Introduction to Environment Engineering PDF

Introduction to Environment Engineering DR. FARAH M. AL-DUWEESH CHE 304 1 Wastewater Treatment FARAH M. AL-DUWEESH 2 Municipal Wastewater Treatment plants receive wastewater from many inputs •Wastewater from domestic, commercial, and industrial users •Stormwater runoff •Infiltration •Inflow F...

Introduction to Environment Engineering DR. FARAH M. AL-DUWEESH CHE 304 1 Wastewater Treatment FARAH M. AL-DUWEESH 2 Municipal Wastewater Treatment plants receive wastewater from many inputs •Wastewater from domestic, commercial, and industrial users •Stormwater runoff •Infiltration •Inflow FARAH M. AL-DUWEESH 3 Characteristic of Domestic Wastewater Raw = untreated wastewater is highly pollutant Yet, from a 1 m3 of wastewater (approximately weights 1 million g), contains only 500 g of containments This small amount contains not only hazardous pollutants, also valuable sources of nutrients. Domestic wastewater appears gray and turbid, and has temperatures of 10-20 ℃. Source: Michelcic and Zimmerman FARAH M. AL-DUWEESH 4 Steps in Conventional Wastewater Treatments 1) 2) 3) 4) Pretreatment Primary treatment Secondary treatment Tertiary treatment (Advanced additional treatment ) [remove nutrients of (N,P)] Umm Al-Hayman Sewage Treatment Reclaim and Reuse (not everyone, the U.S. applies it) FARAH M. AL-DUWEESH 5 Wastewater Pretreatment Prepares the wastewater for further treatment. Removes oily scum, floating debris, and grit that may damage mechanical equipment. Equalization tanks are used to balance flows or organic loading. Effluents may need additional chemical pretreatment using air stripping, acid/base neutralization, heavy metals oxidation, precipitation. FARAH M. AL-DUWEESH Source: Michelcic and Zimmerman 6 Wastewater Pretreatments Pretreatment requires: •Screening (bar screening) •Grit chambers •Floatation •Equalization Source: Michelcic and Zimmerman FARAH M. AL-DUWEESH 7 Screening Wastewater Pretreatments Screening •Bar screens of 10mm or less mesh to retain the coarse solids (large objects like paper, plastic bottles, etc.) •Those reminders are disposed either by incineration or landfilling. FARAH M. AL-DUWEESH 8 Grit Chambers Wastewater Pretreatments Grit Chambers •Grit consists of particulate materials in wastewater that have specific gravities between 1.3-2.7. •Consists of inorganic sand or gravel, eggshells, bone fragments, fruit and vegetables pieces and seeds, and coffee grounds. • An aerated grit chamber, air is introduced along one side of the tank. Grit settles out while small matter gets suspended. FARAH M. AL-DUWEESH 9 Floatation in Wastewater Pretreatments •Floatation is the opposite of sedimentation, when a buoyancy force is applied to separate solid particles such as fats, oils, and greases, which would not settle by sedimentation. •Air is introduced at the bottom of the tank à air bubbles rise to the surface à removed by skimming FARAH M. AL-DUWEESH 10 Flow Equalization in Wastewater Pretreatments Flow equalization: is the process of controlling hydraulic velocity/ flowrate of a wastewater treatment system. FARAH M. AL-DUWEESH 11 Pretreatment of Wastewater FARAH M. AL-DUWEESH 12 Primary Wastewater Treatment is through Sedimentation The goal of primary treatment is to remove solids through gravity settling (settling velocity is the driving force). Wastewater is usually held in settling tanks for 2 hours. Settling tanks can be rectangular or circular. Settling tanks also called sedimentation tanks or clarifiers. Clarifiers remove 35% of BOD and 50% TSS. FARAH M. AL-DUWEESH Can be circular or rectangular clarifiers 13 Primary Wastewater Treatment is through Sedimentation During sedimentation, solids settle at the bottom of the tank, where they are collected as a liquid-solid sludge. Primary treatment removes about 60 % of the suspended solids 30% Biochemical oxygen demand (BOD) 20% Phosphorus (P) Thus reducing the cost of the secondary treatment removal. https://www.pond5.com/stock-footage/item/11889478rotation-huge-circular-sedimentation-tank FARAH M. AL-DUWEESH 14 Secondary Wastewater Treatment is through Aeration •Goal: to remove organic matter, total suspended solids (TSS) and kills pathogens (biological solids). •To degrade the biological contents further using aeration. •Aeration is when bubbles of oxygen are added to digest the organic matter called Aerobic digestion. •Then two streams are formed an effluent and the activated sludge. FARAH M. AL-DUWEESH 15 Secondary Wastewater Treatment is through Aeration FARAH M. AL-DUWEESH 16 Secondary Wastewater Treatment is through Aeration •Activated sludge is added so the microbial organisms in the sludge will kill the bacteria (eat it), then it would recycle it back to the aeration basin. •Then after this separation step, clarifier tanks are used to settle the solids. •85% of water is purified at this stage. (would not be edible for drinking yet!) FARAH M. AL-DUWEESH 17 Secondary Wastewater Treatment is through Aeration How it looks like in design of the batch reactor Which model is more effective? Single or contact FARAH M. AL-DUWEESH 18 Secondary Wastewater Treatment is through Aeration FARAH M. AL-DUWEESH 19 Secondary Wastewater Treatment requires final disinfection before release •Final Step of the Process is Disinfection. •Purpose of disinfecting wastewater is to kill and inactivate disease-causing organisms (pathogens) such as bacteria, protozoa, helminths, and viruses. •Disinfectants can be oxidizing agents (chlorine, ozone), cations of heavy metals (silver or copper) and physical agents (heat or UV radiation). •Most common is chlorine. FARAH M. AL-DUWEESH 20 Secondary Wastewater Treatment requires final disinfection before release •Disinfection is added for more water clarity. •Disinfection does not destroy all microorganisms, it removes some. •Sterilization is a process that kills all microorganisms. FARAH M. AL-DUWEESH 21 A normal Secondary Wastewater Treatment FARAH M. AL-DUWEESH 22 Ternary/ additional Wastewater Treatment is sometimes necessary •Secondary treatment is sometime inadequate additional removal or recovery of pollutants especially Nitrogen (N) and Phosphorus (P) are further treated. •Adding filtration step before disinfecting the effluent. •Can repeat the secondary treatment à layback is cost FARAH M. AL-DUWEESH 23 Ternary/ additional Wastewater Treatment not necessary with new advanced technologies Advanced technologies that make it unnecessary to use a ternary treatment is like an extra filtration step (like a membrane) before effluent discharge. FARAH M. AL-DUWEESH 24 Only Countries of Energy (who have money) have the extra Energy to Reclaim/Reuse Water à Wastewater Treatment While, other countries still struggle to have a partial of energy/water supply. FARAH M. AL-DUWEESH 25 Reclaim and Reuse •Instead of discharge of effluent, effluent is further treated and reused domestically •Measurement and check-ups are done by EPA during the 24-36 hrs for each retreated waste stream Video of Wastewater recovery: https://www.youtube.com/watch?v=FvPakzqM3h8 FARAH M. AL-DUWEESH 26 What does Kuwait Use as Wastewater Treatment FARAH M. AL-DUWEESH 27 Membrane-based Wastewater treatments in Kuwait extend capacity to meet demand The ten largest membrane-based wastewater reuse plants worldwide, April 2012. FARAH M. AL-DUWEESH 28 Kuwait withholds the largest Membrane-based Municipal Wastewater Reuse Plant ~20% of the Worlds Wastewater IMS= Integrated Membrane System (consists of MF/UF-RO) Source: M.Raffin et.al., Abstract: Wastewater Polishing Using Membrane Technology: A Review of Existing Installations FARAH M. AL-DUWEESH 29 Kuwait extends treated Wastewater capacity to meet demand, Oldest is Aljahra WWTP FARAH M. AL-DUWEESH 30 3 1km 9 individuals in Kuwait produce wastewater produced = 16 individuals in KSA Source: E.Aleisa, K. ALshayji, “Analysis on Reclamation and Reuse of Wastewater in Kuwait.” FARAH M. AL-DUWEESH 31 Water treatment cost in Kuwait is unbeneficial Source: E.Aleisa, K. ALshayji, “Analysis on Reclamation and Reuse of Wastewater in Kuwait.” FARAH M. AL-DUWEESH 32 3 m /day Kuwait is generating 1 million 3 Wastewater to produce 154.6 m •Chemical and microbiological characteristics of tertiary treated effluent (TTE) and RO permeate (ROP) approved by both Kuwait Environmental Public Authority (KEPA) and World Health Organization (WHO) standards. FARAH M. AL-DUWEESH 33 of Kuwait uses 58% of recycles/reuse of treated water •75% of all wastewater is treated mostly using RO (high quality) and 58% of it is reused. •19% of the recycled water goes to agriculture (crops, plants, etc…) •31% of the recycled effluent is not utilized. •25% of untreated water is discharged into the sea. FARAH M. AL-DUWEESH 34 Kuwait needs to utilize all it’s Treated Wastewater to cover losses and utilize energy - How ? Another waste cause is Municipal Solid Waste (MSU) Can it be treated ? FARAH M. AL-DUWEESH 35 Farah M. Al Duweesh Assistant Professor of Chemical Engineering [email protected] FARAH M. AL-DUWEESH 36