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HER MAJESTY THE QUEEN IN RIGHT OF ONTARIO AS REPRESENTED BY THE MINISTER OF THE ENVIRONMENT, 1976 BASIC WASTEWATER TREATMENT First Edition November, 1972 Second Edition February, 1973 Third Edition January, 1974 Second Printing May, 1974 Third Printing April, 1975 Fourth Edition June, 1976 Fourth Edition (Rev.) November, 1978 Fifth Edition August, 1991 Training Certification Section & Human Resources Branch Ministry of the Environment 135 St. Clair Avenue West Toronto, Ontario M4V 1PS Copyright Provisions and Restrictions on Copying: This Ontario Ministry of the Environment work is protected by Crown copyright (unless otherwise indicated), which is held by the Queen's Printer for Ontario. It may be reproduced for non-commercial purposes if credit is given and Crown copyright is acknowledged. It may not be reproduced, in all or in part, for any commercial purpose except under a licence from the Queen's Printer for Ontario. For information on reproducing Government of Ontario works, please contact ServiceOntario Publications at .ca Other manuals relating to the water and wastewater treatment processes published by the Training and Certification Section, Ministry of the Environment, include: Basic Gas Chlorination Workshop Basic Water Treatment Operation Surface Water Treatment Workshop Activated Sludge Process Workshop Wastewater Sludge Technology Preventive Maintenance Workshop Pump Operation Workshop Digester Gas Systems Op/Mtce. Water Distribution Systems Mathematics for Water and Wastewater Operations Confined Space Entry Lab Skills for Plant Operators Additional copies of this and of her Ontario Government publications are available from Publications Ontario, 880 Bay St., Toronto for personal shopping. Out-of-town customers write to Publications Ontario, 5th Floor, 680 Bay St., Toronto M7A iNS. Telephone (418) 326-5300 or toll free in Ontario 1-800-668-9938. Hearing impaired call: (416) 325-3408 or toll-free in Ontario 1-800-268-7095. Mastercard and Visa accepted. Cheques and money orders payable to the Treasurer of Ontario. Prepayment required. INTRODUCTION The Basic Wastewater Treatment course based on this manual covers five days at the Ministry of the Environment training facilities. The course consists of lecture- discussions and hands-on training in sewage treatment plant operations. The principal objective of the course is to introduce the operator to the fundamentals of sewage plant operation. The lesson objectives are clearly indicated at the beginning of each topic, and tell the operator exactly what he should know or do after having covered that topic. In order to successfully compete of this course, an overall average of 70% is required. This is a working course in which each person will be expected to take an active part in subject discussions and to acquire as much practical knowledge as possible from the lectures and from the demonstrations presented during the course. TABLE CONTENTS OF BASIC SEWAGE TREATMENT Topic Pag. 1. WASTE WATER CEARACTER.I STI CS GENERAL 1 SOURCES 2 QUANTITY QUALITY Bacteriological Characteristics Physical Characteristics Chemical Characteristics Solids Biochemical Oxygen Demand Dissolved Gases Nutrients EFFECTS OF WASTE DISCHARGES . Human Health 2. BACTERIOLOGY WASTEWATER TREATMENT OBJECTIVES 1 To Remove Organic Material 1 To Eliminate Disease Producing Agents 2 BACTERIAL STRUCTURE 3 Size 3 Shape 3 Arrangement 3 BACTERIAL REPRODUCTION 4 METABOLIC ACTIVITIES AND BACTERIAL GROWTH 5 Extracellular Enzymes 5 Intracellular Enzymes 5 FACTORS AFFECTING GROWTH 6 Temperature 6 Oxygen 6 pH 6 Food Supply 6 i 2. BACTERIOLOGY - Cont'ci... BACTERIA AND THE WASTEWATER TREATMENT PROCESS 7 Removal of Organic Material . ANAEROBIC DIGESTION 8 AEROBIC DIGESTION 9 ELIMINATION OF PATHOGENS 9 SUMMARY 3. PRIMARY TRZATMENT PUMPING STATIONS 1 FLOW CONTROL Manual Operation 3 Float Bubbler (Pneumatic) Electric . . (Probes) Flowmatchers Pneumatic Ejectors . Sonic Transducers PRELIMINARY TREATMENT SCREENS Coarse Screens Fine Screens Mechanically Cleaned Screens Cleaning Screens Disposal of Screenings SHREDDING DEVICES GRIT REMOVAL UNITS Grit Channels Aerated Grit Chamber Detrition . Centrifugal Separators Grit Disposal PRE-AERkTION 17 ii d... 3. PRIMARY TREATMENT - Cont' PRIMARY TREATMENT 18 Clarifier Operation 19 Scum Removal 23 Chemical Precipitation 23 Flotation Processes 23 WASTE STABILIZATION PONDS 24 DESIGN CRITERIA AND CONSTRUCTION DETAILS 27 . . . Location 27 Surface Area 27 Shape 28 Depth 28 Bottom 28 Dikes 28 Inlet Structure 29 Overflow Structure 29 Multiple Ponds 29 Fencing and Signs 29 Primary Treatment 30 AERATED LAGOONS 30 PUBLIC HEALTH CONSIDERATION 31 ECONOMICS 31 SUMMARY 32 iii 4. THE ACTIVATED SLUDGE PROCESS PRINCIPLE 1 THE AERATION TANK 3 Diffused Aeration 3 Surface Aeration 3 SECONDARY CLARIFICATION 6 FACTORS AFFECTING THE ACTIVATED SLUDGE PROCESS 6 VARIATIONS OF THE CONVENTIONAL ACTIVATED SLUDGE PROCESS 8 EXTENDED AERATION 9 CONTACT STABILIZATION 9 BARDENPHO PROCESS 12 PROCESS CONTROL TESTS 13 5. PREVENTIVE MAINTENANCE GENERAL 1 SUMMARY 7 APPENDIX 8 Maintenance Frequency Metering Guide 11 Industrial and Electronic Control 16 . Electrical Motor and Generator 19 . - . Auxiliary Engineers and Associated Equipment 25 Mechanical Equipment 30 Pumping Stations 33 iv 6. DIGESTION OF SLUDGE PRIMARY PURPOSE . THE ANAEROBIC DIGESTION PROCESS 1 CRITICAL FACTORS IN SLUDGE DIGESTION 4 Quality of Sludge and Digester Sizing . 4 . Quality of Sludge Temperature Mixing Gas Production ANAEROBIC DIGESTER START-UP . . . SINGLE STAGE DIGESTION OPERATION 14 General 14 Loading Criteria Process . Supernatant Selection Digested Sludge Removal TWO STAGE DIGESTION General Loading Process Criteria . Sludge Transfer . Supernatant Selection Digested Sludge Removal THE AEROBIC DIGESTION PROCESS 22 General 22 CRITICAL FACTORS IN PROCESS 23 Air Supply 23 Volume of System 23 . Tank Insulation 24 . OPERATION AEROBIC DIGESTER SYSTEM 24 System Start-Up 24 sludge Feed 25 Supernatant Control 25 Transfer Program . 25 Processed Sludge Removal 26 Air Control 26 Scum Control 26 Records 26 v 7. SLUDGE HANDLING GENERAL 1 CONSIDERATIONS IN SLUDGE HANDLING Sludge Concentration Sludge Quantities Sludge Withdrawal Example 1 CONDITIONING OF SLUDGES Use of Chemicals Wet Air Oxidation DEWATERING 9 Drying Beds 11 . Vacuum Filtration 13 Centrifuging 16 . Sludge Lagoons 16 Heat Drying . • . 17 FINAL DISPOSAL Incineration. Land Disposal by Liquid Haulage Sludge Composting 8. CHLORINATION OF SEWAGE PURPOSE CHLORINE PROPERTIES 2 3 REACTION OF CHLORINE IN SEWAGE CONTROL OF CHLORINATION 5 Chlorine Dosage . 6 OTHER USES OF CHLORINE . Odour Control Aid to Sedimentation BOD Removal Grease Removal Activated Sludge Process Control Sludge Thickening Breakdown of Concrete and Mortar vi