Hazardous waste solidification and recovery in automotive industry

Çeşitli endüstriyel prosesler sonucu oluşan zararlı atıkların konvansiyonel metotlar ile uzaklaştırılması çevresel açıdan büyük sakıncalar doğurmaktadır. Bu çalışmada, zararlı atıkların tanım ve tespiti yapılarak, zararlı atık yönetim sistemini ortaya koymak amacıyla, otomotiv endüstrisi zararlı atıklarından metal çamuru, fosfat çamuru ve endüstriyel arıtma çamuruna solidifikasyon/stabilizasyon(S/S) teknolojisi uygulanmıştır. Katılaştırma malzemesi olarak portland çimentosu kullanılarak, hazırlanan briketlere basınç dayanım testleri uygulanmış ve sızıntı özellikleri tespit edilmiştir. Başlangıçta zararlı atık tespiti yapılan atıklar için yönetim biçimi olarak, (S/S) teknolojisi uygulandıktan sonra gerek düzenli depolama sahalarına uzaklaştırma, gerekse grobeton olarak geri kazanım, detoksifikasyon ve atık minimizasyonu sağlanmaktadır. Yapılan çalışmada, zararlı atıkların yönetiminde (S/S) teknolojisinin uygun bir yöntem olduğu görülmektedir.Anahtar Kelimeler: Atık minimizasyonu, detoksifikasyon, geri kazanım, S/S teknolojisi, zararlı atık.Disposal of hazardous wastes originated from several industrial processes after treatment with conventional methods have been causing some problems for treatment plants and environment. During experimental studies, the solidification /stabilization technology have been applied to the metal sludge, as well as the phosphate sludge and the industrial treatment sludge, which was originated from automotive industry. The experiments have been carried out in four stages. At the first stage, these wastes have been classified as hazardous wastes. In the second stage the essays have been done using portland cement and, solidified materials have been prepared. In the third stage, comprehensive strength tests have been done for solidified materials. According to these results, it has been concluded that the solidification is a suitable treatment process for all three types of wastes. Furthermore, recovering the waste as concrete without iron was posssible as humid forms of industrial treatment sludge and phosphate sludge with low waste ratios. In the last stage, the leaching properties of briquettes prepared with solidification process have been determined. After applying solidification treatment technology to the wastes which are previously determined as hazardous waste, it has been proposed either disposal at landfill or recover as concrete without iron. According to these management approaches, it has been concluded that all of three wastes have been detoxified. As a result it has been found that solidification is the most appropriate treatment method for this type of waste material. Keywords: Waste minimization, detoksification, recovery, S/S technology, hazardous waste.

The relationship between chemical parameters and toxicity in effluent-dependent and effluent-dominated systems

Endüstrileşmenin hızlı olduğu bölgelerde, akışı sürekli olmayan, tatlı su miktarı genellikle yağışlarla orantılı olan ve deşarjlar için alıcı ortam olarak kullanılan nehir ve dereler atıksu kanalları haline gelebilmektedir. Bu su kaynakları deşarj-bağımlı ve deşarj-ağırlıklı sistemler olarak sınıflandırılarak, farklı şekilde yönetilmesi gereken sistemlerdir. Bu çalışma, böyle nehir ve nehir kollarına sahip, endüstrileşmenin çok hızlı gerçekleştiği ve yaklaşık 1000 endüstrinin arıtılmış veya arıtılmamış deşarjlarını alan Ergene Nehri ve kollarında yapılmıştır. Çok karmaşık özellikteki birçok deşarjı alan bu nehir ve nehir kollarının, kirlenme durumlarına bağlı olarak zehirliliklerinin belirlenmesi sürdürülebilir kullanımlarının sağlanabilmesi ve yönetimlerinin doğru şekilde yapılması için önemli bir veri sağlayacaktır. Bu çalışmada bu nehir ve nehir kollarından numuneler alınmış ve kirletici parametreler ile Vibrio fischeri organizmasına zehirlilik etkileri ölçülmüştür. Çalışma sonuçlarında, bölgedeki özellikle deşarj-bağımlı sistemlerin kimyasal parametreler ve zehirlilik açısından oldukça etkilenmiş oldukları görülmüştür. Referans bölge olarak seçilen su kaynağının kimyasal parametreler ve zehirlilik açısından kirletilmediği, en çok kirlenmiş bölgenin tekstil ağırlıklı organize sanayi ve deri organize sanayi ile daha birçok endüstrinin deşarjlarını birlikte alan ve deşarj-bağımlı bir sistem olan Çorlu Deresi ile bir kolu olan Sinandede Deresi olduğu görülmüştür. Vibrio fischeri test organizmasının zehirliliğine neden olan parametreler istatistiki analizler yapılarak belirlenmiş ve çoklu regresyon analizi kullanılarak regresyon modeli kurulmuştur. Kurulan regresyon modeline göre zehirlilik ölçütlerinden olan EC10 değeri en çok Çözünmüş Oksijen (ÇO), Kimyasal Oksijen İhtiyacı (KOİ) ve Toplam Çözünmüş Maddelerden(TÇM) etkilenmiştir. Anahtar Kelimeler: Deşarj-bağımlı sistemler, deşarj-ağırlıklı sistemler, Vibrio fischeri, zehirlilik.Effluent - dependent and effluent -dominated systems here we call them effluent - dependent / dominated systems are defined as surface water consist primarily of discharge wastewater and/or runoff from urban and agricultural areas. An effluent - dominated stream contains more effluent than receiving water (> 50% effluent). An effluent - dependent stream is 100 % effluent and would cease flow if anthropogenic sources were to stop discharging. Effluent - dependent / dominated systems have many different properties than natural water bodies as most characteristics of them are dependent on human activities. Mostly without the human generated flow, some effluent - dependent / dominated rivers would be ephemeral. The two major characteristics of such these systems are an increase in pollution and an increase in dry weather base flow. Effluent - dependent / dominated rivers described in this study are in heavily industrialized area. The study area-Ergene River Basin- is situated in the north west of Turkey in Thrace Region. This basin is one of the biggest basins in the region. It has 11.325 km2 drainage areas and Ergene River and its branches collects waters of the watershed and discharges and this basin have effluent -dependent and effluent - dominated streams. In the basin, rapid industrialization caused many problems to environment quality of the waters in recent years. Total about 1000 industries wastewater effluents in the region are flushed directly into the river and streams. Some branches of the river have intermittent flow in dry seasons. So sometimes these streams receive little or no upstream dilution and effluents may comprise the majority of stream flows. In the basin, Ergene River is effluent - dominated and Çorlu and Sinandede streams are effluent - dependent streams. Çorlu stream and Ergene River are important, because they collect complex discharges of textile and leather industries, various industries wastewaters and municipal wastewaters. A field survey is conducted to detect a relationship between chemical parameters and toxicity in the river and streams samples. Understanding relationship of these systems is critical for maintaining water quality and offers challenges in regulatory permitting and monitoring. And these data could be used for proper management of such these systems in similar basins. In the current study toxicity of samples were determined with reconstituted freeze-dried bacteria called Vibrio fischeri. All calculations to determine percent inhibition effect (INH %) was performed with the BiotoxTM Software (Aboatox, Turku, Finland). Chemical parameters for wastewater samples included pH, Dissolved Oxygen (DO), Total Dissolved Solids (TDS), Temperature (T), Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), Total Phosphate (TP), Total Sulfide (TS), Ammonium Nitrogen (NH3-N), Total Suspended Solids (TSS) and heavy metals were determined. After the results of the experiments, cause-effect relationship between chemistry and toxicity, ambient quality of effluent - dependent / dominated systems and degree of necessity of toxicological data for point sources pollution control were determined in effluent - dependent / dominated systems. For all cases data are presented as mean ± S.E. After assessment of the data it is found that Çorlu and Sinandede stream are the most polluted waters regarding to chemical and toxicological parameters. It is supposed that toxicity is caused by complex discharges. Because those streams collected the textile organized and the leather organized areas and lots of the other industries wastewaters. The Ergene stream which is chosen as reference ambient water wasn't polluted in respect of chemical parameters and, because of this result, it is supposed that it didn't show toxicity to Vibrio fischeri. Statistical analyses were conducted to understand chemistry-toxicity relationship between EC10 and various chemical parameters. Statistical analyses are done by using SPSS 13.0 statistic pragramme. Significant correlations were observed between EC10 values and COD, DO and TDS. The present study suggested that COD and TDS can be assumed as a good indicator of the potential toxicity of ambient waters of such these effluent - dependent / dominated systems. After multiple regression analyses, the data of COD, DO and TDS which have smaller than 0.01 P-values elected for setting multiple regression model. R2 of the model was 0.95. It was concluded that toxicity testing is a useful tool supplementing chemical analyses of the potential hazard from point sources in effluent - dependent / dominated rivers. Keywords: Effluent - dependent systems, effluent -dominated systems, Vibrio fischeri, toxicity

Management of hazardous wastes by solidification/stabilization technology

Bu çalışmada, solidifikasyon/stabilizasyon teknolojisi kullanılarak zararlı atıkların yönetimi incelenmiştir. Deneysel çalışmalarda, bir kimya-metal son işlemler endüstrisinden çıkan arıtma çamurunun solidifikasyon/stabilizasyonu için bağlayıcı olarak Portland Çimentosu seçilmiştir. Beton numuneleri hazırlandıktan sonra basınç dayanım ve sızma deneyleri yapılmıştır. Zararlı atığın ve beton numunelerinin sızma özelliklerini belirlemek üzere iki yöntem kullanılmıştır. Bunlardan biri DIN 38 414 S4 Testi diğeri ise Ekstraksiyon Prosedür Toksisite Test Metodudur. Her iki prosedüre göre DIN eluatları ve EP ekstraktları hazırlanmış ve toplam organik karbon ile metal ölçümleri yapılmıştır. Arıtma çamurlarının arıtım ve geri kazanımında, solidifikasyon/stabilizasyon teknolojisinin etkin olduğu sonucuna varılmıştır.Anahtar Kelimeler:, Solidifikasyon/stabilizasyon, zararlı atık arıtımı çimento bazlı solidifikasyon, sızma, EPTox, basınç dayanımıIn this study, management of hazardous wastes in sludge form containing some potentially toxic heavy metals and organic chemicals by solidification/stabilization technology was investigated. During experimental studies, the solidification/stabilization technology was applied to the industrial treatment sludge which was originated from a chemical-metal finishing industry. Hazardous wastes were analyzed by using eluat and extract procedures as defined and the hazard characteristics of the waste were determined based on both Turkish and United States Environmental Protection Agency regulations by means of leaching test methods (DIN 38414-S4 Test and Extraction Procedure Toxicity Test). Portland cement was used as a binder for S/S of hazardous waste. Control and other specimens were prepared with dried sludge, cement, fine aggregate, course aggregate, water and a concrete additive as C 35 class of concrete. Compressive strength tests and leach tests were conducted for solidified concrete specimens. Total organic carbon and the heavy metal concentrations in EP extracts and eluats were determined. Main objectives of this study were to implement the S/S technology on the wastewater treatment system sludge and to investigate compatibility with disposal and recovery. This study indicates the hazard criteria removal of these sludges by S/S technology and leads to solve problems about the management alternatives of these hazardous wastes. It was found out that S/S was an effective technology in treatment and recovery of hazardous wastes.Keywords: Solidification/stabilization, hazardous waste treatment, cement based solidification, leaching, EPTox, compressive strength

Inhibition on treatment of pesticide industry hazardous wastes

Bu çalışmada bir zararlı atık niteliğinde olan pestisit endüstrisinden kaynaklanan sıvı formdaki atıkların atıksu arıtma sistemi içerisinde en uygun arıtım mekanizmasının tespitine çalışılmıştır. Çalışmalar sırasında endüstrinin dengeleme tankından farklı tarihlerde üç adet numune alınmıştır. Uygulanan deneysel plan çerçevesinde numunelere kimyasal arıtma, ozonlama ve bakteriyel çoğalma inhibisyon testlerinden oluşan deneyler yapılmıştır. Kimyasal arıtma uygulanmalarında en uygun koagülan, doz ve pH tespitleri yapılmıştır. Ozonlama işleminde ise 477 mg/l ozon akısı kullanılarak 15, 30, 45, 60 ve 90. dakikalarda numuneler alınmış ve KOİ (Kimyasal Oksijen İhtiyacı) giderim verimleri hesaplanmıştır. Deneylerin son aşamasında numunelere bakteriyel çoğalma inhibisyon testi deneyleri uygulanmıştır. Deneylerin ilk aşamasında toplam KOİ giderimi bazında her ne kadar önce kimyasal arıtma uygulayıp daha sonra ozonlama yapmak daha iyi bir arıtma performansı sergilemiş olsa da, sadece KOİ giderimine bakarak numunelerin zehirlilikleri hakkında bir yorum yapabilmek mümkün değildir. Bu sebeple ortaya çıkan bütün arıtma alternatifleri için (kimyasal arıtma, ozonlama, kimyasal arıtma + ozonlama ve ozonlama + kimyasal arıtma) ve hamsular için bakteriyel çoğalma inhibisyon testi deneyleri yapılmıştır. Elde edilen sonuçlarla EC50 değerleri ve literatürdeki yaygın substrat inhibisyonu modelleri kullanılarak Ki inhibisyon sabitleri bulunmuştur. Elde edilen sonuçlardan sadece ozonlama işlemi uygulanmış numunelerin EC50 değerlerinin (sırasıyla %24, %9 ve %8) hamsuyun EC50 değerlerinden (%21, %6,5 ve %6) çok farklı olmadığı tespit edilmiştir. Tek başına kimyasal arıtma ve kimyasal arıtma ile birlikte ozonlama seçeneklerinin EC50 değerlerini belirgin bir şekilde arttırdığı görülmektedir. Ki inhibisyon sabiti açısından da durum çok farklı değildir. Anahtar Kelimeler: Zararlı atık, inhibisyon, ozonlama, kimyasal arıtma, pestisit endüstrisi atıksuları.According to the stipulations of the RCRA hazardous waste program, the majority of pesticide active materials have been given in priority pollutant lists. They are categorized according to their environmental effects such as biodegradability, toxicity, carcinogenity and persistency. Particularly, toxicity characteristic of pesticides by bioaccumulation may affect most of animals and hold health effect by appearing in food chain. Spent forms of those pesticide active materials have been considered as hazardous waste according to EPA and the Turkish regulations. In this study, a best practical technology was searched to treat a waste which is hazardous according to EPA lists and Turkish regulations in wastewater treatment system, generated by a pesticide industry. During the study, three samples were taken from industry?s equalization tank in different dates. Samples were characterized and than treatment alternatives were applied. First, coagulation and ozonation were applied to the raw sample separately. And than combinations of ozonation and coagulation were performed, than bacterial growth inhibition test was carried out after each treatment alternative. In combination coagulation and flocculation with ozonation chemical treatment was performed first by using FeCl3 and Al2(SO4)3  and proper  coagulant, optimum coagulant dose and pH were determined. NaOH and H2SO4 were used for pH adjustment and non-ionic polyelectrolyte was used. Than these samples were ozonated and COD removal efficiencies has been determined by taking samples in 15, 30, 45, 60, 90. minutes. Ozone generator, used in this study, reaches the optimum operating efficiency by 5 L/min oxygen flux and with this flux it produces 477 mg ozone/min. In the next stage of the experiments chemical treatment was performed after ozone oxidation. Thus, treatment efficiencies of each system were determined in the terms of COD. A series of Jar-Test experiment applying 2 min rapid mixing at 200 rpm, 15 min slow mixing at 15 rpm and 30 min for settling was conducted on wastewater. Chemical treatability test results showed that FeCl3 treatment efficiency was better than Al2(SO4)3. Furthermore the COD values of the samples after chemical treatment by using FeCl3 and ozonation were reduced to 540 mg/L from 9500 mg/L with a %94 treatment efficiency for first sample, 1830 mg/L from 25000 mg/L with a %92 treatment efficiency for second sample and 2200 mg/L from 29000 mg/L with a %92 treatment efficiency for third sample. With an opposite procedure, when ozonation was applied before chemical treatment overall removal efficiencies were found % 78, %75, and %79 respectively in terms of COD. In the last stage of the experimental procedure bacterial growth inhibition test was performed to the samples. In this study it was found that the treatment efficiencies of ozonation following coagulation were higher than other alternatives. In spite of this, it is not possible to interpret toxicity potential of samples depending on only COD values. Therefore, bacterial growth inhibition test was carried out to the effluents of each treatment alternatives (coagulation, ozonation, coagulation + ozonation and ozonation + coagulation) and raw wastewaters. This test was done in a constant temperature shaker and 250 ml narrow-neck, round bottle was used as reactor. The test mixture in the bottles consisted of specific dilutions of wastewater, buffer solutions, nutrients and microorganisms. The dilution water in the standard biochemical oxygen demand (BOD) test was used as dilution water. In addition one reactor was only fed with glucose for blank sample.  The bottles incubated 16 hours at 22 ± 2 0C temperature. After this time bacterial growth has been measured as mg/L with suspended solid experiments. EC50 values were evaluated by using graphs in which per cent of SS plotted versus the log of the dilutions. In order to determine the kinetic constants, four substrate inhibition models were evaluated by Least square technique. The results showed  that samples that are performed only ozonation  have similar EC50 values ( %24, %9, and %8 respectively) compared to raw wastewater (%21, %6,5 and %6 respectively). It was seen that only chemical treatment or chemical treatment with ozonation alternatives increases apparently the EC50 values. Similar results can be concluded for inhibition constant, Ki. Ki values of ozonated wastewater (1021, 848 and 1283 mg/L respectively) and raw wastewater (1484, 1177, 1113 mg /) are quite similar as indicated before. Keywords: Hazardous waste, inhibition, ozonation, chemical treatment, pesticide industry wastewater

Synthesis and biological evaluation of 3'-N-thiocarbamate paclitaxel derivatives

Paklitaksel (Taxol®), porsuk ağacı (Taxus Brevifolia) kabuğundan izole edilen doğal bir diterpen alkaloididir. Paklitaksel,mikrotübül polimerine bağlanarak depolimerizasyona karşı kararlılığın sağlanmasında rol oynar. Günümüzde göğüs ve rahim kanserlerinin kemoterapisinde kullanılan en önemli ilaçlardan biridir.Paklitaksel üzerine yapılan araştırmalardaki amaçlardan biri de yapısal olarak daha basit ancak klinik olarak daha etkili analogların sentezlenmesidir. Sentezlenen paklitaksel analoglarının büyük bir kısmı 3'-N pozisyonunun türevlendirilmesiyle elde edilmiştir.Bu çalışmada yan zincirinde tiyokarbamat ve 2-tiyenil içeren yeni paklitaksel türevlerinin sentezi gerçekleştirilmiştir. Sentezlenen bu paklitaksel türevlerinin A2780 memeli yumurta hücrelerindeki aktiviteleri ölçülmüştür. Yapılan aktivite testlerinde bazı bileşiklerin Taxol ile kıyaslanabilen aktivite değerlerine sahip olduğu görülmüştür.  Anahtar Kelimeler: Paklitaksel, tübülin, tiyokarbamat.Paclitaxel (Taxol®) is a natural occurring diterpene alkoloid originally isolated from the bark of Taxus Brevifolia. It is now one of the most important chemotherapeutic agents for clinical treatment of ovarian and breast cancer for the past decades. Recent clinical trials have also shown paclitaxel's potential for the treatment of non-small-cell lung cancer, head and neck cancer, and other types of cancers. While tremendous chemical research efforts have been made in the past years, which established the fundamental structure-activity relationships of the paclitaxel molecule, and have provided analogs for biochemical studies to elucidate the precise mechanism of action for the devolopment of second-generation agents, many areas remain to be explored. One of the principal goals associated with research is the identification of the structural features of Ttaxol required for its biochemical and physiological performance. Ultimately, such research can be expected to lead to the identification of structurally simpler and clinically more effective analogues. A large number of analogues prepared by others have incorporated modifications at the side chain 3´-N position, and some compounds with such modifications are in clinical trials. In a continuation of the studies on the structure/activity relationships of paclitaxel analogues, we now report the synthesis of novel sulfur containing paclitaxel side-chain analogues. Keywords: Paclitaxel, tubulin, thiocarbamate

Precipitation of magnesium ammo-nium phosphate from source-separated urine

Kaynağında ayrılmış ve ayrı toplanmış insan idrarının tarımsal alanlarda gübre olarak kullanılması son yıllarda önem kazanmıştır. Evsel atıksu içinde hacimsel olarak %1’in altında bulunmasına rağmen, evsel atıksudaki azotun %80’i ve fosforun %60’ı idrardan gelmektedir. İdrarın kaynağında ayrılması ve depolanarak tarımsal alanlara uygulanması yararlı bir sistem gibi görünse de sistemin bir takım zorlukları ve riskleri mevcuttur. Bu çalışmada öncelikle idrar kompozisyonunun depolama süresince değişimi incelenmiş, daha sonra idrarın kaynağında ayrılması, depolanması ve tarımsal alanlara uygulanması sırasında karşılaşılan zorlukları azaltmak için idrardaki NH3-N ve PO43--P, magnezyum amonyum fosfat hekzahidrat (MAF) formuna dönüştürülmüştür. 4/1 oranında seyrelmiş olan idrardaki NH3-N molar konsantrasyonu 6 haftalık depolama süresi sonunda 0.009’dan 0.08 mol/l’ye yükselmiştir. pH 9.5 ve 10’da gerçekleştirilen çöktürme reaksiyonlarında idrardaki NH3-N’unun %87’sinin reaksiyonda yer aldığı saptanmıştır. Minimum MAF çözünürlüğünün gerçekleştiği pH olan pH 10.7’de ise NH3-N geri kazanımı %85.8’e düşmüş, buna karşılık PO43--P ve Mg’un geri kazanılma yüzdeleri sabit kalmıştır (sırasıyla %99.3 ve %99.7). Ayrıca, reaksiyona giren  NH3-N, PO43--P ve Mg’un başlangıç molar konsantrasyon oranlarının reaksiyon verimini etkilediği, magnezyumun molar konsantrasyonunun diğer reaktanlara kıyasla fazla olması durumunda NH3-N ve PO43--P geri kazanımının arttığı saptanmıştır. İdrardaki NH3-N’un başlangıç konsantrasyonunun diğer reaktanlara göre fazla olması durumunda elde edilen çökeltinin MAF açısından daha saf olduğu görülmüştür. Elde edilen tüm katı fazlar kristal MAF olarak tanımlanmıştır.   Anahtar Kelimeler: İdrar, NH3-N geri kazanımı, Magnezyum amonyum fosfat hekzahidrat.In recent years, utilization of source-separated human urine in agricultural farmlands instead of artificial mineral fertilizers has become a favourite method. Urine contributes about 80% of nitrogen and 60% of phosphorus to household wastewater, although it occupies less than 1% of the wastewater volume. Thus, separating urine from household wastewater and recovering the urinary nutrients can be considered as the most important step towards sustainable water and agriculture concepts. Urine fraction utilized in agriculture for vegetation must be free of faeces. To ensure this criterion, urine and faeces are separated at specially designed toilets. Separation of urine in toilets is also known as source separation. Source separating toilets have two bowls where urine and a small amount of flush water are collected in front part of the bowl and the faeces in the back. After the separation urine and mixture passes flush water passes through a separate pipe system to a holding tank. Urine is collected by trucks and transported to storage tanks. When fertilizing season comes, urine is again transported by trucks and applied directly to farmland after being diluted with water. Source separation and separate collection of human urine is mostly preferred in rural area, because small and simpler treatment units are used. Besides, nutrient discharges are minimized (eutrophication is reduced) and nutrient cycle is almost closed. Water is saved and fresh water which is used for flushing is reduced. Finally, the amount of artificial fertilizers which are used for vegetation is lowered. Although source separation is beneficial, there are some disadvantages and risks regarding with the storage, transportation and application of human urine. Researches which have been performed up to now showed that transforming the urinary nutrients into solid state by certain processes minimize the drawbacks. If urine is processed to obtain a urine based solid fertilizer, urinary ammonia which is unstable in the holding tank is stabilized. The amount of urine which is needed to fertilize a farmland is reduced. Ammonia which loss during application is high if urine is applied to the farmland directly. This loss is much more lower when urine based solid fertilizer is preferred. Besides, the amount of urine which is stored and transported decreases. Due to high pH and high NH3-N concentration of stored urine, magnesium ammonium phosphate hexahydrate (MAP) precipitation method is selected as the most appropriate processing method for stabilizing the urinary ammonia. MAP is a white crystalline compound having magnesium, nitrogen and phosphorus in equal molar concentrations. Apart from being a well known kidney stone, this compound is also known to form scales in wastewater treatment plants. MAP is a sparingly soluble salt and solubility decreases with increasing pH. Thus, its low solubility in water enables it to be used as a slow release fertilizer. The present study involves the investigation of the unstable ammonia behaviour during the storage period and the precipitation of MAP from 4 times diluted and stored urine. As a first  step, the change in NH3-N concentration during the storage period was recorded. After determining the final NH3-N, PO43--P and Mg concentrations, MAP precipitation was achieved and optimum process conditions were identified. Each precipitate was identified by X-ray diffraction. FT-IR instrument was used to define the functional groups in each precipitate.According to the results, 6 weeks stored urine contained 0.08 mol/l NH3-N. As the storage period was extended to 14.5 weeks, the NH3-N concentration reached up to 0.14 mol/l. During this period, pH of urine increased with time and the color of urine got darker. As a result of the pH increase, spontaneous precipitation of MAP and hydroxyapatite (Ca5(PO4)3OH) was observed. 86.7% of urinary NH3-N was reacted in precipitation reactions where the pH was adjusted as 9.5 and 10 separately. The percentage recovery of NH3-N decreased to 85.8%  at pH 10.7 which was known as the pH of minimum MAP solubility. In contrast, the percentage recovery of PO43--P and Mg were constant in this pH range. Initial molar concentration ratio of NH3-N, PO43--P and Mg affected precipitation efficiency. According to the results, the percentage recovery of NH3-N and PO43--P increased when the initial molar concentration of Mg was in excess. All the solid phases precipitated from the urine were positively identified as crystalline MAP. Furthermore, all of the  precipitates contained PO43-, NH4, O-H and N-H groups which were all detected in FT-IR analyses.   Keywords: Urine, NH3-N recovery, Magnesium ammonium phosphate hexahydrat

A ferrous oxalate mediated photo-Fenton system: Toward an increased biodegradability of indigo dyed wastewaters

This study assessed the applicability of a ferrous oxalate mediated photo-Fenton pretreatment for indigo-dyed wastewaters as to produce a biodegradable enough effluent, likely of being derived to conventional biological processes. The photochemical treatment was performed with ferrous oxalate and hydrogen peroxide in a Compound Parabolic Concentrator (CPC) under batch operation conditions. The reaction was studied at natural pH conditions (5–6) with indigo concentrations in the range of 6.67–33.33 mg L−1, using a fixed oxalate-to-iron mass ratio (C2O42−/Fe2+ = 35) and assessing the system's biodegradability at low (257 mg L−1) and high (1280 mg L−1) H2O2 concentrations. In order to seek the optimal conditions for the treatment of indigo dyed wastewaters, an experimental design consisting in a statistical surface response approach was carried out. This analysis revealed that the best removal efficiencies for Total Organic Carbon (TOC) were obtained for low peroxide doses. In general it was observed that after 20 kJ L−1, almost every treated effluent increased its biodegradability from a BOD5/COD value of 0.4. This increase in the biodegradability was confirmed by the presence of short chain carboxylic acids as intermediate products and by the mineralization of organic nitrogen into nitrate. Finally, an overall decrease in the LC50 for Artemia salina indicated a successful detoxification of the effluent