Nonylphenol (NP) and its ethoxylates are used in formulation of pesticides and detergents, production of personal care products and many industrial sectors such as textile, metal plating, plastic, paper and energy. They are also used in the formulation of household cleaning agents. Industrial uses in the production line make up 55% of the total use / whereas industrial and domestic cleaning processes constitute 30 and 15%, respectively. Since they are widely used in industry and households, NP compounds enter the environment mainly by industrial and municipal wastewater treatment plant effluents. NP is considered strongly toxic and has adverse effects even with short term exposures. Moreover, with its similarities to natural hormones, NP and its ethoxylates are considered as endocrine disrupter compounds. In studies conducted with human cells, chicken embryo, trout and mice eostrogen receptors, positive responses were observed. Due to their lipophilic and hydrophobic characteristics they accumulate in cells, tissues and organic materials such as sludge. For these reasons, fate of NP and its v ethoxylates in wastewater treatment plants and in sludge treatment processes gained importance. Nonylphenol polyethoxylates (NPnEO) are degraded in microbial media and lose their ethoxylates to nonylphenol diethoxylate (NP2EO), nonylphenol monoethoxylate (NP1EO) and NP. Moreover, nonyl phenoxycarboxylic acids (NPnEC) can be formed during some of these reactions. Because the first degradation reactions are fast, concerns and studies are focused mainly on NP2EO, NP1EO, NP, NP1EC and NP2EC. Even though these general degradation information is available, studies on sludge are very rare. In this study, treatability and toxicity of NP2EO in anaerobic batch reactors is investigated. First, with the use of Anaerobic Toxicity Assay (ATA) test, toxic doses of NP2EO which was added to the reactor as the parent component, were determined. Moreover, the degradation of these chemicals were studied in larger scale batch anaerobic digesters. The aim of this part was to observe the degradation patterns and products. Throughout the study the fate of NP and its ethoxylates was followed in aqueous and solid phases by the use of Gas Chromatography / Mass Spectrometry system (GC/MS). ATA tests showed that NP2EO was not toxic to anaerobic microorganisms at the doses investigated in this study. It was rather stimulating and caused an increase in methane production in the reactors. On the other hand the spiked NP2EO&rsquo / s at 0.5 and 2.5 mg/L concentration were completely degraded in the larger scale batch reactors. At the same time, an increase in the concentrations of NP and NP1EO was observed which supported the fact that NP2EO was degraded into NP1EO and NP under anaerobic conditions. Abiotic degradation was not observed.

Today, numerous studies indicate the presence of synthetic organics such as nonylphenol (NP) compounds in wastewater. NP compounds are a group of chemicals including nonylphenol, nonylphenol polyethoxylates (NPnEO) and nonylphenoxy polyethoxy acetic acids (NPnEC). Since NP compounds have significant industrial, commercial and domestic use, they enter environmental systems and reach human beings from various pathways. Their presence is of concern because they are toxic, carcinogenic and endocrine disrupting due to their ability to mimic oestrogen hormone. The information available on the degradation of NPnEOs, is such that degradation starts with the reduction of ethylene oxide units, resulting in the formation of nonylphenol, nonylphenol mono- or diethoxylate (NP1EO and NP2EO) and nonylphenoxy acetic acid (NP1EC). Although their fate during wastewater treatment was investigated in the past, not many research investigating their fate in sludge treatment can be found. Therefore, the objective of this study is first to come up with reliable extraction and measurement methods for NP compounds and then to investigate the fate of NP2EO in aerobic digesters. After the development of techniques for the extraction and measurement of NP compounds, aerobic reactors spiked with NP2EO were operated. The samples were analyzed for solids content, COD, pH and NP compounds. The results showed that NP2EO degrades rapidly under aerobic conditions. As time proceeded, NP1EC formation was observed with the degradation of NP2EO, and NP1EC became the dominant specie. The solids concentration measurements showed that concentration of NP compounds did not affect the efficiency of aerobic digesters.

In the last few decades, numerous studies have been conducted on xenobiotic compounds due to their vast use in industries, households, etc. and consequently high exposure of these compounds. The main focus of this study is nonylphenol compounds such as nonylphenol monoethoxylate (NP1EO), nonylphenol diethoxylate (NP2EO), nonylphenoxy acetic acid (NP1EC) and nonylphenol (NP), which are among the harmful xenobiotic compounds that can cause endocrine disruption, cancer and other health problems and which are used widely in the production of surfactants and personal care products. In this study, laboratory scale aerobic semi continuous reactors containing Waste Activated Sludge (WAS) spiked with NP2EO were operated for a period of 91 days, to inspect the decomposition of NP2EO in solid and liquid phases. The results obtained on the final day of operation (91st day) showed that NP2EO degraded into product compounds among which NP1EC contributed to 90% of molar mass. In general, NP2EO showed a sharp degradation while NP1EC was produced rapidly. NP1EO also showed a steady degradation. However, NP was accumulated in the reactor. During the study, TS, VS, TSS and VSS degradation was also monitored and the percentage removals were found to be between 40-60%. COD removal on the other hand was between 64-66%.