No abstract

In this study, the treatment of car wash wastewater was investigated by radical based hybrid/combined processes. Proposed processes, (Microwave (MW) + persulfate (PS) + Electrocoagulation (EC)), (ozone (O3) + PS + EC) and (MW + PS + O3), were optimized with Taguchi orthogonal array technique for maximum COD removal. The COD removal under optimum conditions was obtained to be 84%, 64.9% and 61.4%, for (MW + PS+ EC), (O3 + PS+ EC) and (MW + PS+ O3) processes, respectively. Operating costs for (MW + PS + EC), (O3 + PS + EC) and (MW + PS + O3) processes have been calculated as 0.2614, 0.1335 and 0.2653 €/L wastewater under optimum operating conditions. Pareto analysis showed that MW time and PS dose are very effective parameters but especially ozone related parameters have no significant effect on COD removal. Processes were evaluated with the PROMETHEE approach in terms of treatment efficiency, operating cost, sludge formation, and preferability criteria to determine the most suitable among the three alternative processes. As a result, the preference order of the processes for the treatment of car wash wastewater with radical based treatment processes was found as (MW + EC + PS) > (MW + O3 + PS) > (O3 + EC + PS).

Sürdürülebilir bir atık yönetim yaklaşımının ekonomik, sosyal ve çevresel unsurların tümüne hizmet edebilmesi gerekir. Bu çalışmada atık lastiklerin yönetiminde direkt geri dönüşüm, piroliz ve alternatif yakıt olarak değerlendirme alternatifleri değerlendirilmiştir. Sayılan bu alternatif metotlardan Türkiye için en uygun yöntem, çok kriterli karar verme süreci olan PROMETHEE (preference ranking organization method for enrichment evaluations) ve bulanık PROMETHEE yöntemi ile belirlenmiştir. En uygun alternatifin belirlenmesi için belirlenen 4 karar vericinin alternatif yöntemleri, çevresel etki, işletme riski, kurulum maliyeti, işletme maliyeti, elde edilen ürün çeşitliliği ve Türkiye'de uygulanabilirlik açısından değerlendirilmeleri istenmiştir. Karar vericilerin bu değerlendirme kriterlerine verdikleri cevaplar 5 noktalı karar ölçeği ve bulanık sayılar ile ifade edildikten sonra Visual PROMETHEE yazılımı ile çözümlenmiştir. Sonuçlara göre PROMETHEE ve bulanık PROMETHEE çözümlemeleri PROMETHEE I ve II analizleri dikkate alındığında alternatiflerin geri dönüşüm>alternatif yakıt olarak kullanım>piroliz şeklinde aynı tercih sıralamaları vermişlerdir, ancak PROMETHEE Rainbow analizinde alternatiflere etki eden pozitif ve negatif kriterlerde farklılıklar göstermiştir. Dilsel ifadelerin bulanık PROMETHEE ile daha hassas ifade edildiği düşünüldüğünden yukarıdaki analizlerine ek olarak GAIA görsel analizi ve GAIA web analizi gerçekleştirilmiştir. GAIA analizi ile, (i) geri dönüşüm alternatifinin çevresel etkiler, işletme riski, Türkiye'deki uygulanabilirliği ve işletme maliyeti açısından, (ii) piroliz alternatifinin ürün çeşitliliği açısından, (iii) alternatif yakıt olarak kullanma alternatifinin kurulum maliyeti açısından uygun olacağı belirlenmiştir. Sonuç olarak en uygun alternatifinin geri dönüşüm alternatifi olduğu ve bu alternatifinin tercih edilebilirliğinde sadece kurulum maliyeti kriterinin negatif yönde etki ettiği belirlenmiştir.

Diclofenac sodium (DCF) is a non-steroidal anti-inflammatory drug. It has been classified as ecotoxic even at low concentrations. In this study, adsorption of DCF on coconut shell-based granular activated carbon (GAC) and regeneration of spent GAC with hydrochloric acid (HCl) were investigated. The results showed that GAC with heterogeneous surface structure adsorbs DCF endothermically with both chemical and physical forces. Adsorption and regeneration processes were optimized with Taguchi Experimental Design. The effects of all parameters affecting the adsorption and regeneration processes were determined by analysis of variance and Pareto analyses. DCF removal of 79.80% was obtained at optimum conditions and the most effective parameter was evaluated as GAC size. At optimum regeneration conditions, 6.85 mg DCF/g GAC adsorption capacity was found with an operating cost of €0.05 g GAC. The amount of HCl was the most effective parameter. It was determined that the regenerated GAC had an adsorptive capacity higher than the adsorptive capacity of the raw GAC during at least three regeneration cycles. Raw, spent and regenerated GACs were characterized by Fourier transform infrared spectrometry and scanning electron microscopy analysis.

Olive oil mill wastewater (OMW) is environmentally hazardous not only because it contains high recalcitrant and toxic compounds, but also due to its high organic load and turbidity. In this study, oxidation of OMW by microwave (MW)‐activated persulfate is investigated. Box–Behnken design is applied to investigate the effects of operating conditions on operating cost, organic matter, and color removal. Multi response optimization is performed according to minimum operating cost, maximum organic matter and color removal efficiencies. At optimum conditions (persulfate anion dose of 266 g L−1, oxidation duration of 23.58 min, MW power of 567 W, and initial pH 2), chemical oxygen demand (COD) removal of 63.38%, color removal of 94.85%, and operating cost of 0.0633 Euro/g total organic carbon (TOC) removal are found. The biochemical oxygen demand (BOD5)/COD ratio is increased from 0.144 to 0.285. Results of Pareto analysis show individual effect of MW power is 92.81% for TOC removal, 15.52% for color removal, 68.99% for operating cost, respectively. According to the results, it is not recommended to use this process as an ultimate treatment unit due to the high amount of oxidizing agent consumed. Instead, it is recommended to be used as a pre‐ or post‐treatment step.