Rehabilitating Former Landfill Sites: A Case Study in

Habitat Restoration

Peter Ash

AIMS, Amrita University

Amrita Lane, AIMS Ponekkara PO

Kochi 682041 Kerala, India

str8ash@gmail.com

Dan Sullivan

Environmental Journalist / Editor

56 Meck Lane

Alburtis, PA, USA, 18011

writeoneditor@gmail.com

Nikhil K. Kothurkar

Dept of Chemical Engineering &Materials Science

Amrita School of Engineering

Amritanagar, Coimbatore 64112, India

nikhil.kothurkar@gmail.com

Anju Bist

Amrita University

Amritapuri Campus, Clappana PO

Kollam, 690525, Kerala, India

ammasanju@gmail.com

Smitha Chandran

Department of Chemistry

Amrita School of Arts & Sciences

Kollam 690525, Kerala, India

smithachandran@am.amrita.edu

Abstract—This paper describes the dramatic success in the

eco-restoration ) of ) a ) heavy-metal ) contaminated ) open ) garbage

dump. A number of heavy metals (As, Cd, Cu, Co, Pb, Hg, Cr)

were detected in the soil and river sediment at the site. The main

restoration activities included mulching, surface-addition of

compost and fresh soil and phytoremediation using vetiver and

other plants. Within three years of the restoration activities,

heavy metal concentrations in the contaminated soil reduced

drastically. There was relatively low uptake of the heavy metals

by the plants; however, they might have been crucially

responsible ) for ) providing ) a ) favorable ) environment ) for ) soil-

restoring microrganisms in their rhizosphere. Observable

habitat-restoration continues at the site, including the return of

birds and insects and other wildlife, making this an ideal site for

further research and demonstration for community awareness

and education.

Keywords—bioremdiation, habitat restoration, heavy metals,

compost, vermicompost, phytoremeditation, vetiver grass.

I. INTRODUCTION

India now holds the dubious distinction of being among the top 10 waste-generating nations in the world [1]. A 2012 report by Worldwatch Institute placed the United States of America at first place and China at second, with daily municipal solid

waste generation of 621,000 tons and 521,000 tons, respectively [2]. At number 6, India’s daily municipal solid waste generation was estimated at 110,000 tons. The report also calculated that only 25% of the world’s waste was being recycled or composted; 75% was either being incinerated or sent to landfills.

Another 2012 report by the World Bank [3] reinforced these grim statistics. A total of 1.3 billion tons of waste per year was generated by 3 billion urban residents worldwide. Municipal solid waste management was the largest single-budget item for cities in low-income as well as many middle-income countries. India was classified as a lower-middle-income country in this report. The report noted that a city that could not effectively manage its waste was rarely able to manage services such as health, education or transportation.

A previous paper described the efforts of one university campus located in South India to move toward zero-waste [4]. It described in detail how decentralized waste management can help ease the burden on the local environment. As a corollary of those efforts, an initiative was begun to rehabilitate a former landfill site. Since zero-waste implied that all the waste was now being either recycled, composted or incinerated (only a small amount was sent for incineration), it was decided to restore the landfill site and use that space to coordinate waste management operations. This paper describes the eco-restoration efforts of the former landfill site in detail.

978-1-4799-2402-8/13/$31.00 ©2013 IEEE 452 IEEE 2013 Global Humanitarian Technology Conference

II. APPROACH

A. Site Description

The 2012 World Bank report noted that although quantitative data was not readily available, most low- and lower-middle-income countries disposed their waste in open dumps. It is more accurate to describe our former landfill site also as an open dump. The site is a wetland and is located at the coordinates 10° 1'52.33"N / 76°17'19.04"E, on an island in the backwaters off the Arabian Sea, near the Ernakulam-Kochi urban areas in central Kerala, India. The ground is waterlogged in many areas and several depressions are water-filled.

Fig. 1. Aerial view of the island site. November 2010.

Figure 1 shows an aerial view of the island site. The covered structure in the bottom left corner of the picture indicates the spot that was cleaned and subsequently used for composting and vermicomposting operations. This picture, taken in November 2010, shows the dumping spots (top right, white patches) where cleanup was yet to be initiated.

B. Restoration Methods

A shed was constructed to separate recyclable plastics and a washing station was built for washing them. The restoration efforts were divided into three phases. During Phase 1, which lasted about six months, site cleanup was undertaken. Compost was made and spread over the former dumping ground. In Phase 2, clean soil was brought and mixed with the compost layer covering the black mud.

Fresh vermicompost was introduced, which often included live earthworms and their eggs, and the planting of a forest garden began (see Figure 5). In Phase 3, vetiver grass

(Chrysopogon zizanioides) was planted while cleanup continued at all areas where dumping was formerly happening.

The main activities in Phase 1 included cleaning up the site and building good soil on the surface. All dumping and burning stopped in early 2010, when cleanup was initiated. Much of the surface of the island was spongy and often too wet and muddy to walk upon. Hence, dead plant material, also native weeds and grasses and materials like soiled cardboard were laid down to create a mat to walk upon without sinking into the mud.

Upon this, thermophilic compost windrows were built using food waste and other dry carbon-rich material. Each day, approximately 6-8 tons of organic matter was brought in from the Amrita Institute of Medical Sciences as waste for composting. Conditions for good thermophillic composting in the windrows were maintained by keeping a proper moisture content, having a C:N ratio of about 30:1, and adequate level of oxygen in the windrows. Dry carbonaceous matter was added when the waste had more moisture or higher nitrogen content to prevent it from rotting anaerobically, causing bad odors and attracting flies. The compost windrows reached temperatures of up to 70°C. This necessitated the regular turning of the windrows to maintain aerobic conditions.

Figure 2 shows the site in November 2010, 9 months after the start of the surface cleanup. The roof was constructed to keep the compost windrows dry during the monsoon season. The smaller roof just to the left of the main shed is the vermicomposting unit. At the time this photo was taken, compost windrows were being made just to the right of the main structure as indicated by the green netting that was covering them.

When mature, the compost was spread out to cover the toxic black mud. Once spread, new windrows were built on top. This continued for the first six months, resulting in a layer of 12-18 inches of compost covering the old landfill site. At this point, plants began emerging from the compost and grass was creeping in from around the edges. Insects and birds were also returning.

In Phase 2, clean soil was added, and the planting of several varieties of plants was initiated. Vermicomposting was also begun. During monsoon, the water hyacinth clogging the waterways was removed and used as worm-feed. This invasive weed was mixed with cow dung and left to rot for 30 days before being fed to the earthworms.

When ready, the vermicompost was added to the soil while planting, thus introducing earthworms into the system. This was done to help with the restoration as studies have shown that earthworms can detoxify soil containing cadmium, lead and other heavy metals [5]. Thus, earthworms were an important part of our eco-restoration plan.

In Phase 3, as the interior channels were dredged, we planted the aforementioned vetiver grass for the dual purpose of maintaining the dredged mud from eroding back into the channel and removing heavy metals from the soil. Vetiver is a deep-rooted grass that is a known hyperaccumulator of heavy metals [6] and is also used for erosion control.

Fig. 2. Composting facility at the site showing the constructed main shed, the

smaller vermicomposting shed (center left) and the composting windrows covered with green netting (center right). November 2010.

C. Sample Collection and Analysis

Samples of the island soil and the river mud were collected and tested for heavy metal concentration. We examined the results from the start of the restoration (February 2010) to more recently (April 2013) to quantify the effectiveness of the restoration efforts. The river mud was taken from the channel bisecting the site. Island soil samples before restoration were taken on the north side of the site by digging the surface soil. After restoration, island soil samples were taken by digging down to the black mud layer located below the level of the compost and clean soil layer. One soil sample was taken from the same area as the initial tests (north sample). Another sample (south sample) was obtained from the area next to the main shed (see Figures 2 and 5). The soil samples were analyzed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The vetiver sample was taken along the north side of the area, along the banks of the channel bisecting the island. Vetiver grass and a mixed sample of vegetables grown on the site were also tested for uptake of the heavy metals. The vegetables were grown only to quantify the accumulation of heavy metals. The authors do not recommend growing food crops on contaminated land.

III. RESUSTS AND DISCUSSIONS

A. Visual Survey and Vegetative Growth

The true extent of the earlier pollution on the site was revealed while digging for the foundation of the sheds. The site is tidally connected to the Arabian Sea. As such, during high tides, water was filling the dug holes, rising to within inches of the top. The rising water would bring up buried waste with it. The rest of the island hosts a fragile ecosystem consisting of native trees, flora and fauna. Prior to restoration, in February 2010, the open dump had no plants growing and fauna such as earthworms, insects or birds were absent. Both dumping of waste and burning was common (Figure 3).

Fig. 3. Open dumping and burning of waste at the site prior to restoration in

February 2010.

Fig. 4. Vegetative growth on the site after 1½ years of restoration efforts in

July 2011.

Figure 4 shows a picture taken of the same location, from the same angle (as Figure 3), in July 2011. It reveals the significant restoration achieved in a short span of 1½ years. This indicates the success of the Phase 1 and 2 restoration efforts. Cleaning up the site, adding compost and fresh soil and vermicomposting helped in building adequately good soil on the surface for plant growth.

It should be noted that although the surface of the composting site cleaned up, the waste that was buried deep in the mud could not be easily removed. However, the short-term goal was to build healthy soil on the top while allowing the remediation of the deeper layers of the soil to proceed slowly. Figure 5 shows a closeup of the same location as Figures 3 and 4 in April 2013.

Fig. 5. A forest garden growing in the restored site in April 2013.

B. Compost Analysis

The compost prepared on the site was one of the key factors in building good soil on the surface and enabling plant growth. Some physical and chemical properties of the prepared compost were tested and are reported in Table I. The compost had relatively similar values of nitrogen and potassium, as compared to typical values [9]. However it was richer in phosphorous. The compost had an electrical conductivity of 0.26mS/cm at 25°C indicating that it was not saline. The extract had a nearly neutral pH. This compost was suitable for aiding plant growth.

TABLE I. PHYSICAL AND CHEMICAL PROPERTIES OF COMPOST

Measured Quantity Value Typical Values [9]

Nitrogen mg/L 520.77 500

Phosphorous as (PO4)3-

mg/L 1335.51 688

Potassium mg/L 188.54 222

pH of aqueous extract in water having pH of

6.59.

7.33 7

Electrical conducity mS/cm at 25°C.

0.26 <4

C. Soil and Sediment Analysis

The island soil and river (backwaters) sediment showed a substantial presence of heavy metals (see Table II). Except for mercury and cadmium, heavy metal concentrations were greater in the soil sample compared to the river sediment sample. The solid waste dumped and burned on the island and the polluted river water were the two likely sources of heavy metals in the soil and river sediment. The solid waste is more likely to be the dominant source of heavy metal contamination of the island soil. In the case of the river sediment, both the river water and some heavy metal-containing waste getting washed into the river could have contributed to the heavy metal contamination of the sediment.

TABLE II. HEAVY METALS IN RIVER SEDIMENT AND ISLAND SOIL

Metal

Before Restoration

18/11/2013

(mg/kg)

After Restoration

04/04/2013

(mg/kg)

%

Reduct

ion

River

Sediment

Soil North

Soil

South

Soil

Average

values

Arsenic 0.1802 2.6841 NDa ND ND 100

Cadmium 4.4429 0.3051 0.13 0.66 0.395 -29.47

Copper 19.5317 25.0967 8.49 6.32 7.405 70.49

Cobalt 3.809 7.2005 0.61 1.53 1.07 85.14

Lead 8.8318 10.7701 5.55 2.08 3.815 64.58

Mercury 2.8149 1.1916 ND ND ND 100

Nickel 20.1805 31.2946 ND ND ND 100

Chromium 34.0573 45.1451 0.35 0.57 0.46 98.98

a. Not detectable.

After the restoration efforts, drastic reduction in the concentrations of all heavy metals except Cd was observed (Table II), indicating the success of the restoration efforts. Arsenic, mercury and nickel decreased to undetectable levels. Considerable decrease was also seen in the levels of copper, cobalt, lead and chromium. From these results, it is clear that the contamination by heavy metals has significantly diminished in the upper few inches of the black mud, just below the compost and clean soil layer. In the case of Cd, a 29% increase in concentration was observed. However, we believe this to be due to the variation in the levels of contaminants at different locations on the site. Compared with the soil sample from the north side tested before the restoration efforts began, we can actually see a 57% decrease in the Cd concentration. The % reduction was measured on the basis of the average between the north and south samples. Thus, the anomaly can be explained on the basis of the spatial variation in the heavy metal concentration.

D. Heavy Metal Uptake by Plants

Phytoremediation of the site was done by planting a variety of plants, including hyperaccumulators like vetiver. The uptake of the heavy metals by the plants is known to reduce the levels of heavy metal contaminants in soil over a long period (phytoextraction). Vetiver grass and some vegetables planted in the area were tested for uptake and accumulation of the heavy metals. Growing food crops on heavy-metal contaminated land is not recommended. These experiments were undertaken only in order to measure the accumulation of heavy metals as a step in assessing the safety of growing food crops on restored land. The results reported in Table III show relatively low levels of heavy metal uptake by vetiver and the vegetables compared to the levels of the contaminants in the soil. Thus, there is little evidence for significant amounts of phytoaccumulation or phytoextraction. It is likely that the plants assisted in creating suitable conditions for the growth of favorable microorganisms in their rhizosphere

(phytostimulation) leading to the reduction of the contaminants in the soil. However, a more thorough study regarding the role of the plants and the microorganisms in the remediation will be required.

TABLE III. HEAVY METAL UPTAKE BY PLANTS

Metal

Vetiver Grass

04/04/2013

(mg/kg)

Vegetables

04/04/2013

(mg/kg)

Arsenic NDa <0.02b

Cadmium 0.07 <0.02

Copper 2.05 1.70

Cobalt 0.03 0.03

Lead 0.78 0.52

Mercury ND <0.02

Nickel ND <0.02

Chromium 0.26 0.42

b. Not detectable

c. Method detection limit was 0.02 mg/kg.

E. Additional Planned Remediation Activities

In order to further accelerate and expand the ongoing eco-restoration of the site, we have planned a few activities. A four-fold scale-up of our vermicomposting is planned in the next few months. We also feel that it is essential to study and augment the action of soil microorganisms, especially, fungi. Microbial and fungal action has undoubtedly been one of the most important causes for the restoration of the site.

We believe that the mulches, compost, vermicompost and planting (phytostimulation) very likely helped enhance the microbiological activity in the soil leading to its remediation. A thorough microbiological study is under way and will be reported in a future publication. The authors are particularly intrigued by the reported role of fungi in the bioremediation of heavy metals [7,8].

The fungal content in a compost can be easily improved by adding more fungal food such as wood chips, fibers from coconut husks and banana stems. By altering the fungal types and their populations, it can become possible to tailor the biological processes leading to the chelation or deactivation of the toxic heavy metals [8]. We also plan to plant more native trees and nonfood crops, such as bamboo, that will drop their leaves and other biomass on the soil as mulch providing the necessary food for fungi and other soil microorganisms.

The development of this site as a research study is planned for helping create awareness among students and the community at large. As soil pollution is a major and growing environmental concern worldwide, there is an urgent need to educate the community about the hazards of inappropriate waste disposal, irresponsible agricultural practices, industrialization and urbanization. The site will serve to demonstrate simple yet effective methods to address this serious environmental concern.

IV. CONCLUSIONS

This paper describes how dramatic success in eco-restoration of heavy-metal contaminated sites can be obtained by the surface application of mulches and compost and by phytoremediation using vetiver and other plants. At the study site, habitat restoration has occurred to an observable extent, as many birds and insects have returned and the planted forest is flourishing and attracting wildlife. The drastic reduction in the heavy metal concentrations in the contaminated soil in a short span of three years indicates that remediation of the surface soil is achievable in the short term even though the remediation of contaminants buried deep in the ground might take a much longer time. The relatively low uptake of heavy metals by plants grown on the site indicates that the role of the plants in the restoration might be more a function of stimulating the growth of microorganisms that help in soil remediation than of the extraction of the heavy metals and accumulation in their biomass.

Contamination of soils has become a major environmental concern worldwide. To be able to recover whatever degraded land we can, is of critical importance in this chemical age that continues to see increased loss of habitats and species due to human hubris.

ACKNOWLEDGMENT

We thank Sri Mata Amritanandamayi Devi, Amma, globally renowned as a humanitarian and spiritual leader, for giving us the opportunity to collaborate on this work. As Chancellor of Amrita University, Amma takes a keen interest in environmental projects at the university, personally guiding and providing support. We thank Br. Gurudas Chaitanya, who helped coordinate the restoration efforts with Amma’s guidance.

REFERENCES

[1] Aditi N. India among top 10 countries generating municipal solid waste. The Hindu, Business Line, July 25, 2012.

[2] Press Release - Global Municipal Solid Waste Continues to Grow: New Worldwatch Institute report discusses the rising rates of municipal solid waste generated worldwide. Washington DC, July 24, 2012. http://www.worldwatch.org/global-municipal-solid-waste-continues-grow.

[3] Daniel Hoornweg and Perinaz Bhada-Tata. What a Waste – A Global Review of Solid Waste Management. Urban Development Series Knowledge Papers. The World Bank. March 2012.

[4] Peter Ash, Anju Bist. Moving towards Zero-Waste: A Case-Study from Kerala, India. In : IEEE Global Humanitarian Technology Conference, South Asia Satellite Conference, Trivandrum, India, August 23-24, 2013.

[5] Clive A. Edwards, Norman Q. Arancon, Rhonda L. Sherman. Vermiculture Technology: Earthworms, Organic Wastes, and Environmental Management. CRC Press, December 2010.

[6] Yahua Chena, Zhenguo Shena, Xiangdong Lib. The use of vetiver grass (Vetiveria zizanioides) in the phytoremediation of soils contaminated with heavy metals. Applied Geochemistry 2004. 19 : 1553–1565.

[7] Gunther Winkelmann, Metal Ions in Fungi (Mycology). CRC Press, February 1994.

[8] Paul Stamets. Mycelium Running. Ten Speed Press, Berkeley, 2005.

[9] NPK Values of Manures and Compost URL http://www.allotment.org.uk/fertilizer/npk-manures-compost.php. Last Accessed May 24th, 2013.