Nano bioremediation on Anzali wetland

July 9, 2019

Bioremediation is a process used to treat contaminated water, soil and subsurface material, by altering environmental conditions to stimulate growth of microorganisms and degrade the target pollutants. In many cases, bioremediation is less expensive and more sustainable than other remediation alternatives. 

BioGME technology is a treatment method for the pools which uses a combination of organic and chemical compounds that helps to feed the plants, increase the absorption of chemical fertilizers and improves decomposition of organic and chemical wastes, followed by a performance boost.

The scheme was proposed by researchers at Isfahan Science and Technology Park and approved by the Department of Environment, so a memorandum of understanding has been signed to revive the wetland.

International wetland under threat

Covering more than 19,000 hectares in the northern province of Gilan, the wetland is located near the port city of Bandar Anzali, neighboring the Caspian Sea. The wetland was designated as a Ramsar site on June 23, 1975. It is fed by several rivers and separated from the Caspian Sea by a dune system. The lagoon is home to submerged and floating vegetation and also extensive reed beds. It bears international importance in terms of breeding, staging and wintering water birds.

The lagoon has been listed in Ramsar Convention since December 21, 1975.

Anzali wetland has suffered huge sediment and sludge accumulation due to entrance of domestic and agricultural sewage of five surrounding cities, which resulted in a decrease in the wetland’s depth and capacity along with threatening the biodiversity.

The Department of Environment intends to reduce the depth of the sludge through BioGME method, however, environmentalists are worried about the potential risks to the health of citizens and aquatic species believing that the combination used in the BioGME approach is cancerous.

Human involvement caused Anzali wetland a misery

One of the most important concerns, which is referred to Anzali wetland, is a constant drop in depth which was 11 meters before while shrinking to 1 meter or even 50 centimeters in recent years. 

According to a report published by the University of Tehran in the Iranian calendar year 1395 (March 2016-March 2017), the amount of sediment accumulated in Anzali wetland is usually 1 to 7 millimeters per year. 

If the average sedimentation rate is three millimeters, one meter should be reduced from the depth of the wetland in every 30 years, while the wetland’s depth has decreased by 3 meters in past 30 years. 

Undeniably, human involvement has led to such a situation in Anzali wetland.

Qorban Ali Mohammadpour, Gilan province’s DOE chief, said that annually, 580,000 tons of sediments spread over the wetland which come from 4,000km catchment area, in addition to sewage of 5 cities entering the wetland. 

Moreover, the waste water of 238 villages directly or indirectly is released to the international wetland, he regretted, adding, the entrance of household sewage along with industrial and agricultural wastewater has led to the formation of sediments, especially in the western and central parts of the wetland.
On the other hand, the wetland’s capacity has harshly declined water lilies which attracted thousands of visitors annually, he also regretted.

Aquatic species in danger

A fisherman also counting concerns on the reduction of fish in the wetland, told ISNA that fish population is declining, so that the catfish and Zander species have been disappeared in the wetland.

Silver carp population increased in the wetland and as an invasive species due to feeding on native species’ larvae, he lamented.

Huge sediment not removed by traditional methods

Farshid Soheili Najafabadi, who suggested BioGME technology, said that a special working group for conservation of Anzali wetland has issued a permit to employ the technology on 25 hectares of the wetland some 3 years ago.

However, the working group's condition was that the project must be initially reviewed and approved by Japanese experts at the Japan International Cooperation Agency (JICA), he added.

Japanese experts at the time of accepting the plan submitted five proposals, one of which was to implement BioGME project in a pond similar to the wetland environment and, after reviewing the results, decide on the implementation of the project in the wetland, he explained.

So, a total budget of 1.1 billion rials (nearly $27,000) allocated to pilot the scheme on a 12-hectare pond, he noted, adding, during 6 months, some 12,000 tons of sediments have been removed from the pond using the technology.

The sediment and sludge on the wetlands bed is so huge that it cannot be removed by traditional methods, however, the technology will boost up the process and the wetland will reach its ecological capacity, he highlighted.

What caused the controversy on bioremediation?
In this method, titanium dioxide, silver chloride, polysaccharide and fertilizer are used, but what makes the method a hot topic these days is titanium dioxide used in this compound.

Titanium dioxide (TiO2) is considered as an inert and safe material and has been used in many applications for decades. However, mechanistic toxicological studies show that TiO2 nanoparticles predominantly cause adverse effects via induction of oxidative stress resulting in cell damage, genotoxicity, inflammation, immune response etc.

Abdolreza Karbasi, faculty member of environmental science in University of Tehran, said that TiO2 is permitted as an additive in food and pharmaceutical products which is approved by Food and Drug Administration, and TiO2 nanoparticles should be used with great care and low amounts.

Sampling of skin, meat, liver and blood of fish have been analyzed to determine the effects of TiO2 on the aquatic organism, he said, adding, also, since it was possible that TiO2 does not occur in the first generation of fish but has an effect on its larvae, tests for the second and third generations of fish are also ongoing. Studies have shown that the use of TiO2 is not only dangerous but also increases the fish safety, he added.
It is noteworthy that TiO2 constitutes only 1 percent of the compounds, he highlighted.

Project still awaiting approval

At the moment, the project has been stopped by Gilan prosecutor's office, as concerns about toxicity and carcinogenicity of titanium dioxide have not yet been resolved, despite of planning to pilot the scheme on 50 hectares of the wetland.

Researchers at Isfahan Science and Technology Park have provided the prosecutor with scientific reports in order to resolve the issue.

Courtesy of Tehran Times