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AbstractThis paper describes an investigation using biological‐iron removal for the elimination of arsenic (III). Groundwater was spiked with sodium arsenite and filtered through a pilot unit. As the water filtered through the sand, arsenic was retained on the iron oxides which were continuously produced by the bacteriological activity. Under specific aeration and pH conditions, both arsenic and iron were eliminated. This process can be used for the design of a full‐scale biological treatment plant.

AbstractDuring recent years it has become clear that, particularly to protect the quality of sea waters, nitrogen and phosphorus discharges have to be substantially reduced. Nitrogen reduction can take place by conventional biological treatment. However, the problem can be partly, or perhaps completely, resolved by treating the returned liquors resulting from sludge dewatering. These normally create a substantial load on sewagetreatment works; in fact the nitrogen in the returned liquors can contribute 15–25% of the total nitrogen load entering the works. It therefore seems appropriate, particularly with a view to future nitrogenreduction requirements, to treat the returned liquors before they are returned to the works'inlet. Since 1987, Watergroup has been working on these problems, and the company now has full‐scale plants at Frederikshavn, Denmark (population equivalent 130 000) and Eslöv, Sweden (population equivalent 250 000). Normally this treatment can be carried out at a considerably lower cost, per kg nitrogen removed, than when applying traditional methods. An additional advantage is that the method makes it possible to reuse the nitrogen content of the returned liquor, e.g. in the form of ammonium sulphate which is an excellent fertilizer.

Groundwater is one of the most important sources of drinking water in rural area of India, and in urban area maximum of domestic water is procured from ground water. Therefore India is largest extractor of ground water in the world. When ground water is used for drinking purpose, contamination in groundwater is not looked after seriously. Though groundwater at shallow depth is considered as most suitable for domestic use, but due to continuous extraction of groundwater in last decade in uncontrolled manner and groundwater level gone much deeper in aquifer. The quality of groundwater in deeper aquifer varies from place to place and contamination is becoming more concentrated. As per Central Groundwater Board survey, in 387 districts in various states has contaminated groundwater containing arsenic, fluoride, nitrate and iron. In Maharashtra most of the districts exceeds in Nitrate contamination above permissible limit of 45 mg/l. Because of this government has banned the villagers to consume groundwater from such contaminated hand pumps. & tube wells. In India for increasing agricultural production huge amount of fertilizers up to 14% of global total is consumed, therefore Nitrate contamination in groundwater is increasing day by day. Concentration of nitrate above 50 mg/l in drinking watergenerate various health implications such as infant mortality, spontaneous abortion, birth defects, abdominal pain, diarrhea, vomiting, changes in immune system and methemoglobinemia. Because of various sources of nitrate contamination occurring in groundwater Nitrate removal is one of the emerging challenge. There are various methods of removal of Nitrate from wastewater as well as from drinking water. Distillation, reverse osmosis, ion exchange, electro dialysis, blending, chemical denitrification are the in-home methods for removal of nitrate from drinking water. With the advancement in water treatment technologies, adsorption using activated carbon, carbon nanotubes, biological nitrogen and phosphorus removal, membrane ...

SiO₂ deposits which cause technical problems on combustion equipment are built by combustion of biogas containing siloxanes. Therefore, in these cases, the siloxanes must be removed from the biogas. For siloxane removal from biogas, its adsorption on activated carbon is often used. After saturation, the saturated adsorbent must be replaced. The adsorbent cost constitutes the main part of the operational costs of the purification equipment. Therefore it is necessary to find an adsorbent having high adsorption capacity for siloxane at a possible low price. Using laboratory apparatus and biogas produced from waste-water treatment sludge at the wastewater treatment plant Prague Bubenec various activated carbons were tested for siloxane removal and their adsorption capacities for siloxanes were estimated, and the adsorbent cost relative to 1 kg of siloxanes removed from biogas were calculated. The lowest price for the removal of 1 kg of siloxanes was determined by Chezacarb, Sil Extra 40 AP and 4–60 adsorbents. Another important information obtained from the test is that the weakly adsorbed siloxane (OMCTS) is displaced by the larger molecule of DMCPCS during adsorption.

AbstractPhosphorus (P) is an important nutrient for all plant growth and it has become a critical and often imbalanced element in modern agriculture. A proper crop fertilization is crucial for production, farmer profits, and also for ensuring sustainable agriculture. The European Commission has published the Farm to Fork (F2F) Strategy in May 2020, in which the reduction of the use of fertilizers by at least 20% is among one of the main objectives. Therefore, it is important to look for the optimal use of P in order to reduce its pollution effects but also ensure future agricultural production and food security. It is essential to estimate the P budget with the best available data at the highest possible spatial resolution. In this study, we focused on estimating the P removal from soils by crop harvest and removal of crop residues. Specifically, we attempted to estimate the P removal by taking into account the production area and productivity rates of 37 crops for 220 regions in the European Union (EU) and the UK. To estimate the P removal by crops, we included the P concentrations in plant tissues (%), the crop humidity rates, the crop residues production, and the removal rates of the crop residues. The total P removal was about 2.55 million tonnes (Mt) (± 0.23 Mt), with crop harvesting having the larger contribution (ca. 94%) compared to the crop residues removal. A Monte-Carlo analysis estimated a ± 9% uncertainty. In addition, we performed a projection of P removal from agricultural fields in 2030. By providing this picture, we aim to improve the current P balances in the EU and explore the feasibility of F2F objectives.