A Cute visual to describe the Groundwater Mapping programme

Framework for Identifying Lakes and Solutions for Rejuvenation

One of the main issues confronting lakes in Bangalore is to do with the water inflow - both in terms of quality and quantity (current as well as anticipated in the future). While the main channels bring rainwater to these lakes they also carry with them significant amounts of solid waste and sewage. Over a period of time untreated sewage leads to the eutrophication of the lakes. The changes in the topography of the lake catchments (due to urban development) has also led to significant reduction in the runoff from upstream lakes thereby rendering the lakes dry.

With an intent to explore bio remediation solutions to treat the incoming water before it enters the lake, we try to understand the parameters important in identifying a lake for restoration and then coming up with a suitable framework to evaluate the multiple technologies to facilitate bio remediation.

The following graphic illustrates the different factors that have an impact on various aspects of the lake

Since a diverse set of factors are at play here, it is important to have a framework in identifying the lakes which are in dire need for immediate action and subsequently the most suitable technological and regulatory solution for rejuvenating the lake.

Identification of Lakes:

The Ministry of Environment and Forests has set guidelines for Lake Conservation.

This could be a reference point for framing the parameters to help identify the lakes for immediate conservation action.

Criteria	Description
Hydrological Criteria Water Availability Lake Size Lake Depth	A perennial lake can be given more weightage than a seasonal one Larger and deeper lakes to have priority. For instance, greater than 10 hectares in surface area and 3 meters in depth
Scientific Criteria Inflow of Domestic/ Industrial waste Dumping of Municipal Solid Waste	Lake to be observed for Eutrophication Also lake water quality to be monitored with importance to Dissolved Oxygen Biological Oxygen Demand Chemical Oxygen Demand Faecal Coliform pH
Administrative Criteria Public Demand Lake End Use	High demand from a Public forum/ Local Stakeholders towards lake conservation Lake serves domestic uses, recreation, bio diversity hotspot

Technology Evaluation:

The rejuvenated lakes are in all probability going to be managed by a non governmental body and hence apart from the efficacy of the treatment itself, the ease and cost effective maintenance aspect will have extreme importance.

Some of the factors (which are open to further deliberation) are listed below:

Criteria	Description
Capital Expenditure	Total cost of commissioning of the Treatment System (Includes Cost of civil construction and Installation of Electromechanical components/ Plumbing/ Vegetation etc
Operation and Maintenance Expenditure    Act of O&M	Yearly recurring cost for the entire lifecycle of the Treatment System (Includes cost of Consumables, Electricity, Manpower, Annual Repair and anything else as applicable) The ease of operation and maintenance of the system - which is determined by - - the requirement of skilled manpower  for continuous manning of the system - duration and frequency of downtime    for maintenance/ repair - Frequency and quantum of Sludge Disposal - need for replacement of components - need for vendor support
Footprint	The land area that is required for commissioning the system.
Treatment Efficiency	The ability of the system to treat the low quality sewage inflow. Some of the quality parameters that need to be dealt with: Biological Oxygen Demand Chemical Oxygen Demand Total Suspended Solids Nitrates Phosphates Total Faecal Coliform pH
Design Tolerance Input water Quality Input water Quantity	The ability of the Treatment System to be able to handle wide fluctuations in Input Water Quality and Quantity without - Degradation of treated water quality Breakdown of system (Plants not being able to tolerate chemical load, scaling/ corrosion of plumbing fixtures etc)
Other Factors Past Experience Odor Mosquitoes Stabilization Phase	Does the vendor have prior experience in commissioning such projects? Will the system emanate foul odor? Will the system be a breeding ground for mosquitoes? Does the system require an stabilization phase? If yes, what is the duration?

References:

http://cpcb.nic.in/upload/NewItems/NewItem_116_Guidelinesof%20waterqualitymonitoring_31.07.08.pdf

http://www.moef.nic.in/sites/default/files/nlcp/NLCP_guideline.pdf

Wastewater treatment using Soil Biotechnology at Herohalli Lake

Several of the lakes in Bangalore face a common problem of inflow of sewage from neighboring communities into the lake. Though violating a law shying away from the ground reality wouldn't solve the problem in any way. Hence, a group of people which included citizens, developers, organizations from the Sarjapur/bellandur region of Bangalore, embarked on a visit to Herohalli Kere to understand the mechanisms of Soil Biotechnology which has been used to treat wastewater entering the lake. The below write up summarizes the observations made during the visit by the participants:

Lake description

The lake is spread across 25 acres. The jurisdiction of Herohalli Lake is with BBMP. In other words, the maintenance of the lake is the responsibility of BBMP. Couple of years back, the lake had completely dried up. Being a landlocked lake without any natural inflows or outflows, BBMP thought of piloting a solution. The plan was to restore the lake by diverting sewage from a major sewage channel into the lake, treat it in a local STP (Soil Biotechnology in this case) and then release the treated sewage into the lake. In this case, the technology for treating the sewage is called Soil Biotechnology which works on similar principles of sewage treatment yet in a different way.

The lake is surrounded by independent houses which means that their sewage is not treated by privately run STPs. Moreover, majority of sewage inflow is domestic. However, there are some polluting industries in the neighborhood, which release chemicals (dye, etc.) periodically (illegally!) into the sewage. At that time, the inlet sluice gate is closed to prevent the polluted sewage from entering the plant. The staff has to keep a constant watch on the incoming sewage.

Process description

The process is called soil biotechnology (SBT). The technology is developed in-house by IIT-Bombay researchers and been implemented at Herohalli through Vision earthcare.

According to the design engineer, the plant is designed for 1.5 MLD and works at approximately 70% capacity.

Components of the process/system:

1. Jackwell:

1.5 MLD sewage is pumped from Jackwell. A screen chamber separates materials like plastic, etc.

2. After initial pumping from Jackwell, the sewage passes through following chambers for further screening:

• Manual screen chamber
• Mechanized 10 mm screen chamber
• Grit chamber
• Oil layer skimming chamber

3. Primary sedimentation tank (PST)- Settling/Anaerobic/Hydrolysis reaction

Tank capacity 200 cu.m. 3-4 hours retention time.

4. Soil bioreactor:

Area: 50m*40m

Volume of bioreactor: 3000 cu.m

Water holding capacity: 300 cu.m

The plant has two SBT tanks of equal size, one of which is considered as secondary stage and the second tank is considered as the tertiary stage. The roles are reversed every 3 months.

The Soil bed consists of:

1. A thin layer of gravel at top (prevents soil erosion)
2. 1.25m deep active media in the middle, primarily made of crushed laterite rock, soil, and clay brick. The active media also contains bacterial culture. A large number of earthworms are released in this layer, which keep the layer aerated and feed on the biodegradable material to reduce it quickly.
3. 0.2 mm Jelly at the bottom (acts as filter media)

The water is pumped as follows:

1. Water coming from the primary filtering stage is pumped by 2x 5BHP pumps into the first SBT tank.
2. A grid of 2” CPVC pipes is laid on the top of the SBR tank, in which pipes are laid parallel to each other and 1m apart.
3. Each pipe has 8mm dia holes on its sides, 50 cm apart.
   
   Sewage pours out of these holes onto the gravel (top layer of the SBT tank). 
4. The sewage passes through the three layers, and reaches the bottom.
5. The tank bottom has a gentle slope towards the rear end of the plant. The water is collected at the back of the SBT tank, and again pumped to a second identical tank that is used as tertiary treatment stage.
6. According to the design engineer, the first tank treats the BOD/COD, and only then the second tank can treat the nitrates and phosphates.
7. Treated water from secondary treatment chamber collected in the recycling tank and diverted to tertiary treatment plant and finally let into the lake through 4” diameter pipes. Slope has been provided to do so.  

Total process time: approximately 12 hours

Approximately 3 ton of sludge is settled in primary sedimentation tank. In course of time the sludge which settles will be hydrolyzed and will dissolve in the water itself.

 

Discussion points:

Quality of treated sewage	Inlet BOD 250, OUtlet BOD 4. Outlet COD 37.3
Power requirement	3 Pumps, total 7 kw power
Land required	General rule: 1 sq.m per KLD. Possible to customize
Capital cost	2-3 cr
Operation and Maintenance costs	60-70 k per month operating fee, 6-7k electricity cost per month
Maintenance requirement	Cleaning of screens, removal of sludge, de-clogging of pipe holes
Operator attention	Throughout attention by operator needed. Checking the blocked holes of the pipe in the soil bioreactor, color of the incoming sewage as garment industries nearby
Reliability
Resource recovery	Sludge is recovered. Emptied on the soil bed itself. Plastic, paper recovered burnt here but can be recycled in other cases.
Ability to handle load fluctuations/seasonal changes
Chemicals/Industrial effluents	Inflow of garment industry, plant is switched off.

Questions:

Following are some of the questions (some have been responded) that would help evaluate the technology in a better way: 

1. BOD/COD and other water quality parameters after Primary sedimentation tank?

Typically about 70%-75% of incoming BOD/COD. However this is to be tested

2. Final output water quality all parameters? Especially nitrates and phosphates

Test report: https://drive.google.com/open?id=0B3Cww_NACAiDVkVjQTdRa2JaMVE&authuser=0

Nitrate and Phosphate data not available

3. Approved by KSPCB or not?

4. Existing sewage in the lake. What can be done?

Over a period of time, plan is to visit and understand few more technologies like conventional sewage treatment, phytorid, etc. 

Lake Bio-remediation meeting

BIOME, WIPRO, MAPSAS and other lakes communities have come together to try and understand how bio-remediation technologies can be applied to deal with the sewage inflow into some of the rejuvenated/to be rejuvenated lakes around Sarjapura Road.

Hence on 25^th November the first meeting was arranged to discuss bioremediation methods, to bring together the community working on different lakes in Bangalore on a same platform and decide on the further agenda for 15 lakes selected for the project was the objective of the meeting.

Following are the key points/deliberations happened during the meeting:

   A.     The lakes that have been narrowed down for this project are:

 

   B.     An initial discussion was led by Priya from MAPSAS who explained about the links between the lakes through kaluves and hence the importance of controlling the sewage entering in the lakes.

   C.     Mr. Vishwanath explained about viewing lakes as an ecosystem with space for biodiversity, treatment, recharge zones, etc. He cited example of Jakkur lake wherein a treated sewage water from BBMP maintained STP goes into a constructed wetland and then into the lake. He suggested that things that can be studied for lake should include percolation study, water balance, nitrate and phosphate removal, biodiversity, etc.

   D.    Some legal issues were also discussed:

1. Areas without BWSSB underground drainage network are not allowed to dispose of their sewage either with or without treatment. Zero discharge i.e. 100% reuse of wastewater generated within the premises
2. Areas with BWSSB underground drainage network are allowed to dispose of their sewage with at least secondary treatment 
3. The discharge standards for sewage treated water are close to drinking water standards

   E.     An important part of the meeting was presentations by vendors implementing bio-remediation technologies. Presentations were made by Visionearthcare on soil biotechnology (SBT), Hydrocreatives on Phytorid, and CDD on Decentralized wastewater treatment system (DEWATS).

  

Soil biotechnology (SBT): Have done for Herohalli Lake in Bangalore.

Their detailed presentation can be found http://www.slideshare.net/biomeshubha/sbt-for-lakes-bioremediation

a.     No external aeration is required as the different porous layers in the medium/bed help in aeration.

b.     One time media installation. No need to change soil media frequently

c.      No sludge formation

d.     Space: 1 sq.m/KLD

e.     No foul odor

f.       Have established 65 plants across India. Also experience in designing for lakes

g.      Not designed for removal of nitrates and phosphates specifically yet it works in their removal

h.     Herohalli plant details: Design capacity-1.4 MLD, Area- 1650 sq. m, cost- 3 crores, power consumption-125 units/day

Phytorid technology

Their detailed presentation can be found here: http://www.slideshare.net/biomeshubha/phytorid-for-bioremediation-of-lakes

a.     Plants have been designed particularly for BOD reduction and some amount of COD reduction also happens

b.     Power Cost: Rs. 1/KL

c.      Sedimentation tank: needs to be cleaned once in a year

d.     Issues with phytorid bed: Plants grow over a period and hence need to be cut as suited by the community. The disposal of cut plants is similar to other plants.

e.     No foul odor as water is not seen from above, no exposure

f.       Bacterial addition: once in a lifetime of the plant

g.      Space: for sedimentation tank/underground primary settling tank- 0.2/0.3 sq.m/KL and for phytorid bed- 0.9 sq.m/kl

h.     Cost per MLD: 1.3 crores

i.       Sensor based system

j.       Capacity range: 3 KLD -1.5 MLD

k.      The system needs to be placed in open as it needs sunlight for the plants to grow

l.       Water load fluctuation: the plants can survive without water (especially this may happen in dry season) for two months. Even if little amount of water is available, the plants can survive on fewer nutrients.

m.   If slope/gradient is available then no pumping is required

Decentralized wastewater treatment system (DEWATS):

Their detailed presentation is available here: http://www.slideshare.net/biomeshubha/how-dewats-can-be-implemented-to-bioremediate-lakes

a.     Shared case study of Bandhwa Talab in Raipur, Chattisgarh.

b.     This system based on phytotechnology which uses Canna indica plant which has shallow fibrous root system

c.      No color, odor and pathogens after passing the water through the bed of plant

d.     Based on requirement design can be customized

e.     The flow should be checked daily, sludge removal from the settling tank (primary treatment) is also required

f.       Treats only organic waste, domestic sewage

g.      Cost varies with capacity

   F.      Further deliberations and studies are needed on:

1.     Assuming that some amount of sewage already exists within the lakes, which of the systems would be useful?

2.     It is essential to conduct water balance study for every lake. Water balance means, calculating percentage of water coming, sewage coming, water percolating, evaporation, etc.

3.     Understanding the suitability of the system based on cost, maintenance, power consumption and mostly its ability to handle water load fluctuation, etc.

Based on primary data collection from each of the implemented technologies, water balance for some of the lakes and finally deliberations on bio-remediation technologies would help in seeking most suitable method to tackle the issue at hand.

We would like to thank the participants:

Vendors: Sharan Kumar from Visionearthcare for SBT, Mr. Himanshu from Hydrocreatives for Phytorid, Mr. Andrew Jacobs from CDD for DEWATS

Devarabisanahalli lake/Adarsh residents

Halanayakanahalli lake group

Priya representing MAPSAS

WIPRO

Students from Christ University