# The Influence of Spent Portable Battery Waste on the Aquatic Environment
## 4 Conclusions  
In many countries, and especially in underdeveloped and developing countries, used portable batteries are not rigorously collected selectively. As a result, part of them end up in municipal waste deposits together with residual waste. During their stagnation in these waste deposits, used batteries can come into contact with different liquid environments, either with leachate or with surface waters, where they are subjected to corrosion over time. Under these conditions, these battery wastes' metals and other dangerous components can be released. Considering these circumstances, a simulation was made of the conditions in which three types of spent batteries, a zinc-carbon battery (A), lithium manganese dioxide battery (B), and zinc-manganese alloy battery (C), were contacted with synthetic liquid environments of different pHs: an acidic environment (pH 4.00), an environment similar to rainwater (pH 5.63), and an alkaline environment (pH 8.00) These three types of used batteries were immersed in these liquid environments and allowed to stagnate for 180 days. During this time interval, pH and conductivity were measured once every 30 days. During the test period, the pH had a decreasing trend, while the conductivity recorded an upward trend. The pH monitoring showed the possible influence of batteries on the water acidification state over a certain period (180 days). At the end of the test period (after 180 days), no major damage to the battery case was observed, the corrosion process being superficial for all types of used batteries. The concentrations of heavy metals (Cd, Mn, Cu, Pb, Zn, Ni, and Fe) in the stagnation solution were compared with those regulated for surface waters in Romania by Order 161/2006 to establish the water quality class. Mn and Cd were below the detection limit of the spectrometer, except for battery A in the pH 5.63 solution, where the Mn concentration was 0.31 mg L\({}^{-1}\), and the pH 8.00 solution, where the Mn was 0.69 mg/L (quality class IV). To determine the water quality class correlated with each metal, the highest metal concentration was taken into account: Cu: 20.92 u\({}^{-1}\) (quality class II); Pb: 4.09 u\({}^{-1}\) (quality class I); Zn: 12.05 u\({}^{-1}\) (quality class I); Ni: 22.93 u\({}^{-1}\) (quality class II); and Fe: 30.64 mg L\({}^{-1}\) (quality class V). Metal concentrations in aquatic environments are not strictly influenced by the pH of the initial solutions but by the type of used batteries. Battery A stands out through the release of Pb and Fe ions, battery B through Ni ions, and battery C through Cu and Zn ions. Thus, in order to assess the degree of pollution that the presence of used batteries in aquatic environments would have, the highest and lowest concentrations of released metals were taken into account. It was noted that at the same pH, the same element was released into the environment both at the maximum value and at the minimum value, the difference caused by the types of batteries. The maximum and minimum values of the metals were associated with different pHs, with the exception of Fe and Ni, which had maximum and minimum concentrations at the same pH value (Fe in the solution with pH 8.00 and Ni in the solution with pH 5.63). Technical analyses and tests of the batteries were not carried out so that some results can be interpreted and accepted based on assumptions correlated with technical data for the characterization of the batteries provided in the specific technical sheets. To be able to evaluate the quality of the solutions at the end of the test, the metal concentrations in the solutions were compared with the maximum allowed values provided in the National Normative Act for surface waters (Order no. 161/2006). The maximum concentrations of the elements in the solution gave a certain degree of quality to the respective aquatic environment. The heavy metals in aquatic environments pose a threat to the quality of environmental factors and human health.