Stabilization of Sludge in Zakho Municipal Wastewater by Anaerobic Digestion for Biogas Production in Kurdistan Region, Iraq

Abstract

Raw wastewater sludge samples were collected from two sanitary point sources in Zakho city wastewater pipes. Anaerobic digestion is utilized sludge stabilization as it was effective in reducing the volume of sludge and cheap source of clean biogas. the sludge of municipal wastewater of Zakho district is worth to be used for the generation of biogas and just 15 -17 kg sludge produced 233 to 350 m3 gas in solid retention time of 18 and 24 day respectively. Suspended solid is close related to the amount of COD that removed from sludge and approximately 1 kg COD generate 0.5-0.55 Kg suspended solid in the water. Volatile solid (VS) /total solid (TS) ratio is 0.46 after anaerobic digestion which locate in the range of anaerobic lagoon stabilization. Anaerobic digestion lead to reduction in total solid of wastewater especially organic or volatile suspended solid. Specific gravity of the sludge solid is1.5 which indicate that the sludge is stabilized by anaerobic digestion. Sludge volume index (SVI) indicate that the settleable biosolids are old, good quality and low turbidity. Sludge density index (SDI) increased from 1.83 to 2.9 ml/g after stabilization by anerobic digestion. CO2 and H2S are reduced to zero after stabilization by anaerobic digestion. Nutrients N, P, Ca, Mg, Cl are elevated significantly in final stabilized sludge to be used as organic fertilizer, except sulfate is decreased to acceptable ranges after stabilization.

Enhancement of Electrochemical–Anaerobic Digested Palm Oil Mill Effluent Waste Activated Sludge in Solids Minimization and Biogas Production: Bench–Scale Verification

“…Digesters were carried out at a sludge retention time (SRT) of 15 days with the mesophilic temperature of 30 ± 0.5 • C. SRT is important for the anaerobic digestion of POME WAS as it serves the purpose of ensuring that sufficient time was given for hydrolysis to take place [30]. A typical mesophilic digester requires a SRT range of 15 to 30 days for better solids minimization [31]. However, it is important to take into account that a prolonged SRT would lead to the bulking of inert compounds that would slow down the microbial activity, while a short SRT would cause the washing out of methanogens [32].…”

Validity of Primary Treated Wastewater for Irrigation and Assessment of their Potential Health Risk

“…The municipal waste water in Iraqi Kurdistan region suffer from proper sanitary sewer system and produce sewage sludge contain high amounts of pollutant as they accumulated over long time without removal and treatments [22]. The biological oxygen demand (BOD) is crucial for heterotrophic aerobic microbial population in order to break down the organic waste for carbon and energy source.…”

Influences of Spatial and Seasonal Variation on Khabur River Pollution by Municipal Wastewater in Zakho District, Iraq Kurdistan Region

“…This hurts aquatic ecosystems. [9] reported that the Zakho city releases huge amounts of non-treated sewage sludge in the Khabur river and the sludge produced is worth to be utilized as a cheap source for producing biogas by anaerobic stabilization. The physic-chemical properties of rivers are varied among seasons as in winter more silt and trash are carried with flood water and deposited in rivers, as well as these characteristics are affected by the watersheds that feed the rivers and the spatial location of rivers, especially passing pass through big cities that release many pollutants in rivers [10].…”