Emerging Environmental Technologies and Policies

By Sabarna Roy, Rajat Chowdhury, Basanta Bera and 2 more

Emerging Environmental Technologies and Policies deals with five intriguing subjects: Comparison between conventional sewer system by way of gravity sewer collection, pressurized piped sewerage transmission and vacuum piped sewerage transmission; water and circular economy; continuous 24x7 smart water supply projects; comparative study on ZLD and MLD for wastewater management, and irrigation efficiencies for canal-based system and pipeline system. This is a practicing manual for the critical thinkers in the field of environment dealing with water, wastewater, and irrigation. The authors while dealing with such complex topics have balanced the language with lucidity, diagrams, and flow charts to make the subject comprehensible and interesting even for a lay reader.

• Language: English
• Publisher: One Point Six Technologies Pvt Ltd
• Release date: Nov 22, 2021
• ISBN: 9789354586323

Sabarna Roy

SABARNA ROY is Senior Vice President [Business Development] at Electrosteel Castings Limited, an author of eight Literary and three Technical bestselling books, TEDx Speaker, Champions of Change Award 2020 Winner, Times Excellence Award 2021 Winner in Indian Literature, and Golden Glory Award Winner for Critically Acclaimed Bestselling Author of the Year 2021.Sabarna Roy has been awarded the Right Choice Award for Author of Eminence of 2022. He has been selected among the India Today Group: Icons of India.Roy has also received the Best Author to Watch 2022 Award from Indo-Global Entrepreneurship Conclave Delhi organized by Business Connect, and Best Author in Indian English Literature of 2022 at the Ninth Asia Education Summit 2022.Sabarna Roy has received a letter of confirmation from Confederation of International Accreditation Commission [CIAC] Global Foundation stating that he will be receiving an Honorary Doctor of Arts, Honoris Causa from Azteca University, Mexico.

Book preview

1.

Comparison between Conventional Sewer System by way of Gravity Sewer Collection, Pressurized Pipe Sewerage Transmission, and Vacuum Pipe Sewerage Transmission

Sabarna Roy¹

1.Business Development, Applications Technology, Engineering and Strategy Department, Senior Vice President, Electrosteel Group, Kolkata-700017, India

Rajat Chowdhury²

2.Business Development, Applications Technology, Engineering and Strategy Department, Assistant Manager, Electrosteel Group, Kolkata-700017, India

Abstract:Sewers are a means of collecting wastewater from multiple sources and delivering the wastewater to an existing collection sewer, and/or to semi-centralized secondary treatment system such as constructed wetlands (free-surface, horizontal or vertical), or waste stabilization ponds. Conventional sewers transport wastewater and sludge by gravity and therefore require a slope and pumping station. This can lead to high construction cost in hilly or flat terrain. In some cases, a conventional system is almost impossible to construct, e.g. where the groundwater table is high or the topography is extremely flat. As populations branched out to lower elevations, gravity no longer could do the job, and lift stations were needed to restore flow. Today, not all waste flows downhill. The law of gravity hasn’t reversed, but technology — specifically vacuum and low-pressure sewer systems — enable municipal waste to go where no waste has gone before: over undulating bedrock, through wetlands and across vast rural regions. Most people are accustomed to a gravity system. In this paper, the issues related to components of various conventional and non-conventional systems, their costing, energy, operation and maintenance related issues, have been presented in a comparative manner.

Key Words: Sewerage, Gravity sewerage, Vacuum sewerage, Pressure Sewerage

INTRODUCTION TO CONVENTIONAL WASTEWATER COLLECTION SYSTEM

There are three types of public sewers, each classified according to the kind of wastes it is required to handle.

1.Combined sewers: Combination public sewers are the oldest variety of the three types of sewers and they are required to carry storm and sanitary wastes to some safe terminal. Rain water should be carried to some terminal not associated with the disposal plant.

2.Sanitary sewers: Sanitary sewers are those which are required to carry domestic sanitary wastes only. All rain water must be excluded from them. Combination and sanitary sewers generally are placed about ten feet under the street grade and usually are found below the center line of the street.

3.Storm sewers: Storm sewers are a comparatively new installation, made necessary because of sewage treatment. These sewers are made to carry only storm water and may terminate at any natural drainage area¹.

Conventional wastewater collection systems transport sewage from homes or other sources by gravity flow through buried piping systems to a central treatment facility¹.

a)These systems are usually reliable and consume no power¹.

b)However, the slope requirements to maintain adequate flow by gravity may require deep excavations in hilly or flat terrain, as well as the addition of sewage pump stations, which cansignificantly increase the cost of conventional collection systems¹. Manholes and other sewer appurtenances also add substantial costs to conventional collection systems¹.

GRAVITY SEWER SYSTEM AND ITS ALTERNATIVES

Sewer Appurtenances in a Gravity Sewer System are devices necessary (except pipes and conduits) for proper functioning of the sanitary, storm and combined sewers. The appurtenances include:

Manhole, Drop Manhole, Lamp-holes, Gully-traps, Intercepting chambers, Flushing tanks, Street Inlets, Siphons, Grease traps, Side-flow weirs, Leaping weirs, Venturi flumes and Outfall structures.

Advantages and Disadvantages of Combined Sewers.

1.It is initially economical to set up a combined sewer rather than separately installing domestic sewers and stormwater sewers

2.During dry season lack of stormwater causes a low flow rate. Low flow rate gives rise to low velocity of flow. At low velocities, due to less turbulence, the deposition of sewage solids are more. Result is siltation and consequent foul odor generation due to degradation of the settled solids.

3.In contrast, during wet or rainy seasons, the flow rate is very high. Therefore, pumping costs are more, causing high operation and maintenance cost.

4.Pumps that are designed to operate at high flow rate to tackle the wet season flow, runs in low flow