6.5 Wastewater Treatment6.5 Wastewater Treatment

Primary treatment

Secondary treatment

Tertiary treatment - N, P

Advanced treatment

Design of sedimentation basin ; overflow rate

Introduction to Environmental Engineering and Science , G.M. Masters & W.P. Introduction to Environmental Engineering and Science , G.M. Masters & W.P. ElaEla, 2008, 2008

Chemical TreatmentChemical Treatment

� 용존 및 현탁 물질의 물리적 상태를 변환시켜 침전에 의해 제거할 수 있도록

화학약품을 첨가하는 것

� 목적 : 물리적 조작과 함께 사용되어 질소나 인을 제거;

화학적 침전

폐수의 2차 처리 공정을 완전히 하기 위함

� - 명 반 : Al2(SO4)3�18H2O, Al2(SO4)3 �14H2O

- 염화철(III) : FeCl3

- 황산철(III) : Fe2(SO4)3, Fe2(SO4)3 �3H2O

- 황산철(II) : FeSO4 �7H2O

- 석 회 : Ca(OH)2

Activated sludge process (biological aeration) Activated sludge process (biological aeration)

�� 생물학적생물학적 처리처리 공정공정

활성활성 슬러지슬러지 공정공정 (Activated Sludge Process)(Activated Sludge Process)

침전조반응조

미생물 반송미생물 반송

침전조반응조

미생물 폐기미생물 폐기

Trickling filterTrickling filter

Rotating biological contactor Rotating biological contactor

Sludge treatment Sludge treatment –– 2% of the orginal volume, 97% water2% of the orginal volume, 97% water

� 먹는 물 수질기준

국가명 한국 일본 미국(EPA) WHO 독일

계 55 51 98 96 49

미 생 물 4 2 5 1 2

유해 무기물질 16 17 19 17 19

유해 유기화학물질 12 9 29 28 7

농 약 4 2 27 32 4

� 일본, 유럽 등이 우리나라와 비슷하나 미국, WHO는 우리나라보다 많음.

� 미국과 WHO에서는 유해한 유기물질(농약, 화학약품, 소독부산물)에 대한 수질기준 항목이 많음.

농 약 4 2 27 32 4

소독부산물 9 11 16 17 2

심미적인 영향 물질 9 10 9 2 6

방사성물질 - - 5 1 2

Disinfection byproducts structual formulaDisinfection byproducts structual formula

�� THMs(Trihalomethanes)THMs(Trihalomethanes)

ClCl

ClCl

ClCl

HHCC ClCl

BrBr

ClCl

HHCC BrBr

BrBr

ClClHH

CC

BrBr

BrBr

BrBr

HHCC

�� HANs(Haloacetonitriles)HANs(Haloacetonitriles)

ChloroformChloroform DichlorobromoDichlorobromo--methanemethane

DibromochloroDibromochloro--methanemethane

BromoformBromoform

Cl

Cl

Cl

C

Trichloro-acetonitrile

C N Cl

H

Cl

C

Dichloro-acetonitrile

C N Cl

H

Br

C

Bromochloro-acetonitrile

C NBr

H

Br

C

Dibromo-acetonitrile

C N

대표적 비 THMs계 DBPs Fomula

Haloacetic acids

C

O

Cl

Cl

C

H

OHH

H

C

Cl O

C OH C

O

Cl

Cl

C

Cl

OHCl

Cl

Cl

C

Trichloro-

C N

Cl

H

Cl

C C N

Haloacetonitriles

Dichloroacetic acid

Monochloroacetic acid

Dibromoaceticacid

Br C

OBr

C OH

H

Trichloroacetic acid

Monobromoaceticacid

H

H

C

Br O

C OH

Trichloro-acetonitrile Dichloro-

acetonitrile

Cl

H

Br

C

Bromochloro-acetonitrile

C NBr

H

Br

C

Dibromo-acetonitrile

C N

Disinfection and Disinfection byproductsDisinfection and Disinfection byproducts

위

험

도

소독 부산물미생물

소 독

6.4 Water Treatment System6.4 Water Treatment System

Water Treatment ProcessWater Treatment Process

Screening

1. Mixing : Rapid Mixing

2. Coagulation, Alum (Al2(SO4)3 18 H2O), Ca(OH)2, Na2CO3

3. Flocculation

4. Sedimentation, Sludge Processing

5. Filtration, Sand, Activated Carbon

6. Disinfection, Cl2, NaOCl, Ca(OCl)2, O3

ConventaionalConventaional water treatment process?water treatment process?표준식표준식 정수정수 처리처리 공정이란공정이란??

전 염소처리 후 염소처리

원원수수

혼화지 응집지 침전지 여과지 정수지

기존의정수처리공정 : 내분비계장애물질및약성물질의처리효율에한계

응집

원수

침전처리수

여과

후염소

분리막을 이용한 정수처리

처리수

원수

분리막전처리 (오존 등)

(Option)

처리수

분리막을이용한고도정수처리공정

Membrane Technology for the Separation: Classification

Water shortage problem

� Water shortage population : 1.1 bilions in 2005 and 3

bilions in 2025

� WHO reports that 3.4 million per year are killed by

waterborne disease.(2005)

21www.roplant.org

5.3 billion

7.2~8.3 billion

1990 2025

World population

0.3 billion

2.4~3.2 billion

1990 2025

Water shortage population

Better to use seawater? How?

How to solve water scarcity?

RO membrane for desalination

22UNESCO, 2009

Seawater desalination (Using RO membrane)

MSF (Multistage flush)

Process

RO (Reverse

Osmosis) Process

Introduction

MSF 40%

MED 3%

Other 2%

Distribution of desalination production capacity by process technology for the

world

23

RO 44%

ED 6%

VC 5%

Philippe et al., 2009

In 1999 approximately 78% of the world’s seawater desalination capacity was

made up of MSF plants while RO represented 10%

RO (Reverse Osmosis) Process : low energy, low construction cost, simple

process

Production process Price (won/m3)

Groundwater purification (MF) 200 ~ 300

Waste water reuse (MF+RO) 200 ~ 400

RO desalination 600 ~ 800

MSF desalination 900 ~ 1400

Water price using membrane processes

Seawater desalination (Using RO membrane)

Won/m3

24

Types of water Price (won/m3)

Tap water 100 ~ 7000

Industrial water 100 ~ 700

Ultrapure water 5000 ~ 10,000

Mineral water 200,000 ~ 3,000,00

91 96 99 01

MSF desa

linatio

n

Groundwater p

urifica

tion

Waste w

ater reu

se

A worldwide water price

Decrease of water price by Membrane and process technologies

Toray co., 2007

Major components of membrane fouling

- Salt precipitation

- Colloidal particulates

- Organics

- Microorganisms

Vrouuwenvelder et al., 2003

Khedr et al., 2000

� Biofouling + organic fouling : 58%

� Biofouling causes :

- Declining membrane flux

- Increasing energy requirements

- Elevating salt passage

- Membrane biodegradation25

Total Configuration of desalination plant

CO2

RO process

Post-

treatment

process

To high

pressure

NaHSO

3

Chlorine

Cartridge

NaHCO3

Pretreatment process

Point of measuring SDI/MFI

26

Cl2

Media

filter

tank

Acid

tanke

Ferric

chlorid

e

Filtrate

clear

well

pump

Acid

tank

Acid

tank

Scale

r

Scale

inhibito

r

Filter backwash pump

Cartridge

filter

SEA WATER

�MF/UFmaterials : Cellulose acetate (CA), Polyvinylidene fluoride (PVDF), Polyacrylonitrile (PAN),

Polypropylene (PP), Polysulfone (PS), Polyethersulfone (PES)

� RO/NFmaterials : Cellulose acetate (CA), Polyamide (PA)

Membrane materials

27

Manufacturing of composite polyamide membrane

Polysulfone polymer Solvent

Polysulfone casting solution

Polysulfone casting on polyester backing

material

MPD solution TMC solution

Interfacial polymerization on polysulfone layer

Polysulfone

casting

Membrane

28

*MPD : metaphenylenediamine

*TMC : trimesoyl chloride

Interfacial polymerization on polysulfone layer

Solvent evaporation and heat annealing

casting

Standard commercial TMC/MPD polyamide membrane

Seperation systemstechnology, inc., 1999

Polysulfone

(40µm)

Polyamide

(0.2µm)

Hybrid Membrane Processes

Chemical Chemical flocfloc formed and recovered by MF or UFformed and recovered by MF or UF

Natural organic matter (NOM) from raw waterNatural organic matter (NOM) from raw water

Chemically Assisted MembranesChemically Assisted Membranes

Sorbents + MembranesSorbents + Membranes

Powdered adsorbents in MF/UF circuitPowdered adsorbents in MF/UF circuit

Trace organics (POPs) from waterTrace organics (POPs) from water

Sorbents + MembranesSorbents + Membranes

Membrane BioreactorsMembrane Bioreactors

Bioreactor with MF or UF membranes Bioreactor with MF or UF membranes

Biodegradable organics from wastewaterBiodegradable organics from wastewater

Where hybrid systems fitWhere hybrid systems fit--Membranes for Water & WastewaterMembranes for Water & Wastewater

Sea waterSea waterWater ProductionWater Production

Hybrid

Systems

Sea waterSea water

Surface WaterSurface Water

Secondary EffluentSecondary Effluent

(MF)

+ROMF/UForN

FMF + RO AOT

Water ProductionWater Production

Domestic & Domestic &

Industrial Industrial

useuse

MBRBiological WasteBiological Waste

Membrane BioreactorMembrane Bioreactor ReuseReuse

Recovered WaterRecovered Water

Membranes

Liquid WasteLiquid WasteIndustrial liquidIndustrial liquid

EffluentsEffluents Recovered Recovered

ResourcesResources

MBR (Membrane Coupled Biological System )

Permeate(Effluent)

Retentate

Membrane Unit

Activated Sludge

Reactor

Influent

Principle of MBR? 하폐수 유입MBR 여과수

정밀여과막(MF)

/ 한외여과막(UF)

활성슬러지 반응조

(중수도)

분리막 생물반응조

(MBR)

처리수

유기물질 유해미생물박테리아 조류물

처리수

분리막

흡입펌프

가동

공기및수류

Water reuse process 오산환경사업소 처리시설

1단 유입수 1단 유입수2단 유입수