not pose any risk of toxicity. At a satisfactory level, organic matter removal and methane formation were observed in batch anaerobic tests. A rapid microbial adaptation was achieved and the system reached equilibrium in a short time without any acid accumulation. The electrical and caloric energy potentials of the obtained methane gas were calculated as 2.12 and 4.25 kWh/m3, respectively.

Use of EO-1 Advanced Land Imager (ALI) multispectral image data and real-time field sampling for water quality mapping in the Hirfanli Dam Lake, Turkey.

This paper focuses on the evaluation of water quality variations in Hirfanli Water Reservoir, which is one of the most important water resources in Turkey, through EO-1 (Earth Observing-1) Advanced Land Imager (ALI) multispectral data and real-time field sampling. The study was materialized in 20 different sampling points during the overpass of the EO-1 ALI sensor over the study area. A multi-linear regression technique was used to explore the relationships between radiometrically corrected EO-1 ALI image data and water quality parameters: chlorophyll a, turbidity, and suspended solids. The retrieved and verified results show that the measured and estimated values of water quality parameters are in good agreement (R (2) >0.93). The resulting thematic maps derived from EO-1 multispectral data for chlorophyll a, turbidity, and suspended solids show the spatial distribution of the water quality parameters. The results indicate that the reservoir has average nutrient values. Furthermore, chlorophyll a, turbidity, and suspended solids values increased at the upstream reservoir and shallow coast of the Hirfanli Water Reservoir.

Adsorption of Cr(VI) on ureolytic mixed culture from biocatalytic calcification reactor.

Ca-rich water and wastewater have caused problems in water use, wastewater reuse and the operations of reactors treating Ca-rich wastewater. Nowadays, reuse of wastewaters is fast gaining importance as water sources have been polluted. Therefore, the concept of biocatalytic calcification reactors (BCR) based on urea hydrolysis, pH increase and calcite production has been studied to remove Ca from wastewaters. This biological process produces significant amounts of waste sludge. In the present study, Cr(VI) adsorption on the ureolytic mixed culture (UMC) waste by-product from BCR was investigated to evaluate its potential for metal removal. The biosorption process was investigated using equilibrium batch tests and the data were fit to the Langmuir, Freundlich and Temkin isotherm models. The Cr(VI) ion concentration dependence of sorption (1-100 mg/L) could be fit to the Langmuir isotherm model. Monolayer adsorption capacity, qm (mg/g), of the adsorbent was 8.67 and the Langmuir constant b (L/mg) was 0.881. Based on the obtained results, the waste UMC appears to be a potential biosorbent for the removal of Cr(VI) from wastewater, although its adsorptive capacity is lower than those of other biosorbents.

Determination of arsenic levels in the water resources of Aksaray Province, Turkey.

Arsenic levels were determined in 62 stations utilized as drinking and potable water resources by local community for Turkey's Aksaray Province (4589 km(2); 980 m above sea level). The samplings were implemented every two months for 1 year. The arsenic values were found to be ranging between 10 and 50 µg/L in 22 points and were found to be >50 µg/L in 5 stations, according to the mean value of the 6 samples. WHO and the Turkish Standards have permitted an arsenic concentration of 10 µg/L in drinking waters. The multivariate statistical technique, cluster analysis (CA), followed by principal component analysis (PCA) were applied to the data on 17 water quality parameters in 47 stations that are used for drinking and other domestic resources. Two significant sampling locations were detected based on the similarity of their water quality. The chemical correlations were observed in the two sub-sampling locations by Principal Component Analysis.

Effect of hydraulic retention time on continuous biocatalytic calcification reactor.

High calcium concentrations in the wastewaters are problematic, because they lead to clogging of pipelines, boilers and heat exchangers through scaling (as carbonate, sulfate or phosphate precipitates), or malfunctioning of aerobic and anaerobic reactors. As a remedy to this problem, the industry typically uses chemical crystallization reactors which are efficient but often require complex monitoring and control and, as a drawback, can give rise to highly alkaline effluents. Biomineralization are emerging as alternative mechanisms for the removal of calcium from aqueous environments. Biocatalytic calcification reactors (BCR) utilize microbial urea hydrolysis by bacteria for the removal of calcium, as calcite, from industrial wastewater. Hydraulic retention time (HRT) effect on calcium removal was studied with a continuous feed BCR reactor treating a simulated pulp paper wastewater. Study showed that HRT is important parameter and HRT of 5-6 h is optimum for calcium removal from calcium-rich wastewaters.

Inhibitory effect of heavy metals on methane-producing anaerobic granular sludge.

Heavy metals could potentially have a negative impact on methane-producing anaerobic granular sludge. The objective of this study was to investigate the inhibitory effect of zinc(II), chromium(VI), nickel(II), and cadmium(II) on the methane-producing activity of granular sludge sampled from the upflow anaerobic sludge blanket reactor that treats the wastewaters of a yeast factory, for a range of concentrations between 0 and 128 mg L(-1). The modified Gompertz, Logistic, and Richards equations were applied to describe the inactivation of anaerobic culture by heavy metals. According to these models, the values of methane production potential (mL) for a heavy metal concentration of 128 mg L(-1) were in the following order: Ni (44.82+/-0.67)>Cd (28.73+/-0.11)>Cr (15.52+/-1.63)>Zn (0.65+/-0.00). The IC(50) values, the metal concentrations that cause a 50% reduction in the cumulative methane production over a fixed period of exposure time (24h), for the individual heavy metals were found to be in the following order: Zn (most toxic; 7.5 mg L(-1))>Cr (27 mg L(-1))>Ni (35 mg L(-1)) approximately Cd (least toxic; 36 mg L(-1)).

Sulfide removal in petroleum refinery wastewater by chemical precipitation.

Sulfide removal by chemical precipitation from petroleum refinery wastewater was investigated. The wastewater samples were taken from the flocculation pond influent of TUPRAS Kirikkale Middle Anatolia Petroleum Refinery Wastewater Treatment Plant (WWTP) and physicochemical treatments using conventional coagulants which were partial precipitant [FeCl(3) . 6H(2)O and FeSO(4) . 7H(2)O] and coagulant-aids [Ca(OH)(2) and CaCO(3)] were applied to both raw and sulfide added wastewater. Sulfide and chemical oxygen demand (COD) removal efficiencies of Fe(3+) ions alone for sulfide added wastewaters having different pH values varied between 62-95 and 45-75%, respectively. In addition, removal efficiencies of sulfide (96-99%) and COD (50-80%) were obtained by using Fe(2+) ions together with Ca(OH)(2) as precipitant-aid under the same conditions. In experiments performed with raw wastewater which had different pH values, COD removal efficiencies of Fe(3+) and Fe(2+) ions together with Ca(OH)(2), were 50-80 and 32-50%, respectively.